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Study on the effect of condensing temperature of walnut shells pyrolysis vapors on the composition and properties of bio-oil

Wang, Chu, Luo, Zejun, Diao, Rui, Zhu, Xifeng
Bioresource technology 2019 v.285 pp. 121370
acetic acid, biofuels, condensation (phase transition), furfural, guaiacol, pyrolysis, temperature, vapors, walnut hulls
The effect of condensing temperature on composition of bio-oil obtained via fractional condensation was investigated by pyrolysis-condensation experiments of walnut shells at condensing temperatures from 290 K to 370 K. The condensing efficiency of the first stage condenser decreased from 0.59 to 0.12 with increasing temperature. Moisture of bio-oil decreased from 40% to 5%, but the C/O ratio increased from 0.50 to 1.50. Compared with contents observed at the lowest condensation temperature, the maximum content of each component increased by 50%–500%. Combined with variations in condensing efficiency and composition content, the optimum condensing temperature range for declining water in bio-oil was 340–350 K. The condensing temperature associated with the enrichment of acetic acid and furfural was 345 K. The 355 K optimum condensing temperature could be selected to achieve the maximum enrichment of guaiacol and its derivatives.