Surface chemistry and catalytic performance of chromia/alumina catalysts derived from different potassium impregnation sequences
Surface chemistry and catalytic performance of chromia/alumina catalysts derived from different potassium impregnation sequences
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不同钾浸渍顺序衍生的氧化铬/氧化铝催化剂的表面化学和催化性能
DOI：
10.1016/j.apsusc.2015.05.128
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发表时间：
2015
影响因子：
6.7
通讯作者：
Yan Zifeng
中科院分区：
文献类型：
--
作者：
Liu Daolan;Bai Peng;Wu Pingping;Han Dezhi;Chai Yongming;Yan Zifeng
比较了采用不同 K 浸渍顺序制备的铬/氧化铝催化剂在丙烷脱氢中的作用。这些材料通过多种技术进行表征。在负载 Cr 之前浸渍 K 的催化剂（样品 Cr/K/Al2O3）表现出比采用相反浸渍顺序制备的催化剂（样品 K/Cr/Al2O3）更高的丙烯选择性。与 K/Cr/Al2O3 催化剂相比，Cr/K/Al2O3 催化剂具有更多的表面酸性位点和更容易还原的铬物质。在 Cr/K/Al2O3 催化剂上观察到大多数铬物质以聚合物形式存在，而在 K/Cr/Al2O3 催化剂上主要发现分离和低聚铬物质。催化性能和表征结果之间的详细相关性表明，分离的低聚物物质比聚合铬物质具有更高的裂化和焦化活性，这可能是催化剂丙烯选择性差异的原因。
Chromia/alumina catalysts prepared with different K impregnation sequences were compared in the dehydrogenation of propane. The materials were characterized by a variety of techniques. The catalyst with K impregnated prior to Cr loading (sample Cr/K/Al2O3) exhibited higher propene selectivity than that prepared with the reverse impregnation sequence (sample K/Cr/Al2O3). Catalyst Cr/K/Al2O3possesses a higher amount of surface acid sites and more readily reducible chromium species compared with catalyst K/Cr/Al2O3. The majority of chromium species were observed to exist as polymeric species on catalyst Cr/K/Al2O3, while isolated and oligomeric chromium species were mainly found on catalyst K/Cr/Al2O3. A detailed correlation between catalytic performance and characterization results demonstrated that isolated and oligomeric species possessed higher cracking and coking activities than polymeric chromium species, which may account for the difference in the propene selectivity of catalysts.