Chemistry and Chemical Biology ETDs

Publication Date

8-8-1975

Abstract

Normal-pulse laser interaction with organic solids was studied. Extensive interaction between the carrier gas and the plasma occurred in the quenching process. When hydrogen was used as the carrier gas, significantly greater quantities of products were detected from the laser pyrolysis of graphite and coal compared to laser pyrolysis in helium. Acetylene was shown to be the principal hydrocarbon product from plasma quenching. Equilibrium product distributions calculated at high temperatures by the minimization of free energy revealed that hydrogen and acetylene were the primary gaseous plasma quenching products for hydrocarbons. Organic solids with oxygen present in the molecule yielded carbon monoxide as an additional plasma quenching product. The model of quenching assumed that H and C2H quenched to H2 and C2H2, respectively. Experimental products agreed well with calculated results, indicating a plasma quenching temperature of 3000-3500 K. Methane, ethylene, and carbon dioxide are assumed to be formed primarily as thermal blow-off products from the lower temperature thermal degradation of the samples. It was shown that nickel loading of transparent samples is a simple and effective method to bring about laser pyrolysis of these samples. Greater relative quantities of lower temperature thermal degradation products resulted from laser pyrolysis of nickel loaded cholesterol. Laser pyrolysis gas chromatography and plasma stoichiometric analysis proved useful for the characterization of coal samples and oil shale samples. The experimental results suggested a plasma quenching temperature of 3300 K for the coal samples and 3500 K for the oil shale sample. Correlations of the hydrogen, carbon monoxide, and acetylene products were shown to indicate the relative carbon, hydrogen, and oxygen stoichiometries of the coal samples. Correlations to the carbonate content, water content, organic hydrogen content, organic carbon content, and Fischer Assay oil yield were obtained from analysis of the low molecular weight gaseous products from laser pyrolysis of oil shale samples. Oil shales produced a greater relative quantity of thermal blow-off products than were produced from coals. The model for plasma quenching presented in the dissertation proved useful for explaining all of the experimental results. The computer program for the calculation of equilibrium product distributions by the minimization of free energy is presented in the appendix.

Project Sponsors

The Coal Gasification Research Project at The University of New Mexico

Language

English

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Guido Herman Daub

Second Committee Member

Fritz Schreyer Allen

Third Committee Member

Bernard Thomas Kenna

Fourth Committee Member

Roy Dudley Caton Jr.

Fifth Committee Member

Nicholas Ernest Vanderborgh

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