Calcium formate, decomposition

Isothermal a—time curves were sigmoid [1024] for the anhydrous Ca and Ba salts and also for Sr formate, providing that nucleation during dehydration was prevented by refluxing in 100% formic acid. From the observed obedience to the Avrami—Erofe ev equation [eqn. (6), n = 4], the values of E calculated were 199, 228 and 270 kJ mole"1 for the Ca, Sr and Ba salts, respectively. The value for calcium formate is in good agreement with that obtained [292] for the decomposition of this solid dispersed in a pressed KBr disc. Under the latter conditions, concentrations of both reactant (HCOJ) and product (CO3") were determined by infrared measurements and their variation followed first-order kinetics. 

Tropsch expanded the investigations of calcium oxide as a cataly for reactions in water-gas mixtures and included a study of the synthesi and decomposition of formates.118 In explaining the mechanism o methane synthesis Vignon assumed that at temperatures below the decom position of calcium carbonate (900° C.) water-gas reacts with calciur oxide to give calcium formate. 

Hofmann (53) found an appreciable amount of formaldehyde (about 25%) and small amounts of methyl formate during the decomposition of zinc formate. Lithium formate produced acetone (about 20%) from lead formate, formaldehyde and methyl alcohol were formed. Pichler (127) found that during the decomposition of calcium formate, oxalate was formed. In general it appeared that the nature and the amount of the organic by-products depended largely on the reaction conditions [Hofmann (53)]. 

Reactions where a new lattice has to be formed are usually dependent upon the formation of nuclei. In the calcium carbonate decomposition, for example, the chemical change normally progresses at the boundary of the calcium carbonate and of the oxide. Calcium oxide molecules are more stable in a lattice of other calcium oxide molecules than they would be in the midst of calcium carbonate molecules. This is known from the fact that the oxide and the carbonate do not form solid solutions. The rate of decomposition therefore depends upon two factors, the rate of nucleus formation and the rate of growth of such nuclei as are already formed. 

As it is known, that the heat consiunption of the clinkering process is mainly due to the calcium carbonate decomposition and the long period (about 20 min) of clinker heating in sintering zone at maximirm temperamre, to assirre full alite formation. Therefore the energy consirmption increases with lime saturation factor (see Chap. 2). 

When investigating the aqueous-phase bicarbonate hydrogenation with ruthenium and rhodium complexes, Benyei and J06 observed certain activity for the reverse reaction, that is, formate decomposition. [RuCl2(mTPPMS)2]2 (mTPPMS = meta-monosulfonated triphenylphosphine) decomposed sodium formate and formic acid (41), while RhCl(mTPPMS)3 slowly decomposed calcium formate and promoted calcium carbonate precipitation (42). 

A study showed that reduced zinc oxide solubility improved the cycle fife of Zn/NiOOH batteries. There have been several studies of the rate of formation and decomposition of calcium zincate in solutions of Ca(OH)2, ZnO and KOH. The rate equations developed in these studies evaluate the effectiveness of adding Ca(OH)2 with calcium zincate formation and decomposition reactions. At a discharge rate of C/3, about 26% of the zincate is still in the solution. At a charge rate of C/6, the liberation of zincate from calcium zincate is complete. Because the calcium zincate formation is a slower process, the discharge rate could effect how weU the addition of Ca(OH)2 controls shape change in a battery. Since the calcium zincate decomposition is a faster process, the addition of Ca(OH)2 will reduce the growth of dendrites. 

The sodium formate process is comprised of six steps (/) the manufacture of sodium formate from carbon monoxide and sodium hydroxide, (2) manufacture of sodium oxalate by thermal dehydrogenation of sodium formate at 360°C, (J) manufacture of calcium oxalate (slurry), (4) recovery of sodium hydroxide, (5) decomposition of calcium oxalate where gypsum is produced as a by-product, and (6) purification of cmde oxahc acid. This process is no longer economical in the leading industrial countries. UBE Industries (Japan), for instance, once employed this process, but has been operating the newest diaLkyl oxalate process since 1978. The sodium formate process is, however, still used in China. 

Methods of EGA using selective sorption, condensation of effluent gases, infrared absorption and thermoparticulate analysis have been reviewed by Lodding [144]. The use of simple gas burette systems should not be forgotten and an Orsat gas analysis apparatus can provide useful measurements in studies of the decomposition of formates [169]. Problems have been encountered in the determination of water released Kiss et al. [170—172] have measured the formation of this compound from infrared analyses of the acetylene evolved following reaction of water with calcium carbide. Kinetic data may be obtained by wet methods ammonia, determined by titration after absorption in an aqueous solution, has been used to measure a—time values for the decomposition of ammonium salts in a fluidized bed [173],... 

Finally, there was also spontaneous incandescence of a calcium car-bide/selenium mixture and the formation of an explosive compound in the presence of an alkali or alkaline earth amide. In addition, selenium catalyses the explosive decomposition of nitrogen trichloride. 

At 305°C, iodine mixed with calcium carbide produces incandescence in the mixture. Can it be explained by the formation of diodoacetylene followed by its decomposition ... 

Scale formation in the scrubber can lead to sodium carbonate as an additional dry sorbent in the scrubber. Alternatively, limestone is also introduced into combustion chambers to treat sulfur dioxide emissions. Decomposition of CaC03 into CaO and CO2 occurs in the combustion chamber, and the resulting CaO combines with S02 to produce calcium sulfite. Notice that this process produced another potentially environmentally harmful pollutant (CO2) as it gets rid of a definite environmentally harmful pollutant (SO2). 

Calcium substitution on the La site reduces the sinterability of LaFe03 and dense La, xCaxFc()3 (LCF) can be obtained at sintering temperature of 1320°C [90], The compositions with x < 0.2 show good thermal expansion compatibility with YSZ electrolyte and high electronic conductivity (88 Scnr1 at 800°C for x = 0.15). Increasing Ca substitution leads to the decomposition of the LCF and the formation of the second phase. 

The precise mechanism by which NO causes glutamase neurotoxicity is unknown. Calcium must be required because of the requirement for NMDA- and glutamate-induced NO formation in brain tissue (Garthwaite etal., 1988). Although both NMDA-receptor agonists and sodium nitroprusside induce specific neurotoxicity as well as cyclic GMP formation in brain tissue (Dawson et al., 1991), it is unlikely that cyclic GMP is the ultimate cause of the neurotoxicity. Instead, NO is most likely involved in producing target cell death. One possible mechanistic pathway is that locally synthesized NO and superoxide anion react with each other to yield peroxynitrite anion (Beckman et al., 1990), which can destroy cell membranes either directly via interaction with cellular thiols (Radi et al., 1991) or indirectly via decomposition to hydroxyl and other free radicals (Beckman et al., 1990). 

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