Studies on polyoxymethylene dimethyl ethers production from dimethoxymethane and 1,3,5-trioxane over SO42-/ZrO2-TiO2

Polyoxymethylene dimethyl ethers (OMEs) with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression. Herein, series of SO2- 4 /ZrO2-TiO2 catalysts were developed for OMEs production from dimethoxymethane (DMM) and 1,3,5-trioxane through sequential formaldehyde monomer insertion into C-O bond of DMM. Not Lewis but Bronsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit, however, both of them are effective for the chain propagation of DMM via formalde-hyde unit insertion into C-O bond. Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Bronsted and Lewis acid sites due to the same reac-tion mechanism and very similar chemical structure of OMEs. Also, the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition, and the decay factor could be exponentially correlated with the amount of coke accumulation.& COPY; 2023 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.