Preparation of SiO2 immobilized Co-based catalysts from ZIF-67 and the enhancement effect for Fischer-Tropsch synthesis

• FTS performance on ex-soaking Co 3 O 4 /SiO 2 catalysts increased with increasing penetration ability of the silicon precursor. • The Co 3 O 4 @SiO 2 catalysts greatly improved FTS performance due to the better immobilization effect of SiO 2 on Co species. • FTS activity is closely related with TEOS amount for in-soaking Co 3 O 4 @SiO 2 catalysts with E-Co 3 O 4 @4SiO 2 the best. ZIF-67-derived Co@C catalysts show great potential for Fischer-Tropsch synthesis (FTS) due to high cobalt (Co) loading and proper cobalt crystalline size, while improving the FTS activity and stability is still a major challenge. In this work, SiO 2 was embedded to immobilize Co particles by introducing a silicon source into ZIF-67 using ex-situ or in-situ methods to prevent cobalt particles from aggregating. Due to exposure of more active cobalt sites and elimination of microcrystalline Co on the ex-situ soaking catalysts, increased FTS activity and decreased CH 4 selectivity were achieved, but undesirable stability was observed due to the weak immobilization ability of SiO 2 . To enhance the immobilization effect of SiO 2 , E-ZIF-67@nSiO 2 precursors were prepared by an in-situ soaking method in which the formation of ZIF-67 and introduction of SiO 2 occurred simultaneously. The obtained E-Co 3 O 4 @4SiO 2 catalyst exhibits not only much high FTS activity but also good stability.