222 ANNUAL REPOBT SMITHSONIAN INSTITUTION, 1923 



power years per ton nitrogen fixed as ammonia, while if electrolytic 

 hydrogen and liquid-air nitrogen is produced the corresponding fig- 

 ure would be around 2% horsepower years. 



THE CLAUDE PROCESS 



This process, the invention of M. Claude, of France, is a modifi- 

 cation of the Haber process. It is as yet more or less in the experi- 

 mental stage, but seems to offer great possibilities. Claude thus 

 works with a pressure of 900 atmospheres as compared to 200 with 

 the Haber process. By means of this high pressure about 40 per 

 cent ammonia conversion is obtained per catalyzer unit, and the 

 cndothermic reaction will raise the temperature of the catalyst to 

 the required temperature of 900° to 1,000° F. with only a slight pre- 

 heating, which is readily provided by simply passing the gas through 

 an outer passage in the catalytic chamber. By using three catalyzer 

 units in series, 80 per cent of the gases is converted into ammonia 

 and only 20 per cent needs to be recirculated. The ammonia is 

 readily removed by simply cooling it in a coil submerged in water, 

 when practically all the ammonia will liquefy. 



The hydrogen and nitrogen may be obtained in the same manner 

 as with the Haber process previously described. It is claimed, how- 

 ever, that the hydrogen from producer gas can be very efficiently 

 purified at this super pressure. The compressed gas is passed 

 through ether at a low temperature, when all the gases but the hydro- 

 gen are dissolved by the ether. The solvent with the gases in solu- 

 tion is drained off, and when expanding to atmospheric pressure the 

 dissolved gases escape, leaving the solvent ready for reuse. 



THE CASALE PROCESS 1 



This is also a synthetic ammonia process which has been developed 

 in Italy, where it is said to be used in one or two plants. It operates 

 at a pressure around 600 atmospheres, or considerably higher than 

 the Haber process, for which reason a higher ammonia conversion 

 should be expected. It is also claimed that a very satisfactory 

 catalyzer has been found which is less affected by impurities in the 

 hydrogen and nitrogen gases. 



2 Since this article was written several Casale plants have been p.ut in operation in 

 Japan, France, and at Niagara Falls. 



