纳米铁基催化剂在CO2加氢制烃中的性能

使用尿素沉淀凝胶、机械混合和等体积浸渍相结合的方法, 制备了一系列的纳米尺寸FeK-M/γ-Al₂O₃(M=Cd, Cu)催化剂, 采用扫描电镜(SEM)、透射电镜(TEM)、N2物理吸附、X射线衍射(XRD)光谱和H₂程序升温还原(H₂-TPR)仪对催化剂进行表征, 并在小型固定床反应器上考察其对CO₂加氢反应的催化性能. 结果表明:3 MPa, 400 °C, 3600 h^-1, H₂/CO₂摩尔比为3 的条件下, 15%(w, 下同)Fe10%K/γ-Al₂O₃催化剂可稳定运行100h 以上, CO₂转化率为51.3%, C₂₊烃类的选择性达62.6%. Fe 含量降至2.5%时, C₂₊烃类的选择性仍能达到60.0%. 随着K含量由0%增加至10%, 低碳烯烃选择性增加, 烯烷比增加至3.6. Cd和Cu助剂可促进Fe 物种的还原, 改善目的产物的分布, 其中Cu的加入使低碳产物烯烷比增至5.4, Cd的加入使C₅₊产物选择性增加了12%.

Properties of the Nano-Particle Fe-Based Catalyst for the Hydrogenation of Carbon Dioxide to Hydrocarbons

Combining co-precipitation-gelation,mechanical mixing and impregnation methods,a series of catalysts of FeK-M/γ-Al2O3(M=Cd or Cu) have been attained.The catalysts were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),N2 physisorption,X-ray diffraction(XRD) and temperature-programmed reduction of hydrogen(H2-TPR).The hydrogenation of carbon dioxide over these catalysts was also investigated in a fixed bed.Given a reaction time of 100 h,CO2 conversion over a 15%Fe/10%K/γ-Al2O3 catalyst reached 51.3 %,with a selectivity towards C2+ of 62.6 % at 3 MPa,673 K,a space velocity of 3600 h-1 and at a molar ratio of H2/CO2 of 3.At the lower Fe content of 2.5%,the selectivity towards C2+ was still greater than 60.0%.Increasing the potassium content from 0% to 10%,increased the selectivity towards C2-C=4 and the molar ratio of C2-C=4/C2-C04 increased to 3.6.The addition of Cd and Cu improved the reduction and catalytic activities.Specifically,Cu improved the molar ratio of C2-C=4/C2-C04 from 3.6 to 5.4,and the Cd increased the selectivity of C5+ by 12%.