New catalysts containing phosphomolybdic acid (PMA) and vanadophosphomolybdic acid (VPMA) in a titania matrix were synthesized by the sol–gel process with different heteropolyacid loads (5%, 15%, and 30% (w/w): 5PMA-TiO₂, 15PMA-TiO₂, 30PMA-TiO₂, 5VPMA-TiO₂, 15VPMA-TiO₂, and 30VPMA-TiO₂). The techniques used to characterize the materials were XRD, DRS, SEM, FT-IR, ³¹P MAS-NMR, potentiometric titration with n-butylamine, and N₂ physisorption at −196 °C. The materials were used as heterogeneous catalysts in the oxidation of 2,3,6-trimethylphenol (TMP) to 2,3,5-trimethyl-p-benzoquinone (TMBQ), a key intermediate in vitamin E synthesis. The catalysts allowed an ecofriendly TMBQ synthesis, using ethanol as solvent and aqueous hydrogen peroxide as a clean oxidizing agent, at room temperature. The conversion of TMP reached 90% and 99% for the samples with 15PMA-TiO₂ and 15VPMA-TiO₂, respectively, after 4 h. The amount of Mo and V in the reaction medium was determined by ICP-MS, which showed leaching of only 17–18% Mo, but 48% V. Reuse of the catalysts was performed. For 15PMA-TiO₂, the conversion was maintained in the second cycle. A homolytic mechanism was proposed for TMBQ synthesis, which involved the formation of a peroxometallic species through an HPA-Ti center.

通过溶胶-凝胶法合成具有不同杂多酸负载量（5％，15％和30％（w / w））的新型催化剂，该催化剂在二氧化钛基质中包含磷钼酸（PMA）和钒钛磷钼酸（VPMA）：5 PMA-TiO ₂，15 PMA-TiO ₂，PMA-TiO 30 ₂，5VPMA-TIO ₂，15VPMA-TIO ₂，和30VPMA-TIO ₂）。用于表征材料的技术为XRD，DRS，SEM，FT-IR，³¹ P MAS-NMR，正丁胺电位滴定法和在-196°C下的N ₂物理吸附。该材料用作2,3,6-三甲基苯酚（TMP）氧化为2,3,5-三甲基-p的非均相催化剂-苯醌（TMBQ），维生素E合成的关键中间体。在室温下，使用乙醇作为溶剂，使用过氧化氢水溶液作为清洁氧化剂，该催化剂可实现环保的TMBQ合成。TMP的转化率达到了样品90％和99％与15 PMA-TiO ₂和15VPMA-TIO ₂分别，经过4小时。反应介质中Mo和V的量通过ICP-MS测定，结果表明只有17-18％的Mo浸出，但是有48％的V浸出。重复使用了催化剂。对于15 PMA-TiO ₂，在第二个循环中保持转化率。提出了一种用于TMBQ合成的均解机制，该机制涉及通过HPA-Ti中心形成过氧金属物种。