CexZr1-xO2/Co/C-N催化CO2加氢性能研究

将不同比例的铈锆前驱体负载到ZIF-67，氮气气氛焙烧制备CexZr1-xO2/Co/C-N催化剂，对催化剂进行了XRD，H2-TPR、XPS表征，并在固定床反应器评价其CO2加氢制甲醇性能。XRD结果表明，在铈中加入适量锆形成铈锆固溶体，铈锆固溶体与钴物种较强的相互作用力可以阻止表明金属Co的氧化。但过量加入的锆又会削弱这一作用力，部分金属Co被氧化为Co3O4。H2-TPR结果表明适量的锆的加入改善催化剂的还原性能，催化剂还原温度降低。XPS证实了25%Ce0.67Zr0.33O2/Co/C-N催化剂中含有更多的氧空穴及氮含量，氧空穴和碱性氮都有利于CO2的解离吸附。优化后的25%Ce0.67Zr0.33O2/Co/C-N 催化剂在225 oC，2 MPa，GHSV = 6 L/gcat/h反应条件下取得最高甲醇时空收率，为3.0 mmol/gcat/h。

The Study of CO2 Hydrogenation Activity over CexZr1-xO2/Co/C-N Catalysts

A series of CexZr1-xO2/Co/C-N catalysts are prepared with calcination of ZIF-67 supported different ratio of Ce/Zr precursor at N2 atmosphere. The catalysts are characterized with XRD, H2-TPR and XPS, and their methanol synthesis activity of CO2 hydrogenation is studied in a fixed bed reactor. Ce0.75Zr0.25O2 solid solution is formed when addition Zr into Ce from XRD results. The strong interaction between Ce0.75Zr0.25O2 solid solution and Co prevents the oxidation of metal Co on the surface of catalysts, however, too much addition of Zr will weaken this interaction, Co species will be oxidized into Co3O4 again. H2-TPR results confirm that the addition of Zr decreases the reduction temperature of catalyst and improves the catalyst activity. 25%Ce0.67Zr0.33O2/Co/C-N has the most content of oxygen vacancies and nitrogen element from XPS results, which both take advantage of CO2 dissociative adsorption. The highest methanol space-time yield of 3.0 mmol/gcat/h is obtained with 25%Ce0.67Zr0.33O2/Co/C-N at the reaction condition T = 225 oC, P = 2 MPa, GHSV = 6 L/gcat/h.