Embed Size (px)
Citation preview
STUDY OF THE MECHANISM OF THE
DISPROPORTIONATION OF PROPYLENE OVER A
COBALT OXIDE-MOLYBDENA-ALUMINA
CATALYST THROUGH THE USE OF A
RADIOACTIVE TRACER
by
Fred L. Woody
Thesis submitted to the Graduate Faculty
Virginia Polytechnic Institute
in candidacy for the degree of
MASTER OF SCIENCE
in
Chemical Engineering
APPROVED:
Dr. G. B. Wills, Chairman
Dr. N. F. Murphy Dr. D. L. Michelsen
November, 1968
Blacksburg, Virginia
I.
II.
III.
-ll-
TABLE OF CONTENTS
INTRODUCTION ••••••••••••••••••••••••••••••••••
LITERATURE REVIEW•••••••••••••••••••••••••••••
Olefin Disproportionation by Molybdena-Alumina Catalysts
Mechanisms of Heterogeneous
• • • • • • • • • • • • • • •
Page
l
2
2
Catalytic Reactions ••••••••••••••••••••••• 4
Diffusion in Heterogeneous catalysis . . . . • . . . . . . . . . . . . . . . . • . . . . . . 4
Adsorption on Catalytic Surfaces ••••••••••••••••••••••••••••• 7
Reaction on Catalytic Surfaces • • • • • • • • • • • . • • . • • • • • • • • • • • • • • 10
Theory of Radioectivity • • • • • • • • • • • • • • • • • • • 12
Types of Radioactive Decay••••••••••• 13
Rate of Radioactive Decay•••••••••••• 16
Detection of Radioactivity by Ionization Instruments • • • • • • • • • • • •
The Use of Radioisotopes as Tracers • • • • • • •
The Effect of Isotopes on
17
20
·chemical Reactions ••••••••••••••••••• 21
Carbon -14 as a Tracer••••••••••••••• 22
EXPERIMENTAL ••••••• ti •••••••••••••••••••••••••• 23
Purpose of Investigation•••••••••••••••••• 23
Plan of Investigation••••••••••••••••••••• 23
-iii-
Page
Selection of Reaction System••••••••• 24
Preliminary Studies . . . . . . . . . . . . . . . . . . 24
Selection of Analysis System••••••••• 24
Materials
Apparatus
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Method of Procedure . . . . . . . . . . . . . . . . . . . . . . .
27
28
32
Operation of Reaction System••••••••• 32
Analysis of Reaction Products • • • • • • • •
Operation of Chromatographs • • • • • • • • • •
34
38
Operation of Proportional Counter •••••••••••••••••••••••••••••• 39
Controlled Conditions • • • • • • • • • • • • • • • • 39
Variables Studied•••••••••••••••••••• 40
Results • • 0 • • • • • • • • • • • • • • • • • • • • • • • Q • • • • • • • •
Effect of Temperature on Propylene Conversion and Selectivity of Reaction over Girdler Catalysts •••••••••••••••
Propylene Conversion Versus Time-on-Stream over Girdler Catalysts ......•.•... " ........•..•...
Response of Step Change to Reactor-Sampling Bomb System • • • • • • • • •
Radioactivity of Products from Propylene - 1 - Cl4 Dispropor-tionation over Girdler Catalysts • • • • •
Sample Calculations • • • • • • • • • • • • • • • • • •
41
41
41
42
42
72
IV.
v. VI.
VII.
VIII.
-iv-
DISCUSSION•••••••••••••••••• • • • • • • • • • • • • • • • •
Page
78
Discussion of Experimental Procedures •••••••••••••••••••••••••••••••• 78
Reaction System • • • • • • 0 • • • • • • • • • • • • • • •
Preliminary Studies . . . . . . . . . . . . . . . . . . Analysis System • • • • • • • • • • • • • • • • • • • • • •
Discussion of Results • • • • • • • • • • • • • • • • • • • • •
Preliminary Stuuies • • • • • • • • • • • • • • • • • •
Final Studies • • • • • • • • • • • • • • • • • • • • • • • •
Analysis and Preparation of R~dioactive Propylene • • • • • • • • • • • • •
Recommendations • • • • • • • • • • • • • • • • • • • • • • • • • • •
Reaction System
Reaction Studies
• • • • • • • • • • • • • • • • • • • • • •
• • • • • • • • • • • • • • • • • • • • •
Limitations • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
Activation of Catalyst • • • • • • • • • • • • • • •
Reaction System . . . . . . . . . . . . . . . . . . . . . . Analysis Conditions ••••••••••••••••••
Preparation of Radioactive Samples ••••••••••••••• o ••••••••••••••
Analysis of the Radioactive Propylene •••••••••••••••••••••••••• • •
CONCLUSIONS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BIBLIOGRAPHY • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
ACKNOWLEDGMENTS • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
78
79
80
81
81
82
83
86
86
86
87
87
87
87
88
88
89
90
92
96
IX.
-v-
VITA ••••••••••••••••• • • • • • • • • • • • • • • • • • • • • • • • • •
APPENDIX ••••••••••••••••••••••••••••••••••••••
Experimental Data••••••••~••••••••••••••••
Effect of Temperature on Conversion and Selectivity
Propylene Conversion Versus
• • • • • • • • • • •
Time-on-Stream•••••••••••••••••••••••
Propylene - 1 - c14 Conversion over Girdler Catalysts •••••••••••••••
Page
97
99
100
100
100
100
Table
I.
II.
III.
IV.
v.
VI.
VII.
VIII.
-vi-
LIST OF TABLES
Effect of Temperature on Propylene Conversion ove~ Commercial Girdler Catalyst of 10% Mo01 and 3.5% CoO on Alumina at 15 psig and W1ISV = 1. 3 for 15 min Sample ••••••••••••••••••••••
Effect of Temperature on Propylene Conversion over Com~ercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig and WHSV = 1.3 for 24 min Sample •••••••••••
Effect of Temperature on Selectivity of Reaction over Commercial Girdler Catalyst 0£ 10% Mo03 and 3.5% CoO on Alumina at 15 psig and WHSV = 1.3 for 15 min Sample ••••••••••••••••••••••
Effect of Temperature on Selectivity of Reaction over Commercial Girdler Catalyst of 10% Mo03 and 3o5% CoO on Alumina at 15 psig and W1ISV = 1. 3 for 24 min Sample•••••••••••••••••••••••
Propylene Conversion Versus Time over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig, 3000 F, and W1ISV = 1.3
Propylene Conversion Versus Time over Commercial Girdler Catalyst
• • • • •
of 10% Mo03 and 3.5% CoO on Alumina at 15 psig, 350° F, and W1ISV = 1.3 •••••
Response of Step Change of Dry Nitrogen Applied to Reactor-Sampling Bomb System at 350° F and O psig ••••••••••••
Propylene - l-Cl4 Conversion over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at O psig and W1ISV = 1.1 •••••••••••••••
Page
43
44
47
48
· 51
52
55
57
Table
IX.
x.
XI.
XII.
XIII.
XIV.
-vii-
Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 300° F, vffiSV = 1. 1 Test I••••••••••"•••••••••••••••••••••••
Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - Cl4 Dispropor-tionation at O psig, 300° F, WHSV = 1.1, Test II •••••••••••••••••••••
Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 300° F, "\ffiSV = 1.1, Test III ••••••••••••••••••••
Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 350° F, WHSV = 1.1, Test I••••••••••••••••••••••
Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - Cl4 Dispropor-tionation at O psig, 3500 F, WHSV = l~l, Test II ••••••••••••••••••••••
Radioactivity Versus Time for Chromatograph Effluent from Prapylene - 1 - cl4 Dispropor-tionation at psig, 350° F, 1ffiSV = l• .. l, Test III •••o•e••••••••••••••
Page
58
59
60
61
62
63
XV. Radioactivity of Propylene -1 - cl4
XVI.
Disproportionation over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at O psig, 300° F, WHSV = 1.1, and Counter Flow= 37.5 ml/min. 70
Radioactivity of Propylene - 1 - c 14 Disproportionation over Commercial Girdler Catalyst of 10% Mo03 and . 3.5% CoO on Alumina at O psig, 350° F, WHSV= 1.1, and Counter Flow a 37.5 ml/min •••••••• 71
Table
XVII.
XVIII.
XIX.
xx.
XXI.
XXII.
-viii-
Data for the Effect of Temperature on Propylene Conversion and Selectivity over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 15 psig and WHSV = 1.3
Page
for 15 min Sample ••••••••••••••••••••••• 101
Data· for the Effect of Temperature on Propylene Conversion and Selectivity over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 15 psig and 1vtlSV = 1. 3 for 24 min Sample • 102
Data for Propylene Conversion Versus Time over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 15 psig, 3000 F, and WHSV = 1.3 .•....• 103
Data for Propylene Conversion Versus Time over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 15 psig, 350° F, and WHSV = 1.3 ••••••• 104
Data for Propylene - 1 - c14 Conversion over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 0 psig, 300° F, and WHSV = 1.1 •••••••• 105
Data for Propylene - 1 - cl4 Conversion over Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 on Alumina at 0 psig, 3500 F, and WHSV = 1.1 ••••••••••• 106
Figure
1.
2.
3.
-ix-
LIST OF FIGURES
Charge Versus Voltage in Ionization Instruments • • • • • • • • • • • • • • • • • •
Reactor ••••o••••••••••••••••••••••••••••••
Schematic Diagram Reaction System
of • • • • • • • • • • • • • • • • • • • • • • • • •
4. Schematic Diagram of
Page
18
26
33
Sampling System••••••••••••••••••••••••• 36
5. Proportional Counter•••••••••••••••••••••• 37
6. Effect of Temperature on Propylene Conversion over Commercial Girdler of 10% Mo03 and 3.5% CoO on Alumina at 15 psig and WHSV = 1.3 for 15 min Sample ••••••••••••••••••••••••••• 45
7. Effect of Temperature on Propylene Conversion over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig and WHSV = 1.3 for 24 min Sample ••••••••••••••••••••••• 46
8. Effect of Temperature on Selectivity of Reaction over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig and WHSV = 1.3 for 15 min Sample •••••••••••••••••••••••• 49
9. Effect of Temperature on Selectivity of Reaction over Commercial Girdler Catalyst of 10% Mo03 and 3o5% CoO on Alumina at 15 psig and WHSV = 1.3 for 24 min Sample ••••••••••••••••••••••• 50
10. Propylene Conversion Versus Time over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig, 300° F, and WHSV = 1.3 •••••••••••••••••• 53
-x-
Figure Page
11. Propylene Conversion Versus Time over Commercial Girdler Catalyst of 10% Mo03 and 3.5% CoO on Alumina at 15 psig, 3500 F, and WHSV = 1.3 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 54
12. Response of Step Change of Dry Nitrogen applied to Reactor-Sampling Bomb System at 3500 F and O psig •••••••••••••••••••••••••••••• 56
13. Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - Cl4 Dispropor-tionation at O psig, 300° F, WHSV = lol, Test I ••••••••••••••••••••••• 64
14. Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at 0 psig, 3000 F, WHSV = 1.1, Test II••••••••••••••••••••• 65
15. Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 300° E, WHSV = 1.1, Test III•••••••••••••••••••• 66
16. Radioactivity Versus Time for Chromatograph Effluent from Propylene-1 - cl4 Disproportionation at 0 psig, 350° F, W1ISV = 1.1, Test I • • • • • • • • • • • • • • • 67
17. Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 350° F, WHSV = 1.1, Test II • • • • • • • • • • • • • • • • • • • • • 68
18. Radioactivity Versus Time for Chromatograph Effluent from Propylene - 1 - cl4 Dispropor-tionation at O psig, 3500 F, WHSV = 1.1, Test III•••••••••••••••••••• 69
I. INTRODUCTION
The use and importance of catalysts in the chemical
industry can easily be seen. Today catalysts have be-·
come a necessity in cracking processes, hydrogenation
processes, and thousands of other chemical and industrial
processes.
Although the action of catalysts has been investi-
gated and theories have been developed, the procedure of
selecting a specific catalyst for a certain chemical
process has remained largely a trial and error situation.
The great amount of time and money spent has not yet
given us definite knowledge as to the behavior of catalysts.
The development of a procedure for determining the effec-
tiveness of a catalyst for a specific situation would be
a great scientific breakthrough.
The purpose of this investigation was to study the
mechanism of the disproportionation of propylene over a
cobalt oxide - molybdena - alumina catalyst through the
use of radioactive tracers.
-2-
II. LITERATURE REVIEW
A review of the literature was conducted to obtain
information on the disproportionation of olefins by
molybdena-alu~.1ina catalysts, to review present theories
of heterogeneous catalysis, and to review existing con-
cepts of rediochemistry and isotopic trace analysis.
