Fast pyrolysis of tannins from pine bark as a renewable source of catechols

Abstract

Fast pyrolysis of water-insoluble (W-I) tannins-mainly composed of condensed tannins-obtained from Pinus radiata bark methanol-water extraction was carried out in pursuit of a renewable source of high-value chemicals, in particular catechols. Micropyrolysis in an isothermal furnace unit (Py-GC-MS/FID) was performed between 450-600°C. Catechin and W-I tannins were compared to establish thermal degradation behavior between this fraction and its representative monomer constituent. Additionally, W-I tannins were compared with typical sources of renewable phenols such as pine bark and organosolv-lignin in order to highlight its potential. Benchscale experiments of W-I tannins were performed in a fluidized bed reactor between 400-600°C to provide information related to yield and concentration of catechols. The Py-GC-MS/FID results showed that W-I tannins are prolific of catechol and 4-methylcatechol, similar to their most abundant monomer constituent catechin. However, W-I tannins are not only composed of condensed tannins and some substituted polycyclic aromatic hydrocarbons, triterpenes and carbohydrate-derived compounds were detected. The comparison of pyrolysis products among the renewable sources of phenols showed that W-I tannins yielded the highest relative content of catechols while guaiacols and carbohydrate-derived compounds predominated in the composition of lignin and bark products, respectively. The optimal pyrolysis-oil yield for bench scale assays (37 wt%) was found at 550°C and maximum yield of both catechol (4.4 wt%) and 4methylcatechol (2.3 wt%) were also obtained at 550°C.

Physico-chemical analysis of pyrolyzed bio-oil from swietenia macrophylla (mahogany) wood

“…The 723.1cm −1 as C–H bonds indicates the presence of another group of aromatic compounds considering the band between 785–540cm −1 of the C–H stretch group. Majority of the functional groups have been identified by researchers working with other woody biomass classes (Kumar et al., 2010; Pinto et al., 2018; Ogunsanwo et al, 2014) and their classifications are similar to those reported in this study.…”

Utilization of Partially Liquefied Bark for Production of Particleboards

“…It was previously reported by Yang et al (2007) that cellulose pyrolysis occurs in a higher temperature range than lignin and hemicelluloses, and lignin is the most difficult polymer to decompose with a solid residue of 45.7 wt.% [44]. As shown in Figure 4b and Table 2, decomposition of bark (Tonset) initiated at 219 °C and reached a maximum mass loss (Tmax1) at 361 °C, thus representing typical pyrolysis of lignocellulosic material [45,46]. The respective Tonset of PLB and purified PLB were, respectively, 152 and 148 °C and were both lower than that of bark.…”

Environmentally Friendly Methods for Flavonoid Extraction from Plant Material: Impact of Their Operating Conditions on Yield and Antioxidant Properties

“…Therefore, researchers have focused their work on improving the flavonoid recovery methods of some barks, especially when highly lignified barks are wasted from the forestry industry. Recent work has mentioned the extraction of flavonoids from the bark of Pinus radiata [ 24 ], chestnuts species [ 25 ], Caesalpinia ferrea C. [ 26 ], Pinus halepensis [ 27 ], Quercus laurina , Quercus crassifolia , and Quercus scytophylla [ 28 ].…”