Rare-earth element doping-promoted toluene low-temperature combustion over mesostructured CuMCeOx (M = Y, Eu, Ho, and Sm) catalysts: the indispensable role of in situ generated oxygen vacancies
Rare-earth element doping-promoted toluene low-temperature combustion over mesostructured CuMCeOx (M = Y, Eu, Ho, and Sm) catalysts: the indispensable role of in situ generated oxygen vacancies
复制标题
稀土元素掺杂促进介孔结构 CuMCeOx（M = Y、Eu、Ho 和 Sm）催化剂上的甲苯低温燃烧：原位产生的氧空位的不可或缺的作用
DOI：
10.1039/c8cy01849a
复制
发表时间：
2018-11-21
影响因子：
5
通讯作者：
He, Chi
中科院分区：
文献类型：
--
作者：
Jiang, Zeyu;Chen, Changwei;He, Chi
首次采用可重复的自沉淀法制备了具有介孔结构和氧迁移能力的新型CuMCeOx（M = Y，Eu，Ho，Sm）三金属氧化物催化剂.稀土元素（特别是Y、Eu和Ho）的引入可以增加CuCeOx催化剂上的还原性和表面吸附氧的迁移率，这导致甲苯氧化中的催化活性显著增加。在这些催化剂中，CuHoCeOx催化剂具有最高的氧化活性，在220 °C和相对较高的GHSV（50 000 h-1）下甲苯完全矿化，这归因于Ho和CuCeOx骨架的协同作用，在混合氧化物上产生了丰富的活性氧空位。 拉曼光谱和密度泛函理论（DFT）研究表明，Ho元素与两个氧原子配位，占据了Ce原子的位置，改变了Ce在CuCeOx二元氧化物中的π键，从而削弱了Ce-O键，提高了储氧能力.通过原位DRIFTS和DFT研究，提出了甲苯在CuHoCeOx催化剂上燃烧的可能反应途径和机理，证明了甲苯的氧化过程遵循Mars-van Krevelen机理，在分解为CO2和H2O之前，主要的有机中间体是醛和酮.
Novel CuMCeOx (M = Y, Eu, Ho, and Sm) trimetal oxide catalysts with developed mesoporosity and an enhanced oxygen migration capability were fabricated by a reproducible self-precipitation approach for the first time. The incorporation of a rare-earth element (especially Y, Eu, and Ho) can increase the reducibility of, and mobility of surface adsorbed oxygen on, a CuCeOx catalyst, which leads to a remarkable increase in catalytic activity in the oxidation of toluene. Among these catalysts, the CuHoCeOx catalyst possesses the highest oxidation activity, with the complete mineralization of toluene at 220 °C at a relatively high GHSV of 50 000 h−1, which is ascribable to the synergetic effect of Ho and the CuCeOx framework, which creates abundant active oxygen vacancies over mixed oxides. Raman spectroscopy and density functional theory (DFT) studies reveal that Ho element is coordinated to two oxygen atoms and occupies the site of a Ce atom, which changes the π-bonding of Ce in the CuCeOx binary oxide and thus leads to the weakening of Ce–O bonds and an enhanced oxygen storage capacity. A possible reaction pathway and a mechanism for the combustion of toluene over a CuHoCeOx sample are proposed by means of in situ DRIFTS and DFT studies, which prove that the toluene oxidation process obeys the Mars–van Krevelen mechanism, with aldehydes and ketones as the primary organic intermediates, before decomposition to CO2 and H2O.