Passivation agents and conditions for Mo2C and W2C: Effect on catalytic activity for toluene hydrogenation
Passivation agents and conditions for Mo2C and W2C: Effect on catalytic activity for toluene hydrogenation
复制标题
DOI：
10.1016/j.jcat.2017.01.002
复制
发表时间：
2017-03-01
影响因子：
7.3
通讯作者：
Jentoft, Friederike C.
中科院分区：
文献类型：
--
作者：
Mehdad, Ali;Jentoft, Rolf E.;Jentoft, Friederike C.
通过热重分析和废气分析研究了 Mo2C 和 W2C 的钝化和再活化，并通过比较新鲜碳化物与钝化和再活化碳化物的甲苯加氢活性（21 bar，H-2:甲苯 = 33、150 或 200 摄氏度，WHSV = 10 或 20 g g(cat)(-1) h(-1)）。与文献相反，CO2 和 H2O 不适合 Mo2C 钝化剂。 Mo 2 C和W 2 C在40℃下容易与O 2 反应。氧化过程中获得的质量可以通过在300℃(Mo 2 C)或400℃(W 2 C)下在1巴H-2中还原来定量除去。仅对于已用0.1体积％的初始O 2 浓度钝化的Mo 2 C，甲苯转化率完全恢复，而对于其他钝化条件或W 2 C则没有。在300或400℃下进行甲苯加氢的干预操作增强了先前被氧化和还原或剧烈还原的样品的活性。这种增强表明碳化物的形成可以在比通常使用的温度更温和的温度下进行。 (C) 2017 Elsevier Inc. 保留所有权利。
The passivation and reactivation of Mo2C and W2C were investigated by thermogravimetry with effluent gas analysis, and by comparison of the toluene hydrogenation activity of fresh carbides with those of passivated' and reactivated carbides (21 bar, H-2:toluene = 33, 150 or 200 degrees C, WHSV = 10 or 20 g g(cat)(-1) h(-1)). Contrary to the literature, CO2 and H2O were unsuitable passivation agents for Mo2C. Mo2C and W2C reacted readily with 02 at 40 C. The mass gained during oxidation could be quantitatively removed through reduction in 1 bar H-2 at 300 degrees C (Mo2C) or 400 degrees C (W2C). The rate of toluene conversion was fully recovered only for Mo2C that had been passivated with an initial 02 concentration of 0.1 vol.% and not for other passivation conditions or for W2C. Intervening operation of toluene hydrogenation at 300 or 400 degrees C enhanced the activity of samples that were previously oxidized and reduced or harshly reduced. This enhancement suggests that carbide formation is possible at milder temperatures than typically employed. (C) 2017 Elsevier Inc. All rights reserved.