Approaches and nature of improving Rh-based catalyst performance for CO hydrogenation to C-2-oxygenates

Thermodynamic analysis results revealed that the formation of C_2-oxygenates from syngas is much more unfavorable than the formation of hydrocarbons. Therefore, the crucial and effective method to promote the C_2-oxygenate synthesis is to develop high selective catalysts. According to the mechanism of C_2-oxygenate formation, the natures and the approaches to improve the catalytic performance of the Rh-based catalyst for CO hydrogenation to C_2-oxygenates were the improvement and the balance in CO dissociation and insertion activity, the proper hydrogenation activity, and the optimal Rh size on the catalyst surface. The impregnation and reduction conditions were optimized to suppress correctly the catalytic activity of the Rh-Mn-Li-Fe/SiO_2 catalyst for CO hydrogenation. Consequently, CO insertion competed favorably with hydrogenation, resulting in a maximum selectivity (91.6% in mass fraction) for C_2-oxygenates with a high yield and a much low methane selectivity (6.3% in mass fraction).