Uranium catalysts

From this time on, and after further progress made by Haber in the year 1909, the aim of C. Bosch and his associates in the B. A. S. F. was to transform Haber s findings into an economic technical large-scale process. One of the main points in this program was the replacement of the costly osmium and uranium catalysts used by Haber by equally effective, but less sensitive and commercially acceptable materials. The catalytic laboratory experiments which were now started on a new basis in the B. A. S. F. were, following Haber, carried out at a pressure of about 100 atmospheres. 

Bayer [41-49]. Uranium-based catalysts yield BR and IR with a significantly higher cis- 1,4-content than the established Co- and Ti-catalysts. Because of radioactive residues present in the respective polymers, however, the efforts aiming at the large-scale application of uranium catalysts were abandoned soon after by both companies. 

DeChirico, A. Lamzani, P. Eaggi, E. Bruzzone, M. High cw-polybutadiene by uranium catalyst. Makromol. Chem. 1974, 175, 2029. 

Suitable catalysts for oxidation (22) are oxides of cobalt, cerium, vanadium, and uranium. Catalysts for ester formation are oxides of lead, molybdenum, silicon, uranium, and cerium. The best flavors are produced by the use of oxides of lead, copper, nickel, molybdenum, cobalt, titanium, and silicon. 

Catalysts. The catalysts used were commercial cobalt molybdate and a laboratory-prepared depleted uranium catalyst. The cobalt molybdate consisted of cobalt and molybdenum oxides on 6- to 8-mesh alumina granules. The uranium catalyst consisted of 7.7% depleted uranium (uranium from which the U-235 has been removed) in the oxide form on 1/8-in. H-151 alumina balls. This catalyst had produced high gas yields in previous hydrogenation experiments with shale oil, and these results suggested its possible use as a hydrogasification catalyst. Both catalysts were maintained under a hydrogen atmosphere at approximate reaction temperature and pressure for about 12 hours before each experiment. 

Table II. Gasification of Crude Shale Oil over Depleted Uranium Catalyst"...

Depleted Uranium Catalyst. Table II shows the results from five experiments in hydrogasifying crude shale oil over depleted uranium catalyst at a space velocity of 0.5 volumes of oil per volume of catalyst per hour. Average reaction temperatures varied from 880° to 1102°F. 

Table III. Liquid Products from Gasification over Depleted Uranium Catalyst...

Table III shows the properties of the liquid products from the hydrogasification experiments with depleted uranium catalyst. Sulfur percentages in the liquid products were considerably lower than the percentage in the feed, but nitrogen percentages were high. The naphthas became aromatic as the operating temperature was raised from 880° to 1102°F.

Cobalt Molybdate Catalyst. Yields of products from hydrogasifying crude shale oil over cobalt molybdate catalyst at a space velocity of 1.0 volume of oil per volume of catalyst per hour are shown in Table IV, and properties of the liquid products are shown in Table V. The average reaction temperatures from 974° to 1183°F. were higher than those used with depleted uranium catalyst. Consequently, greater gas yields were obtained. However, similar trends were shown in the results obtained with both catalysts. 

Sulfur percentages in the liquid products were low. Nitrogen percentages were much lower than those of the liquid products obtained by hydrogasification over depleted uranium catalyst. The percentages of... 

Conditions used with the cobalt molybdate were generally not the same as those with the depleted uranium catalyst. However, the gas yields obtained at 1062°F. and 0.50 space velocity over cobalt molybdate were similar to those obtained at 1053°F. and 0.50 space velocity over depleted uranium. Better elimination of nitrogen from the liquid products was achieved with the cobalt molybdate. No special advantages were found for the depleted uranium, but further research would be needed to evaluate it fully over the entire range of conditions investigated with the cobalt molybdate. 

The Haber-Bosch catalytic process for production of ammonia is perhaps an invention that had the most dramatic impact on the human race (Ritter 2008). The inexpensive iron-based catalyst for ammonia synthesis, which replaced the original, more expensive osmium and uranium catalysts, made it possible to produce ammonia in a substantially effective manner. The objective here was not improvement in selectivity but higher reaction rates for rapid approach to the equilibrium conversion at the specified temperatme and pressme. Higher rates meant lower catalyst volume and smaller high-pressme reactors. The iron catalyst was improved by addition of several promoters such as alkali metals. In contrast to this simple single reaction case of ammonia synthesis, most organic reactions are complex with multiple pathways. 

The outstanding physical properties of the lanthanide-derived products as synthetic rubber (24, 27) related to their very high cis content, and some advantages or simplification in the polymer synthesis (25, 28) are the likely reasons for the widespread interest in lanthanide-catalyzed processes. Studies on cis-polydiolefins have been carried out by us over many years. After the early activity on uranium catalysts (29), we devoted our attention to lanthanides since 1974 with the aim of improving the synthesis and of understanding the related chemistry. 

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