合成气费托合成制重质烃Ru-Co/SiC催化剂的制备及性能

doi:10.11949/0438-1157.20210260

摘要/Abstract

摘要：

费托合成是以合成气生产清洁燃料和其他化学品的重要途径。传统费托合成产物遵循A-S-F分布，只有甲烷和重质烃的选择性没有极限值。因此，费托合成研究以最大程度地合成重质烃，提高合成产物中重质烃的选择性为目标。基于此，首先详细探究了Al₂O₃、SiO₂和SiC载体对费托反应性能的影响。结果表明 Co/SiC催化剂具有最高的CO转化率（83.5%）和C₅₊选择性（80.3%）。与浸渍法相比，原位还原法更为有效地引入Ru到Co/SiC催化剂，将C₅₊选择性提高至90.1%。Ru助剂能在保持较高催化活性不变的前提下，有效提高Co/SiC催化剂C₅₊选择性。催化剂表征（XRD、H₂-TPR、XPS、H₂-化学吸附和TEM）结果表明，Ru能与Co发生相互作用，提高了催化剂的可还原性和活性组分的分散性，进而改善了Co/SiC催化剂重质烃的选择性。

关键词: 费托合成, 钴基催化剂, 原位还原, 重质烃

Abstract:

Fischer-Tropsch (F-T) synthesis is an important way to produce clean fuels and other chemicals from syngas. The traditional F-T synthesis follows Anderson-Schulz-Flory distribution, except for methane and heavy hydrocarbons, where its selectivity has no limit. Therefore, maximizing the yields of heavy hydrocarbons to further obtain high quality diesel and aviation kerosene by hydrocracking and hydroisomerization has been the research focus for F-T synthesis. The present work compared the effects of different supports (SiO₂, Al₂O₃ and SiC) on the catalytic performance of cobalt-based catalysts for F-T synthesis, in which SiC showed the highest activity (83.5%) and C₅₊ selectivity (80.3%). Compared to impregnation method, introducing Ru promoter by in-situ reduction method is more effective, with C₅₊ selectivity being further increased to 90.1%. Ru promoter could improve the C₅₊ selectivity while maintaining a high catalytic performance of Co/SiC catalyst. The characterization (XRD, H₂-TPR, XPS, H₂-chemisorption and TEM) results demonstrated the interaction between Ru and Co, thereby enhancing the reducibility and dispersion of active components and improved the selectivity for heavy hydrocarbons of Co/SiC catalyst.

Key words: Fischer-Tropsch synthesis, cobalt catalyst, in-situ reduction preparation, heavy hydrocarbons

中图分类号:

TQ 546.4

陈康伟, 熊文婷, 符继乐, 陈秉辉. 合成气费托合成制重质烃Ru-Co/SiC催化剂的制备及性能[J]. 化工学报, 2021, 72(7): 3648-3657.

TAN Khangwei, XIONG Wenting, FU Jile, CHEN Binghui. Preparation and catalytic performance of Ru-Co/SiC catalysts for the synthesis of heavy hydrocarbons from syngas by Fischer-Tropsch reaction[J]. CIESC Journal, 2021, 72(7): 3648-3657.

图/表 15

图1 制备钴基催化剂主要步骤

Fig.1 Preparation process of cobalt based catalyst

图2 费托合成反应装置

Fig.2 The experimental set-up of F-T synthesis

表1 不同载体的钴基催化剂的性能

Table 1 Effect of supports on the catalytic performance of Co-based catalysts

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co/SiC	83.5	9.0	9.7	80.3	1.0
Co/SiO₂	71.9	9.2	11.2	78.5	1.1
Co/Al₂O₃	75.4	15.4	14.0	69.1	1.5

表1 不同载体的钴基催化剂的性能

Table 1 Effect of supports on the catalytic performance of Co-based catalysts

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co/SiC	83.5	9.0	9.7	80.3	1.0
Co/SiO₂	71.9	9.2	11.2	78.5	1.1
Co/Al₂O₃	75.4	15.4	14.0	69.1	1.5

表2 不同钴源前体对Co/SiC催化剂性能的影响

Table 2 Effect of cobalt sources on the catalytic performance of the Co/SiC catalysts

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co(N)/SiC	83.5	9.0	9.7	80.3	1.0
Co(A)/SiC	55.6	18.9	20.9	57.7	2.5

表2 不同钴源前体对Co/SiC催化剂性能的影响

Table 2 Effect of cobalt sources on the catalytic performance of the Co/SiC catalysts

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co(N)/SiC	83.5	9.0	9.7	80.3	1.0
Co(A)/SiC	55.6	18.9	20.9	57.7	2.5

表3 Ru助剂的添加对钴基催化剂的费托合成性能影响

Table 3 The effect of Ru addition on the catalytic performance of Co-based catalysts for F-T synthesis

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co/SiC	83.5	9.0	9.8	80.3	1.0
Ru/Co/SiC	82.3	5.2	6.5	86.6	1.7
Ru-Co/SiC	83.1	4.6	3.7	90.1	1.5

