Comparative Study on Ethanol-based Oxygenate Synthesis via Syngas over Rh-Mn Bimetallic Catalysts Supported on Different UiO MOFs

Highly ordered microporous structures of UiO metal-organic frameworks (MOFs) with different cavity sizes and secondary building units were synthesized and selected as the host to prepare Rh-Mn bimetallic catalysts. The catalysts were investigated for the ethanol-based oxygenate synthesis via syngas conversion. Compared to RM@Ce-UiO-66, the Rh-Mn catalysts supported on Zr-UiO MOFs showed the better catalytic performance, while RM@UiO-67 achieved the highest yield of C-2(+) oxygenates [322.0 g/(kg h)]. Characterization results revealed that the topology structures of the UiO MOFs were propitious to the fix of the confined ultrasmall bimetallic Rh-Mn nanoparticles and restricted the reduction of Rh-Mn particles. However, the unstable framework of Ce-UiO-66 in RM@Ce-UiO-66 would collapse after calcination and reduction, and the formed Rh/CeO2 interfaces promoted the transformation of adsorbed CO into stable carbonate species, resulting in low CO conversion. Moreover, the best oxygenate synthesis performance over RM@UiO-67 should be mainly attributed to its highest ratio of Rh+/Rh-0.

Automated summary

Highly ordered microporous structures of UiO metal-organic frameworks (MOFs) with different cavity sizes and secondary building units were synthesized and selected as the host to prepare Rh-Mn bimetallic catalysts. The Rh-Mn catalysts supported on Zr-UiO MOFs showed better catalytic performance compared to RM@Ce-UiO-66, while RM@UiO-67 achieved the highest yield of C-2(+) oxygenates. The topology structures of UiO MOFs were propitious to the fix of confined ultrasmall bimetallic Rh-Mn nanoparticles and restricted the reduction of Rh-Mn particles. The best oxygenate synthesis performance over RM@UiO-67 should be mainly attributed to its highest ratio of Rh+/Rh-0.