Campus Units

Mechanical Engineering, Agricultural and Biosystems Engineering, Chemical and Biological Engineering, Bioeconomy Institute (BEI)

Document Type


Publication Version

Accepted Manuscript

Publication Date


Journal or Book Title

Journal of Analytical and Applied Pyrolysis

First Page





The high ash content of agricultural residues and other kinds of herbaceous biomass makes it a challenging feedstock for fast pyrolysis to bio-oil. Using corn stover as a representative feedstock, this study investigates fast pyrolysis of high ash, herbaceous biomass in a pilot-scale fluidized bed reactor using both conventional, nitrogen-blown and autothermal, air-blown operation. Initial efforts to pyrolyze corn stover were challenged by bed fouling, which prevented steady reactor operation. Substitution of coarser bed material allowed operation at higher superficial velocities, which promoted attrition and elutriation of recalcitrant biochar particles from the reactor. This resulted in dramatic improvement in stable reactor operation for both conventional and autothermal pyrolysis with bio-oil yields among the highest reported for pyrolysis of corn stover. The oxygen-to-biomass equivalence ratio required for autothermal operation was 6.8%. Autothermal operation also resulted in significant process intensification, increasing corn stover throughput from 7.8 kg hr-1 to 21.9 kg hr-1 for this 8.9 cm diameter reactor. Air-blown, autothermal operation did not significantly reduce bio-oil yield despite the presence of partial oxidation reactions. Carbon balances indicate carbon yields of biochar and aqueous, bio-oil light ends decreased by 18.5% and 4.7%, respectively, during autothermal pyrolysis compared to conventional pyrolysis while the more valuable, organic-rich heavy ends of the bio-oil were essentially preserved.


This is a manuscript of an article published as Polin, Joseph P., Howard D. Carr, Lysle E. Whitmer, Ryan G. Smith, and Robert C. Brown. "Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues." Journal of Analytical and Applied Pyrolysis (2019): 104679. DOI: 10.1016/j.jaap.2019.104679. Posted with permission.

Copyright Owner

Elsevier B.V.



File Format


Available for download on Thursday, August 12, 2021

Published Version