Effect of acidity on ferric oxide nanoparticles supported on γ–χ–Al2O3 in the methanol dehydration reaction toward dimethyl ether

Abstract

In this work, the low cost synthesis of the Fe2O3/γ–χ–Al2O3 catalyst, carried out by the wet impregnation method, promoted a conversion in methanol dehydration by 46% (an increase of 5% with respect to γ–χ–Al2O3 support), and with a selectivity of 100% towards DME (at 250 °C and 1 atm pressure), due to a higher abundance in the density of moderate acidic sites generated by the synergistic metal-support interaction. The slight decrease in catalytic activity for the Fe2O3/γ–χ–Al2O3 system, compared to the γ–χ–Al2O3 from 260 °C, was linked to the effect of changes in the shape and size of the Fe2O3 nanoparticles. These particles went from semi-spherical to nano-needles at 290 °C reaction temperature. Finally, the great structural stability of Fe3+ measured by XPS, RAMAN spectroscopy and UV–Vis, and the low activation energy of the Fe2O3/γ–χ–Al2O3 material (102.66 kJ/mol), place the Fe2O3/γ–χ–Al2O3 catalyst as an excellent candidate for methanol dehydration, under conditions of 240 to 250 °C and methanol partial pressures between 9.8 and 7.8 kPa, respectively.