Selective catalytic synthesis of short chain oxymethylene ethers by a heteropoly acid – a reaction parameter and kinetic study

Abstract

Oxymethylene ethers (OME) are considered as a low-emission additive or replacement to diesel fuel. They can be synthesized by different routes based on C₁ platform chemicals in different oxidation states. The challenge is to tune the acidic catalyst for the condensation reaction to a selectivity for a certain oligomeric fraction (OME_3–5) for optimal fuel properties. Herein, we report the use of heteropoly acids that showed an outstanding activity and selectivity for the production of the respective OME fraction under very mild reaction conditions. Trioxane and dimethoxymethane (OME₁) were used as substrates which are both products of the methanol value-added chain. Reaction parameters such as catalyst/substrate ratio and temperature could be reduced considerably due to a high catalytic activity and selectivity. Kinetic data were obtained experimentally and modelled to estimate the reaction rate, activation energy and pre-exponential factor as a solid basis for further reaction engineering.