Study On The Synthesis Of Dimethyl Carbonate By Gas-phase Oxidative Carbonylation Of Methanol On The Supported Solid Catalyst

Dimethyl carbonate (DMC) is an environmentally benign building block; the development of clean technology to synthesize DMC is achieving increasing importance. This paper selected ?Study on the Synthesis of Dimethyl Carbonate by Gas-phase Oxidative Carhonylation of Methanol on the Supported Solid Catalyst?as the research suhjeci: of thesis for Master抯 1)egree, and was of theoretical importance and practical value.By the study of preparation, characterization, deactivation-regeneration of the catalyst used in the synthesis of DMC. a new solid catalyst PdCI2-CuCI,-KOAc/AC with high activity. high selectivity, and high stability was developed for the first time. The mechanism of the synthesis of DMC by oxidative carbonylation of methanol was proposed on the basis of catalyst characterization. The reason for the catalyst deactivation was investigated, and the regeneration method was developed. Furthermore, oxide catalyst used in this reaction system was developed in order to eliminate the drawbacks of chloride catalyst.Single metal chloride catalysts, bimetallic chloride catalyst, and multicomponent catalysts were prepared by incipient impregnation, and their activities were measured under atmospheric pressure in a fixed-bed flow system. The solvent and the drying method for the catalyst preparation were determined. The effect of Cu precursor, Pd content, and support in the catalyst PdCI2-CuCI2-KOAc/AC on the catalytic properties were examined. Up to now, both the catalyst and its preparation method has not been reported in the literature.The effect of different promoters such as Li, Na, K on the reaction performance of synthesizing DMC in gas-phase was studied. Among these promoters, K was the best one. The precursor and content of K promoter were determined. Under the reaction conditions, 慖?~ I 52擟, GHSV= I 483W?and LIISV=4h? CO/022.83, over PdCI2-CuCI2-KOAc/AC catalyst, the STY of DMC is 3l7~36lg/L-cat.h. and the conversion of methanol is 1 4.8?16.9%, which are higher than that of the literature.IllI~眫A~t~5CThe bulk and surface properties of catalyst PdCI,-CuCI-KOAc/AC were studied by XRD and XPS techniques. On the basis of the catalyst characterization and evaluation, the active species of this catalyst were investigated. The interaction between active component. promoter and support was examined. The reason for catalyst deactivation was found out. The mechanism of the synthesis reaction was proposed, by which the ditTeren~e of catalytic properties ~s explained.The effect of catalyst pretreatment conditions for catalyst PdCI2-CuCI2KOAcIAC on the catalytic properties was investigated. The optimal pretreatment temperature and atmosphere were determined. By adding methanol solution of methyl chloroacetate when the catalyst is pretreated in N2 stream under 2OO~C, the catalytic activity is improved~ and the service life is up to lOOh.The regeneration method of deactivated catalyst was studied. The deactivated catalyst was treated with methanol solution of methyl chloroacetate in the reactor in N2 stream under 200C for 4h, and was further treated in N2 stream under 200C for2h.As a result, the regeneration induction period would be shortened, and the restoration of catalytic activity would be promoted. The catalytic activity of the deactivated catalyst which was regenerated twice still restored to 93% of that of the fresh one.in order to get rid of the drawbacks of the chloride catalyst, a new oxide catalyst used in the synthesis of DMC was developed. The solid oxide catalyst CuOLa203/AC used in this system was prepared, and the active species of the oxide catalyst were also investigated.