Vapor-phase Synthesis of Dimethyl Carbonate by Copper Catalysts

• Main Authors: HUANG CHAO SHUEN, 黃昭順
• Other Authors: 劉端祺
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/92347375877914105912

碩士 === 國立臺灣科技大學 === 化學工程系 === 93 === Abstract The aim of this investigation is to examine the activities of CuCl2/C and CuCl2-PdCl2/C catalysts in the oxidative carbonylation of methanol. The reactions were carried out in a continuous flow micro-reactor under atmospheric pressure and at 160C. The feed contained methanol, carbon monoxide and oxygen. The desired product was dimethyl carbonate. The experimental results show that both CuCl2/C and CuCl2-PdCl2/C are active for the reaction. The most active CuCl2/C catalyst contains 14 wt% CuCl2. The activity of CuCl2/C may be enhanced by the incorporation of palladium chloride. The incorporation increases not only the activity of the catalyst but also the selectivity of dimethyl carbonate. The optimum amount of palladium chloride in CuCl2-PdCl2/C catalyst is 0.5 wt%. Excess amount of the chloride will only make the catalyst less active. The yield of dimethyl carbonate in the reaction is related to the feed composition. The optimum feed composition for maximum yield depends on the catalyst used. With the oxygen contain being limited to 8% to avoid explosion, the optimum feed ratio of CO/CH3OH for 10% CuCl2/C is 12. Under the ratio, the reaction may have 40% methanol conversion and 87% dimethyl carbonate selectivity. When CuCl2-PdCl2/C is used as the catalyst, the optimum ratio becomes 6.6. The reaction under the ratio may have 38% conversion and 95% selectivity. Deactivation was found in either CuCl2/C or CuCl2-PdCl2/C and the situation for CuCl2/C is more severe. The growth of crystalline copper compounds, as found by XRD, during the reaction is one of the causes for the deactivation. CuCl2-PdCl2/C catalyst has less of the crystalline compounds indicating PdCl2 is capable of preventing the growth of the crystals. Both ESCA and EDX analyses have shown that the chlorine content in the catalyst is significantly reduced during the reaction. Therefore, the loss of chlorine may be another reason for the deactivation.