Slow Pyrolysis Kinetics of Two Herbaceous Feedstock: Effect of Milling, Source, and Heating Rate

Abstract

Kinetic models for pyrolysis of switchgrass and tall fescue were obtained using thermogravimetric analysis and a newly proposed parameter-extraction methodology. The optimization strategy demonstrates the use of the Akaike information criterion for the statistical identification of the number of distinct processes and a robust global search method. The effects of sample mass, heating rates, particle size, and crystallinity index on the kinetic parameters of each feedstock were considered. For whole biomass particles, the kinetic parameters of the cellulose component was found to be similar to that of pure microcrystalline cellulose. Further particle size reduction through extensive milling reduced the activation energy of cellulose by 48%. X-ray diffraction indicated that the cellulose fraction of highly milled whole biomass becomes largely amorphous and that the amorphization of the cellulose, not the particle size reduction, is likely responsible for the decrease in activation energy.

Biomass Fast Pyrolysis Using a Novel Microsphere Microreactor Approach: Model-Based Interpretations

“…In general, this data set suggests that the apparent activation energy (and heating rate) decreases as (1) particle size increases or (2) reactor temperature decreases. A similar result was observed in previous studies of the authors with the same material, but at a lower heating rates (i.e., for TGA experiments conducted with a heating rate of 5–50 K/min) …”

“…A similar result was observed in previous studies of the authors with the same material, but at a lower heating rates (i.e., for TGA experiments conducted with a heating rate of 5−50 K/min). 45 In the previous study, the activation energy for pyrolysis of the lignin and hemicellulose components of tall fescue and switchgrass increased as the heating rate increased, suggesting that the reaction pathway changes as the heating rate increases, the activation energy is higher from the reactor temperature of 600−800 °C for large particles (>100 μm in radius), and from 600 to 900 °C for small particles (<100 μm in radius).…”

Biocarbon from peanut hulls and their green composites with biobased poly(trimethylene terephthalate) (PTT)

“…As compared to the original 1 cm sized samples, the milled PHs may have released more hydrogen and carbon monoxide but less carbon dioxide 22 . Beneficially, the reduced size of the biomass required less activation energy to pyrolyze the samples 21,48 . A cost to benefit ratio would be required for implementation of this material on a larger scale.…”

Biomass Fast Pyrolysis Using a Novel Microparticle Microreactor Approach: Effect of Particles Size, Biomass Type, and Temperature

“…Figure illustrates a timeline of experimental techniques that have been used to study pyrolysis beginning in the mid-20th century to present. A broad range of works has been published on biomass pyrolysis (especially cellulose) using bulk, batch, slow pyrolysis since the beginning of the 20th century. − Likely, the most used method have been thermogravimetric analysis (TGA), which became widely applied by about 1960. − Py-GC/MS was introduced shortly after and has been a major tool used in the elucidation of reaction pathways. − Techniques such as the free fall reactor (drop tube), radiant flash pyrolysis, wire-mesh heating and other laboratory-scale micropyrolyzers are less frequently cited among others. Gravimetric-based bulk, slow pyrolysis methods provide information only about the amount of oil, gas, and char produced, whereas real-time gravimetric analysis (i.e., TGA) provides some, yet lumped, kinetic information.…”