TEMPERATURE-PROGRAMMED OXIDATION OF SULFIDED COBALT-MOLYBDATE ALUMINA CATALYSTS

被引:28
作者
YOSHIMURA, Y
MATSUBAYASHI, N
YOKOKAWA, H
SATO, T
SHIMADA, H
NISHIJIMA, A
机构
[1] National Chemical Laboratory for Industry, Tsukuba
关键词
D O I
10.1021/ie00054a004
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
Temperature-programmed oxidation of cobalt-molybdate, molybdate, and cobalt catalysts was carried out in thermogravimetric and fixed-bed reactors. During oxidation of the sulfided cobalt-molybdate catalyst in air, the SO2 formation profile exhibited two maxima at about 508 and 708 K, and about 10% of the total sulfur remained after oxidation at 773 K. The SO2 formation profile for sulfided molybdenum and cobalt catalysts indicated that the first SO2 maximum resulted mainly from oxidation of MoS2-like sulfides. EXAFS data of the Mo K edge revealed that some unoxidized MoS2-like sulfides survived after formation of the first SO2 peak. XPS data showed that these unreacted sulfides were covered with oxide/sulfate layers. The formation of the second SO2 maximum, accompanied with an exothermic reaction, might mainly result from oxidation of the unreacted sulfides. The presence of cobalt contributed to an increase in the residual sulfate after oxidation up to 773 K. A thermodynamic investigation supported this result.
引用
收藏
页码:1092 / 1099
页数:8
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