FIXED NITKOGEIs RESEAECH LABOEATOEY. 501 



which gives the necessary chemical control of the product and at the 

 same time makes large-scale production possible. As a consequence, 

 we are now in possession of such reliable information concerning 

 at least one tjipe of ammonia catalyst and its manufacture that one 

 of the principal obstacles to the successful operation of such plants as 

 United States nitrate plant No. 1 at Sheffield, Ala., has been removed. 



There is still, of course, the possibility that a much more reactive 

 catalyst may be found. As a consequence, this laboratory has con- 

 tinued during the past year its study of this phase of the problem. 

 Before any marked improvement over the present catalyzers can be 

 effected there must be a much better understanding of the way in 

 which the catalyzer makes hydrogen combine with the nitrogen. 

 Consequently, an extensive study of the mechanism of the reaction 

 has been in progress. It is hoped that the results of this work may 

 soon be published. 



Although it is not too much to expect that painstaking research 

 may reveal catalyst materials much more active than those which we 

 have now discovered, it is felt that the greatest advances in the direct 

 sj^nthetic ammonia process within the near future may lie in the 

 direction of increased pressures. Contrary to popular belief, there is 

 nothing inherently impracticable in carrying out the synthesis of 

 ammonia at pressures considerably in excess of those employed at 

 Sheffield. During the past year tests have been made at various 

 pressures up to 1,000 atmospheres. In these tests the activity and the 

 longevit}^ of the catalyst have been most satisfactory. From a chemical 

 viewpoint there are many advantages to be gained by high-pressure 

 operation, and when the engineering problems which arise at higher 

 pressures have been solved there is the possibility that capital and 

 operating costs can be very substantially decreased. 



During the past year most of the demands for information con- 

 cerning the synthetic ammonia process have come from groups par- 

 ticularly interested in the production of liquid ammonia from by- 

 product or waste hj^drogen. Liquid ammonia commands a price 

 which makes the operation of small units (say 1 ton per day) com- 

 mercially feasible. Much of the engineering research on the process 

 during the past year has had in mind the special requirements of 

 these small producers. ^Vliile the amount of their product is insig- 

 nificant compared to total national production, they would perform 

 a highly important function in spreading knowledge and experience 

 concerning the art in this country. As a result of tliis work we 

 believe that the laboratory is now able to offer considerable assistance 

 in the design of 1-ton plants. 



The primary interest of the laboratory has been, however, the 

 much larger problem of reducing the cost of fixed nitrogen suitable 

 for fertilizer purposes. This study has involved a consideration of 

 the advantages and disadvantages of operation at various pressures. 

 The principal pressures suggested by the proponents of diiferent 

 systems for commercial operation have been 100, 200, 300, 600, and 

 1,000 atmospheres. Since the details of the process are determined 

 in part by the pressure at which the process is operated, naturally 

 the cost of producing ammonia may be expected to vary somewhat 

 as the pressure conditions are changed. In making an analysis of 

 the possibilities of operation at these various pressures, the labora- 

 torv has been considerably handicapped because of its inability to 



