Highly selective synthesis of LPG from CO2 hydrogenation over In2O3/SSZ-13 binfunctional catalyst

Abstract

Highly selective synthesis of liquefied petroleum gas (LPG, C03, C04) from CO2 hydrogenation have realized over the In2O3/SSZ-13 bifunctional catalyst. The physicochemical properties of the bifunctional catalyst were characterized by X-ray diffraction spectroscopy (XRD), N2 physical adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and NH3 temperature-programmed desorption (NH3-TPD). The particle size effect of In2O3 and reaction conditions were investigated for CO2 hydrogenation to LPG over the In2O3/SSZ-13 bifunctional catalyst. Results indicate that CO2 conversion and CO selectivity are related to the particle size of In2O3, and fresh 5 nm In2O3 shows the highest CO2 conversion (11.7%) and the highest CO selectivity (61.0%), since it is more prone to reverse water gas reaction (RWGS). However, the hydrocarbon distribution does not exhibit a dependence of In2O3 size changes, and the selectivity of LPG maintains at 90% and the selectivity of propane reaches up to 76.8% due to the 8-MR micropores and strong acid sites of SSZ-13 zeolite. Additionally, the yield of LPG shows a volcano type with increasing reaction temperature, and the optimal reaction temperature is 370°C. Low space velocity is more favorable to the CO2 conversion, and LPG selectivity in hydrocarbon products still maintains about 90%. High reaction pressure is beneficial to improving the yield of LPG via promoting the secondary hydrogenation reaction over the SSZ-13 zeolite and inhibiting CO formation. Furthermore, no obvious deactivation is observed after a time on stream (TOS) of 100 h over the In2O3/SSZ-13 bifunctional catalyst at 350°C, 3 MPa and 9000 mL/(gcat·h). The research provides a new strategy for highly selective synthesis of LPG from CO2 hydrogenation.