Studies On Rh-based Catalyst For Conversion Of Syngas To C₂ Oxygenates

The effect of SiO₂ prepared by PVP-modified St?ber method on the catalytic performance of Rh-Mn-Li/SiO₂ catalysts for the synthesis of C₂⁺oxygenates from CO hydrogenation was investigated.Activity testing result showed that the Rh-Mn-Li catalyst supported on the SiO₂ modified by 1 g PVP exhibited the highest CO conversion?24.8%?and selectivity of C₂⁺oxygenates?43.5%?compared with other catalysts.Characterization results indicated that the addition of appropriate amount of PVP is beneficial to the formation of weakly H-bonded hydroxyls groups on the surface of SiO₂,which promotes the Rh dispersion and weakens the Rh-Mn interaction.The higher Rh dispersion and weaker Rh-Mn interaction promote the CO absorption,enhance the CO dissociation ability and restrain the hydrogenation activity,which are favorable for the CO insertion into metal-CH_X band,finally resulting in the excellent catalytic performance for C₂⁺oxygenates synthesis.The effect of titanium promotion on the catalytic performance of Rh-Mn-Li/SiO₂catalysts for C₂⁺oxygenates synthesis from CO hydrogenation was investigated.The catalysts were characterized by a various techniques of XRD,H₂-TPR,in situ FT-IR,TPSR,and XPS toinvestigatethephysic-chemicalpropertiesofRh-Mn-Li/xTi/SiO₂catalysts.Characterization results indicates that the addition of Ti promotes the adsorption of geminal CO and the formation of Rh⁺,which is favorable for the CO insertion,and increases the selectivity of C₂⁺oxygenates.The effect of CNTs promotion on the catalytic performance of the Rh-Mn-Li/SiO₂catalysts for C₂⁺oxygenates synthesis from syngas was explored.The catalysts were characterized by a various techniques of XRD,TEM,N₂ adsorption-desorption,H₂-TPR,CO-TPD,TPSR,and XPS to investigate the physic-chemical properties of CNTs modified Rh-Mn-Li/SiO₂ catalysts.The result shows that Rh-Mn-Li-5%CNTs/SiO₂ catalyst obtained the highest selectivity toward C₂⁺oxygenates?64.6%?,that is,the yield of C₂⁺oxygenates reaches 287.6 g/?kg·h?.Characterization results indicated that the addition of Ti promotes the Rh dispersion,increases the number of absorbed CO species,which promotes the formation of C₂⁺oxygenates.