CoZr/H-ZSM-5 hybrid catalysts for synthesis of gasoline-range isoparaffins from syngas

Different CoZr/H-ZSM-5 hybrid catalysts were prepared by a hydrothermal synthesis method, where H-ZSM-5 was enwrapped onto the Co-ZrO2 Fischer-Tropsch synthesis (FTS) catalyst. The catalysts were characterized by BET, XRD, Al-27 NMR, SEM, TEM, XPS, H-2-TPR, NH3-TPD and IR techniques. The catalytic performance for the direct conversion of syngas to high-octane gasoline-range (C5-11) hydrocarbons was studied. Coke formation on the spent catalysts was measured by TGA. Compared with the base Co-ZrO2 catalyst or the physically mixed catalyst of Co-ZrO2 with H-ZSM-5, the reducibility of the hybrid catalyst was much lower due to the strong interactions of cobalt phase with zeolite and/or zirconia. The catalytic performance results showed that the as-prepared hybrid catalysts had high selectivity towards gasoline-range isoparaffins and relatively low methane selectivity in spite of the relatively low catalytic activity. The hybrid catalysts could effectively minimize the accumulation of carbonaceous deposits. The catalyst with aluminum isopropoxide as Al source exhibited excellent selectivity on the isoparaffin synthesis and relatively good stability. (C) 2011 Elsevier B.V. All rights reserved.