Influence of step duration in fractionated Py-GC/MS of lignocellulosic biomass

Abstract

Fractionated pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC/MS) appears as an interesting analytical tool for elucidating lignocellulosic biomass structure, as it allows the progressive release of chemical fragments representative of biomass macromolecular composition. In this paper the effect o f fractionated pyrolysis time (from 5 s to 300 s) on the degradation of lignin and carbohydrates from beech wood was studied at temperatures between 250 °C and 500 °C. Fractionated Py-GC/MS showed that the release temperature of the volatile degradation products varied between the volatile species detected. In addition, the step duration time changed the thermal degradation behavior of lignocellulosic components. Shortening the constant step duration time from 300 s to 5 s shifted the maximum weight loss to the higher temperatures. The result was opposite at long step duration times. Time optimization at each pyrolysis temperature (250 °C, 40 s; 300 °C, 30 s; 350 °C, 25 s; 370 °C, 20 s; 400 °C, 15 s; 450 °C, 10 s; 500 °C, 5 s) enhanced the yield of both lignin and carbohydrate volatile pyrolysis degradation products. In addition, two multiple temperature maxima were shown for some lignin and carbohydrate derivatives. This behavior may be due to the two different pathways of formation and macromolecular origins of compounds in beech wood. At optimized conditions lignin derivatives having a 3carbon side chain substituent had a maximum at lower temperature than that of lignin derivatives with a 1carbon side chain substituent. That phenomenon follows the order of primary and secondary pyrolysis reactions. Similar behaviors were observed among the degradation products of hemicelluloses and cellulose. Degradation products of hemicelluloses were mainly released at lower temperatures than those of cellulose derivatives, which illustrates the lower thermal stability of hemicelluloses compared to cellulose.

Torrefaction of Woody and Agricultural Biomass: Influence of the Presence of Water Vapor in the Gaseous Atmosphere

“…Neutral sugar composition was determined by the ASTM E1758 standard method. Characterization data from neutral sugar composition were normalized to 100% as described in [38]. The macromolecular composition is in agreement with previous studies in the literature [39][40][41][42].…”

Pyrolysis Products Distribution of Enzymatic Hydrolysis Lignin with/without Steam Explosion Treatment by Py-GC/MS

“…The possible reason for presence of carbohydrate derivatives was that cellulose and hemicellulose were not completely removed during the enzymatic hydrolysis of feedstock, resulting in feedstock containing a small portion of cellulose or hemicellulose (about 5 wt-10 wt%) [28]. Due to the cleavage of bonds between lignin and polysaccharide, a certain amount of carbohydrate derivatives could also be partially formed [29]. By comparing the product lists of two lignin substrates (see Table 2), pyrolysis products of EHL were more abundant and complex.…”

Assessing the impact of woody and agricultural biomass variability on its behaviour in torrefaction through Principal Component Analysis

“…The species included in the third group mainly presented an increasing production with increasing torrefaction temperature (propionic acid, guaiacol, acetylfuran, 3-furaldehyde, furan, 2-methoxy-4-vinylphenol, eugenol, cathecol and 2,3-pentanedione). In the case of phenols, the fact that the longer was the side chain substituent of the lignin-base units, the lower was the starting release temperature in torrefaction, except for vinyl derivatives [15,48], was checked in this case for vanillin, isoeugenol and guaiacol. Results on cathecol and eugenol are not considered as representative, due to their remarkable minor amount.…”