CO_2加氢活性与担载铁催化剂表面Fe-O键强度的关系

Relationships between Catalytic Activity of CO_2 Hydrogenation and Fe-O Bond Strength on Supported Iron Catalyst Surface

采用浸渍 -还原法 ,制备了 Al2 O3、 Ti O2 、 Zr O2 担载铁催化剂 ,并在温度 6 2 3K、压力 1.5 MPa、空速80 0～ 10 0 0 h- 1、原料气组成 CO2 /H2 为 1∶ 2等实验条件下 ,考察了不同还原温度的催化剂在 CO2 加氢制低碳(C2 ～ C5 )烃中的反应活性 .结果表明 ,以 CO2 转化率计 ,各催化剂均存在最佳还原温度 (Fe/Al2 O3:873K;Fe/Ti O2 :773K;Fe/Zr O2 :72 3K) .将此温度与催化剂表面 Fe- O键强度相关联 ,发现在相同条件下 ,与载体 M-O键长有关的 Fe- O键越强 ,催化剂越容易被还原 ,最佳还原温度越低 ,反应活性越好 .

Supported iron catalysts prepared by a novel method possess good catalytic activity in the synthesis of light hydrocarbons from CO 2 and H 2. The results indicate that catalytic activity has a good relation with the pre\|reduction temperature of catalyst. According to the conversion of CO 2, the optimum reduction temperatures for catalysts are 873 K for Fe/Al 2O 3, 773 K for Fe/TiO 2 and 723 K for Fe/ZrO 2 respectively. Connecting the temperatures with the Fe-O bond strength on the catalyst surface, it was found that the stronger Fe-O bond, the lower optimum reduction temperature and higher catalytic activity, while the Fe-O bond strength increases with the M-O bond length of the supports elected.