Kinetic Analysis of Complex Solid-State Reactions. A New Deconvolution Procedure

TLDR

The kinetic analysis of complex solid‑state reactions involving simultaneous overlapping processes is challenging. The authors propose a method that deconvolves individual processes from overall differential kinetic curves obtained under linear heating, then performs kinetic analysis of the discrete processes using combined kinetic analysis. The method deconvolutes overlapping processes from differential kinetic curves under linear heating, tests various fitting functions—including Gaussian, Lorentzian, and Fraser–Suzuki—to assess curve shape, and applies combined kinetic analysis to each discrete process. The study shows that Gaussian and Lorentzian fits produce inaccurate kinetic curves and incorrect parameters, whereas the Fraser–Suzuki function accurately fits the curves regardless of kinetic model, yielding correct kinetic parameters, and the method was validated on both simulated and experimental complex processes.

Abstract

The kinetic analysis of complex solid-state reactions that involve simultaneous overlapping processes is challenging. A method that involves the deconvolution of the individual processes from the overall differential kinetic curves obtained under linear heating rate conditions, followed by the kinetic analysis of the discrete processes using combined kinetic analysis, is proposed. Different conventional mathematical fitting functions have been tested for deconvolution, paying special attention to the shape analysis of the kinetic curves. It has been shown that many conventional mathematical curves such as the Gaussian and Lorentzian ones fit kinetic curves inaccurately and the subsequent kinetic analysis yields incorrect kinetic parameters. Alternatively, other fitting functions such as the Fraser−Suzuki one properly fit the kinetic curves independently of the kinetic model followed by the reaction and their kinetic parameters, and moreover, the subsequent kinetic analysis yields the correct kinetic parameters. The method has been tested with the kinetic analysis of complex processes, both simulated and experimental.