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

2

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

3

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

4

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

?

5

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

6

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

7

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 ）

8

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

9

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

10

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

11

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

Tianjin University

12

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

Tianjin University

13

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

Tianjin University

14

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.

Tianjin University

15

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

16

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

Tianjin University

17

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.

Tianjin University

18

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.

Tianjin University

19

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

Tianjin University

20

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.

21

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

Tianjin University

22

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