Fluidized Bed Thermal Degradation Products Of

8/6/2019 Fluidized Bed Thermal Degradation Products Of

1/17

Fluidized bed thermal degradation products of

HDPE in an inert atmosphere and in air/nitrogenmixtures

F.J. Mastral *, E. Esperanza, C. Berrueco, M. Juste,J. Ceamanos

Department of Chemical and Environmental Engineering, Centro Politecnico Superior, University of

Zaragoza, C/Mara de Luna, 3, 50018 Zaragoza, Spain

Received 25 October 2001; received in revised form 17 January 2002; accepted 7 June 2002

Abstract

Different processes involving thermal decomposition such as incineration, pyrolysis,

gasification or co-combustion are becoming important for energy generation using plastic

wastes as combustible materials. The thermal degradation of the material, the product

distribution and consequently the economics of the process are strongly influenced by the

experimental conditions used. In this work, the thermal degradation of high-density

polyethylene (HDPE) has been carried out using a fluidized bed reactor under different

temperature conditions. Two types of experiments have been performed, pyrolysis experi-

ments, in which nitrogen has been used as inert gas, and gasification experiments, meaning

that the thermal decomposition has been carried out in a nitrogen/air mixture with low

oxygen concentration. The influence of the operating parameters on the product distribution

and gas composition has been investigated using GC and MS/GC for the analysis of the gas,

wax and oil fractions obtained. The results obtained show a widely differing product yield in

both processes. The main objective of the paper is a comparison of pyrolysis and gasification

in terms of the generation of products of high heating value, and the energy requirements for

the thermal degradation and production of residues and polyaromatic compounds. An

optimum interval of operation temperatures is suggested in order to obtain high yield to gases

of high heating values and low yield to PAHs.

# 2002 Elsevier B.V. All rights reserved.

Keywords: Polyolefins; Pyrolysis; Gasification; Fluidized bed; HDPE; Polyethylene

* Corresponding author. Tel.: '/34-976-76-2160; fax: '/34-976-76-1879.

E-mail address: [email protected] (F.J. Mastral).

J. Anal. Appl. Pyrolysis 70 (2003) 1/17

www.elsevier.com/locate/jaap

0165-2370/03/$ - see front matter # 2002 Elsevier B.V. All rights reserved.

doi:10.1016/S0165-2370(02)00068-2
mailto:[email protected]:[email protected]


2/17

1. Introduction

The high consumption of polymeric materials means that they are a significant

share of solid waste (either municipal or industrial). The disposal of this waste hasbecome a technological, business, political and social issue that has attracted the

attention of researchers, businessmen, politicians, environmental activists, and the

general public.

Given their high calorific value, plastics can be recycled for energy recovery. When

mixed and incinerated with municipal solid wastes, plastics contribute to the safe

combustion of the mixture and generate valuable energy. In other thermal

degradation processes, they can replace other fuels in different proportions, saving

primary fossil fuels. Fuels derived from specific, separated plastics and combined

with a lignocellulosic fraction can be an important substitute for coal in cement

manufacture or for electricity generation in a power plant. In pyrolysis processes, theenergy necessary is supplied by partial combustion of the feed material or the gases

produced. In the latter case, it would be very interesting to compare the yields and

the product distributions obtained both in strict pyrolysis conditions, using nitrogen

as fluidizing agent, and in partial combustion conditions, using air and nitrogen as

fluidizing agent.

One of the materials present in significant quantities in municipal solid waste is

polyethylene. The pyrolysis of polyethylene has been the subject of numerous

studies, such as thermal decomposition kinetics [1/4] or temperature influence on

product yields [5/8]. These experimental studies have been carried out in fluidized

bed, with an inert gas as fluidizing agent. Other studies using steam or pyrolysis gas

as fluidizing agent have been carried out by Kaminsky et al. [9]. The reaction

mechanisms that generate the different pyrolysis products have been considered by

Bockhorn et al. [2], Ranzi et al. [3], Williams and Williams [8], Poutsma et al. [10],

McCaffrey et al. [11], and Savage et al. [12].

