Pyrolysis of organic materials

Disposal of exhausted soHds can be easily overlooked at the plant design stage, particularly when these have no intrinsic value alternative disposal methods might include landfiU of inert material or incineration, hydrolysis, or pyrolysis of organic materials. Liquid, soHd, and gaseous emissions are aU subject to the usual environmental considerations. 

Carbon fibers are special reinforcement types having a carbon content of 92-99 wt%. They are prepared by controlled pyrolysis of organic materials in fibrous forms at temperatures ranging from 1,000-3,000°C. 

Although the pyrolysis of organic materials (organic hollow fibers) is used in the commercialization of a new family of inorganic membranes (Fleming 1988) there are only a few descriptions in the open literature. Koresh and Soffer (1980, 1986, 1987) have published a series of articles on this subject. There is also a paper by Bird and Trimm (1983) which is based on a previously described preparation procedure of Trimm and Cooper (1970, 1973). 

EPR has been observed and studied in porous carbons by numerous authors 178-182). The carbons studied have been prepared by pyrolysis of organic material such as dextrose 180), coal 181), and natural gas or oils 181,182). Porous carbons are of considerable technological importance and show catalytic activity for the ortho-parahydrogen conversion, the hydrogen-deuterium reaction, and many reactions of inorganic complex ions 156). Relationships between the characteristics of the EPR absorption and the catalytic activity of porous carbons for the o-p Hj and Hj-D reactions have been demonstrated by Turkevich and Laroche 183). 

PAH have very low vapor pressure at room temperature. These substances, however, may deposit on the dusts in the air. PAH may be produced during pyrolysis of organic materials. These compounds can contaminate the air near coke ovens, as well as during loading and unloading of pencil pitch. 

Let us consider, as the example, a process of pyrolysis of organic material in a fluidized bed where the fluidizing agent is air. The primary organic material is fed into the head of the column of pyrolysis, and the product is removed from the bottom. The fed air comes to the bottom part of the column, and the gas rest is removed from the head of the column. The temperature distribution along the column and the pressure inside it are controlled. The chemical composition of the primary material is known, whereas those of the product and removed gas are measured by methods of analytical chemistry. The process is carried out close to steady-state. 

Thermodynamic models analyzed above are applicable to the treatment of results of measurement of characteristics of microporous materials, especially active carbons prepared by pyrolysis of organic materials. 

The nonequilibrium statistical thermodynamic approach in the description of microporous materials prepared by pyrolysis of organic materials (active carbons) comprises two principal methods these for systems with regular and random fluxes. These methods comprise steady-state and nonsteady-state models which can be formulated for homo- and heterogeneous systems. 

Bone may also show a stable signal due to carbon (1) derived from the pyrolysis of organic material in the bone. In principle, careful measurement of the parameters of this signal and calibration with modern equivalents allow the quantification of the thermal history of ancient samples that may provide insight into ancient cooking methods. In practice, overlap between the different signals makes accurate characterization difficult. 

K. M. Holland, Pyrolysis of organic material. EP409835. Proprietor Holland, Kenneth Michael, 1993. 

Charcoal is basically the solids that remain after nonoxidative pyrolysis of organic material for present purposes, the range of organic material is restricted to the cellular material of plants. Such solid residues are composed of graphite-like materials as the principal constituent, and such other inorganic compounds as are usually found between 40 and 0.02 percent of the total weight of the charcoal. The inorganic residues in the charcoal are usually expressed as so much metal oxide and... 

Fibers are available in a variety of forms. For example, carbon fibers are obtained from the pyrolysis of organic materials such as polyacrylonitrile (PAN) and rayon for long fibers and pitch for short fibers. 

Figure 3.10 Schematic illustration of the pyrolysis of organic materials.

COKE is a solid, high in elemental carbon content and structurally in the NON-GRAPHITIC state. It is produced by pyrolysis of organic material which has passed, at least in part, through a liquid or liquid-crystalline state during the CARBONIZATION process. COKE can contain mineral matter. 

PITCH is a residue from the pyrolysis of organic material or tar distillation, which is solid at room temperature, consisting of a complex mixture of numerous, essentially aromatie hydrocarbons and heterocyclic compounds. It exhibits a broad softening range instead of a defined melting temperature. When cooled from the melt, pitches solidify without crystallization. 

It has been known for a long time that pyrolysis of organic materials produces paramagnetic materials (1 3), and that the paramagnetism is very persistent. If the pyrolysis is carried out below 600 C or so, the paramagnetism is believed to be due to free radicals that are produced in intermediate stages of the process by which heteroatoms are eliminated from the material and a carbon network is formed (4,5), These free radicals are often very stable, and persist in the sample over hundreds or even thousands of years. The number and nature of these radicals can be investigated with electron spin resonance (ESR) spectra. 

The pyrolysis (or thermal decomposition) process requires a reducing atmosphere, usually maintained by restricting the air supply to much less than stoichiometric levels. The pyrolysis of organic materials causes their thermal degradation and a distillation of the volatile fraction, forming combustible liquids and vapours. The vapours are composed primarily of methane, hydrogen, carbon monoxide, carbon dioxide, water and the more complex hydrocarbons such as ethane, propane, oils and tars. The material remaining after pyrolysis is char, a... 

In principle, any type of magnetic or quadrupole mass spectrometer can be utilized for the analytical pyrolysis of organic materials, if a direct introduction system capable of producing a desired tempera-ture/time profile is available. For example, direct insertion probes (DIPs) and direct exposure probes (DEPs) are Avidely used for sample introduction and such probes are supplied with control units that allow heating and temperature programming of the sample up to 500-800°C. Therefore, such modules should be considered as the most readily available probes for Py-MS studies. 

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