磷酸钛硅铝分子筛TAPSO-5亲/疏水性与活性位调控及催化环己酮氨肟化研究

Cyclohexanone oxime is the key intermediate for the production of caprolactam. The design of new catalysts and their catalytic performance nowadays is an important point in the research area of the production of cyclohexanone oxime via cylohexanone ammoximation. There are some reports showed that the hydrophilicity/hydrophobicity and active sites of the catalyst had great influence on its catalytic performance on ammoximation of cylohexanone. The researches on the relationship between the simultaneous modulation of hydrophilicity/hydrophobicity and active sites of the catalyst and its catalytic performance on the ammoximation of cyclohexanone have great important meanings. However, research in this area has not been reported yet. In this project, a novel method, titanium alkoxide grafting, is proposed for modulating the hydrophilicity /hydrophobicity and active sites of titanium silicoaluminophosphate TAPSO-5 simultaneously. The variation law and mechanism of modulation will be studied systematically on molecule levels. A possible reaction way of cyclohexanone ammoximation on TAPSO-5 and the role of hydrophilicity/hydrophobicity on TAPSO-5 performance will be studied in detail. The implementation of this project has great important values on scientific and practical applications. It will provide the theoretical basis for the design of catalyst with high catalytic performance on cyclohexanone ammoximation, and a new effective method for modulating the hydrophilicity/hydrophobicity and active sites of other sieves containing titanium.

环己酮肟是生产己内酰胺的关键中间体。目前，新催化剂的设计与性能研究仍然是环己酮氨肟化制备环己酮肟的研究重点。有研究表明，催化剂亲/疏水性与活性位是影响其催化环己酮氨肟化性能的关键因素。研究催化剂亲/疏水性与活性位的同时调控、调控机制及变化规律与催化环己酮氨肟化性能之间的关系具有重要意义。然而，目前关于这方面的研究未见报道。项目创新性地采用嫁接钛酸酯的方法，对磷酸钛硅铝分子筛TAPSO-5亲/疏水性及活性位进行同时调控，从分子水平上研究调控变化规律与机制，探究环己酮氨肟化随TAPSO-5亲/疏水性及活性位变化规律，揭示TAPSO-5催化环己酮氨肟化的催化作用机制。项目的实施为设计、开发高性能环己酮氨肟化催化剂提供理论依据，同时为其它类型含钛分子筛的亲/疏水性、活性位调控提供一种新方法，具有重要的科学与实际应用价值。

20世纪80年代，钛硅分子筛TS-1的问世掀起了研究狂潮，TS-1成为分子筛和多相催化领域的里程碑。尽管如此，生产成本高、寿命短等不足限制了TS-1的应用范围，这使得含钛分子筛的制备和应用迅速成为研究热点之一。TAPO-5是一种具有AFI结构的含钛磷酸铝分子筛，由于钛原子价态可变的性质，在以过氧化氢作为氧化剂的一系列有机物液相选择性氧化反应中表现出独特的催化性能。然而，与TS-1相比，其催化性能仍待提高。本项目围绕TAPO-5分子筛的制备、改性、表征及其催化性能展开研究工作。采用嫁接法、一锅法、微波等方法制备出性质各异的TAPO-5分子筛，并研究了其催化性能，研究发现：亲/疏水性是影响TAPO-5分子筛催化活性的重要因素，随着表面疏水性的增强，TAPO-5的催化氧化性能提高；与在TS-1中不同，非骨架钛在TAPO-5催化环己酮氨肟化反应中起着重要作用，其强的L酸强度有利于提高TAPO-5催化活性；由于避免了钛活性中心的四配位与六配位的转变过程，嫁接法所得催化剂TAPSO-5在催化环己酮氨肟化反应中表现出优于TS-1的催化稳定性。本项目的研究结果为其它类型钛掺杂分子筛尤其是磷酸钛铝分子筛的制备及催化应用提供了理论依据及实验指导。