Olefin Disproportionation by Molybdena-Alumina
Catalysts
Through a search of the literature, three publications
were found that pertained to this topic, two by Banks and
Bailey (2 , 3 )and one by Bradshaw, Howman, and Turner (ll)
Banks and Bailey described reactions in which linear
olefins could be converted to homologs of both longer and
shorter carbon chains with catalysts comprising molybdenum
compounds supported on alumina. Disproportionation con-
versions near equilibrium were obtained at temperatures
of about 200 to 400° F. Propylene could be disproportion-
ated to ethylene and n-butenes at conversions as high as
40 per cent with efficiencies of 95 per cent. In all
cases, approximately equal molar quantities of linear
olefins having chains longer and shorter than the feed
were produced.
..., -.)-
Bradshaw, Howman, and Turner studied the conversion
of n-butenes into olefins of lower and higher carbon
number. All the results obtained supported the theory
that reaction occurs via a "g_uasi-cyclobuta:c1.e 11 inter-
mediate formed by alignment of the double bonds of two
reacting olefins. Applied to the n-butenes, with allow-
ance for the isomerization of butene - 1 to butene - 2,
the reaction of butene - 1 is pictured as follows:
C • • ·C-C-C . . . . C • ••C-C-C
C II C
C • • • C-C-C C : : Ii . .
C-C • • •C-C C-C
C-C-C ii C-C-C
C-C-C Ii C-C
The reaction or two mol~cules of butene - 2 would not
produce a new olefin species
C-C=C-C C-C C-C ii Ii
C-C=C-C c~c C-C
Recently, however, infrared spectroscopy studies indicate
that delocalization of the double bond in olefins may
occur to some extent upon adsorption, depending upon
the preparation of the catalyst (IS).
-4-
Also, an unpublished dissertation by Lewis ( 33 ), who
studied the kinetics of the disproportionation of propy-
lene, concluded that the rate of reaction is controlled
by a surface mechanism. His experimental results strongly
indicate that the surface mechanism is a dual-site mecha-
nism, and that the mechanism is independent of temperature
in the range studied.
Mechanisms of Heterogeneous Catalytic Reactions
The overall process in a fluid-solid catalytic sys-
tem can be broken down into five steps (46 ):
1. Transport of the reactants from the bulk-fluid
phase to the solid-fluid interface.
2. Adsorption of reactants on the solid surface.
3. A surface reaction on the solid catalyst.
4. Desorption of products from the surface to the
fluid-solid interface.
5. Transport of the products from the interface
to the bulk-fluid stream.
Fortunately, in many fluid-solid catalytic reactions,
certain of the resistances associated with the five steps
are negligible and need not be considered in formulating
a rate expression.
Diffusion in Heterogeneous Catalysis. The ~ransport
of reactants and products to and from the surface of the
-5-
catalyst occurs by diffusion, diffusion here being under-
stood as including the effects due to turbulence or the
mixing influence of the packing, as well as ordinary
molecular diffusion and the convective mixing due to
temperature differences (2o). For porous catalysts,
both internal or porous diffusion and external diffusion
usually occur.
For external diffusion (3s), data on mass transfer
from fluid to solid are commonly expressed in terms of a
mass transfer coefficient k, defined by C
where:
N = k (C - C ) C O S
N = diffusional flux
C = concentration at the surface s C = concentration in ambient fluid.
0
(1)
In gas systems, the potential is taken to be the partial
pressure of the diffusing substance, and it is convenient
to define a coefficient k by g N = k (P - P) g O S
(2)
where k = k /RT. g C
For internal or pore diffusion, the net rate of flow
of molecules past a given cross-section of pore depends on (49) three factors :
1. The magnitude of the pore radius as compared to
the length of the mean free path of molecules between
intermolecular collisions.
-6-
2. The presence or absence of total pressure dif-
ferences along the pore.
3. The presence of physically adsorbed layers of
the pore wall.
Pore diffusion may occur by one or more of three
mechanisms ( 37 ): ordinary diffusion, Knudsen diffusion,
and surface diffusion. In a gas-solid system, if the
pores are large and the gas relatively dense, the process
is that of bulk, or ordinary, diffusion. If the gas
density is low, or if the pores are quite small, or both,
the molecules collide with the pore wall more frequently
than with each other. This is known as Knudsen diffu-
sion. Evidently, the molecules hitting the wall are
momentarily adsorbed and then given off in random directions.
Molecules adsorbed on solid surfaces evidence considerable
mobility. Transport by movement of molecules over a sur-
face is known as surface diffusion. It contributes little
to overall transport through a porous mass unless appre-
ciable adsorption occurs.
The effect of total pressure on the diffusion of gases
in pores obviously depends on the relative importance of
Knudsen and ordinary diffusion. The former is independ-
ent of pressure; the latter is inversely proportional to
pressure (39). As for the effect of temperature,. the Knudsen
-7-
diffusion coefficient increases as the square root of the
temperature, whereas the ordinary diffusion coefficient (40) increases moderately fast with temperature
Adsorption on Catalytic Surfaces. It is now generally
accepted that two main types of adsorption on catalytic
surface may occur, namely, physical adsorption and chemi-
sorption. Physical adsorption is sometimes called van der
Waals adsorption since the forces involved are of the same
type as the van der Waals forces that produce condensation
in liquids ( 35 ). The typical physical adsorption takes
place at low temperatures and is governed principally by
the available surface area. The heat evolved is of tna
order of magnitude of the heat evolved in the process of
condensing the gas, and the amount adsorbed may correspond
to several monolayers (l 2 , 19 , 50).
Also, it is not highly dependent upon the irregular-
ities in the nature of the surface but is usually directly
proportional to the amount of surface (44 ). Relative to
chemisorption, physical adsorption is rapid and involves
low heats of adsorption.
There are two distinct uses of physical adsorption:
(1) measurement of the surface areas of finely divided
catalysts; and, (2) measurement of pore size catalytic
materials ( 2 i, 44 ). The first use involves measuring the
-8-
adsorption isotherms of suitable gaseous adsorbates at
temperatures close to their boiling points and in deter-
mining, by appropriate p:ots, the points on the adsorption
isotherms corresponding to the volume of gas required to
form a monolayer on the adsorbent. The second applica-
tion first received attention from Barrett, Joyner, and
Halenda ( 22 ), who measured the pore distribution from
desorption isotherms. Wheeler (21) pioneered the theory
of the influence of pore size on many characteristics,
such as the catalytic reaction order 9 the fraction of
surface participating in the catalytic reaction, and the
specificity of the catalyst.
Chemisorption involves forces much stronger than
those in physical adsorption. According to Langmuir, the
adsorbed molecules are held to the surface by valence
forces of the same type as those occurring between atoms
in rr~olecules. This idea is often presented as indicating
the formation of an activated complex, or intermediate
temporary chemical compound, which is formed slowly and . (34) (6 47) determines the velocity of the reaction • Taylor '
a~tributed the greatest catalytic action to the most un-
saturated atoms and the least catalytic action to the most
saturated atoms in the surface of the catalyst. Smekal
and Zwicky ( 6 ) went even further, for they considered
-9-
every irregularity in crystal growth appearing on the
surface as an area of greater catalytic activity.
Chemisorption, unlike physical adsorption, is specific,
with no more than a monolayer being adsorbed, and it in-
volves relatively high heats of adsorption. Because of the
high heats of adsorption, the energy possessed by chemi-
sorbed molecules can be considerably different from that
of the molecules by themselves. Hence, the energy of
activation for reactions involving chemisorbed molecules
can be considerably less than that for reactions involving
the molecules alone ( 32 , 44 ).
There are also two main applications of chemisorption
in the study of catalysis: (1) measuring the fraction of
a catalytic surface which consists of a catalyst active
component compared to the portion which consists of a
material that either acts as a support or as a promoter to
the principal catalyst and (2) determining the way in which
chemisorption can be related to the mechanism of a catalytic
reaction, and also the amount of chemisorption that occurs
on the surface ( 2 l). In order to treat these quantitatively,
adsorption isotherms are used. Many theories of adsorption
have been developed, but most developments are based upon
the work of Langmuir and Freundlich.
The Langmuir isotherm ( 45 ) is the most suitable methou
upon which to base the kinetics of solid catalytic reactions.
-10-
Langmuir's derivations may be carried out by using as a
measure of the amount adsorbed either the fraction of the
surface covered or the concentration of the fluid adsorbed
on the surface. Also, several assumptions are used: (1) all the surface of the catalyst has the same activity for
adsorption, (2) there is no interaction between adsorbed
molecules, and (3) all the adsorption occurs by the same
mechanismo
m1he F dl . h t. ( 19 ) . t · reun 1c equa ion is some 1mes more success-
ful than the Langmuir equation from the empirical stand-
point. The Freundlich isotherm can be derived assuming
a heterogeneous surface with adsorption on each class of
sites obeying the Langmuir equation. According to the
Freundlich equation, the amount adsorbed increases inde-
finitely with increasing concentration or pressure. There-
fore, this equation is unsatisfactory for high coverages.
Reaction on Catalvtic Surfaces. It is now generally
recognized that at least one of the reactants in any
catalytic reaction must chemisorb or chemically interact
with the surface of the catalyst prior to reaction taking
place ( 23 ). The theory of active centers, that is,
surface sites that are more active than others, has been
demonstrated experimentally (lo, 42 ), .and it is known that
chemical processes occur predominantly on these sites.
-11-
Since the general expression for the kinetics of a
chemical reaction is
where: V = rate of reaction
c1 , etc.= concentration of reactant
k = reaction rate constant,
(3)
the definition of catalytic action is that it involves ·an
increase in the rate by the presence of a substance which
increases either k or e's ( 24 ). Since the reaction rate
constant (4 l) is usually represented as
where:
k = Z • e -q/RT
Z = number of collisions per unit time
q = activation energy
T = absolute temperature,
(4)
it is evident that the rate of reaction increases not only
because of increased collisions which lead to the formation
of products, but also to a lowering of the activation energy,
or the minimum energy a molecule must have to react. For
gas-solid systems, Langmuir pointed out that the essential
difference between catalyzed and non-catalyzed reactions from
an energetic point of view is due to the fact that colli-
sions between gaseous molecules and a solid differ from
-12-
ordinary kinetic collisions in a homogeneous gas phase in
being comparatively inelastic. The colliding gas molecule
remains on the catalytic surface for an interval of time
which is long in comparison to that in ordinary gaseous
collisions; therefore, a greater opportunity is given for
activation·to occur (7 ,s). As stated before, the activa-
tion energy for reactions involving chemisorbed molecules
can be considerably less than that for reactions involving
the molecules alone because of the high heat of adsorp-
tion (44 ).
As for the general mechanisms of bimolecular surface
reactions, the Langmuir-Hinshelwood mechanism (3 l) and
the Rideal-Eley mechanism ( 9 ) are the most popular. Accord-
ing to Langmuir and Hinshelwood, such reactions proceed
through the adsorption of two molecules on adjacent sites,
followed by their interaction and the desorption of the
product (s)°. Rideal and Eley, however, suppose that it
it only necessary for one of the two molecules to be
adsorbed, and that reaction occurs on collision of the
second molecule, coming from the gas phase, with the surface.
Theory of Radioactivity
Radioactive elements undergo spontaneous transfor-
mations from one chemical element into another. These
-13-
transformations are not affected by temperature, pressure,
physical state, etco, and are accompanied by energetic
radiations which interact with the atoms and molecules in
matter (l 6 ) o Unlike chemical reaction energy, which is
produced as a consequence of a rearrangement of the atoms
of elements taking part in the reaction, atomic energy
results from rearrangements within the interior of the atom
·t lf ( 23 ) 1 se •
Types of Radioactive Decav. Radioactive nuclides
break down spontaneously in three principal ways: alpha
decay, beta decay, and gamma emission. In passing through
matter, these radiations interact with atoms and molecules,
by which they lose their energy and produce ion-pairs or . . t· (16) 1on1za ion • Of course, the number of ion-pairs pro-
duced depends upon the various types of radiation. The
essential nature of the rays is the same, the alpha part-
icle always being a doubly-charged helium atom, the beta
particle an electron, and the gamma ray an electromagnetic
wave. However, the specific properties of the radiation,
such as the velocity of the alpha particle and beta part-
icle, their power and penetrability of ionizing gases, and
t~e wave length of the gamma rays, vary with the particular
radioactive element from which they originate ( 23 ).
Alpha particles travel approximately one-tenth the
speed of light and, in passing through matter, give up
-14-
their energy and become neutral helium atoms. Since they
are much heavier than· electrons, they are deflected ve~y
slightly·and therefore travel very short ranges in rela-
tively straight lines. Alpha particles belong to a limited
number of energy groups and therefore are not emitted with
a continuous energy distribution ( 26 ).
Beta particles travel with a maximum velocity ranging
from about 25 to 99 per cent of the speed of light ( 3o). Since the masses of beta particles and orbital electrons
are equal, the former can lose a large fraction of its
energy in a single collision; consequently, beta particles
are scattered out of the beam path all along its length.
In beta decay, there is a small change in mass, with the
decrease in mass appearing principally as the kinetic
energy of the products (l 6 ). The beta particles are emitted
with a continuous energy distribution ( 3o) corresponding
to
where:
E = energy of beta particle
M = rest mass of electron 0
C = velocity of light
V initial speed of beta particle.
