Gases thermal decomposition

Hazardous Decomp. Prods. CO, COj, other harmful gases thermal decomposition may result in NO,... 

Also presented were data on carbon-coating of graphite powder using a propylene gas thermal decomposition processes. High weight percent amorphous carbon-coatings are possible with this method, and the process appears uniquely suited to materials that are reductively stable to 700°C. The coated materials work better in the 30% PC electrolyte solutions, thus showing better resistance to solvent co-intercalation problems versus uncoated types. 

H2S is found with the reservoir gas and dissolved in the crude (< 50 ppm by weight), but it is formed during refining operations such as catalytic cracking, hydrodesulfurization, and thermal cracking or by thermal decomposition of sulfur[Pg.322]

It can be isolated by elecytrolysis of the fused cyanide and by a number of other methods. Very pure, gas-free cesium can be prepared by thermal decomposition of cesium azide. 

Thermogravimetry The products of a thermal decomposition can be deduced by monitoring the sample s mass as a function of applied temperature. (Figure 8.9). The loss of a volatile gas on thermal decomposition is indicated by a step in the thermogram. As shown in Example 8.4, the change in mass at each step in a thermogram can be used to identify both the volatilized species and the solid residue. 

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

In order for a soHd to bum it must be volatilized, because combustion is almost exclusively a gas-phase phenomenon. In the case of a polymer, this means that decomposition must occur. The decomposition begins in the soHd phase and may continue in the Hquid (melt) and gas phases. Decomposition produces low molecular weight chemical compounds that eventually enter the gas phase. Heat from combustion causes further decomposition and volatilization and, therefore, further combustion. Thus the burning of a soHd is like a chain reaction. For a compound to function as a flame retardant it must intermpt this cycle in some way. There are several mechanistic descriptions by which flame retardants modify flammabiUty. Each flame retardant actually functions by a combination of mechanisms. For example, metal hydroxides such as Al(OH)2 decompose endothermically (thermal quenching) to give water (inert gas dilution). In addition, in cases where up to 60 wt % of Al(OH)2 may be used, such as in polyolefins, the physical dilution effect cannot be ignored. 

Phosphoms oxyfluoride is a colorless gas which is susceptible to hydrolysis. It can be formed by the reaction of PF with water, and it can undergo further hydrolysis to form a mixture of fluorophosphoric acids. It reacts with HF to form PF. It can be prepared by fluorination of phosphoms oxytrichloride using HF, AsF, or SbF. It can also be prepared by the reaction of calcium phosphate and ammonium fluoride (40), by the oxidization of PF with NO2CI (41) and NOCl (42) in the presence of ozone (43) by the thermal decomposition of strontium fluorophosphate hydrate (44) by thermal decomposition of CaPO F 2H20 (45) and reaction of SiF and P2O5 (46). 

Coal can be converted to gas by several routes (2,6—11), but often a particular process is a combination of options chosen on the basis of the product desired, ie, low, medium, or high heat-value gas. In a very general sense, coal gas is the term appHed to the mixture of gaseous constituents that are produced during the thermal decomposition of coal at temperatures in excess of 500°C (>930°F), often in the absence of oxygen (air) (see Coal CONVERSION PROCESSES, gasification) (3). A soHd residue (coke, char), tars, and other Hquids are also produced in the process ... 

At the high temperatures found in MHD combustors, nitrogen oxides, NO, are formed primarily by gas-phase reactions, rather than from fuel-bound nitrogen. The principal constituent is nitric oxide [10102-43-9] NO, and the amount formed is generally limited by kinetics. Equilibrium values are reached only at very high temperatures. NO decomposes as the gas cools, at a rate which decreases with temperature. If the combustion gas cools too rapidly after the MHD channel the NO has insufficient time to decompose and excessive amounts can be released to the atmosphere. Below about 1800 K there is essentially no thermal decomposition of NO. 

Decomposition and Decarboxylation. Maleic anhydride undergoes anaerobic thermal decomposition in the gas phase in a homogeneous unimolecular reaction to give carbon monoxide, carbon dioxide, and acetylene [74-86-2] in equimolar amounts. The endothermic... 

Miscellaneous. Electron beams can be used to decompose a gas such as silver chloride and simultaneously deposit silver metal. An older technique is the thermal decomposition of volatile and extremely toxic gases such as nickel carbonyl [13463-39-3] Ni(CO)4, to form dense deposits or dendritic coatings by modification of coating parameters. 

Kerogen Decomposition. The thermal decomposition of oil shale, ie, pyrolysis or retorting, yields Hquid, gaseous, and soHd products. The amounts of oil, gas, and coke which ultimately are formed depend on the heating rate of the oil shale and the temperature—time history of the Hberated oil. There is Htde effect of shale richness on these relative product yields under fixed pyrolysis conditions, as is shown in Table 5 (10). 

The air bag industry has become one of the principal users of pyrotechnic compositions in the world. Most of the current air bag systems are based on the thermal decomposition of sodium azide, NaN, to rapidly generate a large volume of nitrogen gas, N2. Air bag systems must function immediately (within 50 ms) upon impact, and must quickly deploy a pulse of reasonably cool, nontoxic, unreactive gas to inflate the protective cushion for the driver or passenger. These formulations incorporate an oxidizer such as iron oxide to convert the atomic sodium that initially forms into sodium oxide, Na20. Equation 1 represents the reaction. 

---