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

Ding, Dan, Yu, Jun, Guo, Qiangsheng, Guo, Xiaoming, Xiao, Xiuzhen, Mao, Dongsen, Lu, Guanzhong
RSC advances 2017 v.7 no.76 pp. 48420-48428
Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, absorption, carbon monoxide, catalysts, catalytic activity, dissociation, hydrogen bonding, hydrogenation, moieties, silica, thermogravimetry, transmission electron microscopy
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.