Hydrogenation of CO<sub>2</sub> to Methanol and Dimethyl Ether over a Bifunctional Cu·ZnO Catalyst Impregnated on Modified γ-Alumina
Davi Carvalho, Guilherme C. Almeida, Robson S. Monteiro, Cláudio J. A. Mota
Abstract
Bifunctional catalysts of Cu·ZnO supported on modified γ-Al2O3 were prepared and tested in the direct hydrogenation of CO2 to methanol and dimethyl ether (DME). The γ-Al2O3 modification was carried out using a solution of (NH4)2SiF6, aiming to incorporate Si atoms in the alumina structure. The metals were added to the support by wet impregnation. The catalysts were characterized by the Brunauer–Emmett–Teller area, chemical composition, 29Si and 27Al magic angle spinning nuclear magnetic resonance, acidity, and temperature-programmed reduction. All of the prepared catalysts were able to convert CO2 into methanol and DME in the temperature range of 270–290 °C and 30 and 50 bar of pressure. The yield of DME was higher over the catalyst supported on γ-Al2O3 containing more incorporated Si atoms. The results were interpreted in terms of the acid strength of the supports.