摘要
研究了乙醇在双功能Ｐｄ－Ｃｕ／分子筛催化剂上一步合成乙酸乙酯的反应，发现Ｐｄ是氧化活性中心的主组分，ＣＵ主要对Ｐｄ的氧化功能起调变作用，以减少乙醇深度氧化副反应，提高酯化选择性．分子筛的酸性强弱对活性，特别是对酯化选择性有明显的影响，酯化要求在较强的酸中心上进行．探讨了氧化活性中心和酸中心的匹配关系以及ＣＵ对Ｐｄ的调变作用，提出了乙醇氧化酯化机理．
ne-step oxidative esterification of gaseous ethanol to ethyl acetate over bifunctional Pd-Cu/zeolite catalysts was studieds It is found that palladium is the main component of oxidative active center; copper is used to modify mainly the oxidative properties of palladium, which reduces the side reaction of deep oxidation of ethanol, and thus enhances the ester selectivity. The acidic strength of zeolite has influence on the activity, especially the ester selectivity. The order of the reactive activity of catalysts is Pd-Cu/HZSM-5>Pd-Cu/HM>Pd-Cu/HY which is the same as the order of the acidic strength of zeolites. This indicates that the esterification reaction is carried out on the more strong acidic sites. The better matching of the oxidative centers with acidic sites and the modification of Pd by Cu are discussed. The mechanism of oxidative esterification is proposed.
关键词
乙醇
酯化
钯铜分子筛
乙酸乙酯
ethanol,oxidative esterification, Pd-Cu/zeolite,bifunctional catalyst, ethyl acetate
