Tuning oxygen vacancy defects in VOx/Ce1-xLaxO2−δ nanorod catalysts through La doping for selective methanol oxydehydrogenation to dimethoxymethane

Abstract

Methanol oxydehydrogenation to produce dimethoxymethane (DMM) and its use as a key feedstock for the synthesis of PODE_3-5, an emerging diesel additive, represents a promising strategy for mitigating diesel exhaust emissions. However, achieving high methanol conversion with high selectivity for DMM remains a significant challenge at low temperatures. Herein, a La-doped ceria-supported vanadia (VO_x/Ce_1-xLa_xO_2-δ) nanorod catalyst was prepared by a one-step hydrothermal method to create sufficient asymmetric oxygen vacancies. Diverse techniques were employed to comprehensively analyze the catalyst structure and active sites. The results indicate that the generated oxygen vacancies not only activate oxygen species but also accelerate the cleavage of O–H and C–H bonds alongside V⁵⁺ active site within the adsorbed methanol during the methanol oxydehydrogenation reaction. The VO_x/Ce_0.8La_0.2O_2-δ catalyst demonstrated superior catalytic efficiency, achieving 81 % methanol conversion and 95 % selectivity for dimethoxymethane under atmospheric pressure and at 200 °C in a fixed-bed reactor.