| Molecule-Based Modeling of Complex Reaction Systems
Our work focuses on reaction systems of such enormous complexity that
they have historically defied fundamental analysis. In this, we are developing
the Chemical Engineering science that will allow the fundamentals of chemical
kinetics, and the supporting sciences of Physical, Organic, Analytical and
Computational Chemistry, to replace the traditional Chemistry-free global
lumps as the basis for kinetics models for complex systems. This work has
recently taken the tangible form of software (the Kinetic Modeler's Toolbox,
KMT) for the automated modeling of the structure and kinetics of complex
systems.
Our approach has been to delineate and reduce the essential elements of
complexity in these reaction systems. It begins with molecular structure
building software that uses Monte Carlo simulation techniques to assemble
a molecular representation of complex feedstocks from analytical information,
e.g., H/C SIMDIS, NMR, etc. This realization of a feedstock as a set of
molecular structures is the first step in the use of quantitative structure-property
relationships. Reactivity is an especially important property, and it can
be phrased in the terms of the quantitative structure/reactivity correlations
(QSRC) developed in our experimental work, which has shown how apparently
independent rate constants can be constrained by a QSRC. This allows prediction
of rate constants given a molecule's or intermediate's structure using computational
quantum chemistry. This also reduces the number of potentially adjustable
parameters in detailed kinetic models by more than 90%.
The KMT software has automated the process of building these detailed
kinetic models. Exploiting Monte Carlo and graph theory techniques, we can
build reaction models containing thousands of species in 1000 CPU seconds
or less. This incredible model building speed has changed the serial model
building-model use paradigm to a new parallel approach, where a model builder
can produce an updated optimal model in seconds. The thus-constructed models
react the molecularly explicit feedstock using QSRC's for kinetic parameters.
This approach is being applied in the development of models for FCC, hydrocracking,
hydroisomerization, catalytic reforming, oxidation, pyrolysis and alkylation
chemistries.
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Recent Publications
Klein, M.T., Broadbelt, L. J. and S. M. Stark, Computer Generated Pyrolysis
Modeling: On-the-Fly Generation of Species, Reactions, and Rates,
I&EC Research, 33, 790-799 (1994)
Klein, M.T., Watson, B.A. and R. H. Harding, Mechanistic Modeling
of n-Heptane Cracking on HZSM-5,
I&EC Research, 35, 1506-1516 (1996)
Klein, M.T. and S. C. Korre,
Development of Temperature-Independent Quantitative Structure/Reactivity
Relationships for Metal- and Acid-Catalyzed Reactions,
Catalysis Today,
31, 79-91 (1996)
Klein, M.T., Broadbelt, L. J. and D. H. Grittman, Computer Generated
Pyrolysis Models: Applications of Monte Carlo Simulation, Graph Theory,
and Quantum Mechanic,
World Congress, San Diego, CA, July 1996.
Klein, M.T. and S. C. Korre,
Hydrocracking of Polynuclear Aromatic Hydrocarbons. Development of
Rate Laws Through Inhibition Studies,
I&EC Research, 36, 2041-2050 (1997)
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