Selective synthesis of carbon monoxide via formates in reverse water–gas shift reaction over alumina-supported gold catalyst

Abstract Thermal decomposition of formic acid on SiO 2 , CeO 2 and γ-Al 2 O 3 was studied as an elementary step of reverse water–gas shit reaction (RWGS) over supported Au catalysts. γ-Al 2 O 3 showed the highest CO selectivity among the tested oxides in the decomposition of formic acid. Infrared spectroscopy showed the formation of four formate species on γ-Al 2 O 3 : three η 1 -type and one μ 2 -type species, and these formates decomposed to CO at 473 K or higher. Au-loaded γ-Al 2 O 3 samples were prepared by a deposition-precipitation method and used as catalysts for RWGS. The supported Au catalyst gave CO with high selectivity over 99% from CO 2 and H 2 , which is attributed to the formation of formates on Au and subsequent decomposition to CO on γ-Al 2 O 3 .