Methyl Acrolein Oxidation Step Of Esterification Preparation Of Methyl Methacrylate

Methyl methacrylate (MMA) is a monomer that is used to polymerize the organic glass and the MBS resin. MMA is mainly produced by the method of acetone-cyanohydrins (ACH) in our country. The synthetic route is complex, the technical line is long, and after many steps the yield is low with high cost, particularly in this method seriously poisonous substance hydrocyanic acid is used as raw material, the treatment of numerous waste acids is difficult and the environment pollution is obviously. Considering all of these, it is greatly necessary to develop a new chemical technology to synthesis MMA.Recently, in many countries isobutene as a raw material to produce MMA has been investigated and this method is already industrialized. Because of its green and economic good effects will be given on both economy and society if this method can be used more widely. The process of isobutene to methyl methacrylate is realized through three stages: First, isobutene is oxidized to methacrolein (MAL), then MAL is converted into methylacrylic acid (MAA) through oxidation, at last MAA is esterified to MMA with methanol. In this article the three-stage method described above was simplified to two-stage method: MMA was prepared from methacrolein (MAL) directly by one-stage oxidative esterification. The original technical process was shortened and the yield increased. The major content of this article is as follow:Firstly, a new catalyst used to produce MMA from MAL by oxidative esterification was prepared by means of impregnation. Effect of composite and preparing condition of the catalyst was investigated, by means of BET, XPS, and SEM et al. The physicochemical properties of the catalyst were characterized. MAL conversion and MMA selectivity with this catalyst are both higher than those with other catalysts.Secondly, under the condition of continuous stirring and atmosphere pressure the effects of reaction conditions (reaction temperature, mass of catalyst, reactant ratio, reaction time and pH of reactive solution) on MAL conversion and MMA selectivity were systematically investigated and the best reaction conditions were obtained. The reaction kinetics was also studied. The global reaction order for MAL and activation energy were calculated out, the kinetics equation could be expressed as follow:Finally, ionic liquid [bmim]PF6 was used in the reaction of one-stage oxidative esterification from methacrolein to methyl methacrylate. It was found that the ionic liquid not only increased the selectivity of methyl methacrylate but also inhibited its polymerization.The results of this article provided foundational data to the industrialization of the reaction besides of the theoretical study. New catalyst composing and preparing method were found in pending patents. A new method of preparing MM A from MAL with existing of ionic liquid was invented. So those results are useful both in theory and practice.