In this work, the results of product yields from the degradation of HDPE obtained

under pyrolysis and gasification conditions are shown. The temperature interval

used ranges from 640 to 850 8C. The main goal is the study of the influence of the

atmosphere in which the thermal decomposition takes place and the temperature on

the product distribution and heatingv

alue of the generated gas.

2. Experimental

2.1. Laboratory scale pyrolysis plant

The experimental system used in this work is shown in Fig. 1. The study was

carried out using a stainless steel, fluidized bed reactor 4.8 cm in diameter and 23 cm

in height. The material bed was 0.25/0.27 mm silica sand with a static bed depth of

80 mm. The reactor was externally heated using an electrical ring furnace. The bedtemperature was measured by a K type thermocouple inside the bed. The HDPE

pyrolysis and gasification runs were carried out at bed temperatures of 640, 700, 730,

F.J. Mastral et al. / J. Anal. Appl. Pyrolysis 70 (2003) 1/172


3/17

780 and 850 8C. HDPE manufactured by HOECHST (HOSTALEN GH 4765),

with a density of 0.958 g cm(3, a softening point of 80 8C and a mean particle

size of 0.225 mm was used in this work. Polyethylene was fed continuously into the

bed at a rate of 3/4 g min(1

using a pneumatic water-cooled feeder in order to avoidthe melting of the material before entering the reactor. In order to obtain a

continuous solid flow into the reactor, an important fraction of the total gas

flow used in the experiments was used in the feeding process, while the rest (either

pure nitrogen in the pyrolysis experiments or a mixture of air and nitrogen

in the gasification experiments) was preheated at the reactor temperature before

entering the lower part of the fluidized bed. Some preliminary experiments were

carried out in order to determine the fraction of the gas flow necessary for the

feeding and the fluidization. For gas velocities three times the minimum fluidization

velocity (Umf), gas flow for feeding amounted to 70% of the total gas flow, whilst for

gas velocities five to seven times the Umf, gas flow for feeding was 50% of the total

gas flow.

Two types of experiments were carried out, designated as pyrolysis and

gasification experiments. A flow of nitrogen was used as carrier gas and fluidizing

agent in the pyrolysis experiments. A flow of either air or air/nitrogen mixtures was

used as the fluidizing gas in the gasification experiments. Since different gas yields

are obtained depending on the temperature used, the mixtures were used to obtain a

similar residential time and air ratio for all experiments. At low temperatures (640

and 700 8C) mixtures of nitrogen and air were used, whilst air only was used in the

gasification experiments carried out at higher temperatures. The air ratio imposedfor all the experiments was in the range of 6/7% of the stoichiometric air for HDPE

combustion.

Fig. 1. Experimental system diagram.

F.J. Mastral et al. / J. Anal. Appl. Pyrolysis 70 (2003) 1/17 3


4/17

The operation flows used provided a fluidizing gas velocity five to eight times the

Umf. The average Umf of the sand used in the bed was experimentally found to be 2.2

cm s(1. The residence time of the gas in the reactor had values between 0.81 and 1.45

s, calculated in each experiment at the bed temperature, taking into account the totalgas flow produced and considering the internal volume of the reactor (the sand bed

and freeboard), the cyclone and the connections between the reactor and the cyclone

and between the cyclone and the water condenser.

The product stream was passed through the cyclone to remove any particulate

matter. The resulting stream of vapors was passed through a cool water heat

exchanger at 20 8C, where some heavy hydrocarbons were condensed (oil or waxes).

