Synthesis of C2 oxygenates from syngas over UiO-66 supported Rh–Mn catalysts: the effect of functional groups

Abstract

UiO-66 and its modified forms (UiO-66-NH₂ and UiO-66-OH) were used as supports to prepare Rh–Mn catalysts by using a co-impregnation method, and their catalytic activities were investigated for the direct synthesis of ethanol-based C₂⁺ oxygenates from CO hydrogenation. The catalysts were comprehensively characterized using N₂ sorption, XRD, XPS, DRIFT, and TPSR analyses. The structural and textural properties of the catalysts clearly show that Rh and Mn are highly dispersed in the pores of MOFs, but the order of the original structure is partially sacrificed due to the loading of metals and the synergistic effect of Rh, Mn, and Zr would be influenced by various functional groups present in UiO-66. On combining both in situ FT-IR and TPSR analyses, it is confirmed that the higher number of active sites of Rh⁰ on RM/UiO-66 promotes the CO dissociation ability and hydrogenation rate, which result in its best catalytic activity with the highest yield of C₂⁺ oxygenates, 197.3 g (kg h)⁻¹.