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Synthesis of Diethyl Carbonate by Ethanolysis of Urea over Metal Oxide Catalysts

Author: GuoLian
Tutor: ZhaoXinQiang
School: Hebei University of Technology
Course: Chemical processes
Keywords: Diethyl carbonate Urethane Urea Ethanol Lead oxide ZnO - PbO Magnesium oxide
CLC: TQ225.52
Type: Master's thesis
Year: 2011
Downloads: 41
Quote: 0
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Abstract


Diethyl carbonate (DEC) is an important organic carbonate, has broad application prospects. Alcoholysis of urea synthesis DEC reaction of metal oxide catalysts were studied. First, the lead oxide catalyzed alcoholysis of urea synthesis - Ethyl carbamate (EC) and the catalytic reaction of the ethanol synthesis of DEC DEC control steps. The results show that the lead oxide having a good catalytic stability, catalytic activity after repeated five no noticeable decline. XRD analysis showed that the recovery of lead oxide catalyst for the cubic phase metal Pb and orthorhombic PbO , the mixture. Binding activity of the evaluation results can be concluded that the active ingredient of the reaction mixture for the the catalytic EC and ethanol synthesis DEC, and metal Pb and PbO of 2 synergy is the main reason for having a high catalytic activity. Secondly, in order to further improve the performance of the catalyst prepared by a series of double metal oxide containing lead oxide, and its the catalytic EC and ethanol synthesis DEC reaction performance evaluation, found that the highest activity of ZnO-PbO. ZnO-PbO catalyst suitable preparation conditions: the Zn 2 (OH) 2 CO 3 and such as PbCO 3 precursor PbO quality fraction of 10%, calcination temperature of 500 ° C. ZnO-PbO as a catalyst in ethanol and EC molar ratio of 7:1, the catalyst, the total amount of material mass fraction of 1%, the reaction temperature of 190 ° C under the conditions of the reaction time of 7 h, EC conversion was 50.2%, the DEC yield of 20.6%, the DEC selectivity was 41.0%. Investigated the catalytic stability of ZnO-PbO, reuse five times its catalytic performance is not significantly decreased. Means of XRD and IR analysis, to determine the composition of the catalyst was recovered by Zn (NCO) 2 (NH 3 ) 2 , the cubic phase metallic Pb and orthorhombic phase the PbO 2 are formed in the mixture, its possible catalytic DEC Synthesis catalytic activity. The experimental results show that the reaction between the DEC and PbO lead PbO is reduced to metallic Pb main reason. Finally, the thermal decomposition prepared by the MgO, and then by H 2 / N 2 treatment for the catalytic urea and ethanol synthesis DEC reaction. MgO preparation conditions on the catalytic properties of suitable preparation conditions: Mg (OH) 2 is the precursor, calcination temperature of 600 ° C, roasting time 4 h in H < sub> 2 / N the 400 ° C treatment for 7 h 2 atmosphere. MgO catalyst in ethanol and urea molar ratio of 10:1, the amount of catalyst is urea and 2% of the total mass of ethanol, the reaction temperature is 180 ° C, the reaction time was 7 h the conditions under DEC closing rate of 11.8% . XPS analysis showed that the combination of activity evaluation of MgO by H 2 / N 2 treatment increased surface oxygen vacancy is the main reason for the improvement of its catalytic activity.

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CLC: > Industrial Technology > Chemical Industry > Basic Organic Chemistry Industry > The production of aliphatic compounds ( acyclic compounds) > Aliphatic carboxylic acid and its derivatives > Of organic derivatives of carbonic acid > Carbonate
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