摘要
以LaCo1-xGaxO3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℃、3MPa、空速(GHSV)为3000mL/(gcat·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LaCo1-xGaxO3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Co^0和Co^δ+的协同作用促使CO2选择性加氢生成乙醇。
A new Co/La2O3-La 4Ga2O9 catalyst was prepared by reducing LaCo1-xGaxO3 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 LaCoO 3 catalyst, the incorporation of Ga dopant can inhibit the formation of CH 4 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 Co^0 and Co^δ+ may contribute to the excellent performance of the Co/La2O3-La 4Ga 2O9 catalyst in CO2 hydrogenation to ethanol.
作者
郑晋楠
安康
王嘉明
李晶
刘源
ZHENG Jin-nan;AN Kang;WANG Jia-ming;LI Jing;LIU Yuan(School of Chemical Engineering, Tianjin University Tianjin Key Laboratory of Applied Catalysis Science and Technology, Tianjin 300072, China;Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China)
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2019年第6期697-708,共12页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金(21872101,21576192)资助~~
关键词
二氧化碳加氢
乙醇合成
钙钛矿型氧化物
钴
镓
carbon dioxide hydrogenation
ethanol synthesis
perovskite-type oxide
cobalt
gallium
