Nonlinear phenomena in chemically reacting systems
Abstract
This work was involved with a number of tools and techniques, both theoretical and experimental, with a potential utility in studies of the nonlinear behavior of chemically reacting systems. The singularity theory formulation of Golubitsky and Schaeffer (1979) was used to completely determine the steady-state behavior of a class of single-species, gas-solid catalytic reactions taking place in an isothermal CSTR. Attractive adsorbate-adsorbate interactions were quantified with a linear increase of the activation energy for desorption with coverage. A maximum of five steady-states was shown to be possible for sufficiently strong adsorbate-adsorbate interactions, when an additional empty site was required for the surface reaction. The analysis of the dynamics of the same catalytic system and of a simple biological system describing substrate-inhibited growth through singularity theory gave only partial results. Nevertheless the local predictions of the theory were instrumental in the numerical discovery of intricate phase diagrams. A reactor system was built for the study of gas-solid catalytic reactions at atmospheric pressure and at different temperatures and reactant streams. A quadrupole mass spectrometer was utilized for the continuous measurement of the composition of the reactor effluent stream. A gas sampling system was developed able to faithfully follow composition changes with time constants of a few seconds. Specialized software was developed to allow the automated operation of the mass spectrometer through integration with a microcomputer. The resulting data acquisition system could request, monitor and record measurements at rates limited only by the mass spectrometer. Finally, a diffusion-aided technique for mass spectrometer calibration was developed. The technique substantially reduced the effort needed to generate extensive calibration databases and also was effective in identifying sources of error in transient measurements.
Degree
Ph.D.
Advisors
Takoudis, Purdue University.
Subject Area
Chemical engineering
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