The remaining lighter components were condensed using an ice/NaCl bath at (/

10 8C. The exit flow was divided into two fractions: the largest one being passed

through silica gel in order to retain the wax and oil carried by the gas in the form ofaerosol. The smaller fraction was passed through two ice/NaCl condensers at (/

10 8C. Part of the flow from the condensers was collected online in a nylon bag for

analysis during the experiment. The rest of the flow from the condensers was passed

through a silica gel tube in order to retain the remains of waxes or oils. This flow was

introduced into an online CO/CO2 detector and exited the system. The experiments

lasted from 20 to 25 min.

2.2. Analysis

The gas fraction was analyzed by gas chromatography using a HP 5890 series II,

with a semi capillary column HPPLOT/Al2O3, 50 m)/0.53 mm)/15 mm, and a

molecular sieve 0 . 9 m)/3 mm packed with 45/60 mesh, using two detectors

connected in series: a thermal conductivity detector (TCD) and a flame ionization

detector (FID). The concentration of H2, N2, CO and CO2 were determined by the

TCD detector whilst the rest of hydrocarbon components from C1 to C6 were

detected by the FID.

Waxes and oils were collected, weighed and analyzed by GC/MS. For purposes of

analysis, the oil and waxes were first dissolved in tetrahydrophurane (THF). The gaschromatography mass spectrometry consisted of an HT-5 aluminum clad column, 25

m)/0.32 mm)/0.1 mm (non polar) with a Tmax 450 8C. Helium was used as carrier

gas with a flow rate of 1 ml min(1. Samples of 1 ml were injected, with a split mode

(20:1).

The high temperature column enabled oven temperatures of 400 8C to be reached

ensuring that hydrocarbons up to C60 could be analyzed. The temperature program

was 40 8C for 2 min followed by a heating rate of 5 8C min(1 up to 180 8C, then an

increase up to 350 8C at a heating rate of 10 8C min(1, and finally 10 min at

3508

C. Since no components were detected at temperatures over 3308

C, themaximum oven temperature used was 350 8C. The ion trap detector had a mass

range from 32 to 800 amu and was linked to a computer with a Wiley library.



5/17

3. Results and discussion

3.1. Product yields

The pyrolysis and gasification of HDPE were carried out in the experimental

system previously described using different reactor temperatures. Table 1 shows the

yields to the different fractions obtained in the two types of experiments, referring to

the mass of HDPE fed, and for reactor temperatures ranging from 640 to 850 8C.

Table 1 also shows the main experimental conditions used in the experiments

performed: residence time, air ratio and real temperature in the reactor. The carbon

and hydrogen mass balances of the products, quite close to 100%, are also shown in

Table 1. The total yields over 100% observed in the gasification experiments are due

to the fact that the oxygen fed appears as a part of the products obtained. In the caseof the pyrolysis experiments, slight variations from 100% are also observed. They can

be explained taking into account that, since the total gas flow exiting the system is

not measured, the balances are solved using the nitrogen balance and the

composition of the different fractions. These compositions are measured at different

moments during the experiment, so slight variations can be observed.

A high quantity of waxes and oils were found in the pyrolysis and gasification

experiments carried out at 640 and 700 8C (real temperature), this mixture

presenting a higher viscosity at 640 8C than at 700 8C. In the pyrolysis experiments,

the yield was 68.5% at 640 8C and 39.6% at 700 8C. In the gasification experiments,

the wax'/oil yield was 51.6% at 645 8C and 35.4% at 700 8C. The variation of

fraction yields (gas, oil and wax) with temperature is shown in Fig. 2. As can be

observed, for low temperatures the yield to gas increases as the temperature increases

in both pyrolysis and gasification experiments. For temperatures in the range of

640/730 8C, this marked increase of the yield to gas ranges from 33.5 to 91.7 wt.%

in pyrolysis and from 54.2 to 104.6 wt.% in gasification. For higher temperatures, in

the range of 730/850 8C, the yield to gas reaches an approximately constant value in

both processes. A small amount of char, not quantified, appeared in waxes and oils.

