Thermal degradation and reactivity of cashew nut shell liquid constituents

This study analyzed the pyrolytic behavior of Cashew Nut Shell Liquid (CNSL) constituents-anacardic acids, cardanols, and cardols (ACC)-to provide a detailed understanding of their degradation mechanisms and predictive modeling of thermal behavior. Through pyrolysis experiments and kinetic modeling, three distinct stages were identified: (1) the decarboxylation of anacardic acids; (2) dual-pathway reactions involving cardanols and cardols, comprising devolatilization (evaporation and cracking into volatile compounds) and condensation/ polymerization into thermally stable "polyphenols"; and (3) the degradation of these polyphenols. Thermal stability analysis revealed that ACC stability decreases with increasing unsaturation following the order: 15:0 > 15:1 > 15:2 > 15:3. Each pseudo-component reaction was modeled and validated, showing that anacardic acid decarboxylation and cardanols and cardols devolatilization follow a geometric contraction reaction model, while polyphenol degradation of polyphenols transitions from a random nucleation model to firstorder kinetics reaction model. Higher initial ACC mass favored polyphenol selectivity. Numerical simulations based on the kinetic model and product selectivity accurately predicted ACC evolution under varying heating rates and initial masses. These insights deepen the understanding of CNSL pyrolysis and offer valuable guidance for optimizing thermochemical conversion processes.