Dynamics of hydrogen loss and structural changes in pyrolyzing biomass utilizing neutron imaging

We present results from neutron-imaging studies of slow, vacuum pyrolysis of beech, poplar and conifer wood, and pelletized biomass from room temperature up to 1000 degrees C. A detailed and quantitative method to extract 2D (in situ neutron radiography, NR) and 3D (ex situ neutron computed tomography, NCT) information on structural transformation and elemental hydrogen content has been developed. NCT and X-ray tomography (XCT) experiments on a carbonized beech twig permitted comparison of the spatial distribution of hydrogen, better sensed by NCT, and carbon, oxygen, and heavier elements, better sensed by XCT. We have developed a methodology to directly compare structure and hydrogen-loss dynamics measured using neutron imaging with thermogravimetric analysis and differential thermogravimetry and thus can better understand the correlations between hydrogen and carbon release dynamics. While the methodology has been developed for the carbonization of biomass, we expect that it could be applied to in situ dynamic monitoring of other hydrogenous reacting systems with the appropriate spatial and temporal scales. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

This study presents a detailed method to extract information on structural transformation and elemental hydrogen content during slow vacuum pyrolysis of wood and pelletized biomass. By comparing the spatial distribution of different elements using neutron imaging and X-ray tomography, the study provides insights into the correlations between hydrogen and carbon release dynamics. The developed methodology could potentially be applied to monitor other hydrogenous reacting systems in real time.