title: Investigation of chemical modifications of micro- and macromolecules in bio-oil during hydrodeoxygenation with Pd/C catalyst in supercritical ethanol.
abstract: Miscanthus bio-oil was subjected to hydrodeoxygenation (HDO) with Pd/C at different temperatures (250, 300 and 350°C) and times (30, 45 and 60 min) to investigate the chemical modification of micro- and macromolecules in bio-oil. Four main products - char, gas and two immiscible oils (light and heavy oil) - were obtained from the HDO reaction. Yields of heavy oil as a targeting product of HDO varied from 60% to 13%, whereas those of gas and char were ranged from 7% to 36% and 6% to 17%, respectively. Water content was estimated to<1% and heating value was 26-31 MJ kg(-1). Reduction of unstable oxygen-containing compounds such as acids (2-hydroxy-butanoic acid), aldehydes (furfural), alcohols (butanedial) and sugars (levoglucosan) were characteristic in heavey oil. Apart from hydrogenation and deoxygenation, micromolecules in bio-oil were plausibly modified to stable ketones, esters and saturated components via demethoxylation, dealkylation, decarbonylation, dehydroxylation and ring opening. Macromolecular lignin fragments (referred to as pyrolytic lignins in bio-oil and phenol polymers in heavy oil) were extracted and subjected to several analyses. Approximately 60% of the pyrolytic lignins were decomposed into low molecular weight compounds during HDO reaction. Moreover, essential functional groups, OCH3 and phen-OH groups attached to pyrolytic lignin, were severely modified during HDO reaction.
authors.affiliation: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
authors.forename: Shinyoung
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
authors.forename: Hyewon
authors.initials: H
authors.lastname: Hwang
authors.affiliation: Department of Environmental Engineering, Yonsei University, Wonju 220-710, Republic of Korea.
authors.forename: Hang Seok
authors.initials: HS
authors.lastname: Choi
authors.affiliation: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea. Electronic address: cjw@snu.ac.kr.
authors.forename: Joon Weon
authors.initials: JW
authors.lastname: Choi
mesh_terms: D056804:Biofuels / Q000032:analysis*; D002384:Catalysis; D000431:Ethanol / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006859:Hydrogen; D006865:Hydrogenation; D010636:Phenols / Q000032:analysis; D006109:Poaceae / Q000737:chemistry*; D011108:Polymers / Q000032:analysis; D011312:Pressure; D013696:Temperature; D013997:Time Factors
chemical_list: D056804:Biofuels; D010636:Phenols; D011108:Polymers; D000431:Ethanol; D006859:Hydrogen
keywords: Bio-oil; Hydrodeoxygenation; Miscanthus; Pyrolytic lignin; Supercritical ethanol