Sustainable methyl formate generation by dehydrogenation of green methanol over Cu_SiO₂/MgO

Copper impregnated SiO₂ and MgO catalysts were prepared, characterised, and tested for the synthesis of methyl formate (MF) from methanol by dehydrogenation. Compared to the Cu-impregnated pure oxides, MF formation was improved when SiO₂/MgO mixtures were used as support. For further comparison, a silver impregnated mixed oxide catalyst, known for its dehydrogenation ability, and a typical methanol catalyst (Cu/ZnO/Al₂O₃) were tested. Both catalysts displayed non or poorer performance under tested reaction conditions. High catalytic activity was assigned, besides the Cu content, to the presence of both medium acidic and basic sites. At 240 °C and 1 bar, the highest MF yield of 34 % has been obtained with the mixture of oxides containing the highest MgO ratio of 35 mol%. By exposing the prepared catalyst to a methanol/water mixture (36 wt% water), methanol conversion drops to 5 %, but compared to the reference Cu/ZnO/Al₂O₃ catalyst, two times the selectivity towards MF was obtained. With respect to sustainable technology development, direct coupling of green methanol synthesis from CO₂/H₂ gas feed and MF production without water removal is not recommended, since the yield to MF is below 2 % in this case.