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

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 SO42-/ZrO2‐TiO2 catalysts were developed for OMEs production from dimethoxymethane (DMM) and 1,3,5-trioxane through sequential formaldehyde monomer insertion into CO bond of DMM. Not Lewis but Brønsted 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 formaldehyde unit insertion into CO bond. Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Brønsted and Lewis acid sites due to the same reaction 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.