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

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 the catalytic activities were investigated for the direct synthesis of ethanol-based C2+ oxygenates from CO hydrogenation. The catalysts were comprehensively characterized by means of N2 sorption, XRD, XPS, DRIFT, and TPSR. The structural and textural properties of the catalysts show clearly that Rh and Mn are highly dispersed in the pores of MOFs, but the order of the original structure are partially sacrificed by the loading of metals and the synergistic effect of Rh, Mn, and Zr would be influenced by various functional groups in UiO-66. Combined with the tests of in situ FT-IR and TPSR, it is confirmed that the higher amount 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 of 197.3 g/(kg•h).