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The Research on One-pot Synthesis of DMC

Author: SunYe
Tutor: DongWenSheng
School: Shaanxi Normal University
Course: Applied Chemistry
Keywords: Supported catalysts Solid Super Base Carbon dioxide Dimethyl carbonate vinegar One-step synthesis
CLC: TQ225.52
Type: Master's thesis
Year: 2007
Downloads: 430
Quote: 0
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Abstract


Human life and production of large emissions caused serious environmental pollution resulting green chemistry, the fundamental goal is to conserve resources and prevent pollution, and thus the prevention and control of environmental pollution and depletion of natural resources and other issues. As a low toxicity and reactivity of chemical reagents, dimethyl carbonate (DimethylCarbonate DMC) synthesis and application in recent years has been widely appreciated. It can replace the highly toxic phosgene and dimethyl sulphate as environment-friendly synthesis of organic intermediates and starting materials used in the hydroformylation and methylation reactions. In addition, because the DMC has a higher oxygen content, it is possible to replace the methyl tert-butyl ether as gasoline additives to enhance the gasoline octane number. As exhaust a lot of carbon dioxide emissions caused by the severe \Chemical utilization of carbon dioxide not only meet the requirements of sustainable development and to meet the requirements of green chemistry, becoming one of the important research direction. As a of Organic Chemistry cornerstone \Currently, industrial DMC main synthetic route is the oxidative carbonylation of methanol liquid phase law, methanol and propylene carbonate (ethylene carbonate), an ester exchange method. Compared with the two-step direct transesterification method, methanol, propylene oxide, carbon dioxide, a simple one-step synthesis of DMC process, low energy consumption, less the cost of investment in equipment and product separation in the economically more attractive. In this paper, activated carbon supported inorganic alkali metal hydroxides, preparation of new supported catalysts to achieve one-step synthesis of dimethyl carbonate from carbon dioxide, methanol and propylene oxide reaction catalyst system, the study focused on a different catalyst activity group points and the carrier and its preparation conditions and methods of catalyst performance, as follows. Studied activated carbon supported alkali metal hydroxide catalyst under the one-step synthesis of dimethyl carbonate, the results show that the catalyst supported on activated carbon as catalyst activity was higher than the other load; calcination temperature for sodium hydroxide supported catalysts , the optimum calcination temperature is 600 ℃; reaction 3h, the reaction temperature was 150 ° C. The reaction conditions are more suitable; improve the ratio of alcohol / ether can improve the selectivity and yield, the best ethers ratio is 8:1. Supported catalyst preparation conditions were investigated, respectively, on different carriers, different precursors and different load, different calcination temperature on the catalytic performance and reaction time, reaction pressure and reaction temperature on the reaction impact do the study, the results showed that the methanol and propylene oxide under the reaction conditions as the carrier activated carbon, sodium hydroxide as a precursor, the loading of 15% (wt), the calcination temperature of 600 ℃, the initial reaction pressure is 4MPa The conversion rate of 28.1% and 99.9%, the highest selectivity of DMC and PG, respectively, 39.8% and 40.5%. Pretreatment activated carbon carrier and supported catalyst preparation conditions, calcination temperature, reaction temperature, catalyst performance were studied using X-ray diffraction technology (XRD), the CO 2 Programs warming off (TPD), X-ray photoelectron spectroscopy (XPS), physical adsorption characterization means of activated carbon supported catalyst carrier super alkaline formation of research into the causes, the results show that the oxidation of sodium NaOH after decomposition formed after calcination at 600 ℃ was the reason that is alkali active sites formed, base strength and alkali have a major impact on the catalyst activity. The catalyst is recycled using the six, its activity and selectivity decreased slightly, but through XPS and XRD analysis of the reaction before and after the surface of the catalyst and the phase structure has not changed, the reasons for the slight decrease of the activity and selectivity is caused by the loss of the quality of the catalyst in the cyclic use and the process of separation. In addition, the characterization results show that the activity of the catalyst and the catalyst has a close relationship in the alkali bit.

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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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