(5)
The average beta energy is approximately one-thir~ the
maximum beta energy Emax• This distribution is explained
-15-
in that a second particle, the neutrino ( 5 , 16 ), is emitted
along with the electron, and that the sum of the energies
of both equals Emax• . Many attempts have been made to
formulate an empirical relation between the range of beta
particles and their energy. No satisfactory equation
has yet been developed, but the following seems to apply
for a beta particle of average energy
R = 542 E - 133 max max where R equals the maximum range in milligrams of mass max per square centimeter (43 )_
A gamma ray, since it has no mass or charge, penetrates
great thicknesses of matter before being absorbed. The
number of ion-pairs produced in a given path by a gamma
ray is only one to ten per cent of that produced by a beta
particle of the same energy (l 6 ). Gamma rays result when
a nucleus undergoes a transition from a state of higher
energy to one of lower energy. The energy Eis equivalent
to
E = he/A (7)
where:
h = Planck's constant
c = velocity of light
n =wavelength of radiation (5) •
-16-
Rate of Radioactive Decay. The probability that a
radioactive atom will decay in a given time is a constant,
independent of temperature, pressure, chemical change,
gravity, magnetic or electric fields, or the decay of
neighboring atoms ( 25 ). The disintegration of individual
atoms is a statistically independent event and is subject
to random fluctuations. In a large number of atoms, how-
ever, the fluctuations average out, and the fraction which
decays in unit time is a constant and is numerically equal
to·the probability that a single atom will decay in that
time. This rate of radioactive decay is known as the
decay constant A (4 )_ Since the number of atoms which
decay in a given time is proportional to the number present,
as shown experimentally, radioactive decay is a first order
reaction. If N is the number of atoms present at time t,
dN = - r1t. dt
Integrating, - I\ t N =·Ne
0
where N equals the number of atoms originally present. 0
Defining the half-life, ti, as the time required for an 2
(8)
(9)
initial number of atoms to be reduced to half that number
by transformations, N
t1 = 0.693/?i 2
= N /2 at t = ti, or 0 2
(10)
-17-
The usual procedure isj however, to determine the activity
A, which is proportional to ?i N, or
A Cf\ N (4)
where C is the detection coefficient ( 25 ) and depends on
the nature of the detection instrument. The decay law now
becomes
where A is the original activity. By plotting log A 0
(12)
versus t, one may find~, or the slope of the straight
line.
Detection of Radioactivity by Ionization Instruments.
Since the interaction of the various types of radiation
with matter is accompanied by ionization, the obvious
method of detecting the radiation is by collecting the
ions produced. The essential features of such a device
are an electrode system, in which the ions may be col-
lected, and a circuit through which the current passes
when ions are attracted to the charged electrodes. A
gas is usually used as a medium, and the magnitude of
the charge produced from ionization of the gas will de-
pend on two factors (29) in particular: (1) the initial
number of ion-pairs produced and (2) the applied voltage.
Figure 1 shows a plot of the charge collected as a
function of the applied voltage.
< 0 w
0
0 w 0 u _J 0 (.)
0
10· '
I l B
FIGURE
-18-
PROPO!~TIONA L
COUtJTiE:R
,. \,, .;.\V
f';;.,:,: ... ~-o('
10·
I l I !
VOLTAGE -1 CHARGE VERSUS VOLTAGE IN IONIZATION I •
IN"STRU}'IENTS Overman,R. T. ::;,nd I-I. M. Cla,rk: "Radioisotopo
Technic::_ues 11 ) pp. 25-29. McG-rm,·-Hill Book Co., Inc., New York, 1960.
-19-
The three main types of ionization instruments are the
ionization chamber, the proportional counter, and the Geiger-
Muller counter, with the primary difference being the voltage
at which each is operated. At very small voltages only a
fraction of' the ions formed in the de-liector may be collected
because the weak electrostatic field allows some of the ions
to recombine. As the voltage is increased, the field in-
creases proportionally, and all the ions produced are col-
lected. This is shown by a leveling off of both curves so
that they represent the collection of a constant charge with
increasing voltage, as indicated by BC and B 1 C 1 in Figure 1.
The ionization chamber is used in this region, with the
voltage range over which the charge is constant depending
upon many factors ( 29 ) 1 such as the nature and pressure
of the gas and the spacing and shape of the electrodes. In
each case, this constant charge continues as the voltage is
increased until the primary ions are accelerated to the
electrodes so that they produce secondary ionizations.
The result is that more ions reach the electrodes than
were formed in the original collisions, and the amount of
charge collected increases as the voltage is increased.
However, for a given voltage, the charge collected is
proportional to the initial number of ions produced ( 27 , 36 );
hence, the proportional counter is used in the r~gions
-20-
CD and C 1 D 1 • A further voltage increase causes all ions,
primary or secondary, to be accelerated so fast that an
avalanche of ions is created; therefore, the charge again
becomes approximately constant, shown as EF. A voltage
increase beyond this region causes a continuous discha~ge
of electricity, Que to the very high potential, so that
counting becomes impossible ( 29 ).
The Use of Radioisotopes as Tracers
There are two assumptions implicit in the use of
isotopes as tracers. It is assumed that radioactive iso-
topes are chemically identical with stable isotopes of the
same element (i 3 ,i 7 , 43 ); that is, neither the type or
strength of the chemical bonds nor the physical properties
are affected. The difference in mass between the various
isotopes does cause some changes in these properties, but
this effect is rather small and is exceedingly difficult
to detect in most cases. The second assumption is that
the radioactive nature of the isotope does not change the
chemical or physical properties (i 7 )_ As the rate of dis-
integration increases, the release of energetic radiations
may cause secondary effects~ However, the level of radio-
activity is usually not high enough to produce radiation
effects which are noticeable.
-21-
The Effect of Isotopes on Chemical Reactions~ Dif-
ferent isotopic species of the same elecent may differ
significantly in chemical reactivity. The mass of the atoms
in·a molecule affects both the volocity and the vibrational
energy of the molecule. If isotopic molecules of the same
temperature are considered, the heavier molecule has the
lower velocity and therefore suffers fewer collisions. This
effect is proportional to the square root of the ratio of
the masses of the molecules. The heavier molecule also has
less vibrational energy than the lighter molecule and there-
fore requires more energy to excite it to the activated
transition state, that is, more energy for dissociation (48)
These energy differences are usually small, however. Isotopic
substitutions can show up markedly in the rate of reaction
when the isotope bond to the molecule is formed or broken
in the rate-determining step, or, in the equilibrium reached
d . . t . t. ( 13) uring iso opic reac ions •
There are various advantages (l 4 ) in using isotopic
labeling instead of substituent labeling in the study of
chemical reactions. The presence of a substituent group
exerts a considerable influence on the energy levels of the
parent molecule, thus possibly changing the nature of the
reaction~ The substituent group may have a great effect
on the entropy change in the reaction. Also, the substituent
group may easily participate in the reaction taking place.
-22-
Carbon - 14 as a Tracer. Carbon -14 has many ad-
vantages in being used as a radioactive tracer in chemical
reaction studies. It decays by the reaction (i 5 )
cl4-? Nl4 + 6 7 /3 (14)
where)S represents a beta particle or an electron. The
beta particle emitted is sufficiently energetic to make
measurements fairly simple but weak enough to make shield-
ing unnecessary. Carbon -14 also has a half-life of 5568
years, making it suitable for counting purposes over a
very long period of time. Also, in most tracer studies,
the isotope effects are rather small and usually difficult
to detect. In chemical reactions, as stated before, the
bonds formed by the isotopes of an element will in general
be broken or formed at different rates. The c12 - c14
bond is stronger than the c12 - c12 bond, thus causing bond
breaking of the c12 - c14 bond to be slower. This effect
can cause a difference in the reaction rate of six to
ten per cent (14)
-23-
III. EXPERIMENTAL
The fellowing section consists of the purpose and
plan of the investigationj listings of the materials a~d
apparatus used, data collected and results calculated,
and sample·calculations showing how the results were
obtained.
Purpose of Investigation
The purpose of this investigation was to study the
mechanism of the disproportionation of propylene over a
cobalt oxide-molybdena-alumina catalyst through the use
of a radioactive tracer.
Plan of Experimentation
The plan of experimentation followed in this inves-
tigation first consisted of a review of the literature
on the general concepts of heterogeneous catalysis and
radioactive tracer theory. Based upon the information
obtained during the literature review, a reactor system
and an analysis system were chosen.
Preliminary studies on the reactor system were then
carried out. This led to the approximate optimum temper-
atures at which the reaction should be operated. Also,
-24-
a sampling procedure for the analysis of the reaction
products was developed.
Selection of Reaction System. The system chosen
for study was the disproportionation of propylene over
a cobalt oxide-molybdena-alumina catalyst. Radioactive
propylene labeled in the one position with carbon -14, 14 c3H6-l-C , was employed as a tracer. Temperatures of
300 and 350° Fat atmospheric•pressure were employed in
a tubular reactor (Figure 2, page 26). A feed flow rate
of one milliliter per second was used, which corresponded
to a weight hourly space velocity of approximately 1.1
gram of feed per hour per gram of catalyst.
Perliminary Studieso In the preliminary studies of
the reaction system, non-radioactive propylene was used
in order to determine the temperatures at which the re-
actor should be operated for achieving both high conver-
sion and high selectivity. Both propylene and nitrogen
were used to determine the time at which sampling should
be made for obtaining representative results.
Selection of Analysis Systemo Since the reactor
effluent to be analyzwd was gaseous and consisted of three
or more olefins, gas chromatography was selected as the
method of separation for the various olefins. Dimethyl-
sulfolane on chromosorb W, which separates light_olefins
-25-
very efficiently, was selected for the chromatograph
column.
Since the radioactive propylene emitted soft beta
particles, a proporiional counter equipped with an ampli-
fier was used for the determination of radioactivity.
THERMOCOUPLE
WELL PREHEATER IMPl::RIAL FIT TING
,~,tc\=,-=:Dfflli~~======>ri c::=,_~:;;_-./ \;~~~.:.--k~ .) !, .J I I ,, • ; ;; } :: l : ;; li : :: : : : ,'-''-'·;;.=-,..,.-.,:-..:,=m.-,)'">"~~y;J1J" _-,-- l:l,;:;.·c~,,.~-
i ~f---~b-_, -----14"---~ I II
I './8
-----------·- _____ J
I N (J\ I
-27-
Materials
This section contains the uses and specifications
for the various materials used in this investigation.
Alumina, Activated. Granular, 8-14 mesh, lot 7-574,
catalog no. A-541. Obtained from Fisher Scientific Com-
pany, Fair Lawn, N. J. Used to dry the propylene feeds.
Catalyst. Cobalt Molybdenum on Alumina, 3.5 per cent
cobalt oxide and 10.0 per cent molybdena, one-eighth inch
pellets. Obtained from Girdler Catalysts Dep't., Louisville,
Kty.
Dimethylsulfolane. 20 per cent dimethylsulfolane
supported on Chromosorb W, 30-60 mesh. Obtained from
Hewlett-Packard, Avondale, Pa. Used as chromatograph
column packing for separation of olefins.
Helium. One size 1-A cylinder of commercial grade
helium. Obtained from Industrial Supply Company, Bluefield,
W. Va. Used as carrier gas in chromatograph and as dilut-
ing agent in preparing radioactive samples.
Nitrogen, Dry. One size l~A cylinder of commercial
grade dry nitrogen. Obtained from Industrial Supply
Compa.ny, Bludfield, W. Va. Used to dry and activate catalyst.
Pr~nylene. One no. 2 cylinder of C.P. grade propylene,
minimum purity 99.0 per cent. Obtained from Matheson Com-
pany, East Rutherford, N. J. Used as feed to th& reactor.
-28-
Propylene, Radioactive. One lecture bottle cylindar
f 1 , c14 1 t 468 021 o propy ene - i - , o no. - • Five liters (STP)
with a concentration of 0.2 me/liter. Obtained from New
England Nuclear Corp., Boston, Mass. Used as feed to the
reactor.
Apparatus
Amplifier. Model 530, University II series amplifier.
Obtained from Baird Atomic Corporation, Cambridge, Mass.
Used for amplifying the radioactive pulses before being
counted.
Ealance. Seeder-Kohlbusch, dial reading chainomatic
with notched beam and magnetic damper, 100 grams capacity,
0.0001 gram increments. Obtained from Phipps and Bird, Inc.,
Richmond, Va. Used for weighing catalyst.
Balance Weights. Checked against each other for
consistency. Obtained from Fisher Scientific Company,
Pittsburgh, Pa. Used with balance to weigh catalyst.
Chromatographs. Two types of chromatographs were
used in the investigation. The first used was a F. and M.
Scientific Corporation model 810-R research chromatograph,
with a dimethylsulfolane column. The second was a glass
column gas chromatograph, model 811 revised to a model
821. Obtained from Perkin-Elmer Corporation, Nor¼alk,
Conn. Both chromatographs used to analyze reactor effluent.
-29-
Column. Glass. One-fourth inch glass tubing coiled.
Consisted of approximately a 30 feet length of tubing.
Obtained from Glass Shop, Chemistry Department, V.P.I.
