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 C2+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/CeO2interfaces 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+/Rh0.