摘要
通过调控前驱体和还原剂,采用化学还原法制备了具有不同晶相的Ru纳米颗粒,分别为fcc Ru和hcp Ru.研究了Ru晶相对氨合成反应活性的影响,发现fcc Ru主要暴露的(200)和(111)晶面对N2 的解离要优于传统hcp Ru的(100)晶面,具有较高的氨合成活性.在400℃,1 MPa的测试条件下,fcc Ru催化剂的反应速率为666.4 μmol·h-1·g-1,是hcp Ru(378.9 μmol·h-1·g-1)的 1.76倍.进一步将两种晶相的Ru负载在CeO2 载体上,所得氨合成活性进一步提高,fcc Ru/CeO2 的氨合成活性仍高于hcp Ru/CeO2,说明Ru的晶相对氨合成活性的影响占主导因素.
Abstract
Ru nanoparticles with fcc and hcp crystal phases were obtained by chemical reduction method using different precursors and reducing agents,and their catalytic properties in ammonia synthesis were compared.The catalytic reaction rate(666.4 μmol·h-1·g-1)of fcc Ru catalyst is higher than that of hcp Ru(378.9 μmol·h-1·g-1)at the reaction temperature(400℃)and pressure(1 MPa).The results indicate that the exposed crystal faces have a certain impact on the catalytic activity.The dissociation ability to N2 of fcc Ru exposed(111)and(200)is better than that of hcp Ru exposed(100).When the ruthenium catalyst was loaded on rod-like CeO2 support,the ammonia synthesis activity was further improved.The ammonia synthesis activity of fcc Ru/CeO2 is 1.4 times higher than that of hcp Ru/CeO2 under the test conditions.
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