Used. as column in glass column gas chromatograph.
Counter, Proportional. Model 530, University II series
proportional counter. Obtained from Baird Atomic Corp.,
Cambridge, Mass. Used for measuring radioactivity of
samples.
Electric Furnace. Band type electric furnace, type
70, 115 V, 750W, range up to 1850° F., Manufactured by
Heavey Duty Electric Company, Milwaukee, Wisc. Used to
supply heat to reactor and preheatero
Manometer. U-tube manometer filled with mercury.
Model 10AA25WM, 30 inch range. Obtained from The Meriam
Instrument Co., Cleveland, Ohio. Used to determine pressure
of sampling system.
Powerstat. Variable transformer, type 116, 115 V, i .. 50-60 cy, ac, output range zero to 135 V, 7- 2 amp, maximum.
Obtained from Fisher Scientific Company, Pittsburg, Pa.
Used to control current to the electric furnace surround-
ing the reactor.
Preheate~. Constructed from 1/8 inch stainless steel
tubing. Consisted of a six foot length of tubing coiled
into a one inch diameter coil 3-½ inches long. Ufied to
preheat feed to reactor.
-30-
Pressure Gage. Test gage with one pound subdivisions.
Obtained from Ametek, Inc., U.S. Gauge Division, Sellers-
ville, Pa. Used to determine reactor pressure.
Pump. Vacuum. W. M. Welch, Duo Seal type, with General
Electric motor; model 115 V, 60 cy, ac, 1725 rpm. Used to
evacuate sample loop on chromatograph and to evacuate
sample traps.
Reactor. A tubular reactor constructed frou a 13 inch
length of 3/8 inch stainless steel tubing. A six foot coil
of 1/8 inch stainless steel tubing was brazed to one end
to serve as a preheater. The other end was fitted with
an imperial fitting. Details are shown in Figure 2, page 26.
Rotameter. Gas rotameter, 0 to 1 standard cubic foot
per hour of air. Manufactured by F. W. Dwyer Manufacturing
Company, Michigan City, Mich. Used to measure nitrogen
flow rate to the reactor during catalyst activation.
Sample Cylinder. Five, Hoke 304 stainless steel low
pressure cylinders with Hoke 1/4 inch NPT male brass bellows
seal valves, vee stem point. Obtained from Fogleman Com-
pany, Inc., South Charleston, W. Va. Used for collecting
and storiJg gas samples.
Sample trap. Two glass sample traps prepared using
glass tubing and three-way stopcocks. Constructed so
that sample volume was approximately ten millilit~rs.
-31-
Prepared by Glass Shop, Chemistry Department, V.P.I. Used
for collecting radioactive samples.
Stopcocks. Four, three-way, hollow plug, T-bore
stopcocks. Spring-loaded for use at high pressure, three
mm. bore. Obtained from Eck and Kreb.s, Inc., Long Island
City, N. Y. Used for making sample traps.
Therraocouple. Made up of 30 gage iron and constan-
tan wire and calibrated individually. Iron and constan-
tan wire manufactured by Leeds and Northrup Company,
Philadelphia, Pa. Used to determine reactor temperature.
Tygon tubing. Three-fourth inch diameter tygon
tub:._:..g. Obtained from Fisher Scientific Company, Silver
Spring, Md. Used for collecting reactor effluent samples
for purpose of determining sampling system time constant.
-32-
Method of Procedure
The following section describes the procedures used
in this investigation. It covers operation of the re-
action system and the procedures used for the non-radio-
active preliminary studies and the final studies with
radioactive propylene.
Operation of Reaction System. The first step in
the procedure for operation of the reaction system in-
volved randomly packing the catalyst pellets into the
reactor. The catalyst bed was located approximately
1/2 inch below the feed inlet to the reactor. The re-
actor, with the preheater, was then placed in a band-
type electric furnace, with the inlet and outlet lines
being attached. In order to dry and activate the cat-
alyst, dry nitrogen was then passed through the reactor
with the temperature of the furnace being raised to
1000° F. The dry nitrogen was allowed to flow over the
catalyst for approximately six hours at 1000° F.
After activation of the catalyst, the reactor was
allowed to cool to the temperature at which the reaction
was to occur. The dry nitrogen flow was then stopped
and the propylene was fed to the reactor viaanalumina
dryer. The propylene flow-rate was controlled by needle
valve F, shown in Figure 3, page 33, to give a flow of
f'rj H
A ORY NITROGEfl !;lj
0 PRO PY LENE tr:J w • C RADIOACTIV~ PROr>YLEME
Ul .<j 0 ROTAf.1E TER 0
F~
t:c: t:tj E DRYr::R (ALUUINA) r- -7 > t-3 I IG F NEEDLE VALVE H 0 I I t:J D H G ELECTRIC FURNACE H I I > I I H P REHEATER Q !;lj E
I I I REACTOR 0 L_ _.J l'rj J PnESSURE GAGE I w t_rj ·-0 J K SAMP Llf~G BOMB w > I 0 t-3 H
L NEEDLE VALVE 0 z L w 1-<j w t-3
. D
A B C
K
-34-
one milliliter per second. The pressure could be controlled
by valve L, and the temperature was measured by a thermo-
couple with a bare junction in contact with the gas and
catalyst. This procedure gave conversion of propylene to
ethylene and 2-butene.
For all preliminary studies, only propylene was used,
with the procedure being that described above. For final
studies, both propylene and radioactive propylene were
used. The procedure was altered only in that the propy-
lene gas flow was i~~errupted after steady-state was
achieved and the flow of radioactive propylene was started
immediately. The flow rate was reset to one milliliter
per second by controlling valve F. The only difference
in the reactor effluent was that it contained radioactivity.
Analysis of Reaction Products. Analysis of the
reaction products was carried out differently for pre-
liminary and final studies. In the preliminary studies,
the F and M chromatograph, described in the apparatus
section, was used. The reaction products were allowed
to flow continuously from the reactor outlet through the
chromatograph sampling loop, by which injection of the
sa~ple takes place. The product stream could thus be
analyzed at any desired time during the reaction.
-35-
The amount of each component in the product sample
was determined by taking the ratio of each peak area to
the sum 6f the peak areas. This method, shown in a
sample calculation later, gives a good approximation to
the weight per cent of each component present.
For the final studies, the reactor products were
passed through a Hoke gas sampling bomb in order that
a relatively large sample might be collected at any de-
sired time. However, after changing the feed from propy-
lene to radioactive propylene, there was a time lag
associated with the sampling; that is, a certain quantity
of effluent resulting from the previous propylene feed
would still be present for a certain length of time.
In order to determine the proper time lag before col-
lecting a sample that was representative of the system,
the time constant for the reactor and the sampling bomb
in series was determined. The procedure for doing this
involved applying a step change to a steady-state propy-
lene flow of one milliliter per second with the reactor
temperature approximately 350° F and the reactor pressure
atmospheric, similar to the conditions of the actual final
studies. The step change involved reducing the propylene
flow to 1/3 milliliter per second and passing dry nitrogen
through the reactor at a flow rate of 2/3 millili~er per
-35-
second at an instant of time. Thus, the flow rate, the
temperature, and the total pressure was approximately the
same as before. A length of tygon tubing was then attached
to the outlet of the bomb. A sample could be taken by
clamping both ends of the tubing at a certain time.
Samples were taken at two, four, six, eight, and 15
minutes after the step change. The samples were analyzed
by the F & M chromatograph. The increase in the nitrogen
peak height versus time gave an approximation to the time
constant of the sampling bomb system, as shown in Figure 12, rr page JO.
The determination of the time constant of the sampl-
ing bomb system, althougD only an approximation, gave an
estimate of the response time for the system. At first,
a portable radioactive counter was employed for determin-
ing the response time, but it was found to be insensitive
to the soft beta rays emitted by the radioactive propylene.
From these results a time lag of about 5 minutes was
judged appropriate for sampling.
After the radioactive propylene had passed through
the reactor approximately five minutes, the bomb was closed
and removed from the system. A portion of the gas sample
was then transferred to a sample trap by using a vacuum
pump to evacuate the sampling system, shown in Figure 4,
page 36.
1-rj H
t_rj
.r:,. •
U2 0 ::tl t_rj :s:: > 1-3 H 0
t::I A H E > Q
I \.,J
°' A SAMPLING BOMB I 0 1-rj
U2 B MANOMETER
C VACUUM PUMP 1-d t-1
D HELIUM H z D
TRAP Q B E SAMPLING U2
U2 1-3 C
.
-37-
FIGURE 5. PROPORTIONAL COUNTER
-38-
The sample trap was filled with approximately 2.5 milli-
liters of radioactive sample and 7.5 milliliters of helium.
The sample trap was ihen used for transferring the sample
into the glass chromatograph for the separation
of its components. Having passed through the chromatograph
and separated, the components immediately passed through
the proportional counter, Figure 5, page 37, where the
radioactivity of each componaat was determined. The pro-
cedure for calculating the radioactivity is shown later
in the sample calculation section.
Operation of Chromatographs. The F and M chromato-
graph was operated at room temperature, approximately
25° C. Helium tank pressure was maintained at 40 pounds
per square inch, gage, with a 3.5 reading being maintained
on the rota~eters, corresponding to a carrier gas flow
rate of approximately 80 milliliters per minute. The
detector bridge was operated at 250 milliamperes. A
polarity setting of "A" was used with the attenuation
varying from "16" to "64". The chart speed was set on
"10 x 2", corresponding to a chart speed of 1/2 inch per
minute.
The glass column chromatograph was operated with
oven and detector cell temperature set at 25° c. Helium
tank pressure was approximately 20 pounds per square inch,
-39-
gage, with a 3~0 reading being maintained on the rota-
meters, corresponding to a carrier flow ~ate of approximately
37. 5 milliliters per mi::rnte o The attenuation was set at
"16" and the chart speed corresponded to one inch per
minuteo
Operation of Proportional Counte~. The proportional
counter was operated at a voltage of 2285 volts, with a
background count ranging from 20 - 30 counts per ten
seconds. The flow through the counter stayed approximately
constant at 37.5 milliliters per minute. Accumulated
counts during intervals of ten seconds were printed out.
Controlled Conditions. For each test made in this
investigation, catalyst pellets as descr'ibed in the mate-
rials section were used. The catalyst was dried and
activated at a temperature of approximately 1000° F. for
six hours while dry nitrogen was passed over it.
The conditions for the operation of the reactor were
not controlled with extreme accuracy, since high precision
was not a necessary factor in the investigationo The
ihermocouple was calibrated to plus or minus five degrees
Fahrenheit, and so the reactor temperature measured should
be reasonably accurate.
The pressure of the reactor was measured by a pres-
sure gage. For the tests at 15 pounds per square inch,
-40-
gage, an accuracy of p:us or ~inus one pound per square
inch was maintained. For tests at atmospheric pressure,
no deflection of the pressure gage needle was recorded.
All flow rates were accurate within a range of plus or
minus one milliliter.
For all preliminary tests, the catalyst charge was
approximately five grams, with an accuracy of about plus
or minus 0.1 gram. For all final tests, the catalyst
charge was increased to six grams, with the accuracy
remaining the same.
During the final tests, the radioactive propylene
flow was started after the propylene had been on stream
approximately 15 minutes. The radioactive flow then
continued for five minutes, wi~h a sampling bomb introduced.
After ihe sample had been transferred from the bomb to
the trap and diluted with helium, the volume of radioactive
sample and helium corresponded to 2.5 and 7.5 milliliters,
respectively? with an accuracy of plus or minus 0.5
milliliterso
Variajles Studied. The only variable studied was
that of temperature with respect to propylene conversion
and selectivity. Deactivation of catalyst was studied at
temperatures of 300 and 350° F over a period of 75 minutes.
-41-
Results
The results obtained from this investigation are
presented in the following section. The data from which
the reaction results were calculated are presented in
the Appendix.
E:.:fed; of Temperature on Pro-pylene Conversion and
Selectivity of Reaction over Girdler Cataivsts. Reactions
were carried out over commercial Girdler catalysts of
3.5 per cent cobalt oxide and ten per cent molybdena at
15 pounds per square inch, gage, and a feed flow rate of
one milliliter per second, corresponding to a weight
hourly space velocity of 1.3 grams of feed per hour per
gram of catalyst, to determine the effect of temperature
on conversion and selectivity.
Results for the effect of temperature on conversion
are given in Tables I and II, and they are illustrated
graphically in Figures 6 and 7~ Results for the effect
of temperature on selectivity are given in Tables III and
IV, and they are illustrated graphically in Figures 8 and 9.
Pronylene Conversion Versus Time-on-Stream over Girdler
Catalysts. Reactions were carried out over commercial
Girdler catalysts of 3.5 per cent cobalt oxide and ten
per cent molybdena at 15 pounds per square inch, gage, a
weight hourly space velocity of 1.3, and temperatures of
-42-
300 and 350° F to observe the deactivation of the catalysts
with time-on-stream.
Results for the reactions are given in Tables V and
VI 1 and they are illustrated graphically in Figures 10
and 11.