As can be seen when comparing pyrolysis and gasification experiments, the wax'/oil

yields arev

ery similar at the different temperatures studied except at 6408

C atwhich a higher yield is obtained under pyrolysis conditions. For the rest of the

temperatures studied, yields to wax'/oil are slightly higher in pyrolysis. Yields to gas

in gasification are higher than in pyrolysis in all temperature intervals studied.

Fig. 3 shows the variation of the yields to the different fractions (gases except CO

and CO2, CO/CO2, olefins, oxygenated compounds and aromatics). Different

observations can be noted: CO and CO2 are obviously not observed in the pyrolysis

experiments and the yield to olefins decreases rapidly as the temperature increases,

this fraction being more abundant in the pyrolysis experiments. As can be observed,

the yield to aromatic compounds increases as the temperature increases and similar

values are obtained regardless of which gas is used in the experiments. Theoxygenated fraction, relatively important in gasification experiments carried out at

low temperatures, decreases down to zero over 730 8C.



6/17

Table 1

Product yields (wt.% of feed) and component mass balances for pyrolysis and gasification of HDPE

Temperature (8C) 640 680 730 780

Process Pyrolysis Gasification Pyrolysis Gasification Pyrolysis Gasification Pyrolysis

Residence time(s) 1.45 1.4 1.3 0.9 1.3 1.2 0.81

Air factor 0 6.1 0 6.9 0 6.1 0 Real temperature 640 645 700 700 730 730 780

Gas yield 33.5 54.2 69.4 86.7 91.7 104.6 102.2

Wax'/oil yield 68.5 51.6 39.6 35.4 18 14.3 9.6

Aqueous phase 0.0 5.2 0.0 4.2 0.0 3.5 0

Hydrogen mass balance 102 90 112 103 112 100 111

Carbon mass balance 102 91 109 105 109 102 112


7/17

3.2. Gas composition

Table 2 shows the yields to the different gas species obtained in the pyrolysis and

gasification processes. As previously mentioned, the main difference observed

between the gasification and pyrolysis experiments is the production of some gasspecies such as carbon dioxide, carbon monoxide and water in gasification, due to

the HDPE partial combustion and reduction reactions. The yield to hydrogen is

Fig. 2. Influence of the experiment temperature on fraction yields.

Fig. 3. Influence of the experiment temperature on product yields.



8/17

Table 2

Product yields (wt.% of feed) for pyrolysis and gasification of HDPE

Temperature (8C) 640 680 730 780

Process Pyrolysis Gasification Pyrolysis Gasification Pyrolysis Gasification Pyrolysis G

H2 0.09 0.23 0.60 0.80 0.60 1.41 0.60 1

O2 0.00 3.40 0.00 1.00 0.00 0.60 0.00 0

CO 0.00 6.65 0.00 11.00 0.00 14.60 0.00 1

CO2 0.00 11.10 0.00 14.30 0.00 11.30 0.00 7

CH4 2.20 2.91 4.80 5.60 7.80 6.40 9.70 9

C2H4 7.60 13.25 17.00 20.00 25.30 24.60 37.00 3C2H6 2.10 1.67 3.40 3.10 4.80 3.10 3.80 2

C3 8.00 8.84 17.40 13.20 23.70 17.50 20.00 1

C4 9.50 9.00 17.00 12.00 17.00 13.90 13.00 7

Oxygenated 0.00 14.35 0.00 15.80 0.00 0.55 0.00 0

Aromatic 1.50 2.28 4.86 8.13 12.62 14.55 21.71 2

C5/C8 14.90 4.43 31.10 6.40 13.14 7.30 5.33 1

C9/C12 7.70 8.70 4.10 3.80 1.90 2.30 0.70 0

C13/C19 14.40 10.30 5.90 5.07 1.70 0.74 0.00 0

C19/C32 23.00 5.25 2.80 1.55 1.10 0.03 0.00 0

C33/C60 11.00 3.40 0.00 0.27 0.00 0.00 0.00 0


9/17

relatively low and increases in both types of experiments as the temperature

increases. Higher values are observed in the presence of oxygen.

