Gaseous zirconium fluorides

The enthalpy of sublimation of solid zirconium tefrafluoride to gaseous Zrp4, as represented by Reaction (V.27)  

The weighted average of the data given in Table V-18 (except for the value from [63GAL/TUM]) is selected for the enthalpy of sublimation of ZrF4(cr)  

This value is in excellent agreement with the value determined by [94KON/HIL] - (1671.2 1.0) kJ-mol and, more recently, by [97VIS/COR] 

The heat of reaction in the formation of ZrF3(g) from Ca(g) and ZrF4(g) was examined by Murad and Flildenbrand [66MUR/HIL], between 1665 and 1747 K, using Knudsen cell mass spectrometry taking ionising energies of less than 20 eV only. The reaction studied was  

Ion intensities were measured for daughter ions of each of the gases in Reaction (V.28) from which an equilibrium constant for the reaction, at each temperature investigated, was derived. From the equilibrium constants, a third law heat of reaction was calculated  

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Barkovskii et al. [88BAR/GOR], [91BAR/TSI] studied the equilibrium between the various gaseous zirconium fluorides according to the following reactions ... 

The vapor pressures above solid a- (201) and /S-zirconium tetra-fluoride (16) are described by the equations in Table XXIII over the temperature ranges specified. The calculated heat of sublimation for the tetrafluoride of zirconium is some 20 kcal/mole greater than the heats of sublimation of the other tetrahalides of zirconium (Table XXIII), which is consistent with the greater complexity of the fluoride solid state compared to the probable structures of the other halides in the solid state. Zirconium tetrafluoride in the gaseous state is known to be monomeric by mass spectroscopy (96). Fluorine bomb calorimetry (223, 224) has been used to determine the standard heats of formation of the tetra-fluorides ZrF4, —456.80 0.25 kcal and HfF4, —461.40 0.85 kcal. 

Larsen and Leddy 333) tried the reduction of zirconium tetrafluoride with zirconium metal, but were unsuccessful. Ehrlich 160) substantiated this observation, but was able to obtain the trifluoride by reacting zirconium hydride with a gaseous mixture of hydrogen fluoride and... 

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. 

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... 

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