A Comprehensive Characterization of Pyrolysis Oil from Softwood Barks.

Haoxi Ben,Guangting Han,Wei Jiang,Fengze Wu,Zhihong Wu,Arthur J Ragauskas

doi:10.3390/polym11091387

Abstract

Pyrolysis of raw pine bark, pine, and Douglas-Fir bark was examined. The pyrolysis oil yields of raw pine bark, pine, and Douglas-Fir bark at 500 °C were 29.18%, 26.67%, and 26.65%, respectively. Both energy densification ratios (1.32–1.56) and energy yields (48.40–54.31%) of char are higher than pyrolysis oils (energy densification ratios: 1.13–1.19, energy yields: 30.16–34.42%). The pyrolysis oils have higher heating values (~25 MJ/kg) than bio-oils (~20 MJ/kg) from wood and agricultural residues, and the higher heating values of char (~31 MJ/kg) are comparable to that of many commercial coals. The elemental analysis indicated that the lower O/C value and higher H/C value represent a more valuable source of energy for pyrolysis oils than biomass. The nuclear magnetic resonance results demonstrated that the most abundant hydroxyl groups of pyrolysis oil are aliphatic OH groups, catechol, guaiacol, and p-hydroxy-phenyl OH groups. The aliphatic OH groups are mainly derived from the cleavage of cellulose glycosidic bonds, while the catechol, guaiacol, and p-hydroxy-phenyl OH groups are mostly attributed to the cleavage of the lignin β–O-4 bond. Significant amount of aromatic carbon (~40%) in pyrolysis oils is obtained from tannin and lignin components and the aromatic C–O bonds may be formed by a radical reaction between the aromatic and aliphatic hydroxyl groups. In this study, a comprehensive analytical method was developed to fully understand and evaluate the pyrolysis products produced from softwood barks, which could offer valuable information on the pyrolysis mechanism of biomass and promote better utilization of pyrolysis products.

Highlights

Increasing world energy consumption [1] and growing carbon dioxide emissions have contributed to the promotion of sustainable energy development
The Higher Heating Value (HHV) (~25 MJ/kg) of pyrolysis oil are higher than bio-oils (~20 MJ/kg) pyrolyzed from wood and
The HHVs (~25 MJ/kg) of pyrolysis oil are higher than bio-oils (~20 MJ/kg) pyrolyzed from wood and agricultural residues and lower than the lignin pyrolysis oils (~30 MJ/kg), and the HHVs of the char agricultural residues and lower than the lignin pyrolysis oils (~30 MJ/kg), and the HHVs of the char

Summary

Introduction

Increasing world energy consumption [1] and growing carbon dioxide emissions have contributed to the promotion of sustainable energy development. Biomass is considered a sustainable raw material for the manufacture of chemicals and fuels [2,3,4] because it is carbon neutral, quite abundant, renewable, and no competition with food [5,6]. As the most promising fuel raw material, bark is a waste produced by forestry-related industries. Compare to the gasification and biochemical conversion of biomass, pyrolysis is a development technology to convert biomass into bio-oil and biochar via heating at 400–600 ◦ C in an anoxic atmosphere [14,15,16], which has been reported as the most economical way of bio-fuel transformation [17] Several researchers have accomplished some experiments of pyrolysis of waste biomass. Pinto et al [19] who fast pyrolyzed tannins from pine bark at

Methods

Results

Conclusion