The variation of the yields to CO and CO2 obtained in the gasification

experiments and the CO/CO2 ratio with temperature are shown in Fig. 4. As canbe observed, the CO/CO2 ratio increases as the temperature increases, favored by the

Boudouard and water shift reactions, given their endothermicity. At low tempera-

tures, up to 700 8C, the combustion reaction is predominant, resulting in relatively

low yields to CO and high yields to CO2.

The variation of H2 and CH4 yields with temperature for pyrolysis and

gasification experiments is shown in Fig. 5. The endothermic water gas and water

shift reactions can also explain the higher yield to H2 observed at high temperatures

in the gasification experiments. In the pyrolysis experiments carried out, propagation

reactions generate hydrogen at low temperatures whilst the dehydrogenation

reactions to generate aromatic compounds are responsible for H2 formation at

high temperatures [10,13/15]. When comparing hydrogen production, similar trends

are observed for pyrolysis and gasification experiments although higher values are

observed for gasification experiments at high temperatures, due to the above

mentioned equilibria. As can be observed in Fig. 5, temperature strongly affects the

yields to CH4, obtaining similar values in both processes. Methane is a stable

product of the propagation reactions of the thermal decomposition of polyethylene,

as has been suggested by different authors [15,16].

The yields to ethylene and ethane and their ratio is shown for both types of

experiments and different temperatures in Fig. 6. For reactor temperatures up to730 8C, the yield to ethylene is higher in the gasification experiments. Under these

experimental conditions a decrease of the yield to heavy hydrocarbons is also

observed. In the temperature interval from 730 to 850 8C, the ethylene yield is higher

in the pyrolysis process. The ethylene/ethane ratio increases in both processes with

Fig. 4. Variation of CO and CO2 production and CO/CO2 ratio with gasification temperature.



10/17

temperature, and is always higher in gasification than in pyrolysis. This would be

explained by the more severe cracking conditions in the presence of oxygen. The

difference between gasification and pyrolysis processes is mainly due to the presence

of the hydroxyl and hydroperoxy radicals, playing a relevant role in the formation of

ethylene. In the presence of oxygen, abstraction of H-atoms by OH radicals shows a

lower activ

ation energy than the H and CH3 radicals (3.5v

s. 10/12 kcal mol

(1

),lowering the apparent activation energy of the overall process from 52/55 to 43/46

kcal mol(1 and explaining the higher reactivity observed in the gasification

experiments.

Fig. 5. Variation of H2 and CH4 production with pyrolysis and gasification temperature.

Fig. 6. Variation of C2H4 production and C2H4/C2H6 ratio with pyrolysis and gasification temperature.



11/17

The fractions C3 (mainly propylene) and C4 (mainly butadiene) show a maximum

yield at 730 8C. These fractions, produced by the cracking of heavy olefins, also

undergo further cracking leading to gas compounds of lighter molecular weight. For

temperatures above 730 8C, these fractions react to generate aromatic compoundsthrough Diels Alder reactions, favored under these conditions by condensation and

dehydrogenation reactions. The maximum yields to these fractions are explained by

the combined effect of cracking reactions and aromatic production reactions.

The heating value of gas products in pyrolysis and gasification processes is shown

in Fig. 7. The heating value increases up to approximately 780 8C, whilst decreasing

slightly from 780 to 850 8C, the latter fact coinciding with the increase in aromatic

formation. The heating value is lower for gasification than for pyrolysis due to the

partial combustion of the HDPE fed.

