Thorium carbides preparation

The method described below for the preparation of thorium bromide combines the method of Troost and Ouvrard3 with that of Moissan and Martinsen.2 The former passed bromine over a heated mixture of thorium dioxide and carbon but did not purify the thorium bromide formed. The latter prepared the halide by the action of bromine on heated thorium carbide and purified the product by sublimation, first in a current of hydrogen and... 

Thorium carbides are prepared in an electric arc furnace. The arc is produced in a graphite crucible containing the reaction mixture. About 200 amp. at 110 v. is required to melt the mixture. 

Chlorides. Anhydrous ThCl [10026-08-1] has usually been prepared by direct interaction of thorium metal, hydride, or carbide with chlorine. 

Carbides of the Actinides, Uranium, and Thorium. The carbides of uranium and thorium are used as nuclear fuels and breeder materials for gas-cooled, graphite-moderated reactors (see Nuclearreactors). The actinide carbides are prepared by the reaction of metal or metal hydride powders with carbon or preferably by the reduction of the oxides uranium dioxide [1344-57-6] UO2 tduranium octaoxide [1344-59-8], U Og, or thorium... 

The Van Arkel process can also be used to prepare actinide metals if the starting compound reacts easily with the transporting agent (I2). The thorium and protactinium carbides react with I2 to give volatile iodides above 350°C these are unstable above 1200°C and decompose into the actinide metals and iodine. Attempts to prepare other actinides, such as U and Pu, through the process were not successful, because from Th to Pu along the actinide series, the vapour pressure of the iodide decreases and the thermal stability increases. 

The fuel particles used in these studies were typical pyrolytic carbon-coated thorium-uranium dicarbide, (Th,U)C2, microspheres. The kernels, — 200/i in diameter, were prepared from Th02, U02, and C and converted to the carbide at temperatures below 2200°C., followed by a spheroidization above the melting point, 2450°-2500°C. The bare kernels were coated with a 30-50fi layer of low density (— 1.0 gram/cm.3) buffer pyrolytic carbon, followed by a 40-70/a layer of high density... 

Thorium and Pa are most conveniently prepared from carbides, but at low temperatures made possible by an iodide intermediate in the iodine vapor process, based on the reaction of carbide with iodine vapor at 300 C. The actinoid iodide is transported to a hot surface (such as a W wire or sphere at 1200°C), where it decomposes and deposits the actinoid metaF". The overall reaction sequence is... 

Nitrogen unites directly with thorium, forming ThaN<4 This compound may be prepared also by heating a mixture of ThOj and magnesium or aluminium in nitrogen or the carbide in ammonia. It is a dark red powder slowly decomposed by cold water and quickly by hot, forming ammonia gd ThOj. 

Iron and its compounds (carbide, nitride), as well as ruthenium, cobalt, rhodium, and molybdenum compounds (sulfide, carbide), are used most frequently to produce high-molecular-weight hydrocarbons. Iron can be prepared as a high-surface-area catalyst (==300 m /g) even without using a microporous oxide support. 7-AI2O3, Ti02, and silica are frequently used as supports of the dispersed transition-metal particles. Recently zeolites, as well as thorium oxide and lanthanum oxide, have... 

The specific heat of thorium monocarbide was measured between 2 and 300 K. A sintered sample was prepared from thorium obtained by the van Arkel process and reported to contain less than 200 ppm impurities. According to chemical analyses (no details given), the overall composition of the carbide sample corresponded to ThC0965N0.015O0.020 The lattice parameter was reported to be a = (5.3444 + 0.0002) A. This sample was measured over the whole temperature range 2 to 300 K. 

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