碱金属K、Li对Ru/γ-Al_2O_3催化剂上CO选择性氧化的助催化作用

Promotion effects of K and Li alkali metals on preferential oxidation of CO over Ru/γ-Al_2O_3 catalyst

以Ru为活性组分,碱金属氧化物K2O和Li2O为助剂,采用浸渍法制备Ru/γ-Al2O3、Ru1K10Oy/Al2O3和Ru1Li10Oy/Al2O3催化剂,对制备的催化剂进行TPR、XRD和SEM表征,采用固定床石英反应器考察催化剂的CO氧化性能。结果表明,碱金属助剂的引入对Ru/γ-Al2O3的催化性能有一定影响,K2O和Li2O的掺杂,显著降低Ru/γ-Al2O3催化剂上CO选择性氧化温度。Ru1K10Oy/Al2O3和Ru1Li10Oy/Al2O3催化剂低温具有较高的CO转化率和选择性,随着反应温度的升高,提高CO转化率的同时,存在更多的氢气消耗,导致CO选择性降低。

Using Ru as the active component and alkali metal oxides K2 O and Li2 O as the promoters,Ru /γ-Al2O3,Ru1K10Oy/ Al2O3 and Ru1Li10Oy/ Al2O3 catalysts were prepared via incipient wetness impregnation method. The catalysts were characterized by TPR,XRD and SEM. The activity of the catalysts for CO preferential oxidation of the hydrogen-rich gas stream produced from reforming gas was evaluated in a fixed bed quartz reactor under simulative condition. The results showed that the addition of K and Li promoters could improve the catalytic performance of Ru / γ-Al2O3 catalyst for CO preferential oxidation in H2-rich stream,and CO selective oxidation temperatures over Ru1K10Oy/ Al2O3 and Ru1Li10Oy/ Al2O3 catalysts were descended obviously compared with Ru / γ-Al2O3 catalyst. Ru1K10Oy/ Al2O3 and Ru1Li10Oy/Al2O3 catalysts possessed higher CO conversion and selectivity at low reaction temperature. With the increase of reaction temperature,CO conversion was enhanced,meanwhile H2 consumption was increased,which resulted in the reduction of CO selectivity.