SPHERICAL P-MODIFIED CATALYSTS FOR HETEROGENEOUS CROSS-ALDOL CONDENSATION OF FORMALDEHYDE WITH METHYL ACETATE FOR METHYL ACRYLATE PRODUCTION

A series of spherical supported catalysts were prepared for the production of methyl acrylate (MA) via cross-aldol condensation with methyl acetate (MeOAc) and formaldehyde-the simplest aldehyde without alpha-H. ZSM-5, gamma-Al2O3, MCM-41, SBA-15, and beta-zeolite were used as supports and phosphorus element (P) was selected for the active component to synthesize the catalyst to study the influence of the catalyst acid-base properties on the yield of MA. The catalyst was characterized with X-ray diffraction, XPS, Pyridine FTIR, BET, SEM, TEM, CO2-TPD, and NH3-TPD and the changes of the catalyst structure and acid properties were explored. The results showed the carbonyl polarity of methyl acetate was boosted by Lewis acid sites (L acid) and the formaldehyde activation and formation of ester enol form could be promoted by Bronsted acid sites (B acid). Using the fixed-bed reactor, the effect of calcination temperature, catalyst loading, reaction temperature, molar ratio of reactants, and sources of phosphorus were optimized, then the catalyst life and regeneration performance were also evaluated. Lastly, the catalytic mechanism of P-modified ZSM-5 catalysts was proposed.