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Heterogeneous catalysis; gas-phase reactions; oxymethylene ether; sulfonated PEEK
Abstract:
Oxymethylene ethers are a diesel additive/alternative, which reduce pollutant emissions. Based on methanol, it is possible to produce them from renewable energy and CO2. Sulfonated ion exchange resins are known to catalyze the synthesis of OME in liquid phase. Here, we report that the sulfonated polymer polyether-ether-ketone (S-PEEK) exhibits outstanding catalytic properties in the gas phase synthesis of OMEn. PEEK was reacted with gaseous SO3 to a degree of 22 % sulfonated monomer units. Using this material as a catalyst in the direct conversion of formaldehyde and methanol, an extraordinary selectivity to OME1 and OME2 of 93 % at equilibrium conversion of 55 % was obtained. Further, it was shown that the catalyst is stable for more than 60 h, and that with increasing reaction time selectivity to OME2 increases.