K–Zr/SiO 2 Catalyst for Efficient Aldol Condensation of Methyl Acetate and Formaldehyde

Cost-effective catalysts for methyl acrylate (MA) synthesis via the aldol condensation of methyl acetate (Ma) and formaldehyde (FA) remain a challenge. This study presents a series of K–Zr/SiO 2 bifunctional catalysts designed by coimpregnation to achieve synergistic acid–base regulation. Characterizations (XRD, FT-IR, N 2 physisorption, NH 3 /CO 2 -TPD, Py-IR, XPS) show that Zr incorporation enhances K dispersion, modulates surface acidity/basicity, and promotes the aldol condensation reaction process. The 4K-3Zr/SiO 2 catalyst achieved 34.15% Ma conversion, 92.55% MA selectivity, and 2.34 mmol·g Cat –1 ·h –1 space-time yield under optimized conditions ( T = 380 °C, LHSV = 0.8 h –1, Ma:FA:MeOH = 1:2:2). Mechanistic studies show that Si–O–K and Si–O–Zr act as Lewis base and Lewis acid sites, respectively, balancing acid–base ratios and suppressing side reactions. The catalyst maintained 95% activity after four regeneration cycles, confirming its industrial feasibility. This work offers a strategy for designing cost-effective K-type catalysts in MA synthesis, highlighting the importance of acid–base synergy.