Research On Methyl Acrylate Synthesis And Separation

As an important industrial monomer, methyl acrylic(MA) and its derivative are extensively used in the production of chemical fiber, plastics, leather treating agents, adhesives and coatings. Traditionally, MA is produced by acetone cyanohydrin process. As a commercial route, MA is produced by oxidation of propylene or propane, acetylene carbonylation and so on. However, these routes consume large amounts of energy, low product yield, and it produces lots of by-product which is difficult to handle. In recent years, the worldwide rising productivity of methyl acetate(MeOAc) and the demand of MA have been increased considerably. Thus, it makes the attention paid to the synthesis of high added value MA with MeOAc.Vanadium phosphorus oxides(VPO) catalyst was developed for the aldol condensation of MeOAc with formaldehyde(HCHO) to form methyl acrylic(MA). The catalysts controlling preparation method was formed. Response surface methodology(RSM) with three independent variables was employed to optimize MA yield with VPO catalysts. The kinetic of aldol condensation to produce MA over VPO catalyst and the separation were also studied. The main contents of the research are as follows.The influence of P/V ratios, organic solvent ratio, liquid to solid ratio on reaction activity and selectivity was revealed and optimized with fixed bed reactor. The catalyst properties was researched and characterized by XRD, BET, TEM, FTIR, NH3 and CO2-TPD. The catalyst with P/V atomic ratio of 1.2,organic solvent ratios 4,liquid to solid ratio10 presented best yield and selectivity. The main phases of VPO catalyst are both VOPO4 and(VO)2P2O7 entities and high amount of VOPO4 entity was also beneficial to catalytic behaviors.The effect of different carrier gas for catalyst anti-deposition carbon was also systematically researched. Response surface methodology(RSM) with three independent variables of molar ratio of MeOAc to HCHO, space velocity, and reaction temperature was employed to optimize MA yield with VPO catalysts. The value of ―R-squared‖ of 0.9981 presented a reasonable correlation of regression model to the experimental data. The highest yield of product was 75.9%, which was obtained with the optimized conditions of molar ratio of methyl acetate to formaldehyde 5, space velocity 1.2, and reaction temperature 370 oC.In order to analyze the reaction system more simple, practical and comprehensive, power exponential function was used for discussed the reaction dynamics. The reaction order of HCHO n=1.843, the pre-exponential factor k0=6.794×10^3 and the reaction activation energy Ea=54.201 kJ.mol-1. The kinetic equation, which fits the experiment data quite well, can better describe the reaction process.In addition, the separation of methyl acetate was studied from methyl acetate – methanol-water-MA-formaldehyde five mixture system by continuous decompression distillation recycling. The Aspen simulation software was used to simulate and optimize the process, choose reasonable model and optimize process parameters(feed position, the number plate, reflux ratio, etc.) to achieve the effective separation of methyl acetate. At the same time, the system separation process experiments were carried out. The experimental results show that the experimental value in conformity with the simulation values and this further verify the reliability of the simulation.