Hollow Porous Core–Shell CsH3PMo11VO40 Catalysts for Methacrolein Oxidation: Effects of Active-Site Accessibility and Acidic-Redox Properties

Conventional H 4 PMo 11 VO 40 (HPAV) catalysts for the selective oxidation of methacrolein (MAL) to methacrylic acid (MAA) are limited by insufficient active-site accessibility and poor mass transport. Herein, hollow porous core–shell UF-CsPAV catalysts were prepared using SiO 2 microspheres, PEO–PS copolymer, and urea-formaldehyde (UF) resin as a dual-template/organic precursor system. The optimized catalyst exhibited a specific surface area of 438.0 m 2 · g –1 and well-developed mesoporous channels. During calcination, NH 4 + species generated from the UF resin regulated the heteropolyacid environment, increasing acidity, the V 4+ /V 5+ ratio, and terminal oxygen species. At 335 ° C and a space velocity of 1020 h –1 , the catalyst prepared with 1 μm SiO 2 microspheres and 50 wt % CsPAV achieved 88.1% MAL conversion, 91.2% MAA selectivity, and MAA space-time yield (STY) of 1.54 mmol·cm –3 ·h –1 over 100 h. This work demonstrates an integrated strategy for coupling porous-architecture control with acid-redox regulation in MAL oxidation.