铁助剂对Rh-Mn-Li/SiO_2催化剂表面上的CO脱附和CO加氢行为的影响

Effects of Fe Promoter on Desorption and Hydrogenation of CO Adsorbed on Rh-Mn-Li/SiO_2 Catalyst

采用一氧化碳程序升温脱附 (CO TPD)和吸附的一氧化碳加氢程序升温表面反应 (TPSR)考察了Fe助剂对Rh基催化剂上CO的脱附行为及吸附CO的加氢行为的影响 .CO TPD实验表明 ,在Rh/SiO2 催化剂上CO有三个脱附峰 .在Rh Mn Li/SiO2 中加入 0 0 5 %Fe后 ,高温脱附的CO比Rh/SiO2 催化剂上相应的CO量大 .增加Fe的负载量 ,CO的脱附量减少 .TPSR实验中 ,CO加氢反应的主要产物是甲烷 .不同组分的催化剂上甲烷的生成温度有如下顺序 :Rh/SiO2 (4 82K) <Rh Mn Li/SiO2 (4 89K) <Rh Fe/SiO2 (4 94K) <Rh Mn Li Fe/SiO2 (5 0 1K) .甲烷峰的产生伴随着CO(s)高温脱附峰的消失 。

The effects of Fe promoter on the desorption and hydrogenation of adsorbed CO over a series of silica-supported Rh-based catalysts were investigated by means of temperature-programmed desorption of adsorbed CO (CO-TPD) and temperature-programmed surface reaction (TPSR) of adsorbed CO with hydrogen. There were three peaks of CO desorption in the CO-TPD spectra over the Rh/SiO2, catalyst. The low-temperature peak of CO desorption was unchanged and the two high-temperature peaks shifted simultaneously toward lower temperature and became narrower when 0.05% of Fe was added into Rh/SiO2. In contrast, the desorption peaks at high temperature moved to higher temperature when 0.05% of Fe was added into the Rh-Mn-Li/SiO2 catalyst, and the amount of CO desorption was more than that over Rh/SiO2. However, the amount of CO desorption decreased with increasing amount of Fe added. The temperature of maximum methane formation in the TPSR spectra was found to be in the following order: Rh/SiO2(482 K) <Rh-Mn-Li/SiO2, (489 K) <Rh-Fe/SiO2(494 K) < Rh-Mn-Li-Fe/SiO2 (501 K). It was interesting to find that the amount of CH4 formation ran parallel to the amount of CO desorption at high temperature, implying that the CO adsorbed strongly on the surface of Rh-based catalysts was hydrogenated to methane.