Selective hydrogenation of carbon dioxide to light hydrocarbons over ZnZrOX/H-MFI composite catalyst with long-term stability

This study investigates the catalytic performance of composite catalyst composed of ZnZrOX and H-zeolite for hydrogenation of CO2 to light hydrocarbons (C2-4). It is shown that deactivation of composite catalyst was caused by ion exchange of Zn2+ and/or coke and differs between various zeolite structures. When ZnZrOX and H-MFI were mixed by mortaring, Zn2+ migrated to H-MFI and caused ion exchange of Bronsted acid sites during the reaction, resulting in deactivation. This could be avoided by separating grains of ZnZrOX and zeolite. As for HMOR, the amount of coke formed during the reaction was large, and coke affected the catalytic activity rather than Zn2+ ion exchange. However, as for H-beta, those two deactivations were observed. The composite catalyst composed of ZnZrOX and H-MFI which were mixed loosely, separating their grains showed a high catalytic activity for 120 h. Therefore, it is a promising catalyst for one-pass catalytic conversion.