Preparation Of TS-1 Powdery And Monolithlic Catalysts And Use For Cyclohexanone Ammoximation

Titanium silicalite-1 molecular sieve (TS-1) is a new kind of catalytic material with MFI topological structure. The system of TS-1 and H₂O₂ exhibits excellent catalytic oxidation performance in mild reaction conditions, and has been paid more attention by many researchers in domestic and abroad. The above process has overcome the shortcomings of serious pollution and unsafe factors of traditional oxidation ones, and it has provided new pathways for the environmentally friendly green chemical processes. But when TS-1 powder was used in slurry reactor, because of small crystal size of solid catalyst the problems in separation of solid and liquid may lose some of the catalyst in running of reactor and therefore increase the production cost.In this paper TS-1 molecular sieve was in-situ synthesized on the surface of a 62cell/cm2 honeycomb-shaped cordierite support with hydrothermal method. Then XRD, FT-IR and SEM were used to characterize the samples.Firstly, based on the researches of the predecessors, but the synthesis route was modified. TPAOH was used as template and TEOS and TBOT were fully hydrolyzed with help of iso propanol (IPA) at 0℃temperature when the hydrolytic effect was preferable. When the molar ratio of TPAOH to SiO₂ was 0.18, the amount of template was the most economic; when molar ratio of H₂O/SiO₂ was in 30⁶0 no obvious changes could be found on the relative crystallinity, yield and catalytic acticity of TS-1. And the result can make a basis for the synthesis TS-1 on the monolithlic cordierite. In the other synthesis conditions include removal of alcohol at 70～90℃, crystallization at 160～170℃and lasting for 4⁵ d, template removal of precursor by calcination at 600℃, the TS-1 samples obtained had higher crystallinity, more uniform crystal size, more amounts of framework Ti and better catalytic performance in the cyclohexanone ammoximation reaction. The experimental repeatability was satisfactory.Secondly, the preparation of TS-1/cordierite was also studied. The viscosity of solution was suitable for synthesis when the molar ratio of H₂O/SiO₂ reached 50, meanwhile, if the crystalline time of 5d and the temperature of 165℃, higher weight increase of the TS-1/cordierite and the relative crystallinity of TS-1 were approached. Some experimental methods were investigated too, such as repeated loading, low temperature aging on in-situ synthesis, pretreating cordierite with 37% hydrochloric acid or dipping the cordierite in the template in advance, The results showed that all of above methods could enhance the amounts of the molecular sieve on the support and the binding between the TS-1 and cordierite. The weight of the cordierite was increased by 10%-16% consequently. For scale up of TS-1 monolithic synthesis system, a rotational dynamic crystallization was preferred to avoid the uneven distribution of the concentration and temperature in the crystallizer.Finally, a reactor used for monolithic catalyst was designed and the catalytic performance of TS-1/cordierite in the cyclohexanone ammoximation reaction was studied in it. Compared to TS-1 powder, although the catalytic activity of monolithic catalyst need improve, the separation and recovery of catalysts could be simplified. In conclusion the monolithic TS-1 catalyst shows the good application prospect.