Ammonia decomposition over vanadium carbide catalysts
Ammonia decomposition over vanadium carbide catalysts
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DOI：
10.1006/jcat.1998.2346
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发表时间：
1999-02-15
影响因子：
7.3
通讯作者：
Choi, JG
中科院分区：
文献类型：
--
作者：
Choi, JG
通过用纯CH 4或49.9%CH4在H-2中的混合物对钒氧化物前体（V2 O 5）进行程序升温渗碳来合成碳化钒。结果表明，这些材料的结构性能与加热速率和空速密切相关，高空速或低加热速率均可制备出高比表面积的碳化钒。碳化钒被证明是活性NH3分解催化剂。由于活性随比表面积和颗粒尺寸的变化而变化，碳化钒上的氨分解似乎是结构敏感的。这种响应被认为是由于表面化学计量随颗粒尺寸的变化。碳化钒催化剂的活性一般比Mo_2C催化剂的活性低2倍左右，而碳化钒催化剂的活性比Pt/C催化剂的活性高1 ~ 2倍。碳化钒和碳化钼的活性差异可能与金属与碳之间的电子转移程度有关。碳化钒和铂金属的催化行为之间的相似性似乎是由于这些材料的相似的电子和磁性，（C）1999学术出版社。
Vanadium carbides were synthesized by the temperature-programmed carburization of vanadium oxide precursors (V2O5) with pure CH4 or a mixture of 49.9% CH4 in H-2. It was found that the structural properties of these materials were strong functions of the heating rate and space velocity employed, The vanadium carbides with high surface areas could be prepared using high space velocities or low heating rates. The vanadium carbides proved to be active NH3 decomposition catalysts. Since the activity varied with changes in the surface area and particle size, ammonia decomposition over the vanadium carbides appeared to be structure-sensitive. This response was considered to be due to variations in the surface stoichiometry with particle size. In general, the activities of the vanadium carbides were about 2 times less than those of Mo2C catalyst while vanadium carbides had higher activities by a factor of 1 or 2 than those of Pt/C catalyst. The difference in activities of the vanadium and molybdenum carbides might be related to the degree of electron transfer between metals and carbon. A similarity between the catalytic behaviors of vanadium carbides and platinum metal appeared to be due to the similar electronic and magnetic properties of these materials, (C) 1999 Academic Press.