Enhanced surface synergistic effect of alkaline earth metal oxide modification on VPO/SiO2 catalysts for gas-aldol condensation of acetic acid and formaldehyde

Preparation of Methyl Acrylate through Catalytic Aldol Condensation over Cs/TS-1 Catalysts

“…For the optimized catalyst of 20% VPO-TiO 2 , the acetic acid conversion and (AA+MA) selectivity achieved 29–31 and 85%, respectively . Noteworthily, VPO catalysts are involved more than surface acid–base-catalyzed aldol condensation, which is also applied to the complex oxidation–reduction because of the complicated crystalline phase and structure, resulting in the formation of byproducts and rapid deactivation of catalysts. ,− Many studies on aldol condensation of MA with FA have been conducted over Cs catalysts supported on Al 2 O 3 , SiO 2 , and SBA-15 via simple impregnation methods with excellent catalytic performance. − Previous research studies have reported that the Si–O–Cs active sites through the interaction of Cs + with Si–OH groups were proposed as active centers to promote the dispersion of Cs species and catalytic performance. ,, Ghosh et al also discovered that the Cs + single sites located within channels of β zeolite through ion exchange showed highly efficient catalytic activity for the self- and cross-aldol condensation and that the active centers were proposed to be monovalent Cs + single sites . Supported Cs catalysts are expected as promising candidates; however, active centers of aldol condensation still need in-depth investigation.…”

“…As versatile resin monomers, methyl acrylate (MA) and acrylic acid (AA) are widely used for the production of polymers, rubbers, adhesives, and plastics. − Currently, nearly most of the MA is manufactured industrially from hydrolysis of acrylonitrile and oxidation of propylene (Scheme ). , The hydrolysis of the acrylonitrile process relies on excessive toxic hydrogen cyanide with large amounts of sulfuric acids as raw materials, leading to environmental pollution as well as a large amount of the low-valuable NH 4 HSO 4 , which has been gradually replaced by the two-step oxidation of propylene.…”