The Adsorption of Nitrogen by Iron Synthetic Ammonia Catalysts

Abstract

Adsorption of Nitrogen by Iron Ammonia Catalysts 3f> were carried out in an unsilvered Pyrex Dewar of about 250 cc. capacity, surrounded by an eutectic mixture of CaCla-HjO. A rubber stopper covered with tin foil closed the neck of the Dewar. Through this stopper projected the thermocouple tube, a hand stirrer of glass and a tube for admitting nitrogen or dry air. It was found best to employ a mixture of about 3 parts of carbon tetrachloride to 1 part of methanol, by weight, since this gave a mixture which was about 50% solid and 50% liquid at the transition point. About 75 cc, of this mixture, previously cooled into the transition, was introduced into the Dewar and slowly stirred while readings were taken on the thermocouple. Three determinations gave -47.67, -47.68 and -47.65°, respectively, as compared with the accurate value of -47.66°. The deviations are barely greater than the limits of reproducibility of the thermocouple and are certainly within the limits of error with this simple apparatus. The melting point of the carbon tetrachloride employed in these determinations was also measured in a nearly similar piece of apparatus,24 and found to be -Colxjmbus, Ohio

The Structural Status of Clay Systems

“…Complete nitrogen adsorption-desorption isotherms for the clay materials at 78 ~ were obtained using a volumetric apparatus based on the original apparatus of Emmett and Brunauer (1934) and incorporating many 8* of the refinements suggested by Harkins and Jura (1944) and Joyner (1949).…”

Predicting Catalysis: Understanding Ammonia Synthesis from First-Principles Calculations

“…[29][30][31][32][33] However, because of the higher price of Ru and its shorter catalytic lifetime, the dominance of iron-based catalysts has only recently been challenged by promoted Ru catalysts. [34][35][36] In the 1930s, Emmett et al 37,38 found strong experimental evidence that N 2 dissociation over Fe catalysts is the ratelimiting step for ammonia synthesis under industrially relevant conditions. The improvements of surface science techniques made since the late 1970s have further strengthened this view.…”

Structure and Surface Chemistry of Industrial Ammonia Synthesis Catalysts

“…The AI-containing phases have been interpreted as Ah03 segregated to the space between the Fe-crystallites based on evidence from chemisorption measurements [163] and X-ray powder diffraction studies [164]; as Al20 3 and FeAh04 based on evidence from EM and X-ray powder diffraction studies [48]; or as FeAl20 4 present as paracrystalline defects in the Fe crystallites based on evidence from secondary ion mass spectroscopy and Mossbauer studies [50,154,165,166]. The presence of FeAl20 4 as paracrystalline defects has been challenged on the basis of Mossbauer spectroscopic studies [112,165].…”