Document Type

Thesis

Date of Award

1-31-1990

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Richard Stephen Magee

Third Advisor

Dana E. Knox

Abstract

The reaction mechanism of dichloromethane reaction (DCM) with atomic hydrogen in a flow reactor at room temper¬ature (300 K) and low pressure (2.1 - 2.7 torr), argon bath gas, has been developed in this research to analyze the above reaction system. The important addition reactions of radicals (or atoms) to olefins and the radical/radical (atom/radical) combination reactions have been analyzed using the bimolecular version of the Quantum-Rice-Ramsperger-Kassel (QRRK) theory.

The detailed reaction mechanism satisfactorily fits the experimental data for the reagent (DCM) conversion from previous experimental over a initial ratio (atomic hydrogen to dichloromethane) range of 6.8 to 40. The initiation reactions are abstraction by atomic hydrogen on the dichloromethane. One channel is for hydrogen atom to abstract chlorine atom in DCM to form methyl chloride radical and HCl, the other is to abstract hydrogen atom in DCM to form hydrogen molecule and dichloromethane radical. After initiation, combination reactions, such as H+CH2Cl, H+CHCl2, CHCl2+CHCl2, CHCl2+CH2Cl, CHCl2+CH3, CH2Cl+CH2Cl, CH2Cl+CH3, and CH3+CH3 follow. The adducts formed are all treated as chemically activated complexes, with reaction from these complexes to products versus stabilization analyzed with QRRK theory. The major products are HCL and CH4, which agree with experiment.

The kinetic reaction mechanism is based on thermochemical principles and Transition State Theory. The rate constant obtained for the primary steps at 300 K are: k ( cm3 mole-1 sec-1 ) CH2Cl2 + H ----> CH2Cl + HCl2.41 * 109 CH2Cl2 + H ----> CHCl2 + HCl2.17 * 107

A second detailed mechanism was developed for the reaction of Chloroform with atomic hydrogen, argon bath gas, at room temperature (300 K) and low pressure (2.22 - 2.82 torr). The rate constants obtained for the initially impor¬tant steps at 300 K are : k ( cm3 mole-1 sec-1 ) CHCl3 + H ----> CHCl2 + HCl3.72 * 1010 CHCl3 + H ----> CCl3 + H22.52 * 108

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