Selective Hydrodeoxygenation of Lignin-Derived Phenols to Aromatics Catalyzed by Nb2O5-Supported Iridium

The dominating catalytic approach to aromatic hydrocarbons from renewables, deoxygenation of phenol-rich depolymerized lignin bio-oils, is hard to achieve: hydrodeoxygenation (HDO) of phenols typically leads to the loss of aromaticity and to non-negligible fractions of cyclohexanones and cyclohexanols. Here, we report a catalyst, niobia-supported iridium nanoparticles (Ir@Nb₂O₅), which combines full conversion in the HDO of lignin-derived phenols with appreciable and tunable selectivity for aromatics (25-95%) under mild conditions (200-300 °C, 2.5-10 bar of H₂). A simple approach to the removal of Brønsted-acidic sites via Hünig's base prevents coking and allows reaction conditions (T > 225 °C, 2.5 bar of H₂), promoting high yields of aromatic hydrocarbons.

Mo single atoms in the Cu(111) surface as improved catalytic active centers for deoxygenation reactions

The surface Mo-doped Cu(111) catalyst feature improved performance towards deoxygenation reactions, acting as a single-atom alloy capable of breaking Brønsted–Evans–Polanyi relations for carbonyl bond scissions.

Highly selective demethylation of anisole to phenol over H4Nb2O7 modified MoS2 catalyst

H₄Nb₂O₇ modified MoS₂ catalyst enables the highly selective demethylation of anisole to phenol which opens a window for the hydrogenolysis of lignin to value-added chemicals.

Identification of electron-rich mononuclear Ni atoms on TiO2-A distinguished from Ni particles on TiO2-R in guaiacol hydrodeoxygenation pathways

Electron-rich mononuclear Ni atoms located at the oxygen vacancies on TiO₂-A are the active sites for selective hydrodeoxygenation of guaiacol to phenolics, while the reduced Ni particles on TiO₂-R catalyze hydrogenative aromatic ring saturation.

Stepped M@Pt(211) (M = Co, Fe, Mo) single-atom alloys promote the deoxygenation of lignin-derived phenolics: mechanism, kinetics, and descriptors

HDO of lignin-derived phenolics on stepped M@Pt(211) (M = Co, Fe, Mo) single-atom alloy was computationally explored. Either C–O bond length or *OH binding energy was confirmed as an effective catalytic descriptor for predicting HDO performance.

Metal-Acid Synergy: Hydrodeoxygenation of Anisole over Pt/Al-SBA-15

Hydrodeoxygenation (HDO) is a promising technology to upgrade fast pyrolysis bio-oils but it requires active and selective catalysts. Here we explore the synergy between the metal and acid sites in the HDO of anisole, a model pyrolysis bio-oil compound, over mono- and bi-functional Pt/(Al)-SBA-15 catalysts. Ring hydrogenation of anisole to methoxycyclohexane occurs over metal sites and is structure sensitive; it is favored over small (4 nm) Pt nanoparticles, which confer a turnover frequency (TOF) of approximately 2000 h^-1 and a methoxycyclohexane selectivity of approximately 90 % at 200 °C and 20 bar H₂ ; in contrast, the formation of benzene and the desired cyclohexane product appears to be structure insensitive. The introduction of acidity to the SBA-15 support promotes the demethyoxylation of the methoxycyclohexane intermediate, which increases the selectivity to cyclohexane from 15 to 92 % and the cyclohexane productivity by two orders of magnitude (from 15 to 6500 mmol g_Pt ^-1  h^-1 ). Optimization of the metal-acid synergy confers an 865-fold increase in the cyclohexane production per gram of Pt and a 28-fold reduction in precious metal loading. These findings demonstrate that tuning the metal-acid synergy provides a strategy to direct complex catalytic reaction networks and minimize precious metal use in the production of bio-fuels.

The role of oxophilic Mo species in Pt/MgO catalysts as extremely active sites for enhanced hydrodeoxygenation of dibenzofuran

The catalytic performance of the selective hydrodeoxygenation of dibenzofuran can be controlled by the MoO_x surface density and varied with the increased MoO_x surface density in a volcano-shape manner.

The role of oxygen vacancies in biomass deoxygenation by reducible zinc/zinc oxide catalysts

Selective removal of oxygen is the key challenge in the upgrading of biomass-derived molecules, and reducible metal oxides have shown the ability to catalytically remove oxygen even at low exogenous H₂ pressures.