Submitted to: BioResources
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/8/2013
Publication Date: 12/1/2013
Citation: Jackson, M.A., Boateng, A.A., Groom, L.H., Eberhardt, T.L., Mullen, C.A. 2013. Evaluation of biochars by temperature programmed oxidation/mass spectroscopy. BioResources. 8:5461-5474. Interpretive Summary: Biochar is the carbon-rich solid coproduct resulting from the pyrolysis and gasification of biomass. Much like charcoal, biochar can be burned or it can be used as a soil amendment to increase the fertility of weathered soils while serving to remove carbon from the atmosphere and slowing the impact of global climate change. We have studied the stability of several biochars to determine if any might be better at storing carbon in soil and have found that biochars from wood and from gasification of wood, in particular, are more stable. This means that these biochars are more likely to remain in soils for longer periods, thereby being better candidates for reducing carbon in the atmosphere and slowing global climate change. These results will benefit bioenergy researchers and policy makers as they address the role of biochar in mitigating global climate change.
Technical Abstract: Biochar from the thermochemical conversion of biomass was evaluated by Temperature Programmed Oxidation (TPO) coupled with mass spectroscopy. This technique can be used to assess the oxidative reactivity of carbonaceous solids where higher temperature reactivity indicates greater structural order. The samples examined include soy and barley straw, switchgrass, oak, poplar, and bamboo biochars. These were collected from a fast pyrolysis reactor used for production of pyrolysis oil. The samples were ground to 2-3 mm prior to feeding a fluidized-bed. They were pyrolyzed at fast pyrolysis optimum temperatures of 450-500°C and short residence times. The TPO profiles of these biochars differ depending on the biomass source. Two forest products-based biochars, derived from softwood (southern pine) and hardwood (a mixture of primarily sweetgum and oak) feedstocks, were also examined. The biochars were collected from a gasification unit for the production of synthesis gas and electricity. The temperature of the gasification unit was 900°C for the softwood feedstock and 850°C for the hardwood feedstock.