Promotion of binary nitride catalysts:: Isothermal N2 adsorption, microkinetic model, and catalytic ammonia synthesis activity
Promotion of binary nitride catalysts:: Isothermal N2 adsorption, microkinetic model, and catalytic ammonia synthesis activity
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DOI：
10.1006/jcat.2002.3571
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发表时间：
2002-05-15
影响因子：
7.3
通讯作者：
Jacobsen, CJH
中科院分区：
文献类型：
--
作者：
Boisen, A;Dahl, S;Jacobsen, CJH
本文研究了铯促进的Co_3Mo_3N催化剂上氨合成和N_2解离的动力学。结果支持最近的DFT计算，并解释了为什么Co 3 Mo 3 N表现出更高的氨合成活性比任何构成金属。在H2：N2 = 3：1和1：1，总压为50、25和10 bar，温度为593 ~ 713 K的条件下，研究了铯促进的Co 3 Mo 3 N的氨合成活性。进行了等温N2吸附实验，结果很好地描述了一个简单的模型。发现催化剂上能够结合氮的表面位点的总数为约30 μ mol/g催化剂。当只有1%的表面活性位对N-2解离具有活性时，双氮在活性位上的初始粘附系数s（0）= 0.1727（.）exp（（-42.8 +/- 5 kJ/mol）/RT）。该结果被用作氨合成的微动力学模型的输入，其中假设N* 和H* 是仅有的表面中间体。以氮结合能作为唯一的可调参数，可以获得与氨合成活性数据的良好拟合。(C)2002 Elsevier Science（美国）。
The kinetics of ammonia synthesis and N-2 dissociation over cesium-promoted Co3Mo3N are studied. The results support recent DFT calculations and explain why Co3Mo3N shows a higher ammonia synthesis activity than either constituting metal. The ammonia synthesis activity of cesium-promoted Co3Mo3N is reported for a series of conditions, with H-2 : N-2 ratios of both 3 : 1 and 1 : 1, total pressures of 50, 25, and 10 bar, and temperatures from 593 to 713 K. Isothermal N2 adsorption experiments were carried out and the results were well described by a simple model. The total number of surface sites on the catalyst capable of binding nitrogen was found to be approximately 30 mumol/g of catalyst. When only 1% of these surface sites is active for N-2 dissociation, the initial sticking coefficient, s(0), of dinitrogen on the active sites was found to be s(0) = 0.1727 (.) exp((-42.8 +/- 5 kJ/mol)/RT). This result was used as input to a microkinetic model for ammonia synthesis where it was assumed that N* and H* are the only surface intermediates. In this way it was possible to obtain a good fit to the ammonia synthesis activity data with the nitrogen-binding energy as the only adjustable parameter. (C) 2002 Elsevier Science (USA).