摘要
以WO3为前驱体考察了CH4/H2混合气氛下程序升温反应制备碳化钨的晶相转变过程,比较了不同晶相碳化钨催化剂的肼分解活性,并以CO为探针分子采用微量吸附量热技术研究了碳化钨晶相转变过程中催化剂的表面活性位.结果表明,随W2C晶相的生成,催化剂对CO的吸附活化能力逐渐增强,纯相W2C表现有最好的肼分解活性.当制备温度高于750℃时,样品表面形成的积炭抑制了碳化钨的催化性能.表面洁净的WC在肼分解反应中具有优于W2C的类贵金属催化特性.
Tungsten carbides with different crystal phases were prepared by temperature-programmed reaction of WO3 in a CH4/H2 atmosphere, and the phase transition occurring during this process was described. The catalytic activity of the tungsten carbides for hydrazine decomposition was investigated, and the active sites were determined by CO adsorption mieroealorimetry. The results showed that the CO adsorption became strong with the formation of a W2C crystal phase, and the W2C exhibited the best catalytic performance for N2H4 decomposition. However, when the preparation temperature was higher than 750℃, there was a significant amount of carbonaceous species deposited on the catalyst surface, WC possessed a higher intrinsic activity for N2H4 than which resulted in severe deactivation. The surface-clean the W2C owing to its stronger nohle metallic properties.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2008年第8期710-714,共5页
基金
国家杰出青年基金(20325620)
国家自然科学基金(20303017,20573108)
关键词
碳化钨
程序升温反应
肼分解
微量吸附量热
积炭
tungsten carbide
temperature-programmed reaction
hydrazine decomposition
microcalorimetry
carbon deposition