表3 Ru助剂的添加对钴基催化剂的费托合成性能影响

Table 3 The effect of Ru addition on the catalytic performance of Co-based catalysts for F-T synthesis

Catalyst	X_CO/%	$S C H 4$ /%	$S C 2 — C 4$ /%	$S C 5 +$ /%	$S C O 2$ /%
Co/SiC	83.5	9.0	9.8	80.3	1.0
Ru/Co/SiC	82.3	5.2	6.5	86.6	1.7
Ru-Co/SiC	83.1	4.6	3.7	90.1	1.5

图3 Co/SiC、Ru/Co/SiC和Ru-Co/SiC催化剂XRD谱图

Fig.3 XRD patterns of Co/SiC, Ru/Co/SiC and Ru-Co/SiC catalysts

表4 Co/SiC、Ru/Co/SiC和Ru-Co/SiC催化剂中Co物种的晶粒尺寸

Table 4 The crystallite sizes of Co species in Co/SiC， Ru/Co/SiC and Ru-Co/SiC catalysts

Catalyst	Particle size of Co₃O₄/nm	Particle size of Co/nm
Co/SiC	41.9	23.1
Ru/Co/SiC	30.1	19.2
Ru-Co/SiC	16.5	8.5

表5 Co/SiC、Ru/Co/SiC和Ru-Co/SiC催化剂BET比表面积和孔结构参数

Table 5 The surface area and pore structure data of Co/SiC， Ru/Co/SiC and Ru-Co/SiC catalysts

Catalyst	BET/(m²/g)	Pore volume/(cm³/g)	Pore diameter/nm
SiC	23.9	0.15	25.0
Co/SiC	21.8	0.12	22.0
Ru/Co/SiC	24.5	0.19	30.4
Ru-Co/SiC	55.1	0.25	17.9

图4 Co/SiC、Ru/Co/SiC和Ru-Co/SiC催化剂H2-TPR表征结果

Fig.4 H2-TPR profiles of fresh Co/SiC, Ru/Co/SiC and Ru-Co/SiC catalysts

图5 Co/SiC、Ru/Co/SiC 和 Ru-Co/SiC催化剂的EDS谱图

Fig.5 EDS spectra of Co/SiC, Ru/Co/SiC, Ru-Co/SiC catalysts

图6 Co/SiC、Ru/Co/SiC 和 Ru-Co/SiC催化剂的TEM图像

Fig.6 TEM images of Co/SiC, Ru/Co/SiC and Ru-Co/SiC catalysts

表6 Co/SiC、Ru/Co/SiC和Ru-Co/SiC催化剂元素含量

Table 6 The element content of Co/SiC， Ru/Co/SiC and Ru-Co/SiC catalysts

Catalyst	Element content/%
Catalyst	Co	Ru
Co/SiC	21.7	—
Ru/Co/SiC	20.8	0.65
Ru-Co/SiC	20.2	0.71

表7 Co/SiC、Ru-Co/SiC和Ru/Co/SiC催化剂中活性组分的分散度和表面积

Table 7 The data of metal dispersion and metallic surface area for Co/SiC， Ru-Co/SiC and Ru/Co/SiC catalysts

Catalyst	H₂-chemisorption
Catalyst	Metal dispersion /%	Metallic surface area /(m²/g)
Co/SiC	0.35	0.47
Ru/Co/SiC	0.38	0.51
Ru-Co/SiC	0.42	0.57

图7 Co/SiC、Ru-Co/SiC和Ru/Co/SiC催化剂的XPS谱图

Fig.7 XPS spectra of Co/SiC, Ru-Co/SiC and Ru/Co/SiC catalysts

表8 Co/SiC、Ru-Co/SiC和Ru/Co/SiC催化剂的XPS表征结果

Table 8 XPS analysis results of Co/SiC， Ru/Co/SiC and Ru-Co/SiC catalysts

Catalyst	BE/eV		Intensity ratio
Catalyst	Co 2p3/2	Ru 3p1/2	I_C_o/I_Si	I_Ru/I_Si	$I C o 3 + / I C o 2 +$	$I R u 0 / I R u 4 +$
Co/SiC	780.9	—	0.4	—	1.3	—
Ru/Co/SiC	780.5	463.8	0.6	0.1	1.9	1.2
Ru-Co/SiC	781.1	464.1	1.8	0.1	2.1	1.3

表8 Co/SiC、Ru-Co/SiC和Ru/Co/SiC催化剂的XPS表征结果

Table 8 XPS analysis results of Co/SiC， Ru/Co/SiC and Ru-Co/SiC catalysts

Catalyst	BE/eV		Intensity ratio
Catalyst	Co 2p3/2	Ru 3p1/2	I_C_o/I_Si	I_Ru/I_Si	$I C o 3 + / I C o 2 +$	$I R u 0 / I R u 4 +$
Co/SiC	780.9	—	0.4	—	1.3	—
Ru/Co/SiC	780.5	463.8	0.6	0.1	1.9	1.2
Ru-Co/SiC	781.1	464.1	1.8	0.1	2.1	1.3

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