Understanding the stability of pyrolysis tars from biomass in a view point of free radicals

• Published in: Bioresource technology Vol. 156; pp. 372 - 375
• Main Authors: He, Wenjing, Liu, Qingya, Shi, Lei, Liu, Zhenyu, Ci, Donghui, Lievens, Caroline, Guo, Xiaofen, Liu, Muxin
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2014; Elsevier
• Subjects: Bio-tars; Biological and medical sciences; Biomass; Coke; Coke - analysis; Free radicals; Free Radicals - chemistry; Fundamental and applied biological sciences. Psychology; Hot Temperature; Juglans - chemistry; Liquids; Pyrolysis; Radicals; Stability; Tars; Tars - chemistry; Zea mays - chemistry; Pyrolysis; Biomass; Bio-tars; Radicals; Stability; Tar; Free radical
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.01.063

•The bio-tars contain large amounts of radicals at a level of 1016spins/g.•The bio-tars generate more radicals and coke at temperature of 573K or higher.•The behavior of tar radicals indicates that they are rich in weak covalent bonds.•The coke formed in the bio-tars contain radicals. Fast pyrolysis of biomass has attracted increasing attention worldwide to produce bio-tars that can be upgraded into liquid fuels and chemicals. However, the bio-tars are usually poor in quality and stability and are difficult to be upgraded. To better understand the nature of the bio-tars, this work reveals radical concentration of tars derived from pyrolysis of two kinds of biomass. The tars were obtained by condensing the pyrolysis volatiles in 3s. It shows that the tars contain large amounts of radicals, at a level of 1016spins/g, and are able to generate more radicals at temperatures of 573K or higher, reaching a level of 1019spins/g at 673K in less than 30min. The radical generation in the tar samples is attributed to the formation of THF insoluble matters (coke), which also contain radicals. The radical concentrations of the aqueous liquids obtained in pyrolysis are also studied.