Structure and Catalytic Performance of CoAl2O4-Al2O3 Supported Cobalt Catalyst for Fischer-Tropsch Synthesis

Structure and Catalytic Performance of CoAl₂O₄-Al₂O₃ Supported Cobalt Catalyst for Fischer-Tropsch Synthesis

Litao Jia^a, Jiankang Han^a,b,Bo Hou^a, Debao Li^a*

^a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, China.

b University of Chinese Academy of Sciences, Beijing 100039, China

*Corresponding author: Tel. /Fax: +86 351 4040410. E-mail addresses: dbli@sxicc.ac.cn

The Fischer¨CTropsch synthesis (FTS) can convert syngas (CO +H2) into clean and renewable transportation fuels, which has received an increasing interest from academia and industry. Amongst the reported catalysts, cobalt-based catalysts showed low activity for the water-gas shift reaction, deactivated less rapidly and yielded a high fraction of linear parrifin. Alumina as a kind of traditional support for F-T synthesis catalysts, has high mechanical strength and good friction resistance. While, the strong interactions between the alumina and cobalt reduced the reduction degree of cobalt, which strongly influence the performance of the catalyst.

In the present study, the Al₂O₃ was modified by CoAl₂O₄ microcrystalline through impregnation method. And then the modified Al₂O₃ acted as support for cobalt. The as-prepared catalysts were characterized by BET, XRD, H₂-TPR, XPS and H₂-chemisorption, and applied in Fischer¨CTropsch synthesis (FTS). The results show that the existence of CoAl₂O₄ on surface of the Al₂O₃ effectively weakened the interaction between Co and Al₂O₃, thus greatly improve the reduction of catalysts and catalytic activity. With the increase of CoAl₂O₄ content, the reduction degree and catalytic activity of catalysts increase, which reach the maximum with 20 wt% CoAl₂O₄ content. The catalytic performance showed that, with the modification CoAl₂O₄, the CH₄ selectivity was decreased and the C₅₊ selectivity was enhanced. In addition, CoAl₂O₄ modification also improves the catalyst stability.

Keywords: Fischer-Tropsch synthesis, cobalt/Alumina catalysts, CoAl₂O₄ modified Al₂O_3,