Kinetics and optimization studies of modified VPO/γ-Al2O3 catalyst prepared in situ for cross-aldol condensation

Abstract

Organic solvent method was used to prepare the active component VPO, which was loaded on ball-milled γ-Al₂O₃ support. VPO/γ-Al₂O₃ catalysts were synthesized by in situ generation for the synthesis of acrylic acid (AA) by the aldol condensation of acetic acid (HAc) and formaldehyde (HCHO). The effects of the calcination temperature and the loading of the active component VPO on catalytic activity were systematically investigated. XRD, BET, SEM, CO₂/NH₃-TPD, FT-IR spectroscopy, and TG techniques were used to characterize the VPO/γ-Al₂O₃ catalysts. The results showed that the catalyst had the best crystal structure and acid–base activity center at a calcination temperature of 350 °C. The catalytic performance was evaluated using a fixed bed reactor. 60% VPO/γ-Al₂O₃ exhibited the highest reactivity, and the yield of AA was up to 51.5%. Response surface methodology (RAM) was used to optimize the reaction conditions for aldol condensation. The kinetic equation and reaction order of the aldol condensation reaction were determined using the VPO/γ-Al₂O₃ catalyst. It provides guidance for the in-depth study of aldol condensation reactions in the future.