Preparation And Catalytic Performance Of Ordered Mesoporous Titanium Silica Molecular Sieves

Periodic mesoporous organic silicon materials have both inorganic and organic components,which has attracted much attention in the field of materials research and application.However,the PMO material itself does not have or has a very low catalytic activity,and its catalytic activity is mainly dependent on optimizing the surface physicochemical properties of the catalyst.Therefore,under the premise of ensuring that the material has excellent surface physical and chemical properties,it is particularly important to introduce other species with certain catalytic activity and synthesize functionalized carriers.This paper focuses on the synthesis of PMOs-Ti_?x?composites of ordered mesoporous silica doped titanium,SBA-15-Ti?x?composites of inorganic silicon doped titanium,and ordered mesoporous PMOs.The oxidation of styrene was used as a model reaction to systematically examine the catalytic properties and recycling of the above materials.The details are as follows:1.Using BTESE as an organic silicon source,TiCl₃ as an inorganic titanium source,and triblock copolymer P123 as a structure-directing agent,an ordered mesoporous organo-titanium silica molecular sieve was prepared by one-step co-condensation using a hydrothermal technique.Surface morphology and structural composition were characterized.Their catalytic activity for styrene oxidation was then investigated.The study found that the optimum conditions for catalyzing styrene were:acetonitrile as a solvent and 50 mg of PMOs-Ti?10?composite as a catalyst at 60°C.The molar ratio of oxidant hydrogen peroxide to styrene was 1:2.In the case of styrene,the conversion rate of styrene itself is the best,the yield of phenylacetaldehyde obtained is the highest,and the selectivity to phenylacetaldehyde is the best.2.With guar gum as binder,ordered mesoporous organic titanium silicalite PMOs-Ti?10?composites are catalytically active components,and columnar catalysts with uniform size are obtained through extrusion molding technology.The reactivity of the catalyst with styrene oxidation was investigated in a fixed bed reactor.The effect of the catalyst on the conversion of styrene under different reaction conditions was investigated.The optimum reaction conditions for the fixed-bed reactor with adhesive-immobilized PMOs-Ti?10?composites were:reaction temperature 60°C;gravity hourly space velocity 6.0 h^-1;styrene to hydrogen peroxide molar ratio 2:1;the mass ratio of the reaction solvent to styrene is4:1.