四价钌取代多钨氧酸盐催化剂的设计合成及其对烷烃氧化催化性能研究

From the point of view of the green chemistry, this project will concentrate on preparation, characterization and catalytic property study of the catalysts for the green oxidation of alkane. Our previously studied work indicated that ruthenium substituted polyoxotungstates exhibited catalytic activities towards the green oxidation of alkane. However,the catalytic activity of the compounds is restricted because ruthenium is in low oxidation state (+2) and coordinated by organic group. Our project will synthesize ruthenium substituted polyoxotungstates in its high oxidation state (+4) without any organic group ligand. We will use (NH4)2[RuCl6] as Ru(IV) resource to synthesize catalysts by two different reaction ways. We will select tetradecane as the catalytic substrate and air as oxidant to systematically explore the influence of different catalytic conditions on the catalytic performance under green conditions without any solvents and additives. The catalytic model will be established based on experimental results and the catalytic mechanism will be explored, the relationship between the components and the structures of catalysts and the catalytic activities will be opened out in order to select the catalyst with high catalytic activity. Subsequently,we will anchore catalysts on the functionalized mesoporous molecular sieve SBA-15 to prepare solid catalysts with good stability. The solid catalysts can be easily recovered and reused for many times.

从绿色化学角度出发，本项目将紧紧围绕烷烃绿色氧化催化剂的合成、表征及催化性能研究这条主线开展工作。我们前期研究工作表明钌多钨氧酸盐在烷烃绿色氧化反应中具有催化活性。但由于化合物中钌处于低氧化态(+2),且钌的端基被有机基团配位，从而限制了钌催化作用的发挥。本课题将合成具有高氧化态(+4)且端基无有机基团配位的钌多钨氧酸盐催化剂，并探索其在烷烃绿色氧化反应中的催化活性。拟以（NH4）2[RuCl6]作为四价钌源，通过两条不同的反应途径来制备催化剂。以十四烷作为催化底物，空气作为氧化剂，在无任何溶剂和添加剂的绿色反应条件下，系统考察各种反应条件对催化活性的影响。在实验基础上建立催化模型，探索催化机理，揭示催化剂的组成、结构与催化活性之间的关系,并筛选出高活性的催化剂。最后通过静电相互作用把催化剂负载到功能化的介孔分子筛SBA-15上来制备高稳定性、易于分离、可回收并可多次循环使用的固相催化剂。

项目从含四价钌多钨酸盐的合成-负载-催化十四烷绿色氧化这条主线开展研究工作。合成了不同组成、结构的钌钨酸盐催化剂；选取具有不同结构、孔尺寸和表面积的载体；通过静电相互作用把催化剂沉积到载体上获得多相催化剂。以十四烷作为催化底物，不加入任何的添加剂，以空气作为氧化剂，在温和的实验条件下研究了制备多相催化剂的催化活性，考察了影响催化反应的各项因素，获得了最佳催化反应条件；研究了催化反应机理为催化剂引发的自由基反应历程。在最佳催化反应条件下十四烷氧化单次转化率接近55%，连续5次催化氧化反应后十四烷的转化率接近90%。而且通过热过滤对照实验、测定催化反应前后多相催化剂的组成和结构证明所使用的多相催化剂具有很好的稳定性和可重复利用性，同一多相催化剂5次重复利用后十四烷氧化的转化率及氧化产物的选择性近似相同。因此我们制备的多相催化剂在长链烷烃的绿色氧化反应中具有潜在的应用前景。