High-resolution in situ analysis of biomass pyrolysis by combining quantitative synchrotron $μ$CT and 3D particle-resolved simulations

Abstract

Understanding the coupling between transport, chemical kinetics, and structural response within solid fuel combustion requires in situ measurements at high spatial resolution. To examine the dynamics of biomass pyrolysis, we optimize synchrotron X-ray micro-computed tomography ($μ$CT), and conduct 3D particle-resolved simulations. A micro-focused heating cell with controlled heating and flow rate is employed, achieving temperatures of up to 1240 K and 3D imaging at 3.24 $μ$m spatial and sub-minute temporal resolutions. The pyrolysis of three biomass materials at sample heating rates of 10-14 K/min are examined. The $μ$CT measurements capture pore deformation, cracking, anisotropic shrinkage, and provide simultaneous thermogravimetric and thermovolumetric analyses to examine specific secondary pyrolysis pathways. Complementary 3D simulations considering detailed kinetics and structural response reproduce the key trends observed, and identify deficiencies in capturing simultaneous mass and volume losses during pyrolysis.