摘要
钼基甲烷化催化剂由于具有抗硫性能而受到重视。有关这类催化剂的表面结构特征也有过一些研究。由于负载型催化剂上钼的高度分散性,利用电子显微镜技术研究其活性组分的分散情况具有一些独特的优点。通用电子显微技术(CTEM)可以了解晶粒的大小和分布特征,选区电子衍射(SAED)
Selective area electron diffraction (SAED) and transmission electron microscopy (TEM) techniques were used to investigate the surface structural changes on sulfided MoO3/Y-Al2O3, MoO,/ZrO2, MoO3/CeO2 and MoO3/La2O3 catalysts during methanation under the conditions of space velocity 2400 h-1, CO:H2 = 1:3 and 450℃. Electron micrographs and electron diffraction patterns of fresh catalysts and catalysts after reaction for 5h, 10h and 20h were obtained. It is elucidated that the growing of particle size of MoS2 on these catalysts is relative to the decrease of methanation activity. MoS2 microcrystal is separated gradually from support during the reaction process, especially in MoS2/ZrO2 catalyst which has the highest activity and the worst stability.The interplanar distance was calculated from SAED patterns. The formation and change of MoS, microcrystal are evidenced.
基金
国家自然科学基金
