(130 AXXl'AT. RKPORTS OF DEPARTMENT Or AGRTCULTUltK. 



UIKKCT SYNTHETIC AMMONIA PROCKSS. 



The direct synthetic ammonia process is the newest of the three 

 commercially developed processes and is the one which at present 

 jipparontly olFeis the o-reatest opportnnity for further development. 

 The laboratory has therefore carried on a large amount of work in 

 connection witli it during the past year. In this process a purified 

 mixture of nitrogen and hydrogen is subjected to a very high 

 pressure and passed oAer a suitable catalyst maintained at about 

 500° C. Under these conditions nitrogen and hydrogen combine 

 chemically to form ammonia to the extent of from 5 to 15 per cent 

 of the gases pi'esent, the percentage depending on the catalyst and 

 operating conditions. The ammonia thus formed is removed and 

 tlie uncombiued gases returned to the apparatus and again treated. 



The main features of this process which require further develop- 

 ment and on which the laboratory lias been engaged during the 

 ])ast year are: The catalyst problem, involving the large-scale pro- 

 duction of an active catalyst, the further development of the present 

 catalyst, and the search for new and improved catalysts ; the pi'oduc- 

 tion and purification of the hydrogen-nitrogen mixture: the de- 

 velopment of apparatus which will stand tlie unusually high 

 pressures and temperatures used; and the removal of the synthesized 

 ninmonia from the unconverted gas. 



The catalyst for effecting the union of nitrogen and hydrogen is 

 in a sense the heart of the direct synthetic ammonia process. The 

 efficiency of the catalyst is in general very greatly reduced by even 

 exceedingl}' small amounts of impui'ities in the gas mixture passing- 

 through it, hence the necessity of pure gas. The laboratory has con- 

 tinued its studies on the developmerit of a catalyst which will be 

 more active and less affected by impurities than those previously 

 used. The laboratoiy has developed a satisfactory ammonia catalyst 

 and has perfected a method for its large-scale production. This is a 

 particularly important advance in the development of the synthetic 

 ammonia process. Research on the theory of catalytic action was 

 continued throughout the year, since the art of catalyst manufacture 

 can be placed on a firm scientific basis only through a thorough 

 knowledge of catalytic action. 



The production of hydrogen of required purity constitutes the 

 main cost of tlie entire process, the cost of nitrogen being relatively 

 small. The production and purification of hydrogen from various 

 commercial sources have been studied and improvements in the 

 method of purifying the gas have been made. Tlie laboratory has 

 given special attention to the utilization of waste hydrogen for the 

 synthesis of ammonia. Such waste hydrogen now occurs in connec- 

 tion with the electrolytic manufacture of bleaching materials, caustic 

 alkali, and oxygen. The individual amounts to be considered vary 

 over a range of 20,000 to 100,000 cubic feet per day at the different 

 plants, but the total amount going to waste in America is large 

 enough to be a factor of importance. For the utilization of these 

 relatively small quantities of waste hydrogen, methods of operation 

 quite different from those in large installations must be considered, 

 since some of the economies whicli can be introduced by large-scale 

 installations are not possible in this case. The laboratory has de- 

 veloped and installed apparatus particuiarlv adapted to* the svn- 



