College of Chemistry, Taiyuan University of Technology
College of Chemical Engineering and Technology, Taiyuan University of Technology

采用溶胶-凝胶法制备了不同Co含量的nCo-Al2O3催化剂(n = 2%、5%、10%、15%、20%)，研究了Co含量对催化剂结构和CO2氧化乙苯脱氢性能的影响。结果发现，nCo-Al2O3催化剂上孤立的Co2 + 离子与催化活性具有良好的对应关系，表明孤立的四面体Co2 + 物种是其活性位点。Co-Al2O3催化剂上的Co物种结构和催化性能与Co含量相关。Co含量较低（≤10%）时，催化剂上优先形成孤立的四面体Co2 + 物种；随着Co含量的增加，孤立的Co2 + 位点增加，催化剂活性随之提高。Co含量较高（>10%）时，催化剂上形成Co3O4晶体颗粒，导致孤立的Co2 + 位点减少，催化剂活性降低。10Co-Al2O3表现出最佳催化性能，550 ℃下乙苯转化率达64.4%，苯乙烯选择性为99.3%，反应30 h后，催化剂仍无明显失活，表明孤立的Co2 + 活性位点具有良好的结构稳定性和优异的抗积炭性能。

nCo-Al2O3 catalysts with different Co contents (n=2%, 5%, 10%, 15%, 20%) were prepared by a sol-gel approach. The effect of Co content on the nCo-Al2O3 catalyst structure and performance in the oxidative dehydrogenation of ethylbenzene to styrene by CO2 was investigated. The results showed that the isolated Co2 + ions on the nCo-Al2O3 catalysts had a positive influence on the catalytic activity, where the isolated tetrahedral Co2 + species were considered as the active sites. Co contents on the Co-Al2O3 catalyst greatly affected the structure of Co species and the catalytic performance. The isolated tetrahedral Co2 + species are preferentially generated on the resultant nCo-Al2O3 catalyst when the content of Co (n) is less than 10%; as a result, an increase of Co content here leads to the formation of more isolated Co2 + sites and then improves the catalytic activity of nCo-Al2O3 in the dehydrogenation of ethylbenzene. When Co content exceeded 10%, crystalline Co3O4 particles were obtained on the formed catalyst, which resulted in the decline of the isolated Co2 + sites and catalytic activity. Among various nCo-Al2O3 catalysts, 10Co-Al2O3 exhibited the best catalytic performance, with 64.4% conversion rate for ethylbenzene and 99.3% selectivity for styrene at 550 ℃. This catalyst remained stable without obvious deactivation for 30 h of reaction, which suggests that the isolated Co2 + species as active sites presented excellent structural stability and excellent anti-coke deposition.

国家自然科学基金（22378286, 21975174）和中央引导地方科技发展资金（YDZJSX2021A014）资助

司智伟, 丹少鹏, 陈树伟, 潘大海, 王英雄, 闫晓亮, 李瑞丰. Co-Al2O3高效催化CO2氧化乙苯脱氢制苯乙烯[J]. 燃料化学学报（中英文）, 2023, 51(11): 1683-1690.

SI Zhi-wei, DAN Shao-peng, CHEN Shu-wei, PAN Da-hai, WANG Ying-xiong, YAN Xiao-liang, LI Rui-feng. Highly efficient Co-Al2O3 catalysts for oxidative dehydrogenation of ethylbenzene to styrene with CO2[J]. Journal of Fuel Chemistry and Technology, 2023, 51(11): 1683-1690.