シリカ担持ロジウム‐コバルト‐アルカリ金属触媒を用いた二酸化炭素の水素化反応

CO2 hydrogenation was carried out over alkali metals such as Li, Na and K promoted silica-supported Rh–Co catalysts (Rh–Co–M/SiO2). Na additive was most effective of the three alkali metals for ethanol formation over 5 wt% Rh–Co(1 : 1)/SiO2. The added amount of Na influenced product selectivity as well as CO2 conversion. The highest ethanol selectivity was obtained over 5 wt% Rh–Co–Na (1 : 1 : 0.5)/SiO2 catalyst. The mechanism of promotion effect of Na added amount was investigated by means of in situ FT-IR observation during reaction. The variation of Na added amount changed the ratio of Rh2–(CO)3 and bridged type adsorbed CO species to linear type one. This finding suggested that the amount of Na affected on the hydrogenation ability of Rh–Co/SiO2 catalysts, leading to the difference in CO2 hydrogenation activity.