Effect of Non-Structural Organics and Inorganics Constituents of Switchgrass During Pyrolysis

Abstract

Non-structural components, such as inorganics and organic extractives, present in switchgrass were extracted with water and ethanol, and the resulting non-structural components-free materials were pyrolyzed to investigate the effect of the inorganic species on the pyrolytic products. The extraction was performed for switchgrass materials harvested from three consecutive growing seasons, removing 8.5 wt% of the organic extractives in the first season biomass, and 5.8 and 6.3 wt% in the second and third season, respectively, on total dry basis of biomass. In addition to organic extractives, from 0.7 to 2.7 wt% of ash were extracted. Specifically, 99% and 59% of total K and Mg were removed from the switchgrass harvested in the second and third growing season. Thermogravimetric analysis demonstrated that a predominant reduction of K and Mg content in the biomass increased temperature at which mass loss rate is maximized in the decomposition of cellulose, hemicellulose, and lignin. The reduction of K and Mg content also affected pyrolytic products generated at 450 • C. The chromatographic peak area percentage of levoglucosan from the extracted samples in the second and third growing season was two to three times higher than that from the extracted samples in the first growing season, showing a strong negative correlation with K and Mg content, whereas most of the light oxygenated and furanic/pyranic/cyclopentanic products exhibited a strong positive correlation with K and Mg content. We concluded that the removal of non-structural components prior to thermochemical conversion processes such pyrolysis can potentially produce a valuable extractives stream while removing catalytic inorganics that negatively impact downstream pyrolysis process.

Bioethanol Production from Vineyard Waste by Autohydrolysis Pretreatment and Chlorite Delignification via Simultaneous Saccharification and Fermentation

“…PC4 explained about 12% of the total variance of the system and revealed a positive correlation on hemicellulose, K and Ba. Similar results were reported by Kim et al [47] who studied the effect of non-structural organics and inorganics constituents of switchgrass during pyrolysis and found a positive correlation between the removal of hemicelluloses and K. A possible explanation is that K has a strong catalytic interaction with carbohydrates. In Figure 10 is presented the PCA biplots.…”

Pilot-Scale Pelleting Tests on High-Moisture Pine, Switchgrass, and Their Blends: Impact on Pellet Physical Properties, Chemical Composition, and Heating Values

“…The carbon content of SYP was also appreciably higher than the SG, but the HHV differed by only 5% between these raw materials. Ash could reduce the performance of biomass conversion reactors, whereas alkali and alkaline earth metals can specifically affect the composition and yield of downstream products during thermochemical conversion of lignocellulosic feedstocks (Edmunds et al, 2018;Kim et al, 2018). Hence, blending these raw materials could potentially reduce heterogeneity and improve their downstream conversion properties.…”

Roles of mineral matter in biomass processing to biofuels

“…Salts and acids from the biomass and those produced during the conversion process can affect the reactions during pyrolysis 81 . Some AAEMs, such as K, Ca, Na, and Mg, which exist in higher concentrations in biomass can act as catalysts that depolymerize cellulose and hemicellulose and produce the unwanted light oxygenate compounds along the process as acids, ketones, aldehydes, and furans 86 . These light oxygenate compounds in bio‐oils can negatively affect the catalysts during bio‐oil upgrading processes, making them less reactive due to coke formation 86 .…”

“…Some AAEMs, such as K, Ca, Na, and Mg, which exist in higher concentrations in biomass can act as catalysts that depolymerize cellulose and hemicellulose and produce the unwanted light oxygenate compounds along the process as acids, ketones, aldehydes, and furans 86 . These light oxygenate compounds in bio‐oils can negatively affect the catalysts during bio‐oil upgrading processes, making them less reactive due to coke formation 86 . Apart from forming more low molecular weight oxygenates, the AAEMs limit the formation of levoglucosan, one of the major components of bio‐oil 40,87 .…”

“…Mineral removal by washing methods is also recommended to reduce its undesirable impacts during biomass processing 120 . The removal of mineral content via leaching treatment, using water or mild or strong acids, has been shown to improve product yield and quality of conversion processes such as fast pyrolysis 86 . During leaching performed before the biomass conversion, minerals are dissolved into the liquid phase.…”