Highly dispersed Ag2O-CuO nanospheres supported on γ-χ-Al2O3 for methanol dehydration to dimethyl ether

Abstract

In this manuscript, the wet impregnation method was used to support Ag2O, CuO, and Ag2O-CuO nanoparticles on γ-χ-Al2O3 to assess their catalytic capabilities in the methanol dehydration (MD) reaction to produce dimethyl ether (DME); the operation conditions were 1 atm and temperature ranging between 200 and 240 °C. It was found that Ag2O-CuO/γ-χ-Al2O3 catalyst result in MD conversions up to 88 % and selectivities of 100 %, under 240 °C conditions. The catalytic activity of the Ag2O-CuO/γ-χ-Al2O3 catalyst is related to the high dispersion, homogeneity and larger size of the Ag2O-CuO nanoparticles (∼12.6 nm) compared to Ag2O and CuO nanoparticles, which have sizes of ∼ 9.52 and 10 nm, respectively. Additionally, the catalytic activity of the Ag2O-CuO/γ-χ-Al2O3 material is related to its total acidity (weak and moderate), 0.056 mmol/g, showing a difference of 25 %, 28.57 and 5.35 % with respect to the γ-χ-Al2O3, CuO/γ-χ-Al2O3 and Ag2O/γ-χ-Al2O3 materials, respectively. Finally, the catalytic stability measurements of the Ag2O-CuO/γ-χ-Al2O3 catalyst remained relatively constant over time, presenting a conversion value of 79 % after 2.6 h of reaction due to the low apparent activation energy, 112.6 kJ/mol. The results of the exergy analysis indicate that the chemical exergy of the system ranges between 1/6 and 1/3 of the physical exergy, and most of the energy available to produce work is in the form of heat.