Global kinetic analysis of complex materials

Abstract

A variety of global kinetic models are reviewed, including first-order, n th-order, nucleation, and sequential models as well as models having Gaussian, Weibull, and discrete activation-energy distributions. The important characteristics of these various models are outlined, with guidance in how to select the correct model. Some of the models have similar characteristics, and the parameter relationships among similar models are discussed. The comparison includes the relationship between conversion-dependent parameters determined by modified Friedman and Coats−Redfern isoconversion methods and reactivity distribution parameters determined by nonlinear regression of rate or fraction-reacted profiles. A new method for deriving discrete activation-energy distribution parameters having ln( A ) = a + bE is also presented. Data accuracy requirements are discussed briefly. Kinetic analyses are given for a variety of materials, including synthetic polymers (polyethylene, polystyrene, polydimethylenenaphthalene, polysulfone, and polyvinyl acetate), petroleum sources rocks (including well-preserved algal kerogens and the Bakken and Monterey shales), oil shales (including kukersite), and the Illinois and Pittsburgh Premium coal samples.