Preparation Of Heteropoly Acid-based Supported Ionic Liquid-phase Catalyst And Research For The Selective Oxidation Of Alcohols

Heteropoly acid, especially phosphorus tungsten acid(HPW), as a kind of catalyst, with no pollution,multifunction and high activity, has gradually shown a good prospect in organic synthesis and other fields. The application field of ionic liquids with task-specific functionality, due to their unprecedented properties, such as high chemical and thermal stability,favorable solubility, tunable physical and chemical properties by the choice of organic cation and/or inorganic anion, has expanded from solvent to catalysis,especially functionalization by phosphorus tungsten acid and molybdophosphoric acid. However, such homogeneous species possess a number of inherent shortcomings, including high price, large consumption, and difficulties in separation and/or recovery. In order to overcome the above-mentioned problems, some attempts have been made to fabricate the task-specific active sites on pore surface and/or in framework of mesostructure. The paper is based on this issues. In this paper,we immobilize HPW on pore surface and/or in framework of mesostructure fabricated by the task-specific ionic liquid. To avoid toxic volatile organic solvent(VOC), we use water as the only solvent, and30%H2O2as oxidant for oxidation of alcohols. The main contents of this paper are as follows: (1) We adpot multi-step to synthesize the catalyst(PW-IL-SBA-15). At the same time, a series of characterations are made, such as FT-IR, N2adsorption and desorption, TG-DTG, XRD,29Si NMR,31P NMR, ICP-AES etc. To avoid toxic volatile organic solvent(VOC), such as CH3CN, CHCl3and so on, we use water as the only solvent, and30%H2O2as oxidant for selective oxidation of benzyl alcohols. The performance of the catalyst is excellent, we obtain97%conversion and>99%selectivity, meanwhile, the reusibility of the catalyst is also very well, This catalyst could be recycled five times without obvious loss of activity.(2) We adopt one-pot method to synthesize the catalyst(4h,5min). In order to comfirm the structure of the catalyst, we employ N2adsorption and desorption. The result represents that the textural properties of SB A-15were substantially maintained over ionic liquid functionalization and on subsequent anchoring of HPW. Further characteration are made, such as ICP-AES,29Si NMR,31P NMR etc. We detect the performace of the catalyst via selective oxidation of benzyl alcohols. As a result, we obtain97%conversion and>99%selectivity, and the catalyst could be recycled five times without obvious loss of activity. Meanwhile, we also expand the reaction to several alcohols, and do some research about the reasons of loss of activity of the catalyst.(3) We adopt one-pot method to synthesize the catalyst(PMO). And N2adsorption and desorption result represents that the textural properties of SB A-15were substantially maintained, though ionic liquid and HPW are inserted. As for detecting the performance of catalyst, selective oxidation of benzyl alcohols is selected.97%conversion and>99%selectivity are obtained, the catalyst could be recycled five times without obvious loss of activity. Meanwhile, we also expand the reaction to several alcohols, and do some research about the reasons of loss of activity of the catalyst.