Functional group approaches to lumped kinetic modeling.

摘要

Three case studies of functional group approaches to kinetic modeling are presented in this work. In the first case study, a pseudocomponent approach is used to model the catalytic cracking reactions of oils. Data on the cracking reactions of model compounds over a silica - alumina - zirconia catalyst were organized into a general framework based on carbon centers. The kinetic behavior of carbon centers was deduced from pure compound studies available in the literature. The models of pure components formed the basis for modeling the catalytic cracking reactions of hydrocarbon mixtures.; In the second case study, a new methodology, a hybrid between continuum and lumped kinetic models, was developed. In this approach, called semi-continuous lumping, the components in the reacting mixture are grouped into compound classes as in traditional lumped kinetic models. The novel feature of this case study is that each compound class is considered to be a continuum of components and is described by a continuous function of a characterization variable. The distribution characterizing the lump evolves as reactions proceed. The rates of interconversion between the kinetic lumps are functions of the carbon number and the functional groups in the lump. Thermal hydropyrolysis of hydrocarbon mixtures was used as a concrete example in this case study.; Finally, functional groups were used as kinetic lumps in an examination of reactions of complex mixtures. All three methodologies presented in this thesis are based on the idea that the functional groups that constitute a compound, or a class of compounds, are sufficient to predict its kinetic behavior. They differ only in the way this idea is implemented. Structural, or pseudocomponent, modeling is the most promising methodology for immediate application since it is based on existing information bases. Many systems have been characterized well enough for representative compounds, pseudocomponents, to be selected with confidence. Semi-continuous lumping provides an alternative methodology for systems that are less well defined.