Preparation of high performance Co3O4/Al2O3 catalysts by doping Al into ZIF-67: Effect of Al sources on Fischer-Tropsch synthesis

Abstract

MOFs derived Co-based catalysts are a kind of potential Fischer-Tropsch synthesis (FTS) catalyst with superior cobalt dispersion and high cobalt loading, but they usually exhibit low activity and high CH4 selectivity. In this study, Al sources were introduced during the synthesis of ZIF-67 by in-situ doping method to obtain the high performance Co3O4/Al2O3-x catalysts. The effect of different Al sources including AlCl3·6H2O, Al(C3H7O)3 and Al(NO3)3·9H2O on the FTS performance of the Co3O4/Al2O3-x catalysts was investigated. Results indicated that the prepared Co3O4/Al2O3-x catalysts exhibited better FTS activity and lower CH4 selectivity than the Co@C catalyst obtained by direct carbonation of ZIF-67. The Co3O4/Al2O3-x catalysts with different Al sources showed different FTS performance. The Co3O4/Al2O3-III catalyst exhibited the highest FTS activity which was ascribed to its strongest metal-support interaction and the most active sites. Moreover, due to the different physical properties, the Co3O4/Al2O3-III catalyst showed higher gasoline selectivity while the Co3O4/Al2O3-II catalyst showed higher diesel selectivity.