The Preparation And Characaterization Of The Catalysts For Oxidative-esterification Of Methacrolein To Methyl Methacrylate

Methyl methacrylate (MMA) is an important organic chemical material, mainly used for the produce of PMMA and other resins.MMA was mainly produced by the old method of Acetone-Cyanohydrin(ACH) process in the world.It is very necessary to develop new produce processes for the environmental and economic benefits. The process of one-step conversion of methacrolein(MAL) to MMA is a green synthetic process with great potential.The catalysts used a hydrophobic catalyst material styrene - divinylbenzene copolymer (SDB) as carrier for one-step oxidative-esterification of MAL to MMA were studied.The active component such as PdCl2 was impregnented on SDB by the incipenent wetness method,and reduced it to prepare a hydrophobic catalyst . The different drying ways were studied for the catalytic activity.XRD shows that dring at normal pressure with a better dispersion than drying at vacuum,catalytic test further illustrates the catalysts with a higher activity.The effect of the content of Pd and promoting component for the catalytic activity was studied.The palladium(Pd) catalyst's catalytic property could be improved drastically with bismium(Bi) or lead(Pb).The MAL conversion was 33.50% and the MMA selectivity was 42.50% with the existence of Pd5/SDB;The MAL conversion was 51.63% and the MMA selectivity was 69.36% with the existence of Pd5Bi/SDB;The MAL conversion was 71.65% and the MMA selectivity was 78.15% with the existence of Pd5Pb/SDB.The catalytic activity of Pd-Pb/SDB is better than that of Pd5Bi/SDB under the same component addition .Technological conditions were optimized by using a new catalyst.Under the reaction conditions:mole ratio of methanol to MAL 40:1,catalyst additive 3.6% (all raws), reaction temperature 50℃,flow rate of oxygen 6ml/min,reaction time 4 hours and PH value 10.5, the MAL conversion and MMA selectivity were 87.68% and 91.20% respectly.