茂钛配合物—纳米氢化钠双组分高活性加氢催化剂的研究

提出了带有不同取代基的茂钛配合物与纳米氢化钠（ＮａＨ）组成的高活性加氢催化剂，在常温常压下，取代茂钛配合物ＴｉＣｌ２／ＮａＨ对１－己烯的加氢反应有极高的初始活性，ＴＯＦｍａｘ达到１１０ｍｏｌＨ２／（ｍｏｌＴｉ．ｓ），催化转换数达到２２２００ｍｏｌＨ２／（ｍｏｌＴｉ）。该催化体系对底物有明显的专一选择性，只有端烃才能发生加氢反应，且无民构化副反应发生，纳米氢化钠的助剂作用是该催化体系高活性关键因素。

Highly Active Hydrogenation Catalysts from Titanocenes and Sodium Hydride of Nanometric Size

The hydrogenation of 1-hexene was catalyzed by titanocene with varioussubstituted groups in combination with nanometric sodium hydride. When the steric hindrance ofthe substituted group on the cyclopentadienyl ring is relatively small, the titanium complexgives high initial catalytic activity but poor stability, whereas when the steric hindrance islarge (for instance, five-membered ring or six-membered ring), the titanium complex giveslower initial catalytic acitivty but better stabilty. At normal temperature and pressure, amaximum turnover frequency(TOFmax) of H2/(mol Ti. s) and a turnover(TO) of22 200 mol H2/(mol Ti) were obtained by using bis (1'-ethyl)cyclohexyl-cyclopentadiTiCl2/NaH as catalyst. Only the terminal olefin could be hydrogenated by using this kind ofcatalytic system. Isomerization of olefins did not occur in the course of hydrogenation. It isthe key factor that the nanometric NaH was used as the cocatalyst in the reaction. Thecombination of titanocenes with commercial sodium hydride which was synthesized at hightemperatures did not display any catalytic activity for the hydrogenation of 1-hexene.