Thermochemistry and kinetics in pyrolysis and oxidation reaction of oxygenate chlorocarbons, neopentane, and ortho-xylene

Author

Hongyan Sun, New Jersey Institute of Technology

Document Type

Dissertation

Date of Award

Summer 8-31-2003

Degree Name

Doctor of Philosophy in Chemistry - (Ph.D.)

Department

Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Lev N. Krasnoperov

Third Advisor

Tamara M. Gund

Fourth Advisor

Sanjay V. Malhotra

Fifth Advisor

Edward Robert Ritter

Abstract

Thermochemical properties of chlorinated alcohols, chlorinated hydroperoxides and corresponding alkoxy, hydroxy alkyl radicals, peroxy and hydroperoxy alkyl radicals are determined by ab initlo and density functional calculations for modeling and optimization of complex chemical processes for combustion or incineration of chlorinated hydrocarbons. The entropy and heat capacities from vibrational, translational, and external rotational contributions are calculated by statistical mechanics, and the hindered rotational contributions to S^°₂₉₈ and C_p(T)'s are calculated by using direct integration over energy levels of the internal rotational potentials. The values of ΔH_f^°₂₉₈ are determined using isodesmic reactions with group balance. Groups for use in Benson type additivity estimations are determined for the carbon bonded to oxygen and chlorine(s). Hydrogen bond increment groups for the chloroalkoxy, hydroxy chloroalkyl radicals and interaction terms for peroxy group with chlorine(s) are developed for group additivity approach.

The reactions of alkyl radical with oxygen are important rate controlling processes in the low and intermediate temperature chemistry of hydrocarbon oxidation, especially the chemistry which occurs prior to ignition in internal combustion engines and in cool flames. Thermochemical properties for reactants, intermediates, products and transition states in neopentyl radical + O₂ reaction system are analyzed with ab initio and density functional calculations to evaluate reaction paths and oxidation kinetics. Rate constants to products and stabilized adducts of the chemically activated neopentyl-peroxy are calculated as function of pressure and temperature using Quantum Rice-RamspergerKassel analysis for k(E) and a master equation analysis for pressure fall-off An elementary reaction mechanism is constructed to model experimental OH and HO₂ formation profiles.

Aromatic compounds are an important component of higher-octane automotive fuels and consequently they are present in emissions from incomplete combustion and other evaporation from solvents and fuels handling and storage. Oxidation reactions of ortho-xylene are studied to identify the important reaction channels of this class of highoctane aromatics. Elementary reactions, energy well depths, and absolute rate constants of benzylic radical derived from ortho-xylene, 2-methylbenzyl radical with O₂, are determined with computational chemistry at density functional levels.

Recommended Citation

Sun, Hongyan, "Thermochemistry and kinetics in pyrolysis and oxidation reaction of oxygenate chlorocarbons, neopentane, and ortho-xylene" (2003). Dissertations. 596.
https://digitalcommons.njit.edu/dissertations/596