Date of Award

Fall 1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Science - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Richard B. Trattner

Third Advisor

Lev N. Krasnoperov

Fourth Advisor

James M. Grow

Fifth Advisor

Jeffrey M. Grenda

Sixth Advisor

John Farrel

Abstract

The reaction systems: methyl tert-butyl ether (MTBE) unimolecular decomposition, MTBE radicals + O2, tert-butyl radical +O2, isobutene + HOO. (HO2),isobutene + OH, sobutene-OH adducts + O2, and allylic isobutenyl radical + O2, are important systems in the understanding the oxidation chemistry of MTBE, tertiary butyl radical (C3C.), and sobutene, are analyzed. Thermochemical parameters are determined by ah initio Møller-Plesset (MP2(full)/6-31g(d)), complete basis set model chemistry (CBS-4 and CBS-q with MP2(full)/6-31g(d) and B3LYP/6-31g(d) optimized geometries), density functional (B3LYP/631g(d)), semi-empirical MOPAC (PM3) molecular orbital calculations, and by group additivity estimation. Thermochemical kinetic parameters are developed for each elementary reaction path in these complex systems, and a chemical activation kinetic analysis using quantum Rice-Ramsperger-Kassel (QRRK) theory for rate constant function of energy (k(E)) and master equation analysis for falloff is used to calculate rate constants as function of pressure and temperature.

Rate constants for HO2 radical addition to carbon-carbon double bond calculated at CBS q//MP2(full)/6-3 IG(d) and CBS-q//B3LYP/6-3 IG(d) levels of theory show similar trends to experimental data: HO2 radical addition to tertiary carbon-carbon double bond (HO2 addition at CD/C2 carbon atom of isobutene) has a lower activation energy than addition to secondary carbon-carbon double bond (CD/C/H), which is lower than addition to primary carboncarbon bond (CD/H2). The Ea for addition to primary carbon-carbon double bonds of ethylene, propene and isobutene also show a decreasing trend.

The oxidation and pyrolysis of methyl tert-butyl ether in argon diluent has been studied in a flow reactor over the temperature range 873 to 973 K at atmospheric pressure with residence times between 0.5 - 2 sec. Three mixture compositions of MTBE and oxygen are studied in this MTBE oxidation as well as pyrolysis. Isobutene and methanol are observed as major products from both oxidation and pyrolysis of MTBE experiments.

A detailed kinetic model is developed for the pyrolysis and oxidation of MTBE. The mechanism includes oxidation and thermal decomposition of MTBE with major products and important intermediate. The computer code CHENIKIMI is used for numerical integration.

Thermodynamic properties for representative multi-chloro alkanes and alkenes determined using the modified group additivity scheme are compared with literature data and show good agreement. The use of limited number of interaction groups provides improved accuracy in calculation of thermodynamic properties for multi-chloro alkanes and alkenes when chlorines are on adjacent carbon atoms. Three multi-chloro Benson type groups plus five interaction groups for chloroalkanes; and two groups plus five interaction groups for chloroalkenes are developed.

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