Detailed characterization of pore structure and transport properties of biomass particles during pyrolysis

This is the authors' abstract. We don't add key points for this paper.

Biomass pyrolysis involves complex structural and transport processes that remain poorly understood at the pore scale. Here, high-resolution image-based reconstruction is integrated with pore network modeling (PNM) to quantify the evolution of pore structure and transport properties in wood particles during staged pyrolysis. The extracted pore networks reveal a contraction–enlargement duality: although particle shrinkage reduces the total number of pores, the remaining pores expand and undergo fracture and coalescence. Orientation analysis further shows a temperature-dependent reduction in structural anisotropy, quantified through the orientation distributions of pore bodies and coordination links. At the representative elementary volume (REV) scale, local porosity and permeability distributions reveal pronounced heterogeneity, while permeability is strongly influenced by pore connectivity and anisotropy. Layer-resolved analyses of wood mass loss and directional conductance demonstrate that pyrolysis progresses radially from the particle surface toward the interior while maintaining anisotropic transport pathways within each layer. The proposed framework establishes a direct link between pyrolysis temperature, pore-scale structural evolution, and transport properties, providing physically informed REV-scale parameters for continuum-scale reactive transport models.