Preparation Of Granular Titanium Silicated-1 By Spray-drying And Its Catalytic Properties For Ammoximation Of Cyclohexanone

Titanium silicalite(TS-1)has a good catalytic activity and unique shape-selective catalytic function in a series of organic oxidation,such as phenol hydroxylation,olefin oxidation and ketone ammoximation,which take hydrogen peroxide or alkyl peroxide as oxidant.So it becomes a hot study issues as oxidation catalysts.used in The process of ammoximation catalyzed by titanium silicalite exhibits some features of low power consumption,zero emissions and mild reaction conditions,which is regarded as a representative application of the environment-friendly catalysts.However,the particle size of the original TS-1 powder is small and it is diffcult to separate from the reaction product,limiting its large-scale applications in industry.Technology to prepare granular TS-1 is expected to become a possible way to solve the above problem.In this thesis,granular TS-1 microspheres is prepared by spray-drying and the catalyst are characterized by laser particle size analyzer,BET?XRD and so on to analysis the macro structure and micro structure.The catalytic activity is tested by the probe reaction of ammoximation of cyclohexanone.Firstly,the adhesives are selected and the influence of different adhesiveson the catalytic properties of TS-1 for ammoximation of cyclohexanone are studied,The bond effect of adhesives and TS-1 in different temperatures is also investigated.The catalytic reaction results of simple mechanical mixture samples show that the boric acid?kaolin?silica have little effect on TS-1 catalytic properties for ammoximation.The the catalytic reaction results of mixed calcined samples show that,when the boric acid is used as the adhesives,the catalytic activity decreased.The main reason is proved by the decrease of the specific surface area for the boric acid coverage the catalyst.When kaolin or silica are used asthe adhesives,it can prevent the sintering of TS-1 so as to protect the catalyst..In the preparation of granular TS-1 with the above three adhesives,the strength of granular TS-1 with silica is the biggest.It is mainly because that the silica is bonded with the hydroxyl group in the surface of TS-1.Adding adhesives,silica sol and pore-expanding agent into the TS-1 powder,the granular TS-1 are prepared by spray technology.The effect of the TPAOH content,the ratio of TS-1 to silica,the solid content,the atomization frequency and the silica sol content on the primary particles size are studied,The effct of calcinations temperature,calcinations tine and the cooling speed on the final particle size are investigatd simultaneously.The results show that the change the atomization frequency has the biggest impact on the particle size and the size distribution of granular TS-1 catalyst.The hydrophilicity of TS-1 and the resistance to shear force of granular TS-1 can be improved by adding TPAOH.The better conditions of the two-step forming technology are 3%TPAOH,the ratio of TS-1 to silica being 80:20,20%solid content,6%silica sol with 50Hz atomization frequency under 575? calcination temperature for 4h by using quench cooling.In the case of the above condition,the average particle size of granular TS-1 can reach 13.3 ?m.Combining the hydrothermal synthesis method with catalyst figuration technology,adding adhesive,pore-expanding agent and coupling agent into the crystallization solution containing TS-1 precursor,the granular TS-1 is prepared by spray-drying.The appropriate adhesives are selected and the effect of solid content and adding time of the adhesive on the particle size and catalytic activity are investigated.The results showed that the addition of the adhesive will not change the crystal structure of TS-1,but it will reduce the relative crystallinity the catalytic activity of the granular TS-1,which is the most obvious when using boric acid as the adhesive.With silica as the adhesive,the best solid content is 30%.The effect of adding time of the adhesive greater on the catalytic activity is great and the catalytic activity is the worst when adding at crystallization 48h.The biggest ultimate particle size of one-step forming TS-1 is that,d(0.1)being 7.0?m,d(0.5)being 35.6?m and d(0.9)being 72.8?m?...