Study On Synthesis Of B-TS-1 And Its Stability In Cyclohexanone Ammoximation

Cyclohexanone oxime (CHO) was the important intermediate in caprolactam production, while the traditional productive process of CHO faces various defects, such as the complexity process, serious equipment loss and large energy consumption. TS-1/H2O2 catalytic oxidation system has been successfully introduced into the cyclohexanone ammoximation by Enichem groups since 1980s, which was proved as a typically representative of the green chemical process. Titanosilicates catalyst served as the crucial role in this green oxidation process, thus how to improve the catalytic activity and stability in this catalytic system from the viewpoint of catalyst have been always attracted amounts of attentions and researches not only in the science field but in technology sector. Therefore, in this paper, the influences of heteroatom on the preparation and catalytic oxidation performance of the modified TS-1 with boron (B) were investigated. The main contents are as follows:1. B/Al-TS-1 molecular sieve that containing heteroatom of B or Al was synthesized by one-pot hydrothermal method. It showed that the inserted B or Al atome did not change the MFI topological structure or porous properties of TS-1, but it gave an effect on the Ti actoms pluging into the framework. The competitive order of insertion fellows Al> Ti> B. Simultaneously, the heteroatom alters the catalyst acidity and the order of acid amount was Al-TS-1> B-TS-1>TS-1>B-S-1.2. The catalytic oxidation performance of B-TS-1 zeolite was studied. The results showed that the inserted B atom influence the catalytic oxidation activity of TS-1 and also decrease the epoxide selectivity. However, the B-TS-1 would not affect catalytic activity and products selectivity of cyclohexanone ammoximation in a batch type process.3. Based on the results of continuous cyclohexanone ammoximation catalyzed by B-TS-1, we found that it can prolong the operation lifetime. Combined the deactivation mechanism and H2O2 reaction behaviors during the liquid-phase ammoximation process, it was concluded that B-TS-1 was able to decrease the free H2O2 residues effectively, and then suppressing the multiple side reactions, thereby it prolongs the catalyst stability in cyclohexanone ammoximation.4. Combined the modification of B as well as Al atom and post-treament with TPABr +EA, a synergistic effect was obtained, and thus a much longer lifetime was gained.