Kinetic modeling of the pyrolysis chemistry of fossil and alternative feedstocks

Combustion, Chemistry, and Carbon Neutrality

“…To this end, an improved understanding of the fundamental reaction chemistry for the respective feedstocks is needed, considering influences of process conditions such as temperature, pressure, heating rate, and residence time . Chemical degradation pathways should be described in reaction models based on similar criteria and using similarly systematic approaches as described for gaseous fuel combustion (Section ), e.g., using rate rule concepts for reaction families, and consistent kinetic, thermodynamic, and transport parameters. , Automatic procedures to generate thermochemical and kinetic parameters may prove helpful also in this context. − , Recent progress in this broad field of thermochemical conversion cannot be described here in depth. The chosen examples will thus address some specific aspects of the noncatalytic gasification of plastics and the pyrolysis of lignocellulosic biomass and respective model compounds.…”

“…Biomass and waste streams offer potential contributions for such demands. Recent reviews are a rich source of information on the progress in pyrolysis and gasification in view of the transformation toward sustainable and circular processes. − Introductory, overview, and perspective articles address general procedures, ,, experimental techniques, − , and modeling strategies ,,, regarding the conversion of biomass, ,− specifically of biopolymeric building blocks such as lignocellulose and lignin, , and of plastics, ,− aiming not only at energy recovery but, e.g., at producing chemicals and fuels. , …”

“…Such information cannot be derived only from semiempirical procedures but needs molecular-level insight, although the large diversity of (bio)­polymers poses challenges for reaction model development. , Dogu et al have summarized detailed mechanistic approaches for the kinetic modeling of thermochemical processing of polymers and have highlighted results from impactful experiments . Similar to combustion, gas-phase pyrolysis and gasification processes proceed via sequences of multiple radical reactions with hundreds of species, and only models that encompass these radical chain reactions will enable predictions for a broad range of conditions. , Typical reaction families, including initiation, propagation, and termination reactions (H-abstraction from different sites, β-scission, addition, recombination, or cyclization reactions) are differently represented in current detailed polymer degradation mechanisms . Further work is needed for a consistent description of polymer conversion processes regarding reaction parameters, fluid dynamics, heat and mass transfer, and phase changes, including gas and solid phases but also the presence of molten polymer if applicable. , Model development could feasibly build on detailed investigations for monodisperse single polymers of limited chain length and related validation experiments.…”

Active learning-based exploration of the catalytic pyrolysis of plastic waste

“…Kinetic modeling of chemical processes is one of the cornerstones of chemical engineering [1,2]. These kinetic models are a valuable source of process knowledge and can be used for reaction scale-up and the design of reactors and catalysts [2][3][4].…”

Learning Molecular Representations for Thermochemistry Prediction of Cyclic Hydrocarbons and Oxygenates

“…A typical kinetic model can contain thousands of species and tens of thousands of reactions, , with the model size increasing exponentially with the number of heavy (nonhydrogen) atoms in the reactant molecule . Due to the transition to alternative feedstocks, such as lignin, plastic waste, or heavy oils, new processes and hence new kinetic models must be created to understand how these feedstocks are converted into useful chemicals and chemical building blocks. , Some of these feedstocks contain many large molecules and are converted using pyrolytic processes, in which many radical species and polycyclic compounds are generated . Since determination of all thermochemical properties experimentally is unfeasible, computational methods are required.…”