The propylene epoxidation using supported titanium silicalite TS-1 catalyst was systematically investigated in a fixed bed reactor. Different supports such as SiO2 and Al2O3 were used and two molding methods were adopted to prepare the catalyst. Strip TS-1 catalyst of 1mm

以四丙基溴化铵为模板剂，以硅溶胶为硅源，采用水热合成法制备了不同铝杂质含量的钛硅分子筛，并系统考察了铝杂质对钛硅分子筛性能的影响。结果表明，原料中的铝杂质可促进钛硅分子筛晶化，但同时也引入了酸性中心；在丙烯环氧化反应中，铝杂质形成的酸性中心会催化环氧丙烷与溶剂的副反应；加入少量碱性添加物可抑制铝杂质的酸催化作用，提高环氧丙烷的选择性，但过量碱性添加物会使钛硅分子筛失活。

以十二胺（DDA）为模板剂，采用室温晶化合成了钛硅中孔分子筛Ti2HMS，并用XRD，IR，UV2Vis和N2吸附对分子筛 样品进行了表征，考察了配料硅/钛比、模板剂用量及晶化时间对合成分子筛的影响，结果表明，Ti2HMS分子筛具有大的比表面，孔径约为3nm。随着配料硅/钛比的降低，Ti2HMS分子筛的比表面积减小，进入骨架的钛量增多，且非骨架钛也增多。n（DDA）/n（SiO2）≤0122时，随着模板剂用量的减少，Ti2HMS分子筛的结晶度下降，骨架钛含量减少，非骨架钛含量增加。晶化时间在9～18h最佳。

Titanium silicalite was prepared using tetrapropylammonium bromide as a template. Propene epoxidation was studied on this catalyst using the mixtures of methanol with water or 2-propanol or acetone and the solvent effect was investigated systematically.

The titanium species existing in titanium silicalite TS-1, which is prepared by hydrothermal method, were investigated using chemical analysis, XRD, FT-IR, 29Si MAS NMR, UV-VIS, ESR. It has been observed that several kinds of titanium species may exist in titanium silicalite. The form that titanium atoms incorporate into the framework of titanium silicalite synthesized using etrapropylammonium bromide (TPABr) as template differs from that using the classical method. But, the symmetry of titanium silicalite changes from monoclinic to orthorhombic with the increase of titanium content in both methods. The Ti-O2-originated from framework titanium and H2O2 has the moderate stability and may be active site in oxidation reaction. TS-1 synthesized using TPABr as template does not contain anatase, but contains a kind of partly condensed titanium species with six-fold coordination. The titanium species may correspond to 270-280 nm band in UV-VIS spectra and also can form Ti-O2-. But, this kind of Ti-O2-is very stable and cannot be catalytic active site. So, the six-fold coordination titanium species may be inactive in both the oxidation reaction and the decomposition of H2O2. The hypothesis has been further proved by the phenomena that the titanium species is easily washed off using acid, and acid treating will not influence the catalytic performance of TS-1.

Titanium silicalite (TS-1)was successfully synthesized by using tetra-propylammonium bromide (TPABr) and n-butylamine as the template and the base, respectively. XRD, IR, SEM, 13C CP/MAS NMR, UV-VIS, and UV-Raman techniques were used to characterize the synthesized products. The results show that TS-1 has MFI structure with high crystallinity and large crystal size, and with two kinds of titanium species. Using epoxidation of propylene as the probe, the catalytic properties of TS-1 in the present work were investigated. The crystal size of TS-1 affects much the initial reaction rate of propylene oxide (PO) formation. The effects of reaction conditions on PO reveal that the PO formation is greatly influenced by the solvent and the solution pH value. Methanol is the most preferable solvent, and a portion of water (<30%) in solution does not have much impact on the reaction. Moreover, the addition of base used to neutralize the residual acidity of the catalyst favor the reaction, the catalyst shows high activity and selectivity upon the adequate amount of base and the catalyst can be used repeatedly without regeneration. In the fixed-bed reactor, using ammonium water as the neutralizer, after 200 h of reaction, both the conversion and the utilization of H2O2 is about 95%, the selectivity of PO is about 90%.

Propylene epoxidation catalyzed by titanium silicalite is easily influenced by acidic or basic impurities. The effect of sodium ions on the reaction was systematically investigated. It has been shown that a proper amount of sodium salt additive can inhibit the further reaction of propylene oxide (PO) with the solvent and can increase the selectivity of PO. But a slightly excessive amount of sodium salt can be a poison to the titanium silicalite catalyst. The sodium salt additive can accumulate on the catalyst in repeated runs of propylene epoxidation in an autoclave, so the catalyst may be poisoned if an equal amount of sodium salt is added in each run. The excessive sodium ions on titanium silicalite can deactivate the catalyst in calcination, while acid treating can restore the activity of titanium silicalite. If the propylene epoxidation is carried out in a fixed bed, the sodium ions on titanium silicalite can gradually come loose and the PO selectivity decreases with time on-stream. A small amount of supplement of sodium salt in the raw material can make the PO selectivity stable for a longer period.

Titanium silicalites have been synthesized in the TPABr

Titanium silicalite (TS-1) is used as catalyst in selective oxidation of thiophene by hydrogen peroxide at 333K. Fourier transform infrared (FT-IR) and UV-vis characterization shows the presence of framework titanium in all TS-1 samples we prepared with different SiO2/TiO2 ratio. Catalytic test over these catalysts confirms that framework Ti species does influence the oxidation of thiophene. The role of non-framework titanium was discussed by studying acid treating of the catalyst. If TS-1 is treated using HCl (2mol/1) four times, part of the non-framework titanium species will be washed off and the activity of the catalyst increases greatly. These results suggest that framework titanium was crucial for thiophene oxidation. Non-framework titanium is not the active site, but provides steric hindrance for this reaction. Obvious diffusive restriction on the thiophene oxidation was also observed when using TS-1 with different crystal size.

Thiophene is a typical thiophenic sulfur compound in gasoline. Using n-octane containing thiophene as the model compound, the oxidation of thiophene, which is a key step for the oxidative deep desulfurization of gasoline, was carried out to study the reactivity of thiophene in oxidation reactions. It has been observed that thiophene oxidation can occur using water or t-butanol as solvent. Kinetics of the reaction shows a pseudo-first-order toward thiophene or catalyst and a zero order toward hydrogen peroxide. The mechanism for this unique reaction was proposed as the activation of conjugated electron in thiophene ring.