The effect of rhodium particle size on ethanol synthesis by catalytic hydrogenation of carbon dioxide over silica supported rhodium catalysts

Abstract

Ethanol synthesis by CO2 hydrogenation was carried out with Rh/SiO2 catalysts with different Rh particle sizes. They were prepared by varying the amount of Rh loaded. The Rh particle size increased with increasing amount of Rh. The effect of Rh particle size on CO2 hydrogenation was investigated by using these catalysts. The main product was CO using a catalyst of small Rh particle size, but using a catalyst of larger Rh particle size, CO selectivity decreased and CH4 selectivity increased. The highest ethanol selectivity was obtained when the size was about 2.5 nm. The result of in-situ FT-IR suggested that the difference in Rh particle sizes changed the electronic state of Rh that in turn changed the product selectivity.