Efficient Conversion of Methyl Lactate to Methyl Acrylate over Cesium-Modified Al-Rich Beta Zeolites

Cesium ion in Beta zeolite strongly hindersthe formationof coke, improving the selectivity of MA due to steric hindrance. Dehydrationof methyl lactate (ML) obtained from biomass is a sustainableroute for the production of methyl acrylate (MA). Herein, we demonstratethat cesium-exchanged Al-rich Beta zeolite (Cs-Beta) is highly efficientfor the dehydration of ML to MA, exhibiting full ML conversion with87.4% MA yield at 340 degrees C. In situ FT-IR spectra and kinetic studiesprovide evidence that the ML dehydration on the Cs-Beta zeolite followsa forward ion-exchange/dehydration/reverse ion-exchange reaction pathway.Model experiments, DFT calculations, TG-DSC analysis, and FT-IR spectrashowed that coke formation competes with the dehydration of ML toMA. Kinetic studies and theoretical simulations demonstrate that cesiumcations in the micropores of Beta zeolite have a strong steric hindrance,suppressing the formation of oligomers and coke. These results offernew insights for developing highly selective and stable catalystsfor the dehydration of ML to MA in the future.