3.3. Liquid composition

An important amount of wax, including hydrocarbons of up to sixty carbon atoms

is produced at low temperatures (645 8C). In the pyrolysis process these hydro-

carbons are mainly olefins and diolefins, paraffins appearing only in minor

proportions. As the temperature increases a more intense cracking of heavy

hydrocarbons occurs to produce gases and light fractions. The yield to the olefinic

fraction decreases as the temperature increases, and falls to negligible values at

temperatures over 780 8C. The yield to aromatic compounds increases as the

temperature increases. Heavier polyaromatic compounds are also generated, theiryield also increasing as the temperature increases.

The influence of the reactor temperature and the experiment type can be observed

in Figs. 8 and 9. The product chromatograms of the product distribution under

different conditions are shown as examples in Fig. 8. In Fig. 9, some products have

been lumped together for the sake of simplicity of data analysis. The most important

difference between the pyrolysis and gasification processes is observed at low

temperatures. In gasification, oxygenated compounds appear, and the olefinic

Fig. 7. Heating value of gas products.



12/17

fraction is smaller than that observed in pyrolysis. For temperatures higher than

730 8C the liquid composition is similar in both pyrolysis and gasification

experiments.

In Fig. 10 aromatic compounds are detailed. Benzene and naphthalene production

increases as the temperature increases. At a given temperature, the results show

similarv

alues in pyrolysis and gasification, being slightly higher in the case ofgasification. In all conditions benzene is the most abundant aromatic compound.

The product distributions observed can be explained qualitatively taking into

account the mechanisms of thermal degradation suggested by different authors

[2,3,10/13,15/18] and shown in Fig. 11. In general, the polymer cracking reactions

to yield smaller olefinic chains and gases (as experimentally observed in Fig. 3). At

higher temperatures secondary reactions yield aromatic and polyaromatic com-

pounds (also observed in Figs. 3, 8/10). In gas-phase, where the substrate

concentration is low, and at high temperatures, the Rice/Kossiakoff mechanism

[17] predicts the formation of mainly alkenes, C2H4, CH4 and H2, with only very

small amounts of alkanes and dialkenes being formed. Similar trends are shown inthe experimental data obtained (Figs. 5 and 6). As temperature is increased, more

scissions in the polymer chain occur leading to a high number of short primary

Fig. 8. CG/MS chromatograms of the liquid products of pyrolysis and gasification.



13/17

radicals, which undergo successive b-scission reactions and eliminate small molecules

(this coincides with the results obtained, with the gas yield increasing as thetemperature increases, and the high production of ethylene). Moreover, the higher

radical concentration favors intermolecular hydrogen transfer (the higher concen-

Fig. 9. Comparison of product distribution under pyrolysis and gasification conditions. Influence of

temperature.



14/17

tration increases the bimolecular reaction probability), to generate alkanes (reaction

V in Fig. 11). Different mechanisms have been suggested for explaining the

formation of benzene and other aromatic compounds such as the combination

reactions between conjugated dienes and unsaturated compounds followed bydehydrogenation [5].

4. Conclusions

The operation temperature has an important influence on the product distribution

and on the gas composition due to the secondary reactions occurring in the

freeboard. As the temperature increases, the gas production increases and the oil andwax production decreases in both pyrolysis and gasification processes. When

considering the partial oxidation of the HDPE, as carried out in the gasification

experiments, the system becomes more complex and a higher reactivity is observed.

In HDPE fed basis, a higher production of light products (H2, CH4, C2H4) and a

decrease of the yield to heavy fractions is noticed. At low temperatures the presence

of oxygen causes a more intense cracking effect. The relative importance of the

temperature (compared with that of the oxygen concentration) in the severity of the

oxidation increases as the temperature increases, so that the difference observed with

the pyrolysis experiments is more important at low temperatures. A higher

production of ethylene is noticed in the presence of oxygen at temperatures below730 8C. This fact coincides with a reduction of the average molecular weight of

heavy products. The products present in higher percentages are ethylene in gases and

Fig. 10. Comparison of aromatic product distribution under pyrolysis and gasification conditions.

Influence of temperature.



