The effects of PVP-modified SiO2 on the catalytic performance of CO hydrogenation over Rh-Mn-Li/SiO2 catalysts

Abstract

Rh-Mn-Li catalysts supported on SiO2 prepared by PVP-modified Stöber method were used for the synthesis of C2+ oxygenates from CO hydrogenation. The catalysts were characterized by TG, XRD, N2-adsorption-desorption, TEM, H2-TPR, in situ FT-IR, TPSR, and XPS. Activity testing results showed that the Rh-Mn-Li catalyst supported on the SiO2 modified by 1 g PVP exhibited the highest CO conversion and selectivity of C2+ oxygenates compared with other catalysts. Characterization results indicated that the addition of an appropriate amount of PVP is beneficial to the formation of weakly H-bonded hydroxyl groups on the surface of SiO2, which promotes Rh dispersion and weakens the Rh-Mn interaction. Furthermore, the higher Rh dispersion and the weaker Rh-Mn interaction promote CO absorption, enhance the CO dissociation ability and restrain the hydrogenation activity, which are favorable for the CO insertion into the metal-CHX band, finally resulting in excellent catalytic performance for C2+ oxygenates synthesis.