Ru-Catalyzed Oxidative Cleavage of Guaiacyl Glycerol-β-Guaiacyl Ether-a Representative β-O-4 Lignin Model Compound

Abstract

The introduction of efficient and selective catalytic methods for aerobic oxidation of lignin and lignin model compounds to aromatics can extend the role of lignin applications in biorefineries. The current study focussed on the catalytic oxidative transformation of guaiacyl glycerol--guaiacyl ether (GGGE)–a -O-4 lignin model compound to produce basic aromatic compounds (guaiacol, vanillin and vanillic acid) using metal-supported catalysts. Ru/Al2O3, prepared with ruthenium(IV) oxide hydrate, showed the highest yields of the desired products (60%) in acetonitrile in a batch reactor at 160 C and 5-bar of 20% oxygen in argon. Alternative catalysts containing other transition metals (Ag, Fe, Mn, Co and Cu) supported on alumina, and ruthenium catalysts based on alternative supports (silica, spinel, HY zeolite and zirconia) gave significantly lower activities compared to Ru/Al2O3 at identical reaction conditions. Moreover, the Ru/Al2O3 catalyst was successfully reused in five consecutive reaction runs with only a minor decrease in catalytic performance.

Fungal enzyme degradation of lignin-PLA composites: Insights from experiments and molecular docking simulations

“…1 contains guaiacyl units with hydroxyl groups at α- and γ-positions. This GGE model has been used to represent the lignin model for quantum chemical density functional calculations (DFT) for various studies, including lignin dissolution in different solvents [ [38] , [39] , [40] ] and bond dissociation mechanisms [ [41] , [42] , [43] , [44] ]. The GGE model compound was oxypropylated (oGGE) at the hydroxyl group positions to study the binding interaction with the enzyme.…”

Revealing of Supercritical Water Gasification Process of Lignin by Reactive Force Field Molecular Dynamics Simulations

“…Before performing ReaxFF simulations, the isolated geometry was optimized using wB97X-D/6-311g(d,p) level of theory as described in the reference [34] using GAMESS code [35]. The GGE model has been used successfully for various studies, including dissolution of lignin, using different solvents [36,37], catalytic cleavage reactions [38][39][40][41] and pyrolysis [42][43][44]. The simulation box was constructed with three GGE models with 200 water molecules using Packmol (18.169, University of São Paulo, Brazil, 2009) [45] and the setup is shown in Figure 1b.…”

Sustainable Catalytic Conversion of Biomass for the Production of Biofuels and Bioproducts

“…The group of Dr. Anders Riisager contributes with an efficient and selective catalytic method for the aerobic oxidation of lignin and lignin model compounds to aromatics. Particularly, their work relates to the oxidative cleavage catalysed by Ru/Al 2 O 3 of a representative lignin model compound, guaiacyl glycerol-β-guaiacyl ether [12]. Karen Wilson et al present the acetic acid ketonization catalysed by Ga/HSM-5 for the upgrading of biomass pyrolysis vapours.…”