TiO_2/SiO_2催化酯交换合成草酸二苯酯

Synthesis of diphenyl oxalate by transesterification over TiO_2/SiO_2 catalysts

使用负载型TiO2/SiO2催化剂催化了草酸二乙酯和苯酚酯交换反应合成草酸二苯酯。采用NH3-TPD探讨了催化剂表面酸性强弱对草酸二乙酯和苯酚酯交换反应的影响。结果表明,催化性能与TiO2/SiO2催化剂上存在的酸中心强度密切相关,弱酸中心的存在导致了催化剂良好的催化活性。同时考察了不同反应温度、回流温度、原料物质的量比和反应时间等对反应性能的影响。当TiO2负载量为10%(质量分数)时,TiO2/SiO2的催化性能最佳,草酸二乙酯的转化率为49.5%,草酸二苯酯的收率为11.8%,乙基苯基草酸酯的收率为37.7%,目的产物草酸二苯酯和乙基苯基草酸酯的总选择性为100%。

The transesterification of diethyl oxalate（DEO） with phenol to produce ethyl phenyl oxalate （EPO） and diphenyl oxalate（DPO） was carried out over TiO2/SiO2 catalysts. The catalysts were characterized by temperature programmed desorption of ammonia （NH^-TPD）, and the relationship between the catalytic properties of TiO2/SiO2 and the weak acid sites on the surface of TiO2/SiO2 was studied in detail. NH3-TPD illuminated that the weak acid sites were responsible for transesterification between DEO and phenol. The effects of reaction temperature, reflux temperature, molar ratio of reagent and reaetion time were investigated. The catalyst of TiO2/SiO2 with 10% TiO2 performed best, giving 49.5% conversion of DEO, 11.8% yield of DPO, 37. 7% yield of EPO and 100% target produet selectivity DPO and EPO.