[Differences in the mechanisms of low-temperature and high-temperature processes in the formation of 3,4-benzopyrene during wood pyrolysis]. 1975

P P Dikun, and L D Kostenko, and A A Liverovskiĭ, and E I Shmulevskaia, and L S Romanovskaia

In 4 series of experiments a dependence between 3,4-benzpyrene (BP) output and the temperature of fir sawdust pyrolysis under isothermic conditions has been investigated. The experimental series differed in the duration of wood pulp particles stay in the reaction zone (tau). Also EPR spectra of pyrolysis products have been recorded. The experimental series did not differ in an output of ether extract from pyrolysis products, while BP output temperature curves in their shape were found to be largely dependent on tau: with an increased tau these curves definitely showed the maximum in the range of 300-350 degrees C and the BP output raised in the range of this maximum and also at the temperature of 600 degrees C. In the temperature range over 350 degrees C the character of dependence of the EPR signal value on temperature would correlate well with the temperature-dependent BP output, in the range of lower temperatures the EPR signal was not detected. The data obtained are considered as an evidence of two processes of BP formation in wood pyrolysis-a high-temperature process (temperature over 500 degrees C) and low-temperature one (300-350 degrees C). The high-temperature process seems to have the free-radical mechanism of BP formation, whereas in low temperatures it is evidently the result of a ion type reaction.

UI MeSH Term Description Entries
D002621 Chemistry A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D001580 Benzopyrenes A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it. Benzpyrene
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures
D014934 Wood A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products. Woods
D055598 Chemical Phenomena The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes. Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical

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