Reductive deconstruction of organosolv lignin catalyzed by zeolite supported nickel nanoparticles

Abstract

Mechanistic aspects of deconstruction and hydrodeoxygenation of organosolv lignin using zeolite and SiO 2 supported Ni catalysts are reported. Lignin was deconstructed and converted to substituted alicyclic and aromatic hydrocarbons with 5 to 14 carbon atoms. Full conversion with total yield of 70 ± 5 wt% hydrocarbons was achieved at 593 K and 20 bar H 2 . The organosolv lignin used consists of seven to eight monolignol subunits and has an average molecular weight of ca. 1200 g mol −1 . The monolignols were mainly guaiacyl, syringyl and phenylcoumaran, randomly interconnected through β-O-4, 4-O-5, β-1, 5-5' and β-β ether bonds. In situ IR spectroscopy was used to follow the changes in lignin constituents during reaction. The reductive catalytic deconstruction of organosolv lignin starts with the hydrogenolysis of aryl alkyl ether bonds, followed by hydrogenation of the aromatic rings to cyclic alcohols. Oxygen is removed from the alcohols via dehydration on Brønsted acid sites to cyclic alkenes that are further hydrogenated. † Electronic supplementary information (ESI) available. See

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis

“…This observation was recently confirmed by two other studies on reductive depolymerisation of lignin to cycloalkanes performed in hydrocarbon solvents. [386,387] An interesting approach is to use the oil product from ab iomass liquefaction process itself as the solvent, as reported for ab iomass liquefaction process in guaiacol which afforded excellent bio-oil (> 93 %c arbon) yields. [388] Following the initial cycle,the produced oil was then used for subsequent biomass liquefaction and was demonstrated to be astill better solvent.…”

Preparative Aspects of Supported Ni2P Catalysts for Reductive Upgrading of Technical Lignin to Aromatics

“…The aromatic HYD level was only 43 wt% in this case. The optimized two-catalyst system presented very promising performance in comparison to other Nibased catalyst systems used for bio-oil and lignin upgrading [27,28].…”

“…Ni/SiO 2 has also been employed to depolymerize lignin in the presence of molecular hydrogen, mainly yielding substituted alicyclic and aromatic hydrocarbons [28]. The use of Ni-phosphide catalysts instead of reduced Ni is explored in this work in order to retain high HDO reaction rate and to lower the rate of aromatic ring hydrogenation.…”

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

“…New transformation processes should be developed in order to utilize the above-mentioned fractions more efficiently. The research in biomass transformation to produce bio-oil via flash pyrolysis [1] and utilize different lignin fractions to produce chemicals and fuels [2,3] has been very intensive in the recent years in part due to the depleting fossil based feedstock and strive towards carbon neutral fuels and chemicals. Further transformation of these fractions, can, however, be demanding, since bio-oil is unstable, exhibiting low pH, whereas lignin is a complex polyphenolic polymer difficult to transform selectively.…”

“…Further transformation of these fractions, can, however, be demanding, since bio-oil is unstable, exhibiting low pH, whereas lignin is a complex polyphenolic polymer difficult to transform selectively. One of the most important research area in transformation of bio-oil [4] and lignin [2,3] is catalytic hydrodeoxygenation (HDO) during which fuels or suitable blending agents are produced including benzene, toluene as well as cycloalkane and-ketones. Several reviews have already been published on HDO of lignin based phenols [5][6][7][8][9][10][11][12][13][14][15].…”