Synthesis of ammonia, catalytic

The catalytic synthesis of ammonia from its elements via the Haber-Bosch process is of major industrial importance. The high pressure synthesis is catalyzed by Fe promoted with K20, CaO and A1203. 

FIGURE 9.14 One of the high-pressure vessels used for the catalytic synthesis of ammonia. The vessel must be able to withstand internal pressures of greater than 250 atm. 

A chemical reactor is an apparatus of any geometric configuration in which a chemical reaction takes place. Depending on the mode of operation, process conditions, and properties of the reaction mixture, reactors can differ from each other significantly. An apparatus for the continuous catalytic synthesis of ammonia from hydrogen and nitrogen, operated at 720 K and 300 bar is completely different from a batch fermenter for the manufacture of ethanol from starch operated at 300 K and 1 bar. The mode of operation, process conditions, and physicochemical properties of the reaction mixture will be decisive in the selection of the shape and size of the reactor. 

This picture changed completely as, in February 1908, F. Haber approached the B. A. S. F. with the proposition to obtain their financial assistance for an intensified continuation of his research on the catalytic synthesis of ammonia, following a suggestion of professor K. Engler of Karlsruhe, a member of B. A. S. F. s advisory board. The catalytic synthesis of ammonia had been investigated previously, but without having met with any practical success. 

Our first example involves an industrial process of immense importance the catalytic synthesis of ammonia (NH3). Ammonia is a central component of... 

Emmett, P. H., "Fifty Years of Progress in the Study of the Catalytic Synthesis of Ammonia," in the "Physical Basis for Heterogeneous Catalysis," Drauglis, E. and Jaffee, R. I., Ed., Plenum Press, 1975. 

Since the formulation of his concepts in 1939 Kobozev has carried out many investigations in the attempt to verify their general validity. In the decomposition of H202 and the oxidation of Na2SCh, the specific effect (173) of small amounts of iron (0.0005 to 40%) added to copper on carbon and the converse in which small amounts of copper were added to iron on carbon were studied. The activity of these catalysts was very effectively promoted by these additives, the extent of promotion being proportional to the concentration of the additives. The catalytic synthesis of ammonia by iron supported on carbon or asbestos was also studied. The results of this study and similar studies of catalytic... 

Schlogl R. Catalytic synthesis of ammonia - a never-ending story [Review], Angew Chem Int Ed. 2003 42(18) 2004-8. 

S.A. Topham, The History of the Catalytic Synthesis of Ammonia, in J.R. Anderson and M. Boudart (Editors), Catalysis, Science and Technology, Springer Verlag, Berlin, 1985, Vol. 7, pp. 1-50. 

For constant volume processes, such as catalytic synthesis of ammonia from nitrogen and hydrogen in pressurised (about 300 atmospheres) reactor, the change in Work Function would be a measure of the feasibility of reaction,... 

Commercially, the catalytic synthesis of ammonia from hydrogen and nitrogen remains of great importance almost ninety years after its initial development. Although Fe is the most widely used catalyst for this process, Ru is known to be more active than Fe.34 Ammonia synthesis using Fe catalysts is relatively well understood. The rate limiting process in the overall Fe-catalyzed reaction is the initial dissociation of N2. The overall reaction can be described as follows ... 

Radial flow fixed bed reactors were developed to handle large gas flow rates with minimum pressure drop and are most suitable for processes in which fluids need to be contacted with solid particles at high space velocity (Chang and Calo, 1981). Radial flow fixed bed reactors are used for a variety of processes including catalytic synthesis of ammonia, xylene isomerization and desulphurization. 

Topham, S.A. The history of the catalytic synthesis of ammonia. In Catalysis Science and Technology Anderson, J.R., Boudart, M., Eds. Springer-Verlag New York, 1985 1-50. 

Mechanism and Kinetics of Ammonia Synthesis If all the experimental evidence presented in the preceding sections is put together, the reaction scheme for the catalytic synthesis of ammonia on iron-based catalysts can unequivocally be formulated in terms of the following steps ... 

W.G. Frankenburg. The Catalytic Synthesis of Ammonia from Nitrogen and Hydrogen. In P.H. Emmett, editor. Hydrogenation and Dehydrogenation. Catalysis, Volume 3. Reinhold, New York, 1955. 

P. Stolze. Surface Science as the Basis for the Understanding of the Catalytic Synthesis of Ammonia. Phys. Scr. 36 824 (1987). 

Contents S.A. Topham The History of the Catalytic Synthesis of Ammonia. - J. V, Sanders The Electron Microscopy of Catalysts. - B.E.Koel, G.A.Somoijai Surface Structural Chemistry. - Subject Index. -Author Index Volumes 1-6. 

Xie, Y. Hua, L. Hou, K. Chen, R Zhao, W Chen, W Ju, B. Li, H. (2014) Long-Term Real-time Monitoring Catalytic Synthesis of Ammonia in a Microreactor by VUV-Lamp-based Charge-transfer Ionization Time-of-flight Mass Spectrometry. Anal. Chem. 86 7681-7687. 

Schlogl, R. (2003). Catalytic synthesis of ammonia—a never-ending story Angewandte Chemie International Edition, 42(18), 2004—2008. 

Reaction Mechanism and Kinetics. At a meeting held in 1974 in honor of P. H. Emmett, he concluded his lecture entitled Fifty years of progress in the study of the catalytic synthesis of ammonia by the statement (16) ... 

R. Schlogl (2003) Angew. Chem. Int. Ed., vol. 42, p. 2004 - Catalytic synthesis of ammonia- A never-ending story ... 

Ertl G (1983) Primary steps in catalytic synthesis of ammonia. J Vac Sci Tech A 1 1247-1253... 

The synthesis of ammonia from its elements ranks as one of the most important discoveries in the history of the science of catalysis, not only because of its industrial application in which synthetic fertilizers have contributed enormously to the survival of mankind, but also from the viewpoint of fundamental science. Even today, some eighty years after the first demonstration of ammonia synthesis, many original scientific papers on the mechanism of the catalytic synthesis of ammonia are still published. Every time a new method, technique, or concept has appeared in the field of heterogeneous catalysis, it has been applied to this reaction. Specific examples of these applications over the years include the concepts of gas equilibrium, activated adsorption, structure sensitivitystoichiometric number and kinetic studies, " nonuniform surfaces, the measurements of surface area, surface composition and promoter distributions, and the use of isotopic and spectroscopic techniques. In particular, various surface science techniques have been applied successfully to this reaction system over well-defined single crystal surfaces in recent years. In this way the effect of promoters on the iron catalyst has been elucidated. Accordingly, the history of ammonia synthesis parallels not only that of industrial catalysis, but also the development of the science of catalysis. 

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