偶联剂改性对Pd/堇青石催化加氢选择性的调控

采用硅烷偶联剂3-(氨丙基)三乙氧基硅烷(APTS)、γ-缩水甘油醚环氧基三甲基硅烷(GPTS)、3-巯丙基三甲氧基硅烷(MPTS)及3-氯丙基三甲氧基硅烷偶联剂(CPTS)分别对堇青石进行改性，再负载Pd粒子，制备了系列Pd/堇青石催化剂，并以1,5-环辛二烯(COD)部分加氢为探针反应，评价所制备催化剂的催化性能。结果表明，在堇青石中引入氨丙基后制备的Pd/堇青石催化剂可使COD深度加氢；而引入氯丙基、环氧基后制备的Pd/堇青石催化剂，则能在获得高COD加氢活性的同时，明显提高环辛烯（COE）选择性。氯丙基、环氧基的引入，显著提高了Pd/堇青石催化剂中Pd的分散度，并且使Pd结合能发生变化。COD加氢反应的COE 选择性是Pd/堇青石催化剂中Pd的粒径及化学态综合作用的结果。以环氧基改性堇青石为载体、乙酰丙酮钯为前驱物、超声波浸渍法制备的Pd/堇青石催化剂用于催化COD加氢反应，可以获得最高的活性与COE选择性。

Modulation of Hydrogenation Selectivity of Pd/Cordierites Modified by Silane Coupling Agent

The Pd/cordierite catalysts were prepared by firstly modifying cordierite by silane coupling agent, such as 3-aminopropyltriethoxysilane(APTS), γ-glycidoxypropyltrimethoxysilane(GPTS), 3-mercaptopropyltrimethoxysilane(MPTS), 3-chloropropyltrimethoxysilane(CPTS), then loading Pd particles. The catalytic performances of these catalysts were evaluated with 1,5-cyclooctadience (COD) partial hydrogenation as model reaction. The results showed that with the Pd/cordierite modified by the silane coupling agent containing aminopropyl group as catalyst the COD deep hydrogenation occurred, while with those modified by the silane agent containing chloropropene or oxygen propyl groups as catalyst the higher conversion rate and cyclooctene(COE) selectivity of COD hydrogenation were obtained. The dispersion of Pd particles on Pd/cordierite was significantly improved by introducing epoxy or chloropropyl groups into it, and Pd binding energy in Pd/cordierite was changed due to the present of those functional groups. COE selectivity of COD catalytic hydrogenation depended on both size and chemical state of Pd particles. With the Pd/cordierite as catalyst, which was modified by the silane coupling agent containing epoxy group and prepared by ultrasonic impregnation technique with palladium acetylacetonate as precursor, the highest conversion and COE selectivity of COD hydrogenation could be achieved.