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

Chemical Engineering Journal



First Page





Fast pyrolysis of lignocellulosic biomass yields little sugar or anhydrosugars compared to pyrolysis of pure polysaccharides because naturally abundant alkali and alkaline earth metals (AAEM) in biomass catalyze the fragmentation of pyranose and furanose rings. Sugar yields can be increased dramatically by pretreating the biomass with sulfuric acid prior to pyrolysis, which passivates the catalytic activity of the metals by converting them into thermally stable salts. However, depolymerization of lignin in biomass also depends on the catalytic activity of AAEM. Thus, passivating AAEM has the unintended consequence of slowing the rate of depolymerization and volatilization of lignin, resulting in a transient melt phase that agglomerates and can foul pyrolysis reactors.

To overcome this problem, various non-alkali metal sulfates were tested as replacements for sulfuric acid. Iron in the form of ferrous sulfate proved the most effective in depolymerizing lignin without fragmenting pyranose rings. Conventional nitrogen-blown pyrolysis of ferrous sulfate pretreated corn stover achieved WHSV of 4 h−1 compared to only 0.6 h−1 for acid pretreated corn stover. Autothermal (air-blown) pyrolysis of ferrous sulfate pretreated corn stover showed even more dramatic improvement, increasing WHSV from 1 h−1 to 10 h−1 compared to acid pretreated corn stover under autothermal operation. Fermentable sugar yields from the pyrolysis of corn stover increased from 0.9 wt% to 11.8 wt% on a biomass basis, a 13-fold increase as a result of the ferrous sulfate pretreatment. These advantages combine to increase volumetric sugar productivity from 62 g L−1 h−1 for conventional pyrolysis of untreated corn stover to 2041 g L−1 h−1 for autothermal pyrolysis of ferrous sulfate treated corn stover.


This is a manuscript of an article published as Rollag, Sean A., Jake K. Lindstrom, and Robert C. Brown. "Pretreatments for the continuous production of pyrolytic sugar from lignocellulosic biomass." 385 Chemical Engineering Journal (2020): 123889. DOI: 10.1016/j.cej.2019.123889. Posted with permission.

Copyright Owner

Elsevier B.V.



File Format


Available for download on Tuesday, December 21, 2021

Published Version