An alumina-coated, egg-shell Pd/alpha-Al2O3@SiC catalyst with enhanced ethylene selectivity in the selective hydrogenation of acetylene
An alumina-coated, egg-shell Pd/alpha-Al2O3@SiC catalyst with enhanced ethylene selectivity in the selective hydrogenation of acetylene
复制标题
氧化铝涂层蛋壳 Pd/α-Al2O3@SiC 催化剂在乙炔选择性加氢中具有增强的乙烯选择性
DOI：
10.1039/c6ra08320j
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Ma Mingjie
中科院分区：
文献类型：
--
作者：
Zhang Huoli;Cao Jianliang;Wu Baojun;Dai Wei;Chen Zehua;Ma Mingjie
在乙炔选择性加氢制乙烯过程中，钯催化剂的选择性至关重要。钯以“皮肤”的形式存在于Al2O3载体表面，分散在“皮肤”上的钯活性位点表现出较高的去除乙炔的活性，这也抑制了乙烯过度加氢生成乙烷和催化剂上低聚物的形成。因此，通过可行的路径，准确控制载体上Pd活性位点的分布范围具有重要意义。在此，我们展示了一种简单的方法来精确控制Pd在支架上的活性位点分布范围。采用一步喷涂的方法在环形SiC衬底外表面直接制备α- al2o3层，得到蛋壳状α-Al2O3@SiC载体。α-Al2O3层厚度可在50 ~ 300 μm范围内自由调节。采用新设计的α-Al2O3@SiC载体作为乙炔选择性加氢反应的催化剂体。正如预期的那样，以α-Al2O3@SiC复合材料为载体的钯催化剂的合理设计能够比传统的挤出球团钯催化剂实现更高的乙烯选择性。在本研究中，蛋壳型Pd-Ag /α-Al2O3@SiC催化剂的乙烯选择性比常规颗粒型Pd-Ag /α- al2o3催化剂的乙烯选择性高16%，实现了对富乙烯流中乙炔的完全去除。
For the selective hydrogenation of acetylene to ethylene, the selectivity of the palladium (Pd) catalyst is crucial. Pd is present as a skin distributed on the surface of Al2O3 supports and Pd active sites dispersed on the skin exhibit high activity for acetylene removal, which also inhibits over-hydrogenation of ethylene to ethane and the formation of oligomeric species on the catalyst. Therefore, it is significant to accurately control the distribution range of Pd active sites on the support by a feasible route. Herein, we demonstrate a facile approach to precisely control the Pd active-site distribution range on the support. An α-Al2O3 layer was prepared directly on the outside surface of a ring-like SiC substrate by one-step spray-coating, to obtain an egg-shell α-Al2O3@SiC support. The thickness of the α-Al2O3 layer could be freely tuned from 50 μm to 300 μm. The newly designed α-Al2O3@SiC support was used as the catalyst body in the selective hydrogenation of acetylene. As expected, the rational design of a Pd catalyst with this α-Al2O3@SiC composite material as the support has the ability to achieve higher ethylene selectivity than a conventional extrusive pellet Pd catalyst. In this work, the ethylene selectivity of the egg-shell Pd–Ag/α-Al2O3@SiC catalyst was 16% greater than that of a conventional pellet Pd–Ag/α-Al2O3 catalyst when achieving complete removal of acetylene in an ethylene-rich stream.