Carbonates, decomposition table

Carbonate Decomposition. The carbonate content of Green River oil shale is high (see Table 4). In addition, the northern portion of the Piceance Creek basin contains significant quantities of the carbonate minerals nahcoUte and dawsonite. The decomposition of these minerals is endothermic and occurs at ca 600—750°C for dolomite, 600—900°C for calcite, 350—400°C for dawsonite, and 100—120°C for nahcohte. Kinetics of these reactions have been studied (19). Carbon dioxide, a product of decomposition, dilutes the off-gases produced from retorting processes at the above decomposition temperatures. 

Because of their often high biological productivity and low rates of decomposition under anoxia, wetlands are one of the largest terrestrial sinks for carbon. They account for about a third of the soil carbon globally (Table 1.4). However there are large differences between wetland types. Organic wetland soils tend... 

The dissociation C02 = CO + 1/2 02 is too slight at temperatures relevant for carbonate decomposition, but a separate table for this reaction has been provided for up to 2400 K. 

The existence of non-equilibrium combustion products is important to at least two considerations. Firstly, the observed propellant performance may depart substantially from the predicted level. This departure may result in performance either less than or greater than the equilibrium predicted level. A striking example of greater than equilibrium performance is that of hydrazine monopropellant decomposition, table m-A-1. Another is that of ethylene oxide monopropellant, as mentioned in section n. B. 4., in which the equilibrium quantities of condensed carbon never are formed. Secondly, the non-equilibrium composition may have significant effects on the expansion process. In particular, nozzle kinetic calculations based on an assumed equilibrium composition initial condition may diverge significantly from expansions occurring from non-equilibrium initial conditions. 

Note that at T > 1400 K, the potassium pressures fall below those expected from KAIO2, but that the SO2, CO2, and H2O pressures are still relatively high. Apparently, at this stage, the K produced by sulfate and carbonate decomposition is retained in the bulk slag. After further heating, the sample was virtually depleted of Na, SO2, and CO2 H2O also continued to fall-off in pressure to a negligible level. Following this initial clean-up period, the sample showed a more no,rmal vaporization behavior and representative data are summarized in Table II. 

Table 4 Macrofaunal effects on organic carbon decomposition/remineralization.

Many of the effects on carbon decomposition and stabilization discussed above for earthworms can be generalized to many groups of soil fauna. Table 10 summarizes the mechanisms by which soil invertebrates control decomposition and stabilization of OM in soils. Wolters (2000) hypothesized that soil invertebrates externally influence SOM destabilization by microorganisms in two ways (1) directly, by selectively grazing on... 

The dimethyl carbonate decomposition has been shown to proceed heterogeneously at relatively high temperatures on a quartz surface - By contrast, alkyl and aryl carbonates with j8-carbon hydrogens, decompose smoothly homogeneously and unimolecularly in surface conditioned reactors at appreciably lower temperatures T > 600 °K) to give olefin, alcohol, and carbon dioxide. Gas phase kinetic results for some 1-arylethyl methyl carbonates S for methyl ethyl carbonate, and for diethyl carbonate are shown in Table 14. Some gas phase relative rate results for substituted 1- and 2-arylethyl carbonates have also been determined (Table 15). 

For comparison purposes, a sample of Eastern U.S. shale was also analyzed by TG-DTG. The absence of the characteristic carbonate decomposition peak in the 700-800°C temperature range is indicative of the lack of carbonate minerals in Eastern U.S. shales. The net organic pyrolysis yield, 47.6 wt%, Table I, is... 

Preparation of Compounds Labeled with Tritium and Carbon-14 Table 1.2 Modes of decomposition of radiolabeled compounds... 

Thermal decomposition of hydroxyalkyl hydroperoxyalkyl peroxides produces mixtures of starting carbonyl compounds, mono- and dicarboxyHc acids, cycHc diperoxides, carbon dioxide, and water. One specific hydroxyalkyl hydroperoxyalkyl peroxide from cyclohexanone (2, X = OH, Y = OOH) is a soHd that is produced commercially as a free-radical initiator and bleaching agent (see Table 5). On controlled decomposition, it forms 1,12-dodecanedioic acid (150). 

Physical properties of hexachloroethane are Hsted in Table 11. Hexachloroethane is thermally cracked in the gaseous phase at 400—500°C to give tetrachloroethylene, carbon tetrachloride, and chlorine (140). The thermal decomposition may occur by means of radical-chain mechanism involving -C,C1 -C1, or CCl radicals. The decomposition is inhibited by traces of nitric oxide. Powdered 2inc reacts violentiy with hexachloroethane in alcohoHc solutions to give the metal chloride and tetrachloroethylene aluminum gives a less violent reaction (141). Hexachloroethane is unreactive with aqueous alkali and acid at moderate temperatures. However, when heated with soHd caustic above 200°C or with alcohoHc alkaHs at 100°C, decomposition to oxaHc acid takes place. 

The temperature at which decarboxylation occurs is of particular interest in manufacturing processes based on polymerisation in the molten state where reaction temperatures may be near the point at which decomposition of the diacid occurs. Decarboxylation temperatures are tabulated in Table 2 along with molar heats of combustion. The diacids become more heat stable at carbon number four with even-numbered acids always more stable. Thermal decomposition is strongly influenced by trace constituents, surface effects, and other environmental factors actual stabiUties in reaction systems may therefore be lower. 

It is not possible, however, to calculate accurately actual gas composition by using the relationships of reactions (27-14) to (27-19) in Table 27-12. Since the gasification of coal always takes place at elevated temperatures, thermal decomposition (pyrolysis) takes place as coal enters the gasification reactor. Reaction (27-15) treats coal as a compound of carbon and hydrogen and postulates its thermal disintegration to produce carbon (coke) ana methane. Reaction (27-21) assumes the stoichiometiy of hydrogasifying part of the carbon to produce methane and carbon. 

Table IV presents the results of the determination of polyethylene radioactivity after the decomposition of the active bonds in one-component catalysts by methanol, labeled in different positions. In the case of TiCU (169) and the catalyst Cr -CjHsU/SiCU (8, 140) in the initial state the insertion of tritium of the alcohol hydroxyl group into the polymer corresponds to the expected polarization of the metal-carbon bond determined by the difference in electronegativity of these elements. The decomposition of active bonds in this case seems to follow the scheme (25) (see Section V). But in the case of the chromium oxide catalyst and the catalyst obtained by hydrogen reduction of the supported chromium ir-allyl complexes (ir-allyl ligands being removed from the active center) (140) C14 of the...

Much detailed information concerning the decompositions of carbonates is to be found in the review by Stem and Weise [733] and selected kinetic data are summarized in Table 14. 

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