Pyrolysis, thermal destruction

Matrix IR spectra of various silenes are important analytical features and allow detection of these intermediates in very complex reaction mixtures. Thus, the vibrational frequencies of Me2Si=CH2 were used in the study of the pyrolysis mechanism of allyltrimethylsilane [120] (Mal tsev et al., 1983). It was found that two pathways occur simultaneously for this reaction (Scheme 6). On the one hand, thermal destruction of the silane [120] results in formation of propylene and silene [117] (retroene reaction) on the other hand, homolytic cleavage of the Si—C bond leads to the generation of free allyl and trimethylsilyl radicals. While both the silene [117] and allyl radical [115] were stabilized and detected in the argon matrix, the radical SiMc3 was unstable under the pyrolysis conditions and decomposed to form low-molecular products. 

The extracts were then atomised and fed into the ROTARC reactor for high temperature treatment. In the first case the atomised extract was mixed with the torch gas (Argon) only. It was a pure pyrolysis, which was effective in the sooting of the reactor walls and it was making the scrubber fluid dirty. The disadvantage of the pure pyrolysis process confirmed our theoretical considerations on thermal destruction of PCB s presented in [9]. To avoid sooting, we fed steam into the reaction chamber in the amount of 10% above the stoichiometry. In this case, which we call the wet pyrolysis , we obtained the destruction efficiency of oil- PCB s at least 99.99%. The offgas analysis on the concentration of oil-PCB s were below the detection limit 0.2 ppm. 

The volatilization of arsenic during the thermal destruction of CCA-treated wood may be reduced by utilizing low-temperature pyrolysis. Low-temperature pyrolysis uses temperatures of approximately 300-400 °C with a limited air supply (Helsen and Van den Bulck, 2004, 286, 290 Helsen and Van den Bulck, 2003). Pyrolysis includes slow and flash methods (Helsen and Van den Bulck, 2004). Flash pyrolysis, which produces an oil byproduct, is not effective with CCA-treated wood because only 5-18% of the arsenic... 

Pyrolysis is simple thermal destruction of the molecular chain of the base polymer in the adhesive or sealant formulation. Pyrolysis causes chain scission and decreased molecular weight of the bulk polymer. This results in reduced cohesive strength and increased brittleness. Resistance to pyrolysis is predominantly a function of the intrinsic heat resistance of the polymers used in the adhesive formulation. As a result, many of the aromatic and multifunctional epoxy resins that are used as base resins in high-temperature adhesives are rigidly crosslinked or are made of a molecular backbone referred to as a ladder structure, as shown in Fig. 15.4. 

Other variants of PU recycling are the pyrolysis and the recovery of the organic products resulting from thermal destruction of PU and energy recovery by the combustion of the PU wastes [6-10]. 

Subsequent study disclosed that pyrolysis of neat 5 in a sealed tube at 395—408 °C for 1 hour gave 96 % yield of 1 and 4% of biphenyl 14 (Eq. 6) Pyrolysis of 5 at higher temperatures (430—445 °C) and for extended reaction times only resulted in thermal destruction of the initial product and thus a lower yields of 1. ... 

The effectiveness and reliability of the thermal destruction system depends not only on the design and type but is critically dependent upon the operational parameters of the system, such as, operating temperature, heating rate, residence time, waste chemical composition, excess air, and chemical and thermal environment surrounding the waste. Lower pollution and higher thermal destruction efficiency requires controlled conditions throughout the waste heat up, pyrolysis. 

The organic portion of solid wastes has a carbon-hydrogen-oxygen ratio similar to that of cellulose (CeHioOsln, a polymer that is widely present in nature [21, 25, 26, 30]. It is therefore expected that the thermal destruction behavior of cellulose will provide useful information on the organic portion of the solid waste. A pyrolysis process can be represented as ... 

Equilibrium thermochemical calculations are presented on the thermal destruction behavior of samples under conditions of pyrolysis, combustion, and pyrolysis followed by combustion. Special interest is on the effect of waste properties... 

A detailed analysis of the products of thermal destruction of poly-hexamethyleneadipamide and polycaproamide is given in [22]. The polyamides were heated at 300-305°C in a stream of dry nitrogen. The gaseous pyrolysis products contain large amounts of NH3, CO2, H2O, small amounts of n-hexylamine, n-pentylamine, and cyclopentanone. Analysis of the hydrolysis products of the residue obtained after pyrolysis of the polyamides permitted the authors to propose a scheme for the process. 

Combustion is the rapid exothermic oxidation of combustible elements in fuel. Incineration is complete combustion. Classical pyrolysis is the destructive distillation, reduction, or thermal cracking and condensation of organic matter under heat and/or pressure in the absence of oxygen. Partial pyrolysis, or starved-air combustion, is incomplete combustion and occurs when insufficient oxygen is provided to satisfy the combustion requirements. The basic elements of each process are shown on Figure 27. Combustion of wastewater solids, a two-step process, involves drying followed by burning. 

In the thermal desorption technique excavated soil is heated to around 200 to 1000°F (93 to 538°C). Volatile and some semivolatile contaminants are vaporized and carried off by air, combustion gas, or inert gas. Off-gas is typically processed to remove particulates. Volatiles in the off-gas may be burned in an afterburner, collected on activated carbon, or recovered in condensation equipment. Thermal desorption systems are physical separation processes that are not designed to provide high levels of organic destruction, although some systems will result in localized oxidation or pyrolysis. 

Thermal processes like pyrolysis use heat to increase the volatility (separation) to burn, decompose, or detonate (destruction) or to melt (immobilization) contaminants in soil. Separation technologies include thermal desorption and hot gas decontamination. Destruction technologies include incineration, open bum/open detonation, and pyrolysis. Vitrification is used to immobilize inorganic compounds and to destroy some organic materials. In contrast, pyrolysis transforms... 

Pyrolysis. Pyrolysis, eg, retorting, destructive distillation, carbonization, is the thermal decomposition of an organic material in the absence of... 

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