Relationship between catalyst acid-base property and condensation performance for ester aldehydes
A series of catalysts with different contents of Na+,K+ and Cs+ for vapor phase condensation of ester aldehydes were prepared by impregnation method using γ-Al2O3 and SiO2 as carriers.The catalysts obtained were then characterized by XRD,BET,NH3-TPD and CO2-TPD for analysis on structure,acidity and basicity,followed by evaluation on their catalytic performance on condensation of methyl propionate and formaldehyde in vapor phase.The results showed that,under the reaction conditions of pressure 0.2 MPa,temperature 370℃,mass space velocity 1.2 h-1,10%(on the basis of the mass of SiO2,the same below)Cs/SiO2 catalyst exhibited better activity with the highest methyl propionate conversion rate of 41.03%and methyl methacrylate selectivity of 99.20%.When there were abundant alkali center,a positive correlation was found between the proportion of weakly basic sites on the surface of the catalyst and its catalytic performance for condensation of ester aldehydes in vapor phase.However,the presence of acidic and moderately strong alkaline sites of the catalyst could lead to a decrease in activity and selectivity.
ester aldehyde condensationcatalystsaciditybasicitymethyl propionatefine chemical intermediates
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