Aldol Condensation of Methyl Propionate and Formaldehyde: Thermodynamics, Reaction Process, and Network

Abstract

The aldol condensation of methyl propionate (MP) and formaldehyde (FA) is an environmentally friendly and sustainable route to produce methyl methacrylate (MMA). However, the side reaction is a huge barrier to achieving high selectivity to the target product. To strengthen the regulation of selectivity for the main reaction, a reaction network was established based on the validation and analysis of side reactions in the system through a combination of experimental and computational methods. The thermodynamics was analyzed through the Gibbs free energy (Δ r G T θ ) of reactions. On the basis of a rigorous material balance of all components, the sources and reaction equations of 15 products were identified. The multivariate nonlinear model between the yield of different products and reaction conditions was established to predict the yield of each product. The mean relative error of the actual yield and predicted yield was less than 5%. The key influencing condition for the synthesis of MMA was the liquid hourly space velocity (LHSV).

Acid Promoter-Modified Cs/Al2O3 Catalyst for Methyl Methacrylate Production by Aldol Condensation of Methyl Propionate with Formaldehyde

“…This finding implies that the number of medium acid sites matters for aldol condensation, in particular, in terms of yield, and that the elevated activity was achieved by the occurrence of multiple medium acid sites on the surface of the catalyst. On the other hand, there are small amounts of strong acid sites that exist on the 5Cs-5Nb/Al 2 O 3 catalyst, which may lead to the creation of unwanted byproducts and exacerbate carbonaceous deposits on its surface. ,, It is concluded that acid–base sites exhibit a synergetic catalytic effect in aldol condensation, and tuning the balance of the acid–base sites can effectively improve the activity of the catalysts.…”

“…On the other hand, there are small amounts of strong acid sites that exist on the 5Cs-5Nb/Al 2 O 3 catalyst, which may lead to the creation of unwanted byproducts and exacerbate carbonaceous deposits on its surface. 51,58,59 It is concluded that acid−base sites exhibit a synergetic catalytic effect in aldol condensation, and tuning the balance of the acid−base sites can effectively improve the activity of the catalysts.…”