CO2 hydrogenation for C2+ hydrocarbon synthesis over composite catalyst using surface modified HB zeolite

Abstract Synthesis of C 2+ hydrocarbons such as LPG (liquefied petroleum gas) from CO 2 is expected to reduce CO 2 emission by the consumption of fossil fuels. In this study, CO 2 hydrogenation over composite catalysts comprised of Cu–Zn–Al oxide catalyst and HB zeolite was examined for the synthesis of C 2+ hydrocarbons by the combination of methanol synthesis over Cu–Zn–Al oxide and concurrent conversion of methanol over HB zeolite. When a non-modified zeolite was used for the composite catalyst, the yield of C 2+ hydrocarbons was poor ( 2+ hydrocarbons were seriously deactivated. The employment of zeolites modified with 1,4-bis(hydroxydimethylsilyl) benzene remarkably improved the catalytic activity of the corresponding composite catalysts to produce C 2+ hydrocarbons in yields of more than 7C-mol%. The best yield of C 2+ hydrocarbons became approximately 12.6C-mol% under a pressure of 0.98 MPa. The disilane modification produced hydrophobic zeolites showing water contact angles more than 130°. The disilane compound was converted to some condensed aromatics during CO 2 hydrogenation at 300 °C, and the hydrophobicity was maintained even after the reaction. The enhanced catalytic activity is caused by suppressing the deactivation of the strong acid sites of HB zeolite with the hydrophobic surface. This improved composite catalyst will promote the production of C 2+ hydrocarbons from CO 2 even under low pressure conditions.