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The heterogeneous propagation of the chains in the reaction of aliphatic aldehydes oxidation
Author(s) -
Bakhchadjyan R. H.,
Vardanyan I. A.
Publication year - 1994
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550260602
Subject(s) - chemistry , radical , chain propagation , aldehyde , homogeneous , electron paramagnetic resonance , chain reaction , photochemistry , phase (matter) , organic chemistry , catalysis , polymerization , thermodynamics , polymer , nuclear magnetic resonance , physics
The low temperature gas‐phase oxidation of CH 3 CHO and C 2 H 5 CHO have been investigated as an example of heterogeneous‐homogeneous reaction. It has been shown that with the increase of S/V (surface/volume) ratio of the reaction vessel the maximum rate of the process increases and the heterogeneous consumption of aldehyde prevails over the homogeneous one. Peroxy radicals have been discovered by EPR method in vessels with different S/V ratios. The concentration of peroxy radicals and the accumulation rate of peracid in the gas phase did not change with the increase of S/V ratio in the same interval. Under the conditions of these experiments excluding the homogeneous propagation of chains the aldehydes oxidized heterogeneously. The peroxy radicals initiate this heterogeneous process which indicate the existence of short chains on the surface. The reaction between the peroxy radicals and aldehyde on the solid surface (SiO 2 , KCl/SiO 2 ) has been shown by EPR, IR‐spectroscopy, and mass‐spectrometry methods. A conclusion has been drawn that the solid surface takes part in the chain propagation stage of aldehydes oxidation. © 1994 John Wiley & Sons, Inc.