Studies Of Cs-P Based Catalysts For Synthesis Of Methyl Methacrylate From Methyl Propionate And Formaldehyde

Methyl methacrylate(MMA)is an essentially important monomer,used to produce organic glasses and other high-value chemicals.The demand for MMA increases rapidly due to its special properties and broad applications.At present,the traditional route for producing MMA is Acetone cyanohydrine(ACH).This route uses large amounts of toxic hydrocyanic acid and produces large amounts of wast water and solid wast.The pressure from environmental protection is increased.Thus,developing the new MMA production process is of great importance.In this work,the new process for synthesizing MMA from methyl propionate and formaldehyde was developed.The acid-base catalysts were obtained.The main research work and innovations are as follows:(1)A series of catalysts with different supports(?-Al2O3,SiO2,TiO2,ZrO2,CeO2)were developed using impregnation method with Cs,P as active components.The performances of Cs-P/Y catalysts were evaluated through the fixed bed reactor.The best support was obtained and different characterizations were used to reveal the intrinsic reason of better activity.The surface area and acid-base property are the key element to promote catalytic activity.(2)The metal Fe was used to modify Cs-P/?-Al2O3 catalyst and physico-chemical properties of Cs-P-Fe/?-Al2O3 catalysts with different Fe contents were investigated systematically through TPD,Pyridine-FTIR and XPS.Adding promoter Fe can increase the amount of medium acid sites.The acid sites on surface of catalysts were medium Lewis acid.Importantly,promoter Fe can adjust the proportion of phosphorus species effectively,which has a huge influence on the amount and strength of Lewis acid.(3)The reaction conditions such as temperature and LHSV were optimized.The best catalytic performance was obtained at 370?,LHSV=1.2 h-1.Conversion of MP was 29.1%and MMA selectivity reached 90.7%.The stability of the optimized catalyst was studied.The deposition of cokes is the main reason for deactivation.After three reproduced circles,the regenerated catalyst presents the same catalytic performance as the initial catalyst.In addition,the optimized catalyst was prepared in large scale and evaluated in a large-scale fixed bed reactor.