Response of Step Change to Reactor-Sanpling Bomb
System. A step change of dry nitrogen was applied to
a steady-state propylene disproportionation over a com-
mercial Girdler catalyst at 350° F and atmospheric pressure
to determine the reactor-sampling bomb system time con-
stant and response time.
Results for the step change are given in Table VII,
and they are illustrated graphically in Figure 120 · 14 Radioactivity of Products from Propylene-1-C
Disproportionation over Girdler Catalysts. Reactions 14 with propylene-1-C were carried out over commercial
Girdler catalysts at atmospheric pressure, a weight hourly
space veloci~y of 1.1, and temperatures of 300 and 350° F.
Results for the radioactivity of the chromatograph
effluent of the reaction products versus time are given
in Tables IX through XIV, and they are illustrated graphi-
cally in Figures 13 through 18. Results for the per cent
radioactivity of each reactor product, as well as the male
per cent concentration of each in the reactor effJuent, are
given in Tables XV and XVI.
-43-
TABLE I
Effect of Temperature .Q.!! Propylene Co~version
over Commercial Girdle1~ Catalvst of 1 C%
Mo03 and 3.5% CoO ,2_g Alumina at 12. psig
and WHSV = 1.3 for 12. min Samnle
Temperature Ethylene Propylene 2-Butene Propylene Conversion
OF mole % mole% mole% %
200 11 • 50 75.80 12 .. 62 24.3
250 12. 90 70.90 15.88 29.2
300 15.22 66.50 17 .05 33.5
325 17.06 62.05 19.24 37.9
350 19.70 61 .05 17. 21 38.9
375 18.65 58.65 19.82 41.3
400 19.98 57.80 18.77 42.2
450 20.00 60.60 16. 63 39.4
500 16. 70 66 .. 65 14. 54 32 .1
-44-
TABLE II
Effect of Temperature g_g Propylene Co:c:.ve1~sion
Commercial Girdler Catalyst of 10%
Mo03 and 3.5% CoO g_g Alumina at 12. £.§i.g
and WHSV = 1.3 for 24 min Sample
Temperature Ethylene Propylene 2-Butene Propylene Conversion
OF mole% mole% mole% %
200 11 .oo 76.50 12.40 23.5
250 13.47 70.25 15.73 29o7
300 15 .. 38 65 .. 50 17 .85 34 .. 3
325 17.45 60.75 19.63 39.2
350 18 .. 60 59.50 19. 61 40.6
375 18080 58 .. 90 19. 55 41.0
400 21 • 19 58.10 18.04 42.0
450 19. 31 62.00 16. 18 38 .. 0
500 15.80 68 .. 10 13.83 30 .. 5
z o 40 (/) 0:: w > z 0 (.) 30
w z w ...J 20 >-a.. 0 0:: a..
10 ..e
200 250 300 350 400 450 500
TEMPERATURE, °F FIGURE 6. EFFECT OF TEMPERATURE ON PROPYLENE CONVERSION OVER COMMERCIAL
GIRDLER CATALYST OF 10% MoO3 AND 3.5% CoO ON ALUMINA AT 15 PSIG AND WHSV = 1.~ FOR 15 MIN SAMPLE
I ..i:,. \J1 I
z 40 0 (/) a:: w > z 30 0 u w z w 20 ..J >-a. 0 a:: a.
10 0
200 250 300 350 400 450 500
TEMPERATURE' °F FIGURE 7. EFFECT OF TEMPERATURE ON PROPYLENE CONVERSION OVER COMMERCIAL
GIRDLER CATALYST OF 10% MoO3 AND 3.5% CoO ON ALUMINA AT 15 PSIG AND WHSV = 1.3 FOR 24.MIN SAMPLE
I
I
-47-
TABLE III
Effect of Temperature Qg Selectivity of Reaction
.QE£ Commercial Girdler Catalyst of 10% Mo03 and 3.5% Co0 Qg Alumina at ll psig and
WHSV = 1.3 for ll min Sample
Temperature Ethylene+ 1-Butene Propylene 2-Butene
OF mole% mole % mole%
200 24.12 0.15 75.80
250 28.78 0.46 70.90
300 32.27 1.22 66.50
325 36.30 1 • 65 62.05
350 36.91 2.03 61 .05
375 38.47 2.79 58.65
400 38.75 3.38 57.80
450 36.63 2.78 60.60
500 31.24 2.10 66.65
-48-
TABLE IV
Effect of Temperature .Q.£ Selectivity of Reaction
~· Commercial Girdler Catalyst of 10% ~oo 3
and 3~5% CoO .Q.£ Alumina at jj_ and
WRSV = 1.3 for 24 min Sample
Temperature Ethylene+ 1-Butene Propylene 2-Butene
OF mole % mole% mole%
200 23.40 0.14 76.50
250 29.20 0.46 70.25
300 33.23 1.08 65.50
325 37.08 2.12 60.75
350 38. 21 2.48 59.50
375 38.35 2.69 58.90
400 39.23 2.70 58.10
450 35.49 2.51 62.00
500 29.63 2.22 68.10
t-0 ::::> 0 0 a: Q.
z w z w t-::::> m •
0
5
4
3
2
0L----.L------1L...-----J1..----'----____. ___ _.:.,..._ ___ _
200 250 300 350 400 450 500
TEMPERATURE, °F FIGURE 8. EFFECT OF TEMPERATURE ON SELECTIVITY OF REACTION OVER COMMERCIAL
GIRDLER CATALYST O_F 10% Mo03 AND 3. 5% CoO ON ALUMINA AT 15 PSIG AND WHSV J.3 FOR 15 MIN SAMPLE
I .i:,..
'° I
4 .,_ (.) ::, 0 0 0:: 3 a.. z w z w 2 I-::> 0)
::,!? 0
200 250 300 350 400 450 500
TEMPERATURE, ° F FIGURE 9. EFFECT OF TEMPERATURE ON SELECTIVITY OF REACTION OVER COMMERCIAL
GIRDLER CATALYST OF 1O%.MoO3 AND 3.5% CoO ON ALUMINA AT 15 PSIG AND WHSV = 1.3 FOR 24 MIN SAMPLE
I Vl 0 I
-51-
TABLE V
Propylene Conversion Versus Time~ Commercial
Girdler Catalyst of 10% Mo03 and 3.5% CoO 0 £!! Alumina at ll psig. 300 E., &nd
WHSV = 1.3
Time Ethylene Propylene 2-Butene Propylene Conversion
min mole % mole% mole% %
5 1 5. 12 65.65 17 .67 34.4
15 15.22 66.50 17 .05 33.5
24 15.38 66.50 17. 85 34.3
29 16.70 64~60 19 .17 36.6
37 16.06 63.90 18. 70 36.1
45 15 .so 64.75 18.29 35.3
53 15.92 64.45 18.50 35.7
61 16.48 65.00 17. 35 35.1
75 15. 77 65 .. 15 17 .81 34.8
-52-
TABLE VI
Propylene Conversion Versus Time~ Commercial
Girdler Catalyst of 10% Mo03 and 3o5% CoO 0 .2.£ Alumina at 12. I>.§i&, 350 ,E, and
vmsv = 1 8 3
Time Ethylene Propylene 2-Butene Propylene Conversion
min mole % mole % mole% %
5 17. 98 60.10 19. 11 40.0
15 19.70 61 .05 17. 21 38.9
24 18.60 59.50 19. 61 40.6
30 18.20 59.10 20.57 41 .o 39 19. 65 57.70 20.30 41.0
48 18.95 60.32 18. 77 39.8
57 19.20 60.00 18. 81 40.0
66 19 .14 60.75 18.40 39.3
75 19 .41 59.75 18. 75 40.2
50
z 40 0 en a:: w > z 30 0 0
w z w 20 _J
>-Q. ·o a:: Q.
10
0
Q 0 0 0 0 0 0-
0
10 20 30 40 50 60 70 80 TIME, MINUTES
FIGURE 10, PROPYLENE CONVERSION VERSUS TIME OVER COMMERCIAL GIRDLER CATALYST OF 10% Mo03 AND 3,5% CoO ON ALUMINA AT 15 PSIG, 300 F, AND WHSV = 1,3
I \J1 \,,) I
50
40 0 0 0 ::.--- 0 0 0 z 0 0 0 (J) a:: w > 30 z 0 0
w z w 20 ...J I
\JJ >- +>--Cl. I 0 0:: Cl.
10 0
0 10 20 30 40 50 60 70 80 TIME, MINUTES
FIGURE 11. PROPYLENE CONVERSION VERSUS TIME OVER COMMERCIAL GIRDLER CATALYST OF 10% Mo03 AND 3.5% CoO ON ALUMINA AT 15 PSIG, 350 F, AND WHSV = 1.3
-55-
TABLE VII
Response of Step Change of l)U Nitrogen Applied
to Reactor-Sampling Bomb System
at 350°~ and Q psig
Time Nitrogen Peak Height
min in.
0 1 • 53
2 2.94
4 4o30
6 4.15
8 4.76
1 5 4.90
1-:r: (!)
w :r:
<t w Q.
N z
w > 1-
5
4
3
<t 2 _J w a:::
I
0
I I I I I TIME CONSTANT= 3 MIN
1/ 0 2 4 6 8 10 12
TI ME., MINUTES FIGURE 12. RESPONSE OF STEP CHANGE OF DRY NITROGEN APPLIED TO REACTOR-
SAMPLING BOMB SYSTEM AT 350 F ANDO PSIG
I V1
°' I
14
-57-
TABLE VIII
Propylene-1-c 14 Conversion~ Commercial Girdler
Catalyst of 10% Mo03 and 3.5% CoO ,Qg Alumina
at Q and WHSV = 1.1
Temperature Test Prcpylene Conversion
OF No %
300 I 3108
II 34.8
III 31. 6
350 I 39 .1
II 38.7
III 38.8
-58-
TABLE IX
Radioactivity Versus~!£!: Chromatograph Effluent from Propylene-i-c 14
Disproportionation~ Q ~, 300 F, WHSV = l.l, Test I
Time Radioactivity
Sec Counts
0 27 10 763 20 3073 30 3870 40 3495 50 2893 60 2490 70 5054 80 6848 90 7802
lOO 7364 110 6751 120 5760 130 4701 140 4025 150 3345 160 2665 170 2323 180 1792 190 1548 200 1212 210 994 220 793 230 691 240 587 250 577 260 521 270 488 280 451 290 368 300 331 310 482 320 660 330 764 340 755 350 677 360 605 370 570 380 584 390 573 400 574 410 472 420 399 430 325 440 323 450 228 460 232 470 179 480 lll 490 124 500 118 510 66 520 67 530 42 540 44 550 37 560 36 570 29
-59-
TABLE X
Radioactivity Versus Time for Chromatograph Effluent from Propylene-1-c 14
Disproportionation at Q Jlliig, 300 E, WHSV = 1.1, Test II
Time Radioactivity
Sec Counts
0 27 10 49 20 600 30 1759 40 2093 50 1995 60 1551 70 1261 80 1605 90 3339
100 4186 110 4141 120 3837 130 3182 140 2607 150 2079 160 1761 170 1442 180 1139 190 988 200 815 210 680 220 553 230 473 240 376 250 286 260 276 270 253 280 277 290 241 300 197 310 167 320 180 330 286 340 385 350 388 360 374 370 324 380 307 390 303 400 338 410 319 420 300 430 242 440 215 450 191 460 161 470 113 480 105 490 102 500 76 510 50 520 61 530 38 540 55 550 46 560 36 570 29 580 26
-60-
TABLE XI
Radioactivity Versus~ fQ£ Chromatograph Effluent~ Propylene-i-c 14
Disproportionation~ Q ~, 300 F, WHSV = l.l, Test III
Time Radioactivity
Sec Counts
0 27 10 40 20 652 30 1704 40 2112 50 1923 60 1587 70 1354 80 1416 90 2992
100 4122 110 4392 120 4202 130 3669 140 3246 150 2674 160 2220 170 1799 180 1570 190 1£91 200 1149 210 907 220 746 230 595 240 534 250 433 260 318 270 338 280 305 290 296 300 293 310 230 320 217 330 196 340 232 350 303 360 401 370 466 380 413 390 403 400 313 410 349 420 333 430 326 440 305 450 279 460 236 470 203 480 193 490 133 500 117 510 125 520 78 530 85 540 67 550 56 560 46 570 39 580 30
-61-
TABLE XII
Radioactivity Versus Time for Chromatograph Effluent from Propylene-1-c 14
Disproportionation at Q 12.§.ig, l, WHSV = l.l, Test I
Time Radioactivity
Sec Counts
0 28 10 119 20 655 30 1128 40 1217 50 1208 60 1046 70 938 80 1612 90 2204
100 2389 110 2309 120 2195 130 1827 140 1625 150 1365 160 1103 170 840 180 732 190 558 200 501 210 436 220 332 230 282 240 233 250 211 260 224 270 216 280 219 290 209 300 185 310 206 320 279 330 306 340 372 350 389 360 376 370 321 380 349 390 351 400 343 410 316 420 283 430 268 440 224 450 161 460 138 470 121 480 104 490 82 500 80 510 60 520 46 530 45 540 41 550 38 560 24 570 31 580 30 590 23
-62-
T.ABLE XIII
Radioactivity Versus Time !Qr. Chromatograph Effluent from Propylene-1-c 14
Disproportionation at Q .P.§ig, L2Q l, WHSV = 1.1, Test II
Time Radioactivity
Sec Counts
0 22 10 74 20 452 30 811 40 902 50 790 60 644 70 577 80 1032 90 1673
100 1798 110 1782 120 1475 130 1301 140 1029 150 835 160 677 170 589 180 450 190 391 200 298 210 231 220 205 230 168 240 156 250 161 260 158 270 153 280 146 290 134 300 117 310 125 320 157 330 241 340 299 350 271 360 274 370 247 380 221 390 231 400 254 410 196 420 197 430 161 440 145 450 147 460 112 470 76 480 74 490 67 500 65 510 52 520 53 530 38 540 42 550 44 560 24 570 25 580 24
-63-
TABLE XIV
Radioactivity Versus~ for Chromatograph Effluent~ Propylene-1-c 14
Disproportionation at Q .J2.§.ig, 222. ~' WHSV = l.l, Test III
Time Radioactivity
Sec Counts
0 24 10 30 20 355 30 704 40 701 50 615 60 527 70 487 80 764 90 1365
100 1601
110 1519 120 1319 130 1070
140 876
150 749 160 602 170 513 180 398 190 344 200 268 210 232 220 182
230 180
240 136 250 105 260 122 270 152 280 125 290 126 300 lOl
310 102 320 151 330 216 340 249 350 229 360 216
370 200 380 207 390 198 400 223 410 194 420 165 430 134 440 138 450 95 460 105 470 72 480 93 490 65 500 55 510 47 520 37 530 37 540 46 550 31 560 20
570 27 580 25
8000-
6000
U)
I- 4000 2 ::)
0 0
2000
0 •=-··· ~-' ---·"L .. ,·-__ ....,;_·-· ~-~.. . . 1 ___ --~-0=2--0--:.L
100 200 300 400 500 600
TIME, SECONDS FIGURE 13. RADIOACTIVITY VERSUS TIME FOR CHROMATOGRAPH EFFLUENT FROM PROPYLENE-
1-C14 DISPROPORTIONATION AT O PSIG, 300 F, WHSV = 1.1, TEST I
I (J'\
+"-I
(j) ._
4000
3000
PROPYLENE
ETMYL[NE
- 2000 .,,_ ::> 0 (..)
