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在25～300℃和0.1～2.5MPa范围内,利用程序升温脱附及原位漫反射红外光谱考察了CO,H2及合成气在费托合成沉淀铁基催化剂上的吸附行为.程序升温脱附表明,CO在铁基催化剂表面上存在线性、孪性及桥式吸附,对H2则有强、弱两类吸附活性中心;CO吸附红外光谱表明,2170和2116cm-1处存在明显的线性吸附双峰,1623～1313cm-1处存在少量表面态吸收峰,且随温度升高,在2360和2319cm-1处出现了CO2的特征吸收峰,催化剂表面对CO的吸附受温度和压力影响;合成气共吸附反应的红外光谱表明,费托合成烃生成机理及含氧化合物生成机理可用吸附态物种的变化解释,升高温度有利于CO加氢反应进行,高温高压有利于C2+含氧化合物生成.
The adsorption behavior of CO, H2 and syngas on Fischer-Tropsch synthesis iron-based catalysts was investigated by temperature programmed desorption and in-situ diffuse reflectance infrared spectroscopy at 25 ~ 300 ℃ and 0.1 ~ 2.5MPa. It is indicated that there are linear, twin and bridge adsorption of CO on iron-based catalyst surface and strong and weak adsorption of H2 on H2. CO adsorption infrared spectroscopy shows that there are obvious linear adsorption double bonds at 2170 and 2116cm-1 Peak at 1623 ~ 1313cm-1, and the characteristic absorption peak of CO2 appeared at 2360 and 2319cm-1 with the increase of temperature. The adsorption of CO on the catalyst surface was affected by the temperature and pressure. The syngas Infrared spectra of the co-adsorption reaction show that the formation mechanism of Fischer-Tropsch synthesis hydrocarbons and the formation mechanism of oxygenates can be explained by the changes of the adsorbed species. Increasing the temperature is favorable for the CO hydrogenation reaction, and the high temperature and pressure are favorable for the formation of C2 + oxygenates.