500 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



which decisive information can hardly be secured on a laboratory 

 scale. Blast-furnace operations have to be on so large, continuous, 

 and expensive a scale that it is difficult to find anyone willing and in 

 position to undertake or permit experiments of this type on an op- 

 erating furnace. However, it is now hoped that during the coming 

 year such an opportunity may present itself through cooperation 

 with the Bureau of Mines and the industry. 



DIRECT SYNTHETIC AMMONIA PROCESS. 



One of the major problems of the laboratory has been the study 

 of the direct synthetic ammonia process, frequently designated as 

 the Haber process. An exhaustive study of this process was under- 

 taken for two reasons: 



1. The United States nitrate plant No. 1 was designed to Operate 

 in accordance with this process. In the test made on this plant it 

 was found that successful operation was not likely until the chemical 

 and engineering problems involved were more thoroughly understood, 



2. The direct synthetic ammonia process is at present generally* 

 considered to be one of the most promising, if not the most promis- 

 ing, method for fixing atmospheric nitrogen. Although the chem- 

 ical and engineering difficulties are serious, the process undoubtedly 

 jjresents great possibilities for the lowering of costs. Therefore, 

 irrespective of the immediate needs of the Government plant at 

 Sheffield, the investigation of this process would still have occupied 

 a large part of the research program of this laboratory. 



The problems involved in the synthetic ammonia process may be 

 divided into two groups, first, those which concern the process' for 

 making hydrogen combine with the nitrogen of the air to form am- 

 monia, and, second, those which concern the process for manufactur- 

 ing and purifying the hydrogen-nitrogen mixture employed in this 

 synthesis. 



The principal problem of the first group centers about the catatyst. 

 In fact, the nature of the entire process is largely dependent upon its 

 characteristics. For example, the properties of the catalyst deter- 

 mine what the purity of the hydrogen-nitrogen mixture must be. 

 Since the purification of the gas represents a very large item in the 

 cost of making ammonia by the process as employed at Sheffield, 

 the importance of the catalyst is not to be underestimated. 



Furthermore, the properties of the catalyst determine such fac- 

 tors as size of the catalyst chambers, the circulating system, and the 

 heat interchangers. The nature of the apparatus for removing the 

 ammonia formed also depends in large part upon the activity of 

 the catalyst. With a poor catalyst the efficient removal of the am- 

 monia becomes a very serious problem. The temperature at which 

 the catalyst gives the greatest yield of ammonia is also an important 

 consideration in the design and construction of the catalyst chambers. 

 Briefly, we t^^sly say that every portion of the synthesis equipment is 

 subject to modification as the charactor of the catalyst is changed. 



Probably the greatest single contribution of this laboratory to date 

 is the development of a very reactive and stable catalyst. As far as 

 we have been able to learn, there is no country in the world which has 

 an ammonia catalyst superior to that developed by this laboratory. 

 A method has also been developed for manufacturing this material 



