Fischer-Tropsch Synthesis Using H2/CO/CO2 Syngas Mixtures over a Cobalt Catalyst

被引:69
作者
Yao, Yali [1 ]
Hildebrandt, Diane [1 ]
Glasser, David [1 ]
Liu, Xinying [1 ]
机构
[1] Univ Witwatersrand, Sch Chem & Met Engn, Johannesburg, South Africa
关键词
IRON-BASED CATALYSTS; PRODUCT DISTRIBUTIONS; SECONDARY REACTIONS; SUPPORTED CO; HYDROGENATION; FE; SELECTIVITY; ADSORPTION; CO/AL2O3; RU;
D O I
10.1021/ie100414y
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
The effect of CO2 on Fischer-Tropsch synthesis (FTS) on a cobalt based catalyst had been investigated in a fixed-bed microreactor. Two feed gases, H-2:CO:CO2 = 2:1:0 and H-2:CO:CO2 = 3:0(:)1, were mixed in various proportions thus varying the ratio of CO, CO2, and H-2 stoichiometrically. The results show that CO and CO2 mixtures can be used as feed to a cobalt catalyst. Comparison of the FTS using different syngas mixtures (CO2/H-2, CO2/CO/H-2, and CO/H-2) shows that: (1) CO2 can be hydrogenated along with CO in the FT reactor over cobalt catalyst, especially in the case of high content of CO2. (2) Hydrogenation of CO2 or CO/CO2 mixture leads to a typical Anderson-Schulz-Flory (ASF) distribution. These could support the hypothesis that CO2 hydrogenation processes might occur with the formation of CO as intermediate. (3) CO feed exhibit the typical two-alpha distribution while CO2 and CO2 rich feeds only exhibit a single-alpha distribution. This may also help us to understand the mechanisms that lead to product distributions in FT with single- and dual-alpha distributions. In spite of the fact that cobalt catalysts are not water-gas shift active, it is shown the rate of hydrocarbon production is maximized at an intermediate composition of the CO/CO2/H-2 mixture. The results could have implications for the design of XTL (anything-to-liquids is a process that converts carbon and energy containing feedstock to high quality fuels and products, such as coal-to-liquids, biomass-to-liquids and gas-to-liquids) using cobalt catalysts in that it might be advantageous to keep some carbon dioxide in the syngas feed to the FTS process.
引用
收藏
页码:11061 / 11066
页数:6
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