节点文献

钯钛氧化物介孔材料的制备以及催化应用

Preparation of Novel Mesoporous TiO2-PdO Composite Materials and Their Catalysis Applications in the Organic Synthesis Reaction

【作者】 王冲

【导师】 柯燕雄;

【作者基本信息】 华东理工大学 , 制药工程与技术, 2011, 硕士

【摘要】 本研究通过一种温和可重复的溶胶凝胶法,以钛酸四丁酯和乙酰丙酮钯作为金属源,制备出两种不同钛钯比例的复合金属材料。通过氮气吸附脱附进行全孔分析,发现两种材料均呈现独特的介孔特性和相当集中的孔径分布,平均孔径在11nm左右。X射线粉末衍射图和高分辨透射电镜共同证明了氧化钯晶体(四方晶相)的存在,能谱分析得到了材料中钯钛的比例。通过C-C偶联反应评价两种材料的催化性能,其中包括Suzuki、Hec、Hiyama反应。在Suzuki反应中,材料显示了广泛的底物适用性和较高的催化活性,其中TP-2(钛钯比为77.6:1的催化剂)的活性更高,优于商品化的钯碳催化剂;TP-1(钛钯比为14:1的催化剂)在碘苯和苯基硼酸的偶联反应中可以重复使用十次,转化率仍然保持在90%以上;而在Hiyama反应中,尽管存在强碱TBAF(四丁基氟化铵),仍然可以循环使用十二次。通过催化氢化和氢解反应评价材料,包括脱溴、脱苄基、和酮的还原。在脱溴反应中,通过循环使用测试分别考察材料在酸碱中的稳定性;并发现在溴代苯甲醛、溴代苯乙酮的还原中,三乙胺可以有效调节反应的活性,选择性得到目标产物。

【Abstract】 Different Ti/Pd ratio mesoporous TiO2-PdO have been easily synthesized by a sol-gel method using Pd(acac)2 and Ti(OBu)4 as precursors. Both of the two N2 adsorption-desorption isotherms exhibit typical type IV isothermal curves with the characteristic mesoporous structures. The pore size distribution displayed sharp peaks in the mesoporous region, and average pore size diameters are about 11 nm. The existence of tetragonal PdO is confirmed by XRD and TEM, and the Ti/Pd ratio can be known from the result of energy dispersive spectrometer (EDS).The materials’catalytic properties were evaluated by C-C coupling reaction, including Suzuki, Heck and Hiyama reaction. In the Suzuki reaction, they show wide functional group tolerance and high activity, especially the activity of TP-2 is higher than Pd/C. While the stability of TP-1 is better than TP-2, and could be reused ten times, with a conversion above 90%. In the Hiyama reaction, TP-1 could also be reused twelve times, even when the strong base (TBAF) exists.The materials’catalytic properties were also evaluated by catalytic hydrogenation and hydrogenolysis, including debromination, debenzylation and reduction of ketone. In the debromination reaction, we test the stability of materials in the acid and base enviroment. It was found that in the reduction of Bromoacetophenone and Bromobenzaldehyde, the activity of substrate could be adjusted effectively by triethylamine, and transform in to the specific product selectively.

  • 【分类号】O643.32
  • 【下载频次】73
节点文献中: