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Gas-phase hydrodeoxygenation of guaiacol over iron-based catalysts. Effect of gases composition, iron load and supports (silica and activated carbon)

Paper ID Volume ID Publish Year Pages File Format Full-Text
46035 46428 2013 11 PDF Available
Title
Gas-phase hydrodeoxygenation of guaiacol over iron-based catalysts. Effect of gases composition, iron load and supports (silica and activated carbon)
Abstract

Fe/SiO2 is shown to be a selective catalyst for guaiacol hydrodeoxygenation (HDO). Guaiacol is used as a model compound to study the conversion of lignin pyrolysis vapours into aromatics (benzene, phenols). The effect of each individual gas present in a pyrolysis gas (H2, CO, CO2, H2O, CH4) on the selectivity of a 10 wt% Fe/SiO2 catalyst is studied (673 K, atmospheric pressure, 50 mol% H2, 1/WHSV = 0.6 gcat h/ggua). The speciation of the iron phase (metallic (α-Fe), carbide (Fe5C2), oxide (Fe3O4), and super-paramagnetic) in spent catalysts is revealed by XRD and Mössbauer spectroscopy as a function of gases composition. At least 3 types of carbonaceous deposit were evidenced by TPO analysis. TEM observations showed that iron particles size is not markedly affected by the reaction and that carbon deposit mainly occurs in the vicinity of iron particles. When all the gases except methane (Guaiacol + H2 + CO + CO2 + H2O) are simultaneously in the feed stream, the conditions are still sufficiently reducing to maintain the activity of the catalyst (66% of benzene and toluene carbon yield, 7.5 gcat h/ggua). The effects of support (silica or activated carbon-AC) and iron loading (5, 10, 15 wt% Fe/SiO2) were also studied. 10 wt% Fe/AC has a higher selectivity in phenol and cresols production than Fe/SiO2. Active sites and reaction mechanisms are discussed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydrodeoxygenation (HDO) of guaiacol is a model reaction for lignin pyrolysis vapours HDO. ► The effect of gases (H2, H2O, CO, CO2, CH4) on HDO selectivity and catalyst composition was studied. ► Iron speciation was analysed by XRD and Mössbauer analysis. Carbon deposit was analysed by TPO as a function of gas composition. ► Fe/SiO2 and Fe/Active carbon are selective catalysts for guaiacol HDO into benzene or phenol respectively.

Keywords
Biorefinery; Lignin; Hydrotreatment; Chemicals; Aromatic
First Page Preview
Gas-phase hydrodeoxygenation of guaiacol over iron-based catalysts. Effect of gases composition, iron load and supports (silica and activated carbon)
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 129, 17 January 2013, Pages 528–538
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis