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

Highly selective synthesis of liquefied petroleum gas (LPG, \rmC_3^0 and \rmC_4^0 ) 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 ℃. 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 ℃, 3 MPa and 9000 mL/(g_cat·h). The research provides a new strategy for highly selective synthesis of LPG from CO₂ hydrogenation.