Elucidation of Active Sites of Gold Nanoparticles on Acidic Ta2O5 Supports for CO Oxidation
Elucidation of Active Sites of Gold Nanoparticles on Acidic Ta2O5 Supports for CO Oxidation
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DOI：
10.1021/acscatal.0c01966
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发表时间：
2020-08-21
期刊：
影响因子：
12.9
通讯作者：
Murayama, Toru
中科院分区：
文献类型：
--
作者：
Lin, Mingyue;Mochizuki, Chihiro;Murayama, Toru
金纳米粒子的小尺寸与高度均匀的分散体，成功地沉积在几种晶体形式的Ta 2 O 5（pseudohexagonal，正交，烧绿石）的溶胶固定化方法。水热法合成的准六方晶系Ta 2 O 5（TT-Ta 2 O 5）作为金催化剂的载体，对CO氧化反应表现出最高的催化活性。对于1重量% Au/TT-Ta 2 O 5，在50% CO转化率下的温度为-11 ℃，并且在100% CO转化率下的温度为23 ℃（空速为20000 mL h（-1）g（cat）（-1））。为了研究反应机理，原位进行，并在-120 ℃下观察到吸附在Ta 2 O 5位点和Au位点上的CO向活性位点的顺序递送。程序升温CO还原实验结果表明，在-100 ℃时吸附的氧主要对CO氧化的高催化活性起作用，而在-60 ~100 ℃时晶格氧对CO氧化的作用较小，这与实际反应条件相同.
Gold nanoparticles of small sizes with a highly uniform dispersion were successfully deposited on several crystalline forms of Ta2O5 (pseudohex-agonal, orthorhombic, and pyrochlore) by the sol immobilization method. The pseudohexagonal Ta2O5 (TT-Ta2O5) synthesized by a hydrothermal method showed the highest catalytic activity for CO oxidation as a support for gold catalysts. The temperature at 50% CO conversion was -11 degrees C for 1 wt % Au/TT-Ta2O5, and the temperature was 23 degrees C at 100% CO conversion (space velocity of 20000 mL h(-1 )g(cat)(-1)). To investigate the reaction mechanism, in situ performed, and the sequential delivery of adsorbed CO on Ta2O5 sites and Au sites to the active sites was observed at -120 degrees C. The results of temperature-programmed CO reduction suggested that the oxygen adsorbed at -100 degrees C contributed mainly to the high catalytic activity of CO oxidation, while the lattice oxygen played a minor role for CO oxidation from -60 to 100 degrees C, which was the same temperature range with the actual reaction condition.