- 作者: 何瑞文
- 作者服務機構: Department of Chemistry, National Cheng Kung University, Taiwan, R.O.C.
- 中文摘要: The variations in catalytic properties for CO hydrogenation and adsorptive properties for H2 and CO of silica-supported cobalt catalyst as a function reduction temperature (400 to 700℃) were investigated. A mild sintering of cobalt metal from 130 A to 145 A occurred only when the reduction temperature was further increased from 600 to 700℃. However, a monotone decrease in the activity (per gram Co) for CO hydrogenation was observed with increasing reduction temperature. This is accompanied with a decrease in methane and an increase in olefin formation. The decrease in activity can not be accounted for by the variation of crystallite size of cobalt metal. A concurrent suppression in the amount of hydrogen and CO adsorptions was observed after reduction temperature was raised to 700℃. The turnover frequencies, based on cobalt dispersion estimated from H2 and CO chemisorption, remained, more or less, similar with increasing reduction temperature from 400 to 600℃, bit increased ca. 3 and 1.5 times, respectively, at 700℃. The relative amount of subcarbonyl species (2062 cm¯1) with respect to the linear adsorbed CO (2010 cm¯1) was found to increase as well. Furthermore, reduction of silica surface at 700℃ was indicated by the presence of -Si-H, which was detected by infrared spectroscopy at 2294 cm¯1. this shows the presence of metal-support interaction for silica-supported cobalt systems after reduction treatment at 700℃.
- 英文摘要: --
- 中文關鍵字: Cobalt Catalyst; Metal-Support Interaction; Reduction Temperature; Adsorption; Desorption
- 英文關鍵字: 鈷催化劑;金屬支撐作用;還原溫度;吸附;脫附