Characterization of Bio-oils Produced from Fast Pyrolysis of Corn Stalks in an Auger Reactor

Abstract

Corn stalks were converted to bio-oils by fast pyrolsis in an auger fed reactor at 400 and 450 °C. Both acidpretreated and untreated corn stalks were pyrolyzed. Proximate and ultimate analyses of the corn stalk feeds and bio-oils were performed, and the bio-oils were characterized by gas chromatography/mass spectrometry (GC/MS), gel permeation chromatography (GPC), 13 C and 1 H NMR spectroscopy, pH, ash, and viscosity measurements, and solids content and water analyses. Corn stalks have lower lignin content than wood, leading to lower bio-oil yields, more water produced and different chemical compositions than pine wood bio-oil generated in the same auger reactor. Acid pretreatment of stalks increased the biooil yields and decreased the char yields at both pyrolysis temperatures. Acid-treated stalks had lower water content, and pH, viscosity, and filterable solid values were lower than those of bio-oil from untreated stalks. Several compounds found in the biooil from untreated stalks were not detected in the bio-oil from acid-treated stalks. Thirty two compounds were quantitated in the GC/MS analysis of the two bio-oils. Gel permeation chromatography analysis indicated the presence of a significant fraction of high boiling point compounds that did not pass through the GC columns with bio-oils from both pretreated and untreated stalks. Weight averaged molecular weights of 490 and 530 for acid-treated and untreated stalks, respectively, were indicated by GPC. Portable auger reactors might be used for local production of corn stalk bio-oils during harvest, thereby avoiding the need to transport bulky, low density corn stalk or stover biomass to biorefineries or power generation units.

Selective Extraction of Bio-oil from Hydrothermal Liquefaction of Salix psammophila by Organic Solvents with Different Polarities through Multistep Extraction Separation

“…In a previous study, Pittman et al (2012) found that the 3.0 to 4.2 ppm range of the 1 H spectrum was related to the methoxy content. As shown in Fig.…”

Co-production of furfural and acetic acid from corncob using ZnCl2 through fast pyrolysis in a fluidized bed reactor

“…The main reasons for the high acetic acid concentration in this study would lie in on one hand that the feed material in this study was corncob which was abundant in hemicelluloses that could produce acetic acid by deacetylation during pyrolysis, and the other hand that the fast pyrolysis was conducted at lower reaction temperatures where lignin fraction of corncob could not be sufficiently devolalitized to be components of bio-oil. A recent study on the fast pyrolysis of corn stalk in a fluidized-bed reactor reported that the bio-oil contained 27.3% acetic acid (Pittman et al, 2012). The furfural concentration in the bio-oils was between 3.5 and 5.5 wt%, showing the maximum yield obtained at 357°C.…”

Assessing the Effects of Different Process Parameters on the Pyrolysis Behaviors and Thermal Dynamics of Corncob Fractions

“…The pyrolysis behaviors of a variety of agricultural wastes, such as apple pomace (Baray et al 2014), hardwood residues (Mazlan et al 2015), corn stalk (Pittman et al 2012), peanut shells (Yao et al 2016a), grape residues (Xu et al 2009), rice husk and straw (Worasuwannarak et al 2007), wheat and corn straw (Lanzetta and Di Blasi 1998), and cherry seeds (Duman et al 2011), have been investigated for different purposes. Miura and Maki (1998) and Arora et al (2009) have focused on developing mathematical dynamic models for predicting the pyrolysis characteristics of various biomass wastes.…”