NASICON基催化材料上甲醇直接氧化制聚甲氧基二甲醚研究OA

Polyoxymethylene dimethyl ethers(DMMx)are highly promising clean diesel additives.Compared to the traditional aldol condensation route,the one-step oxidative method for producing DMMx directly from methanol is a green synthesis route offering significant advantages.However,due to the complexity of the reaction,a balance must be struck between oxidation depth and C-O chain growth efficiency.This imposes specific requirements on the design of catalysts with multifunctional active sites:the catalyst should possess appropriate oxidative activity,suitable acid strength distribution,and effective synergy between these two functions.To address these challenges,this study designed a sulfuric acid-modified molybdenum-doped NASICON catalyst,which demonstrated favorable catalytic performance in the one-step oxidative synthesis of DMMx from methanol.Over the NSC-Mo-0.5-30％catalyst,methanol conversion rate of 81.3％and the DMMx selectivity of 58.7％were achieved,along with the formation of heavier molecules,as evidenced by the DMM2-6 selectivity of 11.3％.The NH3-TPD,Py-IR and XPS results indicate that the introduction of molybdenum increases the number of weak Lewis acid sites,while sulfuric acid impregnation not only generates gradient-distributed Brønsted acid sites but also promotes the formation of Mo5+/Mo6+redox pairs.The cooperation of the two types of active sites significantly enhances catalyst performance.