摘要
采用溶胶-凝胶法制备了CeO2载体,以浸渍法和沉积沉淀法制备了负载型催化剂Pd/CeO2.使用透射电镜(TEM)和Zeta电位仪对催化剂进行了表征.结果表明两种材料的等电点都在5.0左右;Pd颗粒在载体表面具有良好的分散性,且Pd负载量越高,Pd颗粒的粒径越大.采用Pd/CeO2催化剂催化溴酸盐加氢还原,发现在溴酸盐初始浓度为0.39mmol/L时,采用沉积沉淀法和浸渍法合成的Pd/CeO2催化剂反应50min后对溴酸盐的去除率分别为100%和71%,表明使用沉积沉淀法合成的催化剂具有较高的催化活性.改变催化剂用量,溴酸盐的催化还原速率不受传质阻力的影响,反应过程符合Langmuir–Hinshelwood模型,即催化还原反应由溴酸盐在催化剂表面的吸附控制.增加Pd的负载量,溴酸盐的还原速率增大.溶液pH值较低时,有利于对溴酸盐的催化还原.
CeO2 carrier was synthesized via the sol-gel method,Pd/CeO2 catalysts were prepared using the deposition-precipitation and impregnation method.The catalysts were characterized by TEM and Zeta potential measurement.Results showed the isoelectric points（IEPs） of both catalysts were around 5.0,and metallic Pd particles were well dispersed on CeO2 surface,the average Pd particle sizes on the CeO2 surface grown with the increase of Pd loading amount.Bromate with an initial concentration of 0.39mmol/L was removed by 100% over Pd/CeO2 prepared by the deposition-precipitation method and 71% over Pd/CeO2 prepared by impregnation method after reaction for 50min,exhibiting higher catalytic activity for catalyst prepared by the deposition-precipitation method.The catalytic bromate reduction was not influenced by mass transport limitation.Bromate reduction can be described by the Langmuir–Hinshelwood model,indicating that the reaction was controlled by bromate adsorption.Increasing Pd loading amount resulted in enhanced bromate reduction.Decreasing pH was in favor of catalytic bromate reduction.
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2011年第8期1274-1279,共6页
China Environmental Science
基金
国家自然科学基金资助项目(21077050)
江苏省自然科学基金资助项目(BK2010051)
科技部国际科技合作项目(2010DFA91910)
关键词
Pd/CeO2
沉积沉淀法
催化加氢
溴酸盐还原
Pd/CeO2
deposition-precipitation method
catalytic hydrogenation
bromate reduction
