2013-04-20

2013-04-20

学科专业：化学工艺报告学生：付廷俊指导教师：李振花 研究员

碳载体孔容结构和钴颗粒尺寸对钴基催化剂费托性能的影响

天津大学化工学院

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主要内容

2. 实验方法与实验装置

3. 实验结果及讨论

4. 结 论

1. 研究背景

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1.1 催化剂微观结构与费托反应活性的相互关系

The FT activity of supported cobalt catalyst

The area of the exposed

metallic cobalt atoms

Cobalt dispersion and reducibilityTextual properties

of supports

Pore diameter of support

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1.2 钴基催化剂载体种类对费托反应的影响

Conventional support materials ：

Titania ， alumina , silica and zirconia.

Can yield cobalt species with high dispersion.

But highly dispersed cobalt species could be reduced only at elevated temperatures (exceeding 1000K).

New support materials ：

CNTs, Cs CNF

Can allow great metal dispersion. Highly dispersed cobalt species could be reduced at lower.

Textural propertie

s

?

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主要内容

2. 实验方法与实验装置

3. 实验结果及讨论

4. 结 论

1. 研究背景

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2.1 催化剂的制备

等体积浸渍 干燥 热焙烧 还原 静置 催化剂

载体： CNTs8 、 CNTs20 、 CNTs60 、AC

前驱体： Co(NO3)26H2O

： Co/CNTs8

： Co/ CNTs20

： Co/ CNTs60

： Co/AC

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2.2 表征方法

氮气物理吸附（ BET ） 程序升温脱附（ TPD ） 程序升温还原（ TPR ） X 射线衍射（ XRD ） 透射电镜（ TEM ）

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170C 4C

Instu-reduced condition: H2 100 ml/min ， 400 C 10 h

Reaction conditions:

P = 2.0 MPa ， T = 230 C ， H2/CO = 2 ， WHSV=6750 /5400mL/(h.g)

2.3 F-T 合成反应评价装置

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主要内容

2. 实验方法与实验装置

3. 实验结果及讨论

4. 结 论

1. 研究背景

Tianjin University

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SampleBET surface area

(m2/g)Pore volume

(cm3/g)Average pore size

(nm)

AC 1443.9 0.91 1.0

CNTs8 305.8 0.19 3.3

CNTs20 243.2 0.65 10.8

CNTs60 119.0 0.40 14.8

Co/AC

Co/CNTs8 236.5 0.14 3.4

Co/CNTs20 188.2 0.34 8.3

Co/CNTs60 109.8 0.23 10.4

Table 1 Textual properties of carbon supports and as prepared catalysts obtained by N2 adsorption–

desorption.

3.1 催化剂及载体的氮吸附脱附表征

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3.2 载体的石墨化程度

10 20 30 40 50 60 70 80

In

tens

ity (

a.u.

)

2-theta(degree)

AC CNTs8 CNTs20 CNTs60

Fig. 1. XRD patterns of carbon materials

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3.3 催化剂的 XRD 及 TEM 表征

Fig.2. XRD patterns and TEM images of as-prepared catalysts .

10 20 30 40 50 60 70 80

Inte

nsity

(a.

u.)

2-theta(degree)

CoAC CoCNTs8 CoCNTs20CoCNTs60

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Fig.3. TEM images of the different catalysts after reduction followed by a passivation treatment. a:Co/AC, b:Co/CNTs8,

c:Co/CNTs20, d:Co/CNTS60

3.4 还原后催化剂的微观形貌 -- TEM

a

c

b

d

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3.5 催化剂微观结构的定量计算

Catalysts

Particle size(nm) H2 chemisorption

dCo3O4XRD dCo3O4

TEM dCoI dCo

TEM H2 uptake(μmol/g)

DispersionII

(%)TOF(s-1)

Co/AC 3.3 3.0 2.5 4.6 46.6 2.9 0.15

Co/CNTs8 4.2 4.3 3.2 7.7 47.9 3.0 0.23

Co/CNTs20 7.3 6.1 5.5 6.9 88.2 5.6 0.10

Co/CNTs60 8.7 7.6 6.5 20.3 70.6 4.5 0.098

.I determined by the molar volume correction of corresponding Co3O4 size of unreduced catalysts using the equation d(Co) = 0.75d(Co3O4). II Assuming H2/Co =2.

Table 2 Cobalt particle size and dispersion measured from TEM, XRD and H2 chemisorption.

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3.6 催化剂的氢还原性能

CatalystsPeak area/ % H2 consumption/cm3.(g cat.) 1

Reducibility ratio

AI+AII AIII

Sum H2

consumptionCo3O4

reductionCarbon

gasification

Co/AC 38 62 167.9 63.8 104.1 0.66

Co/CNTs8 44 56 159.6 70.2 89.4 0.75

Co/CNTs20 50 50 160.4 80.2 80.2 0.83

Co/CNTs60 58 42 166.5 96.6 69.9 1

Table 3 Quantitative analysis of the H2-TPR profiles of the as-prepared catalysts

100 200 300 400 500 600 700 800

d

c

b

IIII

TC

D S

ign

al

(a.u

.)

Temperature (oC)

II a

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3.7 费托合成反应性能

CatalystsCO

conversion (%)

CO2 selectivity

(%)

Hydrocarbon selectivity (%)

C=/C-a

CH4 C2 C3 C4 C5+

Co/AC 50.9 0.65 25.6 0.98 1.9 1.4 70.0 0.238

Co/CNTs8 80.2 1.45 19.8 0.86 1.3 0.8 77.2 0.244

Co/CNTs20 82.2 0.98 12 0.55 0.97 0.68 85.8 0.405

Co/CNTs60 62.0 0.93 10.6 0.53 0.84 0.63 87.4 0.495

Table 4 The F-T Synthesis results of the different carbon supported Co catalysts

a mainly for C2-C4 products

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3.8 费托合成反应烯烷比与 C5+ 的关系

68 70 72 74 76 78 80 82 84 86 880.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

C5+

C=

/C-

Fig.4. Relation between the C2-C4 olefin/paraffin ratio and

the C5+ selectivity on different catalysts.

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3.9 费托合成反应 TOF 的影响因素

0 2 4 6 8 10 12 14 160.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

TO

F/S-1

Pore size/nm

B

Fig.5. Relation between the TOF and the pore size on different catalysts.

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4 6 8 10 12 14 16 18 20 220.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

TO

F/s

-1

Cobalt Size/nm

Fig.6. Relation between the TOF and cobalt size on different catalysts.

3.10 费托合成反应 TOF 的影响因素

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4 6 8 10 12 14 16 18 20 222

4

6

8

10

12

14

16

18

20

22

Dis

pe

rsio

n/%

cobalt size/nm

Actual dispersionTheoretical dispersion

3.11 费托合成催化剂分散度的影响因素

Fig.7. Relation between the cobalt dispersion and cobalt size on different catalysts.

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主要内容

2. 实验方法与实验装置

3. 实验结果及讨论

4. 下一步计划

1. 研究背景

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4. 下一步计划

1. 整理实验数据，看文献。

2. 继续开展管外钴落位调控及自还原的相关实验。

期待各位专家提出宝贵意见和建议