Gaseous zirconium chlorides

Studies of the enthalpy of sublimation of both solid and liquid zirconium tetrachloride to gaseous ZrCU have been reviewed by van der Vis et al. [97VIS/COR]. Their third law evaluations of data from the studies of the sublimation reaction  

This value is in good agreement with the value selected by van der Vis et al. [97V1S/COR] (110.0 1.0) kJ-mor.  

This value can then be combined with the selected enthalpy of formation for ZrCl4(cr) to derive the selected enthalpy of formation of ZrCl4(g)  

The heat of reaction in the formation of ZrCl3(g), ZrCl2(g) and ZrCl(g) from a number of pathways have been examined by Potter [70POT] using Knudsen cell mass spectrometry. For the formation of ZrCl3(g), the reactions studied were  

Ion intensities were measured for daughter ions of each of the gases in the reactions, from which the equilibrium constants, at each temperature investigated, were derived. From the equilibrium constants, third law heat of reactions were calculated. The third law heat of reaction derived for Reaction (V.43) was of low accuracy [70POT] and, as such, was not used in the derivation of the heat of formation of ZrCl3(g). Data from Reactions (V.44) and (V.45) were then combined with the selected 

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Geometric structure and molecular parameter data were used by [97VIS/COR] to determine the heat capacity and entropy of the gaseous zirconium chlorides at... 

K. The predicted structure of the tetrachloride is tetrahedral, that of the trichloride is planar and the dichloride is linear. From the measured and estimated data, [97V1S/COR] calculated the following heat capacity and entropy values for the gaseous zirconium chlorides ... 

Figure 3.9 shows a schemalic representation of the chemical filing process. The first step of the process involves the chlorination of the surface of the pyrochlore-based ceria-zirconia sample. The extent of the chlorination can be controlled by the concentration of the chlorine gas and/or chlorination time and the cerium and zirconium chlorides partially formed on the surface are vaporized and transported by the formation of gaseous complexes with aluminum chloride. This chemical filing process is carried out at 1273 K to stabilize the surface modification effects at high temperatures. A similar effect can also be achieved by chlorination with ammonium chloride followed by dominant vaporization of formed zirconium chloride. ... 

MERCURIC SULFATE (7783-35-9) HgS04 Noncombustible solid. Reacts with water, forming an insoluble mercury and sulfuric acid. Light may cause slow decomposition. Incompatible with aluminum, ammonia, hydrozoic acid, magnesium, methyl isocyanoacetate, sodium acetylide, sodium peroxyborate, red phosphorus, trinitrobenzoic acid, urea nitrate, powdered zirconium. Reacts violently with gaseous hydrogen chloride above 250°F/121 C. Attacks metals in the presence of moisture. On small fires, use dry chemical powder (such as Purple-K-Powder), water spray, or COj extinguishers. 

The alkylation of paraSins with olefins to yield higher molecular weight branched-chain paraffins may be carried out thermally or catalyt-ically. The catalysts for the reaction fall into two principal classes, both of which may be referred to as acid-acting catalysts (1) anhydrous halides of the Friedel-Crafts type and (2) acids. Representatives of the first type are aluminum chloride, aluminum bromide, zirconium chloride, and boron fluoride gaseous hydrogen halides serve as promoters for these catalysts. The chief acid catalysts are concentrated sulfuric acid and liquid hydrogen fluoride. Catalytic alkylations are carried out under sufficient pressure to keep at least part of the reactants in the liquid phase. 

In this method metal chlorides or oxychlorides are made to react with gaseous hydrocarbons in the vicinity of a localized heat source (1400-2100 K). Clearly, the reaction is thermodynamically favorable (Tables 3 and 4). The method was first used by Van Arkel in 1923 with an incandescent tungsten filament to make carbides of tantalum and zirconium [40]. Although the reaction variables have been studied extensively, problems remain with control of the process and with low productivity. Application to catalyst synthesis has been moderate [41],... 

Dihalides of uncertain purity are prepared by the disproportionation of the trihalides. Alternate routes have also been reported. Swaroop and Flengas (549) prepared ZrCU of 95-99% purity by heating the trichloride and metallic zirconium at 675°C for 30-35 hours in an evacuated quartz tube lined with platinum foil. There is also a reference to the production of liquid dihalides by the reaction of the gaseous tetrahalides with loosely packed zirconium at 700°C for the chloride and 400°C for the bromide and iodide (270). The difluoride has been prepared (357) by the reaction of atomic hydrogen on thin layers of zirconium tetrafluoride at 350°C. New data on hafnium are lacking, although Corbett (542) has concluded that hafnium diiodide does not exist. 

The separation of ammonia from interfering compounds was also based on gaseous diffusion of ammonia from an alkaline medium and absorption by an acidic medium. Walker and Shipman described the isolation of ammonia by the use of a zirconium phosphate cation exchanger. The adsorbed ammonia was displaced from the column by 1.24 M cesium chloride, then oxidized by hypochlorite, reacted with phenol to form a phenol-indophenol complex which was measured at 395 or 625 nm, depending on the concentration range. 

Boric acid Copper oxide (ic) Lithium chloride Lithium fluoride Potassium tetraborate Tributyl borate Zirconium potassium hexafluoride welding flux, gaseous Trimethyl borate welding fluxes, special Zirconium welding gas Oxygen... 

Simultaneous deoxygenation and incorporation of gaseous nitrogen is believed to be effected by an intermediate compound containing a Ti—N bond [45]. Dicyclopentadienyltitanium converts ketones to amines and acyl chlorides to nitriles in this way. A recent Japanese paper [46] described the dehydration of carboxamides at 120-210° by alkoxides of titanium, zirconium or tin (IV). A higher yield of nitrile is obtained if a chloroalkoxide such as TiCl(OR)3 [R = Pr Bu or hexyl] is used. 

The reaction of metallic tellurium, palladium, silver, molybdenum, niobium, zirconium and gaseous hydrogen with alkali chloride melts containing uranyl(VI) chloride leads to its reduction to uranyl(V) chloride and uranium dioxide. In the case of Nb and Zr some uranium(IV) chloride is also formed. Nb(III) and (IV) ions also reduce uranyl(VI) to uranyl(V) and uranium(IV) species and UO2. 

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