Preparation And Catalytic Performance Of Titanium TUD-1 For Cooxidation Of Cyclohexyl Hydroperoxide And Propylene

Propylene oxide(PO) is a very important organic material, mainly for the production of polyether polyols, propylene glycol and various non-ionic surfactants. At present, chlorohydrin andhalcon routes are the main process of producing PO. A new co-oxidation process to produce PO by using CHHP as oxidant is developed in this study, which can avoid the high pollution of chlorohydrinand. In the innovatory process, the use of active oxygen atoms are more effective and it is possible to avoid the deeply oxidation of cyclohexanol and cyclohexanone and to improve the decomposition yield of cyclohexyl hydroperoxide at the same time. The catalytic performance of Ti-TUD-1 samples was tested in the co-catalytic oxidation reaction. The prepared samples of different morphology were in-depth analyzed by means of characterizing, and the relationship between structure and properties of the catalyst were explored.Firstly, the preparation of colloidal to mesoporous catalyst Ti-TUD-1 were investigated, including the order of addition, the ratio of materials, glue temperature and aging time.The structure and catalytic activity of Ti-TUD-1 samples were investigated. The prepared catalyst Ti-TUD-1 was characterized by FT-IR, UV-Vis, XRD, N2 physical adsorption- desorption, ICP, laser particle size, SEM and other means.Ti-TUD-1 were tested in the co-oxidation of propylene with cyclohexyl hydroperoxide(CHHP) as oxidant. The results showed that the best material ratio of Ti-TUD-1 catalyst is SiO2: 0.02TiO2: 0.3TEAOH: 1TEA: 11H2 O. Low-temperature is propitious to lead titanium into the framework. The order of addition of using the titanium source and the silicon source respectively, can increase in the amount of highly dispersed titanium in the tetrahedral framework of the mesoporous silica, thereby improving the catalytic activity. Aging time is not impact on the formation of the mesopores structure of catalyst,but increasing the aging time can increase the specific surface area of mesoporou.Results showed that when the aging time is 48 h, it is more conducive to the formation of Four-coordinate titanium within the framework.Calcination condition is an important factor shaping the catalyst structure. In this thesis, the effect of calcination temperature, calcination time and calcination rate to the mesopores Ti-TUD-1 catalyst morphology and skeleton of titanium are systematically investigated. The results show that four-coordinated titanium and maximum specific surface area and pore volume of mesoporous are easier to form at a lower calcination temperature. Calcination time is too long to affect the structure of catalyst, but also to ensure the elimination of remaining organic matter in catalyst. Four-coordinate titanium cannot be formed at a large calcination rate. Optimum calcination conditions of forming Ti-TUD-1 are that calcination temperature is 600℃, calcination time is 10 h, calcining rate is 5℃/ min.Finally, influences of calcination and silylation modified for Ti-TUD-1 catalyst morphology and catalytic activity were investigated. The effect of different heating time during thermal treatment, different silylation agent, silylation time, and silylation temperature to the structure and activity of the catalyst were studied. The Ti-TUD-1 were characterized by FT-IR, UV-Vis, XRD, N2 physical adsorption – desorption and ICP. In addition, the hydrophobicity of the catalyst surface is characterized by static physical adsorption and TGA. The results show that the catalyst pore diameter can be increased by heating treatment for 8h. HMDS was proved to be the best silylation reagent, while the silanization time and temperature were less affected to structural properties and activity of the catalysts. The activity of Ti-TUD-1 was significantly increased after silylation, the conversion of cyclohexyl hydroperoxide and selectivity of propylene oxide can reach 89.4% and 79.6%, respectively.