1000 -
~UT~N~S
---!.--~--- L . ~~=±. 0 100 200 300 400 500 600
TIME, SECONDS FIGURE 14. RADIOACTIVITY VERSUS TIME FOR CHROMATOGRAPH EFFLUENT FROM PROPYLENE-
1-C14 DISPROPORTIONATION AT O PSIG, 300 F, WHSV = 1.1, TEST II
I
°' Vl I
en ._
4000
3000
z 2000 ::., 0 0
1000
PROPYLENE
l
ETHYLENE
L 0 100 200 300 400 600 600
TIME,· SECONDS FIGURE 1.5. RADIOACTIVITY VERSUS TINE FOR CHROMATOGRAPH EFPLUENT FROM PROPYLENE-
1-C'l 4 DISPROPORTIONA'rION AT O PSIG, 300 P, WHSV = 1 • 1 , 'l'EST III
I 0\ 0\ I
Cl)
I-z ::, 0 (.)
2000
PROPYLEME
1500
I OO Q _ ETHYLE~JE
500
-··'". ~-=--'==---=-__!_ -----•--· --· __,_, __ __ _1t _.:::,,~~:2::: .. J_
0 100 200 300 t'.1,.0Q 500 600
TIME , SECONDS PIGURE 16. RADIOACTIVITY VERSUS TIME FOR CHROMATOGRAPH EFFLUENT FROM PROPYLENE-
1-C14 DISPROPORTIONATION AT O PSIG, 350 P, WHSV == 1 .1, TEST I
I (J\ --l I
en 1-
2000
r 500
z 1000 ::)
0 0
500
ETMYLEME
_) 0 100
PROPYLENE
2-BUTEMES
0 I ~--o-o- I
200 300 400 500 600
TIME, SECONDS FIGURE 17. RADIOACTIVITY VERSUS TIME li'OR CHROMATOGRAPH EFFLUEN'l' FROM PROP'r:LENE-
1-C14 DISPIWPORTIONATIO~ AT O PSIG, 350 F, WHSV :::: 1 .1, '.rEST II
I 0\ 00 I
(I')
1-z :::> 0 0
2000
1500
1000
500
ETHVLEJH~
0 100 200 300 400 500 600
TIME, SECOl\!DS FIGUF?E ·1 8. RADI0ACTJVI'.rY VERSUS THIE FOR. cmw: 11ATOGRAPH EFI~LUEN'r FRO\J PROPYLE:\1~-
1-C14 DISPROPORTIONATION AT O PSlG, 350 F, WJlSf = 1 .1, TEST III
I Cl"\
'° I
-70-
TABLE XV
14 Radioactivity of Propylene-1-C Disproportionation
Commercial Girdler Catalyst of 10% Mo03
and 3.5% Co0 Q,g Alumina at Q E.§i.g, 300°~,
WHSV = 1~1, and Counter Flow= 37.,5 ml/min
Test Product Per Cent Absolute Per Cent * Concentration Counts Radioactivity
I Ethylene 20.52 127,779 18.0
Propylene 68.20 516,234 72.8
2-Butene 10.98 65,294 9.2
II Ethylene 22.90 70i,928 19. 2
Propylene 65.20 265,643 71. 7
2-Butene 11 • 58 33; 561 9. 1
III Ethylene 19 .16 71,448 17. 2
Propylene 68.50 305;591 73.4
2-Butene 12. 12 39,321 9.4
* Based on only Ethylene, Propylene, and 2-Butene as
Reaction Products
-71-
TABLE 1.'VI
R t P A 1LL ~adioactiYi yo:= ropylene-1-C · Dispropor-tior:.ation
Commercial Girdler Catalyst of 10% Mo03
and 3 .. 5% CoO .Q.g Alumina at O psig, 350°]:?
WHSV = 161, and Co"t:.nter Flow= 37 .. 5 ml/min
Test Product Per Cent Concentration
Absolute Counts
Per Cent· ->E-
Radioactivity
I
II
III
*
Ethylene
Propylene
2-Butene
Ethylene
Propylene
2-Butene
Ethylene
Propylene
2-Butene
20.40
16. 50
21.50
61 .45
15 .08
22 .12
61. 10
15004
47,553
164,647
35,703
31,882
112,494
25,254
25,302
96,309
22,003
Eased on only Ethylene, Propylene, 2-Butene as
Reaction Product5
19.2
66.4
14.4
18. 8
67 .1
15 "3
-72-
Sample Calculations
The following section contains the method of cal-
culation used to arrive at propylene conversions and
peT cent radioactivity values found throughout the
results section. Unless otherwise stated, this method
was used to calculate all of the results obtained.
Considering the method of calculating the propy-
lene conversion during a reaction, the weight per cents
of ethylene, propylene, and 2-butene were calculated
using the following equations:
%W A (100) = e e A + A + Ab + Al e p
% w A (100) = p A+ A +Ab+ Al e p
% Wb = Ab (100) A + A +Ab+ Al e p
where:
% w = wt % ethylene e % w = wt % propylene p % Wb = wt% 2,..butene
A = ethylene peak area, sq in. e A = propylene peak area, sq in. p
Ab = 2 .... butene peak area, sq in.
Al = 1-butene peak area, sq in.
-73-
To obtain the results of Table 1, page 43, for 200° F,
the data may be substituted from Table XVII, page 101
for 200° F. % W = 0.159 (100) = 7 65
e 0.159 + 1.569 + 0.348 + 0.004 •
la569 (100) = % WP= 0.159 + 1.569 + 0.348 + 0.004 75 •45
% 0.348 (100) 0 Wb = 0.159 + 1.569 + 0.348 + 0.004 = 16 • 72
Weight per cents were convertec:. to mole per cents by the
following equation (given for ethylene):
where:
% w = wt % ethylene e %W = wt % propylene p % W- = wt % 2-butene b
% w 1 = wt % 1-butene
MW = molecular wt of etl1.ylene e MW = molecular wt of propylene p MW_ = molecular wt of 2-butene
D
MW1 = molecular wt of 1-butene
%M = mole % ethylene e %M = mole % propylene p
-7':--
% M. =mole% 2-butene D
% M1 =mole% 1-butene
For ethylene,
%M e = 7.65/28 + 75.45/42 + 16.72/56 + 0.19/56
%M e = 11.50,
Similarly,
% M p = 75.80
% M, = 12.62 D
% Ml = 0.15
To obtain the propylene conversion, PC, the following
equation was used:
Substituting the above results gives=
PC= 11.50 + 12~62 + 0.15 = 24~3%
In order to calculate the per cent radioactivity
of each reaction product, s method of calculation des-
cribed by Ache and Finn (l) was used. The net counts
for ethylene, propylene, or 2-butene occurring during
flow through the proportional counter were calculated
by the following equation:
N e
N p
-n e
=(Pl+ D +•••P) .,_2 n p -n
B
B p
-75-
where:
N = net e counts for ethylene
N = net p counts for propylene
Nb = net counts for butene
n = ethylene counter time, 10 sec e intervals
n = propylene counter time, 10 sec p intervals
nb = 2-butene counter time, 10 sec intervals
(Pl+P2+•••Pn) = sum of counts recorded during e ethylene flow
(Pl+P2+ •••Pn) = sum of counts recorded during p propylene flow
(Pl+P2+ •••Pn) b = sum of counts recorded during 2-butene flow
B = background counts, 10 sec interval
To obtain the results of Table x:v, page 70, for Test I
at 300° F, the data from Table IX, page 58, for Test I
at 300° F. may be substituted. For ethylene,
N = (763 + 3073 + 3870 + 3495 + 2893 + 2490) -e 6 (27)
N = 16,422 counts. e Similarly,
N = 66,353 counts p
Nb = 8,393 counts.
-76-
The absolute counts for ethylene, propylene, and
2-butene are calculated from the net counts by each of
the following:
.A N (F/C) e e
.A = N (F/C) p p
Ab = N, 0
(F/C)
whe:re:
A = absolute counts of ethylene e A = absolute counts of propylene p A, = absolute counts of 2-butene
D
F = counter flow rate in ml/min
C = counter constant
Therefore,
A = 16,422 (37.5 / 40824) e A = 66,353 (37a5 / 40824) p
= 127,779 counts
516,234 counts
Ab= 8,393 (37.5 / 4.824) = 65,294 counts
Fi:..1.ally, the per cent radioactivity was calculated
each of the products by the following equations:
A % R e = A A + Ab e + e p
A %R = A A + Ab p + e p
% Rb Ab
= A A + Ab + e p
for
-77-
where:
R = radioactivity of ethylene e R = radioactivity of propylene p
Rb = radioactivity of 2-butene
Substituting,
% R 127.778 = 127,778 + 516,233 ' 65,294 e T
% R = 18.0% e Similarly,
% R = 72.8% p
% Rb ·- 9.2%
-78-
IV. DISCUSSION
This section contains a discussion of the pro-
cedures used in this investigation, a discussion of
the results obtained, a listing of the limitations
imposed upon this investigation, e,:r.a. :reccrr,rr,endations
for further Etudiese
Discussion of Experimental Procedures
A discussion of the experimental proce&ure followed
in this investigation is presented in the following
paragraphs.
Reaction System. A detailed drawing of the reactor
is given on page 26, and a schematic drawing of the re-
action system is given on page 33. Throughout the in-
vestigation this reaction performed very well, giving
data that could be reproduced within certain limitations.
The data collected from the reaction system ~hould
not be considered as highly precise. Since the reactor
was heated by a band-type electric furnace, unequal
temperatures along the reactor were probable. There-
fore, the thermocouple reading, although calibrated
within a range of plus or minus five degrees Fahrenheit,
was indicative of only one point in the reactor.
-79-
The reactor pressure and the feed flow rates were
controlled as accurately as possible with needle valves.
Reactor pressure was maintained within plus or minus
one pound per square inch for tests at 15 pounds per
square inch gage. For tests at atmospheric pressure,
no deflection of the pressure gage indicator could be
observed. The feed flow rates were controlled within
plus or minus 0.1 milliliter per second for all tests.
The packing of the catalyst was the same for each
test, and this should not have been a factor in the
results obtained. The effectiveness of the alumina
drier to remove moisture from the feed was not deter-
mined, but faster deactivation of the catalyst would
probably have occurred if a noticeable amount of mois-
ture had entered the catalyst bed.
Preliminary Studies. Preliminary studies led to
the approximate optimum temperatures at which the final
studies would be made and to the development of a
sampling procedure for analysis of the reaction products.
Results showing the optimum temperatures were
obtained by using a pressure of 15 pounds per square
inch, gage, and a feed flow rate of one milliliter per
second. The flow rate was low enough for a relatively
long contact time between propylene and catalys~, but
-80-
not too low for flow control to become difficult. The
pressure was used for easy control, also.
