TY - JOUR
T1 - A SAXS study of the pore structure evolution in biochar during gasification in H2O, CO2 and H2O/CO2
AU - Liu, Yurong
AU - Paskevicius, Mark
AU - Sofianos, M. Veronica
AU - Parkinson, Gordon
AU - Wang, Shuai
AU - Li, Chun Zhu
PY - 2021/5/15
Y1 - 2021/5/15
N2 - Gasification of biomass allows for its efficient utilisation as a renewable fuel through syngas production. This work presents the different effects of gasifying agents (H2O, CO2 and H2O/CO2) on the pore structure evolution in biochar during gasification. The effects of temperature (700, 800 and 900 °C) and biomass particle size (up to 5.6 mm) were also studied. The pore structure of biochar was characterized using synchrotron small angle X-ray scattering (SAXS). The pore development in biochar during gasification in H2O/CO2 was close to that in H2O. Carbon removal is more selective in CO2 than H2O and the derived biochar displayed pore fractal features, whereas the biochars gasified in H2O and H2O/CO2 exhibited a surface fractal network due to the less selective carbon removal in the presence of H2O. The pore structure development produced by various gasifying agents was paralleled by the evolution of the aromatic structures characterized by Raman spectroscopy. The different pore structure features result from the different reactivity of carbon sites with H2O and CO2, which can be attributed to the different amounts of O-containing groups in biochar, as well as the different reactivity of H2O and CO2. Increasing temperature reduced the differences in pore structure between biochars gasified in H2O and CO2. Biomass particle size had little impact on the pore structure of biochar.
AB - Gasification of biomass allows for its efficient utilisation as a renewable fuel through syngas production. This work presents the different effects of gasifying agents (H2O, CO2 and H2O/CO2) on the pore structure evolution in biochar during gasification. The effects of temperature (700, 800 and 900 °C) and biomass particle size (up to 5.6 mm) were also studied. The pore structure of biochar was characterized using synchrotron small angle X-ray scattering (SAXS). The pore development in biochar during gasification in H2O/CO2 was close to that in H2O. Carbon removal is more selective in CO2 than H2O and the derived biochar displayed pore fractal features, whereas the biochars gasified in H2O and H2O/CO2 exhibited a surface fractal network due to the less selective carbon removal in the presence of H2O. The pore structure development produced by various gasifying agents was paralleled by the evolution of the aromatic structures characterized by Raman spectroscopy. The different pore structure features result from the different reactivity of carbon sites with H2O and CO2, which can be attributed to the different amounts of O-containing groups in biochar, as well as the different reactivity of H2O and CO2. Increasing temperature reduced the differences in pore structure between biochars gasified in H2O and CO2. Biomass particle size had little impact on the pore structure of biochar.
KW - Biochar gasification
KW - O-containing functional groups
KW - Pore structure
KW - Reactivity
KW - SAXS
UR - http://www.scopus.com/inward/record.url?scp=85101092507&partnerID=8YFLogxK
U2 - 10.1016/j.fuel.2021.120384
DO - 10.1016/j.fuel.2021.120384
M3 - Article
AN - SCOPUS:85101092507
VL - 292
JO - Fuel
JF - Fuel
SN - 0016-2361
M1 - 120384
ER -