The Composite Catalytic Membrane Is Used In The Study Of The Catalytic Oxidation Of Benzyl Alcohol

Benzaldehyde is usually produced by toluene chlorination,and the product contains chloride or hydrogen ions,which is greatly limited in the application of medicines and spices."Chloro-free benzaldehyde"can be produced by the reaction of toluene oxidation,aromatic acid-catalyzed hydrogenation,etc.,which has the disadvantages of high raw materials,high production cost,low yield,and easy consumption of reagents and environmental pollution.This experiment intends to design and develop a composite membrane to promote the liquid phase oxidation rate of benzyl alcohol,and increase the selectivity of the benzaldehyde product,and provide new materials and ideas for the industrial upgrading of benzaldehyde green preparation.This paper provides a new theoretical and practical basis for liquid-liquid interface reactions and very significant.1. Preparation of double-layer catalytic composite membrane.Firstly,poly（methacrylicacid）（PMAA）microspheres were prepared by distillation-precipitation method,and PMAA microspheres were blended with PVDF powder to form a membrane.The Pd nanoparticles were fixed in the membrane by alkali treatment and in-situ reduction.A semi-interpenetrating network polymer was coated on the surface to obtain a composite film having catalytic properties.The composite membrane was characterized by X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（ATR-FTIR）,scanning electron microscopy（SEM）,and contact angle measuring instrument.The composite catalytic membrane was placed in a double chamber reaction.The catalytic oxidation performance of benzyl alcohol was studied in the device.The results showed that when the IPN coating porosity content of the composite membrane was 5%,the material flow rate was 82.5 m L/min,the temperature was 90℃,and the catalyst loading was 35.637 mg/g,the catalytic performance was the best,and the conversion of benzyl alcohol was 48.5%and the selectivity to benzaldehyde was 82.5%.2. Preparation of Sandwich-Janus catalytic composite membrane.Firstly,based on the catalytic composite membrane prepared in the first chapter,a PVDF coating was coated on the other side of the base membrane to prepare an amphiphilic catalytic composite membrane.Mass transfer is enhanced by adjusting the membrane pore structure of the coating on both sides.The composition of the composite membrane was analyzed by Fourier transform infrared spectroscopy（ATR-FTIR）.The morphology,pore structure and Pd nanoparticle loading of the membrane surface were observed by scanning electron microscopy（SEM）.The prepared membrane was also placed in a two-chamber reactor to study its catalytic oxidation performance for benzyl alcohol.Studies have shown that the lipophilic and hydrophilic layers on both sides of the composite membrane can prevent the water phase and the oil phase from leaking and mixing;When coating on both sides of the composite film,the content of pore-forming agent was 5%,30%H₂O₂ was used as the oxidant,the reaction temperature is 90°C,the liquid flow rate was 82.5 m L/min and the catalyst loading was 30.213 mg/g,the composite catalyst had the highest catalytic activity.The conversion rate of benzyl alcohol obtained by the reaction was 30.25%,and the selectivity of benzaldehyde was 80.04%.