Preliminary studies were also made to develop an
approximate sampling procedure for tµe reaction products.
Dry nitrogen was used as a substitute for radioactive
propylene in a step change to obtain the time constant
and response time of the sampling bomb and reactor in
series. All conditions were duplicated as nearly as
possible to the conditions at which the final studies
would be made.
Analysis System. The analysis used for both pre-
liminary and final studies was both simple and reason-
ably accurate. Data were reproducible within certain
limitations~ Due to the data being considered, precise
calibration of the chromatographs or the proportional
counter was unnecessary.
-81-
Discussion of Results
The following is a discussion of the results obtained
during this investigation, including comparison with pub-
lished information.
Preliminary Studies. The results of the preliminary
studies showed an increase in propylene conversion with
increasing temperature from 200 to 400° F and a decrease
in conversion above 400° F. The maximum conversion with
the greatest selectivity occurred in the 300 to 400° F
temperature range. From these results, it was decided
that final studies would be made at 300 and 350° F.
Propylene conversion at 300 and 350° F showed only a slight
decrease with time-on-stream over a period of 75 minutes
(Figures 10 and 11, pages 53 and 54 ).
Banks and Bailey ( 2 ) reported an increase in con-
version with increasing temperature from 200 to approxi-
mately 400° F and decreasing conver~ion with increasing
temperature above 400° F. Their results also showed
the highest conversion to occur in the 300 to 400° F
temperature range. Banks and Bailey's investigation also
indicated a gradual deactivation of the catalyst with
time-on-stream.
No studies were made as to the change in conversion
of selectivity with pressure, since the results of
-82-
"R ' " B . 1 ( 3 ) . " . ' d , . 'tl "" t " ~anKs and ai ey inaica~e ~iu e e1Iec or pressure
upon propyle~e conversion. They reported conversion to
be essentially equal at 20 ~nd 450 pounds per square
inch, gage.
The results of the preliminary studies also showed
that the time constant for the sampling bomb and reactor
in series was about three minutes. From Figure 12, page
56, it was decided that a radioactive sample that was
representative of the system could be collected after
approximately five minutes of radioactive propylene flow.
Final stuaies, The results of the final studies
show that during the disproportionation of radioactive
propylene, radioactivity is observed in 00th the ethylene
and 2-b~tene products. Approximately equal amounts of
radioactivity are observed for equal molar quantities of
ethylene and 2-butene, both at 300 anQ 350° F.
Bradshaw, Howman, and Turner (ll) reported that
the 11quasi-cyc1o·butane" theory described very well the
mechanism for the disproportionation of n-butenes, and
they suggested that it could be extended to other olefins.
However, if this theory is applied to the disproportionation
of propylene, it appears only partially correct. Assuming
that it is rigorously applicable, the radioactivity found
in the ethylene and 2-butene products should appear only
in the ethylene, pictured as follows:
-83-
-'k ,,..~ C = C - C C .. 0 ° C C C C C ---• .. -- I' ll -.::-- . . tl_)f ct"= c~,., . --C C .. o "C - C c· C - C
The reaction of two molecules of radioactive propylene
would produce no new olefins, nor would this change
the labeled carbon position. That is, -!f
C C - C C O "' .. C --~ -'L ..... -c - C = C~ C 0 " ,, " o o-)t
- C 0 •"C
C --c c* IJ C
C - C IJ
Since the results of this investigation show con-
siderable radioactivity appearing in the 2-butene pro-
duct as well as the ethylene product, reaction occurs
not only by the "quasi-cyclobutane" theory but also by
delocalization of the double bond in propylene while
adsorbed on the ~atalyst surface. This result is not
completely unexpected, however, since recent infrared
spectroscopy studies (IS) indicate that delocalization
of the double bond in certain olefins may occur upon
adsorption.
Analysis and Preparation of Radioactive Propylene.
The radioactive propylene used ·l;h:..~oughout this investi-
gation was an~lyzed for its purity by the method of
chromatography. No analysis was made as to the labeled
carbon position, however, and it was assumed that only
the one- carbon position was labeled, as stated by the
vender.
-84-
The radioactive propylene was prepared by a method
in which ethyl chloride was first reacted with magnesium
in the pr~sence of ether to form the Grignard reagent
ethylmagnesium iodide.
The Grignard reagent w~s reacted with labeled carbon
dioxide to form the magnesium salt of a carboxylic acid,
from which the free acid was liberated by treatment with
mineral acid.
The carboxylic acid was reacted with lithium aluminum
hydride to form propyl alcohol.
Propyl alcohol was next reacted with hydrogen iodide to
give propyl iodide, which was reacted with trimethyl
amine to form the trimethyl propylammonium iodide salt.
CH3cH2cH2I + (CH3 ) 3N -> (CH3 ) 3NCH2CH2CH~I
The ammonium salt was reacted with silver oxide to produce
trimethyl-n-propylammonium hydroxide.
-85-
The ammonium hydroxide was then decomposed by a pyrolysis
reaction to produce labeled propylene.
-86-
Recommendations
On the basis of this investigation, the following
recommendations are made for future studies on the
disproportionation of propylene over a cobalt oxide-
molybdena-alumina catalyst.
Reaction System. For further studies, it is recom-
mended that the reaction system be more accurately con-
trolled. Feed control coula be improved by instal~ing
differential pressure controllers or automatic flow
controllers. The reactor temperature could be controlled
by using a constant temperature jacket to surround the
reactor.
Reaction Studies. It is also recommended that
results be obtained by carefully controlled conditions
in order that quantitative data might be obtained on
the relative amounts of products formed by localization
or delocalization of the double bond in olefins.
-87-
Limitations
This section contains the limitations of the
experimental procedures used in this investigation,
both for preliminary and final studies.
Activation of Catalyst. Each catalyst used during
the investigation was dried and activated at approxi-
mately 1000° F for approximately six hours. Dry
nitrogen was passed over the catalyst throughout the
drying and activation.
Reaction System. The reactor was operated at
tb;:peratures ranging from 200 to 50~° F at a pressure
of 15 pounds per square inch, gage, and a flow rate
of one milliliter per second for all preliminary
studies. Also, approximately five grams of catalyst
was used for each reaction. For the final studies,
temperatures of 300 and 350° F were used at atmospheric
pressure and a flow rate of one milliliter per second.
Analysis Conditions. For the preliminary studies,
the F and M chromatograph was operated at room tempera-
ture (approximately 25° C) with a carrier gas flow
~ate of 80 milliliters per minute. For the final studies, 0 the glass column chromatograph was operated at 25 C
with a carrier gas flow of 37.5 milliliters per minute.
The proportional counter was operated at a voltage of
-88-
2285 volts and a counter flow of 37.5 milliliters per
minute, with the background ranging from 20 to 30 counts
per ten seconds.
Prenaration of Radioactive Samples. All the
radioactive samples used for analysis were prepared by
mixing approximately 2.5 milliliters of the radioactive
effluent collected after five minutes of radioactive
propylene flow with approximately 7.5 milliliters of
helium.
Analysis of the Radioactive Propylene. No analysis
was made as to the l~beled carbon position in the radio-
active propylene used throughout the investigation. It
was assumed that only the one-carbon position was
labeled, as stated by the vender.
-89-
V. CONCLUSIONS
Based upon the results obtained during this
investigation, the following conclusions were reached.
1. The highasi conversion and selectivity of
reaction was achieved in the temperature range from
300 to 400° F.
2. The cobalt oxide-molybdena-alumina catalysts
deactivated only $lightly with time-on-st·rea,n at 300
and 350° F over an interval of 75 minutes.
3. The mechanism of the disproportionation of
propylene over a cobalt oxide-molybdena-alumina catalyst
:proceeds not only by the "quasi-cyclobutane" theory
but also by the delocalization of the double bond in
propylene upon adsorption.
-90-
VI. SFI'-'i:MARY
An investigation was unde~taken to study the
mechanism cf t~e aispr~portionation of propylene over
a cobslt oxide-molyb~ena-alumina catalyst. For the
investigation propylene - l - c14 was used as the
feeQ. A reaction system consisting of a tubular
reac-tor was employed, with a commercia:;_ Girdler
catalyst of 3.5 per cent cobalt oxide and ten per cent
molybdena being used. The catalyst was activated at
approximately 1000° F for six hours, and dry nitrogen
was passed over it throughout activation. The reactor
was operated at atmospheric pTessure at both 300 and 350°F
with a feed llow rate of one milliliter per second,
corresponding to a weight hourly space velocity of
approximately :.1 gram of feed per hour per gram of
ca-l:,alysto At these two ·0emperatures? high conversion
and selectivity of raction was obtained, and the
catalyst ~eactivated slightly with time-on-stream over
a period of 75 minutes~
Radioactive samples were collected in Hoke sampling
cylinders after the propylene-1 - c14 had oeen on
stream five min~tes. 14 Befo~e the propylene -1-C was
fed to the reactor, propylene had been passed over the
-91-
catalyst 15 minutes. From the sampling cylinde~s,
the samples were traLsferred to sample traps for
analysis.
The analysis of the s~mple consisted prirr.arily
of using a proportional counter attached to a gas
C:-1:comatograph. Thus, the radioactivity of each reactor
proQuct could be determined after separation by the
chromatographo This procedure permitted a one-step
analysis.
Results showea considarable radioactivity in both
ethylene and 2-butene productso The "g_uasi-cyclobutane 11
theory on the mechanism of the disproportionation of
olefins, which would re~uire radioactivity to appear
only in the et~ylene, thus does not rigorously apply.
It can therefore be concluded that delocalization of
the double bond in propylene occurs to some extent
upon adsorption.
1. ,,, H· dR .n.cne, • an • 28, 1968,
-92-
VII. BIBLIOGRAPHY
Finn: Personal Communication, August Va. Poly. Inst., Blacksburg, Va.
2. Banks, R. L. and G. C$ Bailey: Olefin Dispropor-tionation, IndJ Enga Chem., Prod. Res. and Develop., 2, 170-173 (1964).
3. ----,-,----,---,-and-~,----- Olefins Dispropor-tionated by New Catalytic Process, Chem. Eng. News, 70-71, April 20, 1964.
4. Benedict, M. and T. H. Pigford: "Nuclear-Chemical Engineering", pp .. 6-7. McGraw-Hill Book Co., Inc., New York, N. Y., 1957.
5. ibid, pp. 25-28.
6. Berkman, s., Jr°' c. Mo1'rell, and G. Egloff: "Catalysis", p. 95. Reinhold Publishing Corp., New York, N. Y., 1940.
7. ioid, pp. 140-146.
8. Bond 9 G. C.: "Catalysis by Metals", p. 3. Academic Press, New York, N. Y., 1962.
9. ibid, pp. 128-129.
10. Boundart, M. J. and G. Par~avano: Heterogeneous Catal;ysis, Ind. Eng. Chem., 50, no. 3, 486-488-
. ( l 958).
11. Bradshaw 9 C. P. C., E. J. Howman, and L. Turner: Olefin Dismutation: Reactions of Olefins on Cobalt Oxide-Molvbdenum Oxide-Alumina, J. Catalysis, 1, 269-276 (1967).
12. Brunnauer, s. J., P~ H. Emmett? and E. Teller: Adsorption of Gases in Multicomponent Layers, Jour. Am. Chem. Soc., 60, 309-314 (1938).
-93-
13. Burr, J. G.J Jr.: "Tracer Applications for the Study of Organic Reactio11.s, 11 pp. 1-12. Inter science Publishers, Inc., ~ew York, N. Y., 1957.
14. Ca ten, J. R.: 11Carbon -14 Compounds, 11 p. 68. Butterworth and Co., Washington, D.C., 1961.
15. ibid, p. 89.
16. C:-1.oppin, G. R.: "Nuclei and Radioactivity, 11 pp. 17-46. W~ A. Benjamin, Inc~, New York, N. Y., 1964.
17. ioid, p. 114.
18. Cvetanovic, R. J. and. Y. Amenomiya :. Application of
19.
a Temperature-Programmed Deso:;.~:ption Technique to Catalvst Studies" in "Advances in Ca·c,alysis" (D.D.Eley 1 et 2L, Editors), 17 , pp. 103-149 (1967L
Daniels, F. and R. Pl'• 607-612a N. Y., 1963.
A. Albe1,ty: "Physical Chemistry", John Wiley and Sons, Inc., New York,
20. Denbigh, K.: "Chemical Ree,ctor Theory", p. 42. Cambridge University Press, 1965.
21. Ernmet·t, P. H.,: Adsorpticn and Catal:zsis 9 J. Phys. Che;:-,1., 63, no. 4, 449-455 (19591.
22. ________ , P. Sabatier, and E~ E~ Reid: "Catalysis Then and Now," PPo 12-17. Franklin Publishing Co., Inc., Englewood, N. J., 1965.
23. ibid, p. 25.
