Analysis on Ammonia Synthesis over Wustite-Based Iron Catalyst

作     者：李小年 刘化章 岑亚青 胡樟能 LI Xiaonian;LIU Huazhang;CEN Yaqing;HU Zhangneng

作者机构：Instituteof Catalysis Zhejiang University of Technology Zhejiang Key Laboratory of Heterogeneous Catalysis 

出 版 物：《Chinese Journal of Chemical Engineering》 (中国化学工程学报（英文版）)

年 卷 期：2003年第11卷第1期

页      面：19-26页

核心收录：

学科分类：081702[工学-化学工艺] 08[工学] 0817[工学-化学工程与技术] 

基　　金：Supported by the National Natural Science Foundation of China (No. 29706011)  the Natural Science Foundation of Zhejiang Province for the distinguished young scholars (No. RC9702) and the Ninth-five Key Project of China (No. 96-550-02-01) 

主　　题：wustite-based catalyst ammonia synthesis catalytic activity reduction behavior kinetics 

摘      要：Wustite-based catalyst for ammonia synthesis exhibits extremely high activity and easy to reduction under a wide range of conditions. The reaction kinetics of ammonia synthesis can be illustrated perfectly by both the classical Temkin-Pyzhev and modified Temkin equations with optimized a of 0.5. The pre-exponent factors and activation energies at the pressures of 8.0 and 15.0MPa are respectively k0 = 1.09 x 1015, 7.35 X 1014Pa0.5.s-1, and E = 156.6, 155.5kJ-mol-1 derived from the classical Temkin-Phyzhev equation, as well as k0 = 2.45 X 1014, 1.83 X 1014Pa0.5s-1, and E = 147.7, 147.2kJ-mol-1 derived from the modified Temkin equation. Although the degree of reduction under isothermal condition is primarily dependent upon temperature, low pressure seems to be imperative for reduction under high temperature and low space velocity to be considered as a high activity catalyst. The reduction behavior with dry feed gas can be illustrated perfectly by the shrinking-sphere-particle model, by which the reduction-rate constants of 4248exp (-71680/KT) and 644exp (-87260/RT) were obtained for the powder (0.045-0.054mm) and irregular shape (nominal diameter 3.17 mm) catalysts respectively. The significant effect of particle size on reduction rate was observed, therefore, it is important to take into account the influence of particle size on reduction for the optimization of reduction process in industry.