【作者】 张震；

【导师】 马新宾；

【作者基本信息】 天津大学 ， 化学工艺， 2004， 硕士

【摘要】 碳酸二乙酯（DEC）作为“绿色化学品”是一种十分重要的有机合成中间体，特别是近年来发现DEC可以作为汽油、柴油的含氧添加剂，取代MTBE的使用，有着广阔的应用前景。本论文对乙醇气相直接氧化羰基合成碳酸二乙酯的CuCl2-PdCl2-NaOH/AC催化剂体系进行了研究，重点考察了钾助剂对其催化反应性能的影响。反应体系的主、副产物的定性分析表明，反应的主要副产物为乙醛、乙酸、乙酸乙酯、1,1-二乙氧基乙烷，并从副产物产生的机理推断其反应历程，进一步对反应体系进行了热力学分析。考察了不同钾助剂对CuCl2-PdCl2-NaOH/AC催化剂体系的反应性能的影响，结果表明氯化钾表现出良好的助催化作用，催化剂的催化活性及寿命得以提高，在保持乙醇对碳酸二乙酯选择性不变的前提下，转化率由16%左右提高到30%以上。对于CuCl2-PdCl2-KCl-NaOH/AC催化剂，在空速3400h-1、反应温度413K，压力0.64MPa下，考察了氧气以及一氧化碳流率变化对碳酸二乙酯的转化率及选择性的影响。当乙醇、氧气、一氧化碳的配比为4: 1: 10时，乙醇转化率达到31.2%，碳酸二乙酯选择性达到96%。通过XRD、XPS、SEM及CO-TPD表征分析表明，氯离子的流失是催化剂失活的主要原因；添加氯化钾助剂后，催化剂活性组分由γ-Cu2(OH)3Cl转变为Cu(OH)Cl，同时改善了活性组分在催化剂载体上的分散程度，CO的吸附量增加，同时脱附温度向上偏移，促进了反应的进行。γ-Cu2(OH)3Cl到Cu(OH)Cl的晶型转变，使得铜－钯之间的电子传递更加容易，提高了催化剂催化反应活性。更多还原

【Abstract】 Oxidative carbonylation of ethanol for preparation of diethyl carbonate (DEC) offers prospects for a “green chemistry” replacement of phosgene used for polymer production and other processes. In recent years, diethyl carbonate is found to substitute for methyl tert-butyl ether (MTBE), which is used as an oxygen-containing fuel additive. The synthesis of diethyl carbonate over the CuCl2-PdCl2-NaOH/AC catalyst from oxidative carbonylation of ethanol was evaluated. The influence of potassium promoter on the catalytic performance was mainly studied.The synthesized products from the oxidative carbonylation of ethanol were analyzed by combined means of programmed temperature-capillary gas chromatography-mass spectrometry. Diethyl carbonate, ethanol, ethyl acetate, acetic acid, acetaldehyde, 1,1-diethoxyethane were separated and qualitatively analyzed, respectively. The reaction mechanism was concluded and the thermodynamic analysis was carried out.The effect of various potassium promoters on the CuCl2-PdCl2-NaOH/AC catalyst for diethyl carbonate synthesis was investigated. The evaluation results showed that there was a significant variety on the catalyst activity when KCl was used as a promoter. The conversion of ethanol reached above 30% without any decrease of the selectivity to DEC. For CuCl2-PdCl2-KCl-NaOH/AC catalyst, the influence of flow rate of oxygen and carbon monoxide on the conversion of ethanol and selectivity of DEC was also investigated. The optimal molar ratio of the reactant (CO:O2:C2H5OH) was around 10:1:4, giving ethanol conversion 31.2% and the selectivity to DEC 96%. The morphological analysis by X-ray diffraction and XPS showed that the deactivation of catalyst was attributed to the leaching of chloride ion. The improved performance of CuCl2-PdCl2-KCl-NaOH/AC catalysts was closely related with the existence of copper chloride hydroxides (Cu(OH)Cl). CO-TPD analysis also indicated that the adsorbed capacity of CO was improved and the desorption temperature was shifted higher on the CuCl2-PdCl2-KCl-NaOH/AC catalyst. The obvious improvement in the catalytic performance for preparation of DEC was attributed to the efficiency of electronic transform between PdCl2 and Cu(OH)Cl crystal by reaction mechanism analysis.更多还原