Toward Efficient Methyl Methacrylate Synthesis: A Mesoporous Confinement Cs/Al-MCM-41 with Adjustable Acid–Base Synergistic Catalysis

The catalytic efficiency for methyl methacrylate (MMA) production via aldol condensation of methyl propionate (MP) and formaldehyde (FA) depends on the acid–base and structural properties of the catalyst. Inspired by this, a synergistic design strategy is implemented by fabricating Cs/Al-MCM-41 catalysts, where Al doping preserves ordered mesopores and tunes acid–base properties. This approach generates an optimal density of medium acid sites together with a balanced distribution of weak-to-medium base sites, leading to 90% MMA selectivity and a space-time yield of 0.29 g/(g cat ·h). Moreover, the mesoporous confinement not only enhances the dispersion of Cs active species but also suppresses the condensation of coke precursors, thereby significantly improving the catalyst stability. Density functional theory (DFT) calculations reveal that basic Cs–O–Si sites and acidic Al sites cooperatively activate MP and FA, promoting aldol condensation. This work demonstrates that the integration of targeted acid–base regulation with structural confinement provides a rational catalyst design principle for efficient aldol condensation.