Co/La-Ga-O复合氧化物用于催化二氧化碳加氢制乙醇

以LaCo_1-xGa_xO₃为前驱体，还原后得到的Co/La₂O₃-La₄Ga₂O₉复合氧化物催化剂，用于CO₂加氢直接制乙醇。通过XRD、XPS、TPD和TEM等技术对催化剂结构进行了表征，采用微型固定床反应器在230-290℃、3 MPa、空速（GHSV）为3000 mL/（g_cat·h）和H₂/CO₂进料物质的量比为3.0的条件下，考察了该Co/La-Ga-O复合氧化物用于CO₂加氢制乙醇的催化性能。结果显示，该Co/La-Ga-O复合氧化物催化剂对生成乙醇具有很高的选择性。与LaCoO₃相比，Ga的掺杂可抑制甲烷的形成，促进醇类（特别是乙醇）的生成。当Co/Ga比为7：3时，还原后的LaCo_1-xGa_xO₃催化剂体现出最好的催化性能，CO₂转化率为9.8%，总醇选择性达到74.7%，其中，液相产物中的乙醇质量分数可达到88.1%。基于实验结果推测，该催化剂上Co⁰和Co^δ+的协同作用促使CO₂选择性加氢生成乙醇。

Direct synthesis of ethanol via CO2 hydrogenation over the Co/La-Ga-O composite oxide catalyst

A new Co/La₂O₃-La₄Ga₂O₉ catalyst was prepared by reducing LaCo_1-xGa_xO₃ perovskite and used in the direct synthesis of ethanol from CO₂ hydrogenation. The composite catalyst was characterized by XRD, XPS, TPD and TEM and its catalytic performance in CO₂ hydrogenation was investigated in a micro fixed-bed reactor operated at 230-290℃, 3 MPa, gas hourly space velocity (GHSV) of 3000 mL/(g_cat·h) and H₂/CO₂ molar ratio of 3.0. The results indicate that the Co/La-Ga-O composite oxide catalyst exhibits high selectivity to ethanol in CO₂ hydrogenation. In comparison with the LaCoO₃ catalyst, the incorporation of Ga dopant can inhibit the formation of CH₄ and then promote the production of alcohols, especially ethanol. With a Co/Ga atomic ratio of 7:3, the Co/La-Ga-O composite oxide catalyst displays the best performance in CO₂ hydrogenation, with a CO₂ conversion of 9.8%, a selectivity of 74.7% to total alcohols and ethanol content of 88.1% (mass ratio) in the alcohols mixture. On the basis of the experimental results, it is speculated that the synergistic effect of surface Co⁰ and Co^δ+ may contribute to the excellent performance of the Co/La₂O₃-La₄Ga₂O₉ catalyst in CO₂ hydrogenation to ethanol.