Promoting effect of unreducible metal doping on OMS-2 catalysts for gas-phase selective oxidation of ethanol

•Acid-base and redox properties of OMS-2 can be tuned by doping with unreducible metal.•Na-OMS-2 shows the highest basicity, reducibility and acetaldehyde productivity.•Na+-doping renders more oxygen vacancies and facile activation of O2 and ethanol.•Ethanol OH and α-CH bond cleavages are both kinetically-relevant.•Superoxide and lattice oxygen species act as dual active sites for ethanol activation.