Uranyl nitrate catalyst

In a much earlier patent, the removal of organics from exhaust gases by oxidation over a supported uranium oxide catalyst was reported by Hofer and Anderson [39]. The catalyst was 4% U3O8 supported on alumina spheres. The authors used the incipient wetness technique to impregnate alumina with uranyl nitrate solution. In this case the catalyst precursors were calcined at 700°C for 3 h to decompose the uranium salt. The use of other uranium compounds as starting materials was mentioned and these included uranyl acetate, uranium ammonium carbonate and uranyl chloride. The alumina-supported catalyst had a surface area of ca 400m g and further added components, such as copper, chromium and iron, were highlighted as efficient additives to increase activity. 

Satyanarayana and Sivakumar [51] developed a simple, rapid, and efficient synthesis of 2,5-dimethyl-N-substituted pyrrole derivatives (15) by tiie Paal-Knorr reaction [45,46] by means of the one-pot condensation of 1,4-dicarbonyl compoxmds (13) and substituted primary amines (14) using uranyl nitrate hexahydrate as catalyst under ultrasonic irradiation (Scheme 5). The authors studied tiie reaction of methanol, ethanol, acetonitrile, dichlorometh-ane, or chloroform in solvents, as well as in the absence of solvent. The best yields were obtained with methanol under sonication for 5 min. 

SCHEME 5 Synthesis of 2,5-dimethyl-IV-substituted pyrrole using uranyl nitrate hexahydrate as catalyst. 

The catalyst was prepared by 72-hour treatment of 100 gm of Linde sodium sieve with 1700 ml of 22.1 wt % ammonium nitrate. During this period the slurry was occasionally stirred. The slurry was filtered, and after working the solid several times with water, it was dried at room temperature. The amount of sodium ion replaced by ammonium ion was determined by analyzing the filtrate for sodium using the magnesium uranyl acetate reagent. The extent of replacement was found to be 52% and this compared favorably with the results of Turkevich and Ciborowski (3), who found, using the same method of preparation but a different method of analysis, a 56% replacement. 

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