Study On The Catalysts For The Condensation Reaction Of Methyl Propionate And Formaldehyde

Methyl methacrylate (MMA), which is an important chemical raw materials, is widely used in inproducing acrylic plastics and polymer dispersions for paints, plexiglass, coatings and soon. The main traditional process for the production of MMA contains the traditional acetone cyanohydrine (ACH) process. The ACH process uses high toxic hydrocyanic acid (HCN) as the raw materials, uses high caustic sulphuric acid in the process and generates solid waste of ammonium bisulfate. The atom utilization efficiency is only47%. The process of methyl propionate (MP) condensed with formaldehyde (HCHO) to produce MMA, which is produced by ethylene, methanol and carbon monoxide attracts more attention due to its short process flow and high atom utilization efficiency.In this dissertation, catalyst and reaction process of methyl propionate with formaldehyde were studied. The main work as follows:(1) The catalysts with different compositions using in methyl propionate and formaldehyde were prepared by wet impregnation method and characterizated by different methods. The influences of the active component, preparation variables of promoter, improved preparation methods on catalytic performance of supported alkali metal catalyst were studied in detail. Additive of zirconium and alkaline earth metal, catalytic activity of catalyst has been improved, which has basic sites and acid sites. Tuning of surface acid-base sites on SiO2surface could improveto improve the catalytic activity. Zirconium is dispersed in the SiO2surface in the form of zirconium oxide. Magnesium could reduce the carbon deposition of the catalyst. The best loading of Cs, Zr and Mg are15%,2.0g/100molSiO2,1.0g/100molSiO2, respectly.(2) The influences of molar ratio of HCHO to MP, reaction temperature, carrier gas flow, and weight hourly space velocity on catalytic performance of catalyst were studied. The activity of catalyst could reach the highest at the best reaction condition. The conversion of MP is21.5%, the selectivity to MMA is93.8%.(3) The catalyst would deactivate at long time reaction. From the analysis of TG-DSC and SEM, the catalyst deactivation was ascribed to the accumulation of the coke on the catalyst surface active sites. Calcining in air could regenerate the activity of catalyst.