24. Falk 1 K. G.: "Catalytic Action, 11 Pa 210 Chemical Catalog Co., Inc., New York, N. Y., l922.
25a Friedlande:r G. &nd Jo I-To Ke:..~necly: nrntroduc-bion to Raciiochemist:ry, 11 pp. 8-9 o John Wiley a:n.d Sons, Inc~J New York, N. Y., 1949.
26. i~id, p. 124.
27. Glascock, R. F.,: "Isotonic Gas Analvsis for Biochemists:1" pp. 48-86. Academic Press, In~., New York, N. Y., 1954.
-94-
28. Glassto:.::.e) S.: nso:n·cebook of Atorr:ic Energy 9 11
D. Van Nostrand Cc., Inc., Princeton, N.
29. ibid, ?P• 138-149.
30. ibid, y. 177.
31. Laidler 9 K. J. : "Chemical Kinetics" 7 pp. 265-276. McGraw-Hill Book Co., New York, N. Y., 1965.
32. Lever..spiel, O.: "Chemical Reaction Engin8ering") pp. 426-430. John Wiley and Sons, Inc., New Yoc~l- NT y 1c,,,..2
..ch, ·• •, ..t..:10 0
33. Lewis, M. J.: Kinetics of Propylene Disproportion&~ion oveY: a Cobalt Oxide-Molybdena-Alur,:Iina Catalyst. Unpublished PHaD. Thesis, Library, Va~ Poly. Inst., Blacksburg, Va., (1967).
34. Lohse:• H. W.: "Catalytic Chemistry 11 , p. 1. Chemical Publishing Company, Inc., Brooklyn, N. Y., 1945.
35. M$,ntell, Ce L.: ".Adsorption," p. 2. McGraw-Hill Book Co~, Inc., New York, N. Y. 9 1951a
36. Overman, R. T. and HD M., Clark: 11Radioisotope Tech-niques", pp. 25-29. McG:;,.~aw-Rill Book Coo, Inc., New York, N. Y., 1960.
37. Satterfield :1 C. N. a:ad T. K. Sherwood: 11The Role of Diff·..ision in Catalysis, 11 p. 12. Addison-Wesley Publishing Co., Inc., Reading, Mass., 1963.
38. i0id, pp. 21-22.
39. ibid, p. 26.
4L Schw2-b, G. M., H. s. Tayler, and R~ Spence: 11Ca,talysis 11 ,
p. 10. D. Van Nostrand Co., Inc., New York, N.Y., 1937.
42. ibid? p. 280.
43. Schweitzer, G. K~ and I@ BQ Wl1itney: "Radioactive Tracer Techniq_ues 11, p. 102. D. Van Nos~rand Co., Inc., New Ycrk, N. Y., 1949
-95-
44. Smith, J.M.: "Chemical Engineering Kinetics", pp. 206-208. McGraw-Hill Book Co., Inc., New York, N.Y., 1956.
45. ibid, p. 211.
46. ibid, pp. 231-232.
47.
48.
49.
50.
Taylor, H. S.: The Mechanism of CatalJtic Action, J. Phys. Chem., 30, 145-158 (1926).
Wahl, A. C.: "Radioactivity Applied to Chemistry", pp. 1-3. John Wiley and Sons, Inc., New York, N. Yo, 19510
Wheeler, A.: Reaction Rates and Selectivity in Catalyst Pores, in "Advances in Catalysis" (W. G. Frankenberi?, et al., Editors), l, pp. 249-327 (1951).
Wolkenstein, T.: The Electron Theory of Catalysis on Semiconductors, in "Advances in Catalysis" (D. D. Eley, et al., Editors), 12, pp. 189-195 (1960).
-96-
VIII. A8KKOWLELGMENTS
The author woult like to express his appreciation
to Dr. G. B. Wills, his thesis advisor, and to Dr. M. J.
Lewis, both of whom provided guidance end advice through-
out this investigation. He also expresses thanks to Dr.
Rans Acl-ie, M:..·. Ronald Finn, and Mr. H. L. Whitaker, Jr.,
for thGir assistance and aavice during t~is investigation.
The author also wishes to express his appreciation
to Texaco a~d the Department of Chemical Engineering for
providing financial assistance in the form of a fellow-
ship.
The two page vita has been removed from the scanned
document. Page 1 of 2
The two page vita has been removed from the scanned
document. Page 2 of 2
-99-
APPENDIX
-100-
E::perimental Dat,a.
The :eaction data obtained during this investigation
are presented in the following section. These data con-
sist of chromatogram peak areas for the various components
of the reaction effluent.
Effect of Temperature on Conversion and Selectivity.
Data for propylene conversion and selectivity of reaction
over commercial Girdler catalysts at te~peratures from
200 to 500° F and 15 pounds p0r square incn, gage, are
presented in Tables 1.'"VII and XVIII. Results calcuiated
from these data are given in Tables I through IV, pages
43 through 48.
Proµ:y:ene Conversion Yersus Time-on-Stream. Data for
propylerre conversion versus time-on-stream at 300 and
350° F and 15· pounds per squa?e inch, gage, over commer-
cial Girdler catalysts are presented in Tables XIX and
XX. Results calculated from these data are given in
Tables V ana VI, pages 51 and 52.
Propylene - l - c14 Conversion over Girdler Catalysts.
D t f l 1 ClL!- . . l a·a or propy ene - - conversion over commercia
Girdler catalysts at temperatures of 300 and 350° F and
atm0s,heric pressure are presented in Tables XXI and XXII.
Results calculated from these data are given in Tables VIII,
XV-, and XVI, pages 57, 70, and 71.
-101-
TABLE 1..'VII
Effect of Te:npe:::·atur-e on P:;_~opylene Conversion and
Selectivi-bv Co~nme:rcial Gi:rdler Catalyst
of 1 0% MoO~ and. 3" 5% CoO o:n Alumina at 1 5 --:; -- --- -- - - -
Temperature Ethylene P:copylene 2-Bute:ne 1-Bu-tene Peak Area Peak Area Peak Area Peak Area
OF sq ino sq_ in. sq_ in" sq in~
200 0 .. 159 1 o 569 0 Q 3Lj-8 OQ004
250 0.182 1.500 0.448 00013
300 0.220 1.445 0.493 0.035 ~, ') -.) .;., '.) 0~222 1 .. 210 0 .. 499 0.043
350 0.306 1.422 00535 C.063
375 00226 1.067 0.480 0.068
400 0.303 1.314 0 .. 570 o. 103
450 0.272 1.237 0.453 0.076
500 0~246 1 .470 0.427 0.062
-102-
TABLE XVIII
-r- n_o I .,0 ry1 l p - ("\ • .i!.iIJ:ec-c O.L ... empe:;:sa-cure .Q.£ ropylene vonversion and
Selectivi tv Commercial Girdle:c· Catalvst
nsig and _W1_ri_SV_= __ -: _. 3_ for 24 min Sam-ple
Temperature Et:hylene Propyle:ae 2-Bu-~ene 1-Butene Peak Area Peak Area Peak Area Peak Area
OF sq_ in. sq_ in, sq in. sq_ ij.J..
200 0.159 1. 650 0.359 0.004
250 0. 191 1.497 0.446 0.013
300 0~227 1 .450 Ov427 0.032
325 0.234 1 • 2: 6 0.524 0.057
350 0.292 1. 392 0.614 0.075
375 0.228 1.069 0.473 0.065
4~00 0.334 1.375 0.,569 0.085
450 0.266 1.278 0.444 0.069
500 0.214 1 • 381 0.374 0.060
-103-
T.ABLE XIX
Propylene Conv"ersion Versus Tine~ Com:nercial
Girdler Catalvst of 10% Mo03 and 3.5% CoO
_.QQ Alumina at 15 -osiP-, 300°f, and
1THSV = 1 a 3
'lime Ethylene Propylene 2-Butene 1-Butene Peak Area Peak Area Peak A:.~ea Pe.:1k Area
min sq_ in. sq_ in. sq_ ll'lo sc1 in.
5 0.213 1.389 0.496 0,045
1 5 0.220 1 .. 445 0.493 0.035
24 0.227 1a450 0.427 0.032
29 0.235 1 365 0.540 0.0-!:-4
37 0.233 1. 390 0.543 0.038
~-5 OJ238 1.462 G~550 0.036
53 0.238 1.445 0.553 0.036
61 0.240 1 • 421 0.505 0.035
7~ .'.) 0. 22"-~ 1.513 0.586 0.038
-104-
TABLE XX
Propylene Conversion Versus Time .QZ§£_ Co~mercial
Girdler Catalyst of 10% Mo03 and 3.5% CoO
.Q.g Alur;1i11a at 12. :2.§.ig, 350 °,E, &-nd
l'i1ISV = 1. 3
Time Et~1ylene Propylene 2-Butene 1-Butene Peak Area Peak Area Paak Area Peak Area
min sq in. sq ino sq in. sq in.
5 0.254 1 .. 270 0.539 0.080
15 0.306 1.422 0.535 0.063
24 0.292 1.392 0.614 0.075
30 0.,269 1 • 313 0.609 0.067
39 0.291 1.280 0.600 0.072
48 0.288 1 .. 378 0.570 0.062.
57 0.294 1. 378 0.580 0.063
66 o. 291 1.388 0.564 0.053
75 0.295 1.,360 0.569 0.063
-105-
TABLE XXI
Propylene-1-C 14 Conversion~ Commercial Girdler
Catalyst of 10% Mc03 and 3a5% CoO .Q:Q Alumina
at Q J?.§i.g, 300 °,E., and \'lliSV = 1 o 1
Test Ethylene Propylene 2-Butene 1-Butene Peak Area Peak Area Peak Area Peak Area
No sq in. sq in. sq in. sq in.
I 1.457 7.255 1.558 0.038
II 1.660 70080 1. 676 0.048
III 1 .479 8.970 1.870 0.043
""/ /"",/" -.Luo-
TABLE XXII
-P - -1 c14- r. • C . 1 G. , -- rony1.ene- 1 - vonversio::~ ommer~ i2, irQl.er
Ca talvst of 'i 0% Mo03 and 3 5% CoO 52..f:. Alumina
at .Q psi r; , 3 5 0 °,!, and W1ISV = 1 1
Test. Ethylene Peak Area
Propylene Peak Area
2-But0ne Peak .Area
1-Bi.:..tene Peak Area
No sq_ i:..1~ sq_ ino sq_ in_ sq_ in.
I 2. 6L'.-O ;1,.800 4 .. 268 o. 571
II 1. 786 7.655 2.508 0c350
III 1 .. 504 6.230 2.044 Oe231
ABSTR) .. CT
STJDY CF THE }~l~CHANISM OF THE
DISPRO?ORTION=TIO~ OF PROPYLENE CVER A
COBALT OXIDE-YOLYBDENA-kLillIINA
CATALYST THROGGH THE USE OF A
:2ADIOACTIVE TR~\CER
by
Fred. L. Woody
An investigaiion was u.n.dertaken to study the
@ectanism of the dispro~ortionation of propylene over
a cob~lt oxide-molyodena-alumina catalysto For the
. . . _,_. 1 c14 - 'h invest1gav1on propy ene - l - was used as~ e
leed. A reaction syst0m consisting of a ~ubular
rcac~or was employed, with a commercial Girdler
catalyst of 3.5 per cent cobalt oxide and ten per cent
~olybdena being usedo The catalyst was activated at
approx~~ately 1000° for six hours, and dry nitrogen
was pass8d over it throughout activation. The reactor
was operated at atmospceric pressure at both 300 and 350°P
with a fee~ 1low rate of one milliliter per second,
corresponding to a weight hourly space velocity of
ap?roxi~a~ely 1.: gram of feed per hour par gram of
catalyst. At these two temperatures, high conv~rsion
and selectivity of reaction was obtained, and the
catalyst deactivated slightly with time-on-stream over
a period of 75 minutes.
Radioactive samples were collected in Hoke sampling
cylinders after the propylene - l - c14 had been on
Cl4 st~eam five minutes. Before the propylene - 1 - was
fed to the rea, -::,or, propyle::ie had been :passed over the
catalyst 15 minutes. From the sampl,ing cylinders,
the samples were transferred to sample traps for
ana:i.ysis.
The analysis of the sample consisted primarily
of ~sing a proportional counter attached to a gas
chromatograph. Thus, the radioactivity of each reactor
prod~ct could be determined after separation by the
chromatograpn. This procedure permitted a one-step
ana:...ysis.
Results showed considerable ~adioactivity in both
t}1e ethylene and 2-butene products. The "quasi-cyclo-
butane II theory on ·the mechanism of the disproportionation
of olefins, which would. require radioactivity to appear
only in the ethylene, thus does not rigorously apply.
It can therefore be coccluded that delocalization of
the do~ble bond in propylene occurs to some extent
upon adsorption.
![Synthesis of Photoluminescence Si Nanoparticles: Size … · 2019. 8. 2. · mechanochemical disproportionation of silicon monoxide (SiO) [63-67], microwave-assisted reduction of](https://img.dokumen.tips/doc/110x75/60f69068a4170821fc7a79f2/synthesis-of-photoluminescence-si-nanoparticles-size-2019-8-2-mechanochemical.jpg)