Critical review of the global chemical kinetics of cellulose thermal decomposition

Historical models for cellulose pyrolysis and mathematical approaches to kinetic analysis are reviewed with the objective of identifying the correct global chemical kinetic models and parameters for cellulose pyrolysis. In most recent experiments, cellulose pyrolysis clearly has sigmoidal reaction character, which is consistent with one of a sequential, nucleation-growth, or random-scission global model. The apparent activation energy of ∼47 kcal/mol is consistent with mechanistic modeling if one allows catalytic acceleration of the concerted initiation reaction. There is a possibility that part of the sigmoidal character is due to adsorption effects at low pyrolysis temperatures, but further work is required to resolve this issue. Reasons are given for why fitting data at a single heating rate to a first-order reaction model gives incorrect results.