Study On Green Catalytic Process For Oxidation Of Benzyl Alcohol To Benzaldehyde

Benzaldehyde is an important organic raw material,which is widely used in food,medicine,spices,dyes and other chemical products.Traditional benzyl chloride hydrolysis and direct toluene oxidation have serious environmental pollution problems,while the produced benzaldehyde contains a small amount of chloride ions or chloride compounds,which limits its application in food and medicine.The selective oxidation of benzyl alcohol to benzaldehyde is an ideal green process route,as it can avoid the production of chloride ion and meet the requirements of environmental protection.It's one of the hot research topics in recent years.However,the development of the efficient catalyst is still a key point.Therefore,it is particularly important to develop and design a novel and efficient catalyst for the selective oxidation of benzyl alcohol.In this paper,we chose APTES to modify SB A-15,and prepared the corresponding catalyst SBA-15-NH2-Au-X(X = Pd,Ru,Pt,Ag)by deposition precipitation method and applied for selective oxidation of benzyl alcohol to benzaldehyde in solvent system.The results showed that,SBA-15-NH2-Au-Pd exhibited good catalytic performance among others.The best reaction conditions were:the total active content 2%,Au/Pd = 3:1,the catalyst 0.1 g,1 mL of benzyl alcohol,10 mL of acetonitrile and 2.75 mL of TBHP,the reaction temperature 80 ? and the reaction time 5 h.The conversion of benzyl alcohol was 85.81%and the selectivity of benzaldehyde was 91.10%The activity of catalysts with different ratios of Au/Pd in SBA-15-NH2-Au-Pd was investigated under solvent-free conditions.The best conditions were:the total metal content 2%and Au/Pd = 7:1,catalyst 0.05 g,20 mmol of benzyl alcohol,20 mmol of TBHP,the reaction temperature 110 ? and the reaction time 3 h,The conversion of benzyl alcohol was 82.05%and the selectivity of benzaldehyde was 82.66%.The catalyst showed a very good stability for four repeated experiments.Au-Ru/CeOx/?-Al2O3 was prepared by homogeneous deposition precipitation method,in which ?-Al2O3 was doped by CeOx as an additive.The selective oxidation of benzyl alcohol to benzaldehyde under solvent-free condition was explored,and Au-Ru/CeOx/?-Al2O3 showed a good catalytic performance,especially when the Au/Ru ratio was 5:1.Within 0.5 h,the conversion of benzyl alcohol reached 64.32%,and the selectivity of benzaldehyde was 70.69%.Finally,the conceptual design of selective oxidation of benzyl alcohol to benzaldehyde with output of 1,000 tons per annual was proposed.The results showed that,this process was economical,technical feasible and would provide some reference for industrial production in the future.