Gasification reactor engineering approach to understanding the formation of biochar properties.
The correlation between thermochemical provenance and biochar functionality is poorly understood. To this end, operational reactor temperatures (spanning the reduction zone), pressure and product gas composition measurements were obtained from a downdraft gasifier and compared against elemental composition, surface morphology and polyaromatic hydrocarbon content (PAH) of the char produced. Pine feedstock moisture with values of 7% and 17% was the experimental variable. Moderately high steady-state temperatures were observed inside the reactor, with aca50°C difference in how the gasifier operated between the two feedstock types. Both chars exhibited surface properties comparable to activated carbon, but the relatively small differences in temperature caused significant variations in biochar surface area and morphology: micropore area 584 against 360 m2g-1, and micropore volume 0.287 against 0.172 cm3g-1. Differences in char extractable PAH content were also observed, with higher concentrations (187 µg g-1± 18 compared with 89 ± 19 µg g-1Σ16EPA PAH) when the gasifier was operated with higher moisture content feedstock. It is recommended that greater detail on operational conditions during biochar production should be incorporated to future biochar characterization research as a consequence of these results.
University of Nottingham , Energy Technologies Building, Innovation Park, Triumph Road, Nottingham NG7 2TU , UK.
Andrew N
0000-0003-3664-3975
AN
Rollinson
biochar; biomass; gasification; polycyclic aromatic hydrocarbon; renewable energy