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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.

© 2018 A dendritic porous supported microstructure simultaneously creates small pore size and broad gas diffusion pathways in a solid oxide fuel cell anode membrane. This microstructure also achieves pore sizes that reduce with increasing depth within the membrane without increasing the structure tortuosity. Such a microstructure supplies high triple phase boundary density, fast gas diffusion and low polarization resistance. Here we characterise the performance of a porous anode with such a dendritic microstructure. The solid oxide fuel cell with this high performance anode achieved 0.92 W cm-2 power density at 600 °C.

© 2018 A ceramic oxygen pump has been investigated as a potential self-heated oxygen generation device using electric potential as driving force. The required high temperature (around 748 °C) can be maintained locally on the membrane while the environmental temperature is kept at lower than 200 °C. The conventional dense membrane structure was found to be inappropriate for this application because it could not withstand the thermal shock induced by rapid heating and cooling. In contrast, the microchanneled membrane used in this work demonstrated excellent thermal shock resistance. It also demonstrated high Faraday efficiency when no electrode was coated on the microchannel surface. The Faraday efficiency exceeded 90% at 748 °C when 6.35 A cm-2 current density was applied. Under these conditions, an oxygen flux density of 20.6 ml cm-2 min-1 was achieved and this continued for 100 h without any degradation. Combined, these factors demonstrate that the microchanneled membrane can be potentially utilized within an oxygen generator having small size and good durability.