多级孔TiO_2担载金钯纳米催化剂在CO氧化反应的应用

Hierarchically TiO_2 supported Au-Pd nano-catalyst applied in CO oxidation

针对贵金属纳米粒子稳定性差,容易发生团聚造成催化活性低的问题,以多级孔TiO_2为载体,利用其介孔孔道限制贵金属纳米粒子团聚,采用浸渍法制备Au-Pd双金属纳米催化剂.通过X射线衍射(XRD)、透射电子显微镜(TEM)等分析手段对催化剂进行表征,结果表明金钯纳米粒子均匀地分布在TiO_2载体上,尺寸约为3~5nm.选择CO氧化反应评价催化剂活性,考察催化剂制备过程中金钯比例对催化活性的影响.结果表明,在120℃的条件下催化剂Au_1-Pd_4/TiO_2达到最高的转化率90%,这归结于双金属间的电子协同效应,金原子从钯原子上吸电子,导致钯原子缺电子,而CO分子提供电子给钯原子,提高了催化活性.

Small Pd nanoparticles have poor stability and they tend to aggregate during the thermal treatment,which lead to the decrease of activity.In this thesis,based on hierarchically porous TiO2 support,Au-Pd nanoparticles were prepared via impregnation method.The catalysts were characterized by TEM and XRD.The obtained Au-Pd nanoparticles were uniformly dispersed on the support with a narrow size distribution at 3-5 nm.CO oxidation were chosen to test the influence of Au-Pd molar ratios on catalytic activities.The Au1-Pd4/TiO2 exhibited the best activity of 90% at 120 ℃,which is due to the bimetallic interaction effect.Au atoms attract electrons from Pd atoms,causing Pd atoms to be short of electrons,while the CO molecules provide electrons to Pd atoms,facilitating the catalytic activity.