Preparation And Study On Monolithic Catalyst For Direct Oxidative Esterification Of Methacrolein With Methanol To Methyl Methacrylate

Methyl methacrylate(MMA), as an important monomer, is widely used in producing acrylic plastics and polymer dispersions for paints, coatings, plexiglass and so on,which can generate polymethyl methacrylate(PMMA) or MMA binary, ternary and quaternary copolymers by homopolymerization or copolymerization. At present, the main commercial process for the production of MMA is the traditional acetone cyanohydrine(ACH) process and the IB oxidation process. The IB oxidation process had attracted more and more attentions for its advantage of highly atom economy, low equipment cost, less side effects and non-corrosiveness.Therefore, many efforts have been devoted to explore this method, especially the reaction of direct oxidative esterification of MAL to MMA.In this dissertation, catalyst and the corresponding fixed bed reaction process of oxidative esterification of MAL with methanol(Me OH) were studied. The main work as follows:1) The granular catalysts with Pd-Pb compositions using in oxidative esterification of MAL and Me OH were prepared by wet impregnation method and characterizated by different methods,such as BET、XRD、SEM、ICP and TEM,investigated the catalytic performance,the abrasion performance and the Pd-Pb turnover rate of catalyst in stirred tank reactor. The results showed that the lifetime of the catalyst will be reduced because of the catalyst broken and noble metal loss in the long period of agitation process.2) The Mg O-Al2O3 coating on the surface of cordierite was prepared by the method of coating and in situ synthesis. The Pdx Pby/Mg O- Al2O3/ cordierite was prepared on the carrier by wet impregnation method, characterizated by different methods,such as BET、XRD、SEM、ICP and TEM and investigated the effects of H2O/Al(i-Pr O)3 ratio、coating time and the preparation method on coating.3) The Mg O-Al2O3 coating on the surface of foamed nickel alloy was prepared by the electrodeposition method. The Pdx Pby/Mg O- Al2O3/ foamed nickel alloy was prepared on the carrier by wet impregnation method, characterizated by different methods, such as BET、XRD、SEM、XPS、ICP and TEM and investigated the effects of preparation parameters on coating,such as the volume content of aluminum sol, Al2O3 content, stirring speed and deposition voltage, etc. The results showed that the optimal reaction conditions were as follows:T=80 ℃, P=0.3 MPa, methanol: MAL=8: 1(molar ratio), liquid materials flux rate =0.5 m L·min-1, oxygen flux rate = 35 m L·min-1 and reaction time = 2 h.4) The catalytic performance of Pd5Pb5/ Mg O- Al2O3/nickel alloy foam and cordierite were performed in a fixed bed reactor, and the new production process on the system of MMA reaction was studied in the fixed bed on the basis of the above research.The reaction conditions were as follows:T=80℃, P=0.3 MPa, methanol: MAL=8: 1(molar ratio), liquid materials flux rate =0.5 m L/min, oxygen flux rate = 35 m L/min and reaction time = 2 h. Under the above conditions, MAL conversion and MMA selectivity reached 76.1% and 81.2%,respectively.It shows that the gas- liquid- solid fixed bed reaction of new technology for production of MMA is feasible. The results can be used for the process optimization of methyl methacrylate production directly from methacrolein.