Enhanced ethanol dehydrogenation over Ni-containing zirconia-alumina catalysts with microwave-assisted synthesis

Bio-based acetaldehyde production by non-oxidative dehydrogenation of ethanol is a promising alternative for the fine chemistry industry, where acetaldehyde is an important part of the synthesis chain and co-production of hydrogen. In this paper, investigations on nickel containing alumina itterbia stabilized zirconia with microwave-assisted synthesis as catalysts for the ethanol dehydrogenation process to acetaldehyde are reported. Ni–xAl2O3–(100 − x)[Zr0,97Yb0,03]O2 (x = 35 and 65 mol%) were prepared by using microwave (MW) irradiation and by traditional heating steps during sol–gel preparation. The textural properties, structure, morphology, surface and phase composition, and RedOx properties (SEM–EDX, BET N2-physisorption, TG–DTA, XRD, EPR) of the samples were compared with the effect of the microwave-assisted synthesis and the Zr:Al ratio on the ethanol dehydrogenation is reported. Two synthesis routes were compared, and it was found that microwave pretreatment of hydrogel during sol–gel synthesis favors catalytic dehydrogenation, whereas catalysts prepared by pretreatment under uniform heating perform much worse. The microwave-assisted synthesis approach turned out to be more promising in terms of selectivity to acetaldehyde in the ethanol dehydrogenation due to form nickel oxide particles with strong support interaction in noncubic coordination catalyzing the ethanol dehydrogenation and at the same time to decrease the formation of nickel aluminate phase involved in competitive dehydration reaction to ethylene. Thus, the highest obtained selectivity to acetaldehyde was ≈ 70% at 400 °C on Ni–65AZ–MW sample. © The Author(s), under exclusive licence to Springer Nature B.V. 2023.