Preparation Of Palladium Composite Membrane And Its Application In One Step Oxidation Of Benzene To Phenol

Phenol is an important organic chemical raw material,which requirement has been increasing in recent years.The production method of phenol is mainly cumene method,but this method has the advantages of long process,high energy consumption,low yield and serious pollution.Therefore,the use of environmentally friendly catalytic reaction system for the synthesis of phenol has become the focus of research.Palladium composite membrane reactor has been widely concerned because of its advantages of simple operation,low energy consumption and high yield.In this paper,Pd composite membrane and Pd/TS-1 composite membrane were prepared by using tubular alumina carrier and catalytic synthesis of phenol from benzene in H2-O2 system.The effects of membrane structure and operating conditions on the preparation of phenol by one-step oxidation of benzene were investigated in detail.The main research contents and results are as follows:1?Palladium composite membranes were prepared by electroless plating on ?-Al₂O₃ ceramic tube and was used in the reaction of benzene hydroxylation to phenol.The effects of feed flow and hydrogen oxygen ratio on the reaction were investigated.The results show that,when the ratio of hydrogen to oxygen was 2.08,the maximum conversion of benzene was 24.8%,and the yield of phenol was about 12.9%.After 30 days of operation,the conversion rate of benzene and the yield of phenol were kept constant,and the hydrogen permeation was maintained at 0.015mol·m-2·s-1,it is proved that the system has good operation stability for a long time.2? The TS-1 zeolite with catalytic performance was synthesized by direct hydrothermal synthesis and characterized.The results showed that the molecular sieve was uniform in size,the size around 150 nm.The TS-1/Pd composite membranes were prepared by coupling agent method and catalytic oxidation of benzene to phenol.The experimental results show that the method of coupling agent can be successfully applied to the surface of palladium membrane with a layer of uniform TS-1 molecular sieve.When the ratio of hydrogen to oxygen was 2.2,the maximum conversion rate of benzene was 26.0%,and the yield of phenol was about 17.1%.Compared with the reaction efficiency of palladium composite membrane,it was found that the benzene conversion rate and the selectivity of phenol were greatly improved.3?Alumina hollow fiber membrane with micro pore structure was prepared by phase inversion spinning method and Pd-Al₂O₃ composite hollow fiber membrane was prepared by using it as carrier.The results show that hollow fiber membranes with finger like pores can be synthesized under the condition of core liquid?ethanol: NMP=3:7?.When the ratio of hydrogen to oxygen was 6,the maximum conversion rate of benzene was 2.1%,the yield of phenol was 0.3%.According to the stability test,it is found that the hydrogen permeability remains stable.