From hydrophilic to hydrophobic: A promising approach to tackle high CO2 selectivity of Fe-based Fischer-Tropsch microcapsule catalysts

• Published in: Catalysis today Vol. 330; pp. 39 - 45
• Main Authors: Javed, Mudassar, Zhang, Guihua, Gao, Weizhe, Cao, Yingnan, Dai, Peiyao, Ji, Xuewei, Lu, Chengxue, Yang, Ruiqin, Xing, Chuang, Sun, Jian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-06-2019
• Subjects: CO2 control; Fischer-Tropsch synthesis; Hydrophobicity; Microcapsule; Silicalite-1 shell; Fischer-Tropsch synthesis; Hydrophobicity; Silicalite-1 shell; CO2 control; Microcapsule
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2018.08.010

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•Silicalite-1 based microcapsule catalysts were prepared with hydrothermal synthesis.•Silicalite-1 shell turned Fe/ZSM-5 core’s surface hydrophilicity to hydrophobicity.•Hydrophobic nature of silicalie-1 layer decreased water-gas shift reaction’s kinetics.•CO2 selectivity was decreased by suppressing water-gas shift reaction activity.•Acidic ZSM-5 and silicalite-1 molecular sieving contributed in high gasoline selectivity.
Zeolite supported Fischer-Tropsch (FT) catalysis has attracted extensive attentions in past few years. Capsule catalysts have unique characteristics of tuning product selectivity more precisely and enhancing stability of catalysts during reaction, which makes them to stand out of the crowed. Fe-based FT catalysts have been facing limitations for syngas conversion to hydrocarbons with their associated problems of high CO2 selectivity and rapid catalyst deactivation. A series of ZSM-5 supported Fe-based microcapsule catalysts, composed of Fe/ZSM-5 core and silicalite-1 shell, was prepared and employed for direct synthesis of gasoline range hydrocarbons from syngas. Tuning silicalite-1 shell thickness significantly affected water-gas shift reaction with increasing hydrophobicity of catalyst surface, and greatly decreased CO2 selectivity. The microcapsule catalysts significantly suppressed the CO2 selectivity as compared with supported Fe-based catalyst. Moreover, all zeolite supported Fe-based catalysts, showed significantly high gasoline range hydrocarbons selectivity (about 60%). The proposed catalyst design suggests a promising approach to overcome high CO2 selectivity challenge associated with Fe-based FT catalysts.