TGA-MS studies of the pyrolysis of corn stover for charcoal production

Abstract

More than two billion people worldwide rely on wood-based fuels for their daily energy needs, which can produce toxic atmospheric contaminants and cause environmental degradation. MIT D-Lab addresses this challenge with "Fuel from the Fields", a simple technique for making charcoal from agricultural waste. In this work, Themogravimetric analysis combined with online mass spectrometry (TGA-MS) was used to study the pyrolysis of corn agricultural waste with the aim of improving understanding of the carbonization process. Non-isothermal mass loss data from TGA was obtained for three types of corn waste, cobs, husks, and stalks; and used to calculate proximate analysis in terms of moisture, volatile matter, and charcoal content. TGA-MS data for the three materials was used to understand the emissions of H20, CO, H2S and C4H2 as a function of temperature. Activation energy, Ea, and pre-exponential factor, A, were calculated using the first order global single reaction model for corn cobs and husks. TG-DTG data suggested that corn cobs are better suited feedstocks for charcoal production. Mass Spectroscopy was found to successfully characterize emissions. For corn cobs, A = 1.3. 105 s-1 and E, = 88.6 kJ/mol, while for husks A = 5.2. 105 s-1 and Ea = 96.4 kJ/mol. Based on this work, a carbonization burn timeline worksheet was created to aid monitoring of char yield in the field.