Direct synthesis of acrylic acid from methanol and acetic acid over a constructed TiO2-coated NASICON catalyst

Direct conversion of methanol and acetic acid (HAc) into acrylic acid (AA) and methyl acrylate (MA) is remarkably significant for the high-value utilization of coal-based chemicals. However, the previous catalysts, due to their single function or poor synergy between multiple active sites, remain large challenges in direct synthesis of acrylic acid. Herein, we designed a novel catalyst system through coating TiO₂ to sodium superionic conductor (NASICON) substrate for direct synthesis of acrylic acid from methanol and acetic acid. It was revealed that the catalyst with TiO₂ coating showed obviously improved performance. The selectivity of AA+MA highly reached 56.1 % at 380 °C, corresponding to the spatiotemporal yield of 46.5 μmol·g⁻¹·min⁻¹. It was demonstrated that TiO₂ coating catalyzes the oxidative dehydrogenation of methanol to formaldehyde, while NASICON substrate exerts important effects on the aldol condensation of formaldehyde and acetic acid, and their effective synergy promotes the direct synthesis of acrylic acid.