Immobilized Ionic Liquids And Its Effenct On The Oxidation Reaction Of Benzyl Alcohol And Styrene

Immobilized ionic liquid could solve the difficult separation of the catalyst in catalytic reaction and the ease of recyclable utilization of the catalyst. Iron-chloride immobilized ionic liquid（SIL-FeCl₃） was prepared by N-methylimidazole reacting with chloropropylsilane linked on the mesoporous silica SBA-15 and coordinating of FeCl₃ to the imidazolium chloride grafted on the surface, as proved by XRD, TEM, 13 C CP NMR, 29 Si MAS NMR, 1H MAS NMR, FT-IR, ICP-MS, UV-vis and N2 adsorption-desorption technique. The results showed that fifty-two percent Si-OH were condensated with Si-OEt in CPTES On the SBA-15 surface. The FeCl₃ species were mainly distributed on the surface with nonuniform distribution, most of them were coordinately linked to the imidazole ring so stronger enough to keep its not leaching from the surface and a few parts were supported on the surface of SBA-15. ICP-MS test results showed the average content of FeCl₃ in the materials,corresponding to the loading of 0.71 mmol/g.The catalytic performances of the composite catalyst SIL-FeCl₃ were tested for solvent-free catalytic oxidation of benzyl（BzOH） into benzaldehyde（BzH） using H2O2 as oxidant, exhibiting high TON 125.8 mol/molFe. The effect of several reaction conditions, such as reaction temperature, time, molar ratio of H2O2 to BzOH and amount of catalyst on the oxidation was explored. The optimal operating conditions were obtained: reaction temperature 90 ℃, reaction time 4h, molar ratio of H2O2 to BzOH 4:1,amount of SIL-FeCl₃ 0.2 g. Under these conditions, the conversion of BzOH was 61.8 %,the selectivity to BzH was 73.6 %. The catalyst could be recycle seven times without appreciable loss of catalytic activity, indicating its excellent reusibility of composite catalyst SIL-FeCl₃.Simultaneously, The SIL-FeCl₃ was demonstrated to be an efficient catalyst for a solvent-free oxidation of styrene to benzaldehyde（BzH） using H2O2 as oxidant, exhibiting high TON 115.0 mol/mol Fe. The effect of several reaction conditions,such as reaction temperature, time, molar ratio of H2O2 to styrene and amount of catalyst on the oxidation was explored. The optimal operating conditions were obtained: reaction temperature 80 ℃, reaction time 5 h, molar ratio of H2O2 to styrene 3:1,amount of SIL-FeCl₃ 0.2 g. Under these conditions, the conversion of styrene was 40.6 %,the selectivity to BzH was 74.8 %. The catalyst could be recycled seven times without appreciable loss of catalytic activity, showing that its reusibility is excellent.