Partial Oxidation Of Styrene Over Titanium Silicalites

Phenylacetaldehyd and styrene oxide are important intermediates of organic synthesis and fine chemical products. The conventional industrial route for the synthesis of phenyl acetaldehyde is the oxidation of phenyl ethanol or Darzen Method. And the industrial process for manufacturing the styrene oxide is Halcon Method. So many problems exist in these methods, such as high energy consumption, low conversion and selectivity, complicated processes, serious environmental pollution and so on. These methods are not environmental friendly process. It is of great theoretics significance and application value in industry to create a novel, clean process for producing phenyl acetaldehyd and styrene oxide. In our research, the partial oxidation of styrene is studied with titanium silicalites as catalyst and H2O2as oxidant. The results and application of this paper are as follows:1、In the present work, TS-1and TS-2catalysts were prepared by hydrothermal synthesis method. The effect of different synthesis conditions on the components of catalyst and the structure of the framework were discussed. The materials are characterized by XRD, FT-IR, UV-Vis and BET. It was found the higher the Ti/Si (mol) of gel was, the larger the quantity of framework Ti was. If the quantity of the template (TPAOH, TBAOH) increased, the content of framework Ti increased too. The temperature of crystallization influenced the catalyst activity. The higher the temperature was, the smaller the crystal size was, and the larger the external surface area was. The acid treatment could remove the extra-framwork Ti and the species which blocked the pore canal. The conventional route for the synthesis of TS-1consumed a big quantity of TPAOH, which were very expensive. The high costs of TS-1restricted the development of its industry application. In present work, the cheap route of TS-1synthesized in the presence of precursors was investigated.2、The influences of reaction conditions were dicussed. The catalyst activity depended on the framework Ti content and the crystal size. A82.61%selectivity to phenyl acetaldehyde was achieved, when the framework Ti content was2.47%. The effect of the materiel ratio, reaction temperature and reaction time on phenyl acetaldehyde selectivity was investigated. With the increase in styrene/H2O2mole ratio, both the conversion of styrene and the selectivity for phenylacetaldehyde increased. But when styrene/H2O2>6:1, the conversion of styrene and the phenyl acetaldehyd selectivity began to decrease.3、The solvent effect to partial oxidation of styrene was studied in the TS-1/H2O2system. It was found that aprotic solvents seemed to favor the epoxidation compared with protic solvents. The higher selectivities were achieved with the former as solvent. The reaction mechanisms had been proposed based on the reaction results of different solvent.In the present work, the optimum reaction condition of styrene oxidation was obtained according to the investigation on various influence factors. When styrene/H2O2mole ratio was5, a71.36%conversion of styrene with a83.06%selectivity to phenyl acetaldehyde was achieved at60℃for4h with aetone as solvent. Compared with the optimum results reported by literatures, the styrene conversion obtained in this thesis was closed to it, but the selectivity obtained was higher.