A General and Simple Method of Preparing Molybdenum- Incorporated Silica Nanoparticles as Potential Catalysts for Epoxidation of Alkenes

Catalytic developments in the epoxidation of vegetable oils and the analysis methods of epoxidized products

Functionalization of vegetable oils (VOs) including edible, non-edible, and waste cooking oil (WCOs) to epoxides (EVOs) is receiving great attention by many researchers from academia and industry because they are renewable, versatile, sustainable, non-toxic, and eco-friendly, and they can partially or totally replace harmful phthalate plasticizers. The epoxidation of VOs on an industrial scale has already been developed by the homogeneous catalytic system using peracids. Due to the drawbacks of this method, other systems including acidic ion exchange resins, polyoxometalates, and enzymes are becoming alternative catalysts for the epoxidation reaction. We have reviewed all these catalytic systems including their benefits and drawbacks, reaction mechanisms, intensification of each system in different ways as well as the physicochemical properties of VOs and EVOs and new findings in recent years. Finally, the current methods including titrimetric methods as well as ATR-FTIR and 1H NMR for determination of conversion, epoxidation, and selectivity of epoxidized vegetable oils (EVOs) are also briefly described.

Recent Progress in Application of Molybdenum-Based Catalysts for Epoxidation of Alkenes

Epoxides are important industrial intermediates applied in a variety of industrial processes. During the production of epoxides, catalysts have played an irreplaceable and unique role. In this review, the historic progress of molybdenum-based catalysts in alkene epoxidation are covered and an outlook on future challenge discussed. Efficient catalysts are demonstrated including soluble molybdenum complexes, polyoxometalates catalysts, molybdenum-containing metal organic frameworks, silica supported molybdenum-based catalysts, polymer supported molybdenum-based catalysts, magnetic molybdenum-based catalysts, hierarchical molybdenum-based catalysts, graphene-based molybdenum containing catalysts, photocatalyzed epoxidation catalysts, and some other systems. The effects of different solvents and oxidants are discussed and the mechanisms of epoxidation are summarized. The challenges and perspectives to further enhance the catalytic performances in alkenes epoxidation are presented.