Document Type

Thesis

Date of Award

5-31-1989

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Richard Clyde Parker

Third Advisor

Piero M. Armenante

Abstract

The decomposition of 1,1,2-trichloroethane in a hydrogen gas bath was carried out at 1 atmosphere total pressure in three different surface to volume ratio flow reactors. Temperature ranged from 440 to 850 °C and the residence times studied were in the range 0.2 - 2.3 seconds. Application of the first order rate expression to this data yields a linear relationship for each temperature studied and thus global rate constants for loss of reactant were determined.

It was found that conversion of the reagent was a function of both temperature and residence time. The major products observed are 1, 2-dichloroethylene (CHClCHCl), 1,1-dichloroethylene (CH2CCl2), vinyl chloride (CH2CHCl), chloroethane (CH3CH2Cl), ethylene, and HCl, with methyl chloride (CH3Cl), dichloromethane (CH2Cl2), and benzene as minor products. Complete decay ( 96 % ) of the reagent occurs at 850 °C and 1.1 sec residence time, where the principal products are ethylene and HCl. Most of the chlorinated by-products have been destroyed at this reaction time at 850 °C except vinyl chloride (1.0 %) and traces of chloroethane.

A detailed kinetic scheme was formulated considering all reaction products detected by GC. A kinetic reaction mechanism, composed of 73 elementary reactions and 37 species, was developed and used to model results obtained from the experimental reaction system. The detailed kinetic reaction mechanism was based on thermochemical principles and transition state theory. This mechanism is shown to fit the experimental results quite well.

Rate constants for the following reactions were determined by optimization of the reaction mechanism to the experimental data.

A (1/s) E (Kcal/mol) CH2ClCHCl2 ---> CHClCHCl + HCl 9.5E12 55.3 (ΔHr+41) CH2ClCHCl2 ---> CH2CCl2 + HCl 4.7E12 55.3 (ΔHr+41) CH2ClCHCl2 ---> CH2ClCHCl + Cl 2.6E15 77.7 (ΔHr) CH2ClCHCl2 ---> CH2CHCl2 + Cl 1.6E15 81.4 (ΔHr) CH2ClCHCl2 ---> CH2Cl + CHCl24.2E17 89.1 (ΔHr)

For the reaction of 1,1,2-trichloroethane to CH2ClCHCl + Cl, the energy of activation determined in this study provides a bond energy for the CH2CHCl--Cl bond of 77.7 kcal/mole.

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