Fixed Nitrogen laboratory catalyst

In Fig. 9 are shown comparable data with a small sample of the Fixed Nitrogen Laboratory Catalyst No. 931. Here there is some evidence of a maximum around —78° C. The curve for lowering temperature is evidence for the phenomenon of desorption-readsorption. 

In the pre-World War II days there was little work done at Princeton on synthesis of catalysts. Copper catalysts were made by reduction of Kahlbaum copper oxide, the iron ammonia catalysts were obtained from the Fixed Nitrogen Laboratory through the courtesy of Dr. Paul Emmett, the nickel on kleselguhr catalyst was obtained from DuPont. Platinum on asbestos was made in the laboratory by soaking asbestos with chloroplatinic acid and then igniting it, mixed chromite catalysts were precipitated and calcined and a study was made. 

In summary then, the group at the Fixed Nitrogen Research Laboratory by 1925 had shown that doubly promoted iron catalysts containing about 3% aluminum oxide and one percent potassium oxide were entirely satisfactory for commercial use and would, if operated on pure gas, have a very long life. Actually, many similar commercial catalysts are said to retain their activity for more than 5 years. 

Professor H.S. Taylor, who was considered during his lifetime to be the dean of American Catalytic Chemists, is quoted as remarking that the work at the Fixed Nitrogen Research Laboratory could be considered as the basis of a textbook on heterogeneous catalysis. It included catalyst development, reactor design and basic catalyst studies. These latter included the usual basic studies of the physical and chemical adsorption of reactants, the kinetics of the reaction, studies of the catalyst surface and finally, mechanism studies and conjectures. In line with this suggestion we shall now give a compact summary of the basic work. 

In summary one may conclude that the Fixed Nitrogen Research Laboratory and its continuation as a section of the Bureau of Soils over the period of 1919 to 1940 did an outstanding job in laying a foundation for a prosperous and well-built synthetic ammonia industry and for doing its share to develop and study the detailed characteristics and mode of operation of the various catalyst systems involved. 

Despite the problems at Sheffield, the Atmospheric Nitrogen Corporation, a subsidiary of the General Chemical Company, had built and operated a second plant with the same design at Syracuse, New York by 1921.The original capacity was 15 tonnes per day anunonia but it was later increased to 40 totmes per day. This plant eventually used a fused iron oxide catalyst, promoted with alumina and potash, developed at the Fixed Nitrogen Research Laboratory by A T Larson. It had first test a catalyst developed by de Jahn of the General Chemical Company. 

In view of these considerations, a large amount of effort is reported in the scientific press on the development of a process to produce benzene from n-hexane by combined cyclization and dehydrogenation. w-Hexane has a low Research octane number of only 24.8 and can be separated in fair purities from virgin naphthas by simple distillation. Recently, an announcement was made of a process in the laboratory stage for aromatiza-tion of n-hexane (16). The process utilizes a chromia-alumina catalyst at 900° F., atmospheric pressure, and a liquid space velocity of about one volume of liquid per volume of catalyst per hour. The liquid product contains about 36% benzene with 64% of hexane plus olefin. The catalyst was shown to be regenerable with a mixture of air and nitrogen. The tests were made on a unit of the fixed-bed type, but it was indicated that the fluid technique probably could be used. If commercial application of this or similar processes can be achieved economically, it could be of immense help in relieving the benzene short-age. 

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