【摘要】 应用原位变温高压MAS核磁共振技术,对比研究了CO在不同Rh基催化剂上的吸附和加氢反应过程.29Si MAS NMR研究结果表明:Rh基催化剂中加入金属助剂后,载体Silicate-1上的表面硅羟基减少,助剂金属与硅羟基作用锚锭在载体表面.13C MAS NMR研究结果表明:当引入CO/H2混合气后,在Rh/Silicate-1催化剂上只能观测到气相CO、线式吸附CO和孪式吸附CO的快速交换信号;而在Rh-Mn/Silicate-1和Rh-Mn-Li/Silicate-1催化剂上,还观测到了倾斜式吸附的CO共振信号,表明助剂Mn或Mn-Li的加入促进了CO的吸附.随着反应温度升高,CO/H2在Rh/Silicate-1催化剂上转化生成CO2,进一步升高温度会有CH4生成;而CO/H2在RhMnLi/Silicate-1催化剂上反应活性更高,在较低的温度下就会转化生成CO2,但未观测到甲烷的生成.1H MAS NMR谱显示,反应后载体Silicate-1上硅羟基的量会减少,表明CO与载体部分表面硅羟基反应生成了CO2.更多还原

【Abstract】 The adsorption and hydrogenation processes of CO on Rh-based catalyst were studied by in situ high-pressure (HP) MAS NMR techniques under batch-like conditions. 29Si MAS NMR spectra showed that the silanol concentrations of the support Silicate-1 were reduced after impregnation of metal species. After introduction of 13CO/H2 below 200 ℃, only the average exchanged signal of CO between gaseous CO, linearly adsorbed CO and dicarbonyl adsorbed CO was observed on Rh/Silicate-1; while the titled adsorbed CO appeared on Rh-Mn/Silicate-1 or Rh-Mn-Li/Silicate-1. So, the addition of Mn or Mn-Li could enhance the CO adsorption. Under batch-like condition, high-pressure 13C MAS NMR showed that the CO/H2 reactants could only be converted to CO2 and CH4 on Rh/Silicate-1, while only CO2 appeared on Rh-Mn-Li/Silicate-1 at relatively lower temperatures. Meanwhile, 1H MAS NMR showed the obvious decrease of silanol groups after reaction that indicated CO could react with silanol groups to produce CO2.更多还原