Quantifying pyrogenic carbon from thermosequences of wood and grass using hydrogen pyrolysis

Previously studied thermosequences of wood (chestnut) and grass (rice straw) biochar were subjected to hydrogen pyrolysis (hypy) to evaluate the efficacy of the technique for determining pyrogenic carbon (C-P) abundance. As expected, biochar from both wood and grass produced at higher temperature had higher C-P amount. However, the trend was not linear, but more sigmoidal. C-P/C-T ratio values (C-T = total organic carbon) for the wood thermosequence were = 500 degrees C suggested the dominant pyrolysis reaction was condensation of PAHs with no additional fractionation. Comparison of hypy with benzene polycarboxylic acid (BPCA), 'ring current' NMR and pyrolysis gas chromatography-mass spectrometry (GC-MS) results from the same suite of samples indicated a consistent overview of the structure of C-P, but provided unique and complimentary information. (C) 2013 Elsevier Ltd. All rights reserved