15/17

Fig. 11. General mechanism of the thermal degradation of polyethylene.



16/17

benzene in liquids, the maximum production of these compounds appearing at

850 8C.

The product distribution can be qualitatively explained taking into account the

mechanisms of thermal degradation of PE. Some of the experimental observationson the variation of the gas yield with the temperature, the significant generation of

ethylene, the formation of alkenes, alkanes and dialkenes in the wax fraction and

their dependence on the temperature variation corroborate the generally accepted

mechanism. The increase in the formation of aromatics as the temperature increases

is also explained. In the presence of oxygen, the thermal decomposition process is

similar to that observed under pyrolysis conditions, although a slight increase in the

reactivity is observed, which favors the decomposition of heavy compounds.

The results obtained show that, by using a correct proportion of air, a self-

sustaining regime could be attained in order to avoid any additional combustible or

external heating as required when the decomposition is carried out under pyrolysisconditions. If gasification is used, a suitable gas composition could be obtained for

electricity generation at relatively low temperatures, the optimum being between 680

and 730 8C. This temperature range also avoids a high production of heavy

polyaromatic compounds, which can be problematic. The low temperatures would

also result in a reduction of heat losses and would decrease the wax fraction and the

generation of oxygenated compounds (except CO and CO2).

Acknowledgements

The authors express their gratitude to CICYT (project QUI 98-0669) for providing

financial support for this work.

References

[1] J.A. Conesa, R. Font, A. Marcilla, Energy Fuels 11 (1997) 126.

[2] H. Bockhorn, A. Hornung, U. Hornung, D. Aschawaller, J. Anal. Appl. Pyrol. 48 (1999) 93.

[3] E. Ranzi, M. Dente, T. Faravelli, G. Bozzano, S. Fabini, R. Nava, V. Cozzani, J. Anal. Appl. Pyrol.40/41 (1997) 305.

[4] R.W.J. Westerhout, J. Waanders, J.A.M. Kuipers, W.P.M. Van Swaaij, Ind. Eng. Chem. Res. 36

(1997) 1955.

[5] J.A. Conesa, R. Font, A. Marcilla, N. Garca, Energy Fuels 8 (1994) 1238.

[6] W. Kaminsky, J. Phys. IV 3 (1993) 1543.

[7] D.S. Scott, J. Piskorz, D. Radlein, Ind. Eng. Chem. Proc. Des. Dev. 24 (1995) 581.

[8] P.T. Williams, E.A. Williams, J. Anal. Appl. Pyrol. 51 (1999) 107.

[9] W. Kaminsky, B. Schlesselmann, C. Simon, J. Anal. Appl. Pyrol. 32 (1995) 19.

[10] M.L. Poutsma, J. Anal. Appl. Pyrol. 54 (2000) 5.

[11] W.C. McCaffrey, D.G. Copper, M.R. Kamal, Polym. Degrad. Stab. 62 (1998) 513.

[12] P.E. Savage, J. Anal. Appl. Pyrol. 54 (2000) 109.

[13] H. Bockhorn, A. Hornung, U. Hornung, J. Anal. Appl. Pyrol. 50 (1999) 77.

[14] G. Montaudo, C. Puglisi, Polym. Degrad. Stab. 33 (1991) 229.

[15] E. Ranzi, M. Dente, A. Goldaniga, G. Bozzano, T. Faravelli, Prog. Energy Comb. Sci. 27 (2000) 99.



17/17

[16] T. Faravelli, G. Bozzano, M. Scassa, S. Fabini, E. Ranzi, M. Dente, J. Anal. Appl. Pyrol. 52 (1999)

87.

[17] F.O. Kossiakoff, Rice, J. Am. Chem. Soc. 65 (1943) 590.

[18] R.P. Lattimer, J. Anal. Appl. Pyrol. 31 (1995) 203.


Documents

Fluidized Bed Thermal Degradation Products Of