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In this study, we explored the catalytic hydrocracking of pyrolytic lignin (PL) under supercritical methanol conditions. This approach aimed to minimize coke formation and prevent solidification of bio-oil, thus improving its manageability and upgrade potential in subsequent steps. Hydrocracking of PL at 250°C for 2 h with HZSM-5, Ni/HZSM-5, and Ni-Ru/HZSM-5 catalysts revealed a dominance of repolymerization over hydrocracking. Consequently, the methanol-soluble oil portion decreased to <37.8 wt%, accompanied by an increase in product molecular weight. However, by co-depositing Ni and Ru on ceria-impregnated HZSM-5 catalysts, the yield of methanol-soluble oil increased to 48.5–56.1 wt%, while the molecular weight decreased. By optimizing reaction parameters using Ni-Ru/Ce-HZSM-5 (NRC4H) at 300°C for 1 h, a methanol-soluble yield of 52.5 wt% was achieved, along with a substantial reduction in molecular weight. The interaction of Ni, Ru, and Ce elements on the catalyst's acidic surface led to smaller Ni and Ru particles and improved reducibility, resulting in a suitable acid-base balance that effectively suppressed repolymerization and enhanced hydrocracking. Furthermore, the detection of methane in the gas product served as an indicator of the hydrogenation reaction of double bonds during the hydrocracking process. • Bimetallic Ni Ru catalyst showed higher yields of methanol-soluble compounds. • Ce deposition in Ni-Ru/HZSM5 impacted dispersion of metals and catalyst properties. • Methane formation was a descriptor for Ni-catalyzed olefin hydrogenation. [ABSTRACT FROM AUTHOR]

Mongolian oak (MO), a lignocellulosic biomass feedstock comprising lignin, hemicellulose, and cellulose, was fractionated via reductive catalytic fractionation (RCF) into holocellulose-rich solid residue and lignin-derived phenol-rich liquid oil. To achieve an economically feasible RCF process, tungstate-zirconia (WZr)-supported metal catalysts, exhibiting bifunctionalities of hydrogen-adsorbing metal and acidic WZr, were used for depolymerizing and valorizing lignocellulose, and their catalytic activity was found to be highly dependent on the deposited metal. Ru/WZr exhibited excellent fractioning ability, achieving a maximum yield of 23.6 wt% of monomeric and dimeric compounds from MO and exhibiting the potential to be techno-economically viable. The superior activity of Ru/WZr can be attributed to the synergistic effects of metal and acid, which were studied by investigating the product distributions of aromatic small molecules depending on the properties of WZr-supported metal catalysts. The stabilization of reactive radical intermediates depending on the surface Brønsted acidity of acid catalysts and hydrogen-adsorbing ability of metals were also investigated. RCF reaction conditions were optimized for the maximum yield of monomeric compounds, which can be beneficial for the further development of industrial processes. [Display omitted] • Hardwood was fractioned using tungstate-zirconia-supported metal catalysts. • Phenols, carbohydrate-derived compounds, and pulp-rich solids were obtained. • Combined acidity and reductivity improved the catalytic fractionation. • Catalysis produced 33.5 wt% phenolic compounds from Mongolian oak. • Catalysis produced 61.9 wt% phenolic monomers from lignin fraction. [ABSTRACT FROM AUTHOR]

Although liquid products derived from the pyrolysis of biomass are promising for the production of petroleum-like hydrocarbon fuels, the catalytic burden of hydrodeoxygenation must be reduced to achieve feasible upgrading processes. Herein, mild hydrotreating of an acid-rich biomass pyrolysis oil (bio-oil) with an unusually high total acid number (588 mg KOH/g bio-oil) was performed to stabilize the low-quality bio-oil. Ru-added TiO 2 -supported transition metal catalysts stabilized the bio-oil by reducing its acidity more compared to what could be achieved by Ru-free catalysts; this process also leads to lower loss of organic compounds compared to when using a Ru/TiO 2 catalyst. Based on the performance of transition metal catalysts, including Ni, Co, and Cu, supported on TiO 2 , tungstate-zirconia, or SiO 2 , supported bimetallic catalysts were prepared by adding Ru to the TiO 2 -supported metal catalysts. The bimetallic catalysts Ru/Ni/TiO 2 and Ru/Co/TiO 2 exhibited good decarboxylation activity for the removal of carboxylic acids and a higher yield of organic compounds compared to that provided by Ru, which can be deemed appropriate for feedstocks when hydrodeoxygenation needs to suppress the loss of organic reactants. Using these catalysts, the carboxylic acid concentration was reduced to 319–323 mg KOH/g bio-oil with organic yields of 62–63 wt% at reaction temperatures 150–170 °C lower than the temperature required for direct conversion of carboxylic acids to alcohols or deoxygenates. The improved catalytic hydrotreating activity of Ru-added transition metals can be attributed to the high acid site densities of these catalysts along with their improved hydrogenation activities. Image 1 • Biomass pyrolysis oil was mildly hydrotreated using Ru/Ni/TiO 2 and Ru/Co/TiO 2 catalysts. • Ni and Co catalysts increased the organic yields while decreasing acid numbers. • Acids other carboxylic acids were removed at approximately 150–170 °C. • Mild hydrotreating of biomass pyrolysis oil can reduce the process burden of deoxygenation. The hydrotreating of bio-oil under mild conditions using inexpensive bimetallic catalysts advances the production of petroleum-like hydrocarbons from biomass wastes. [ABSTRACT FROM AUTHOR]

A calcium carbonate (CaCO 3)-supported Ru catalyst (Ru/CaCO 3) prepared by a wet impregnation method was used for the hydrodeoxygenation (HDO) of eugenol, a lignin model compound representing coniferyl alcohols, and was shown to surpass Ru supported on neutral (ZrO 2) and basic supports (MgAlO x , hydrotalcite, and MgO) in terms of deoxygenation activity. The production of deoxygenated compounds was observed during the batch reduction of eugenol with H 2 (room-temperature-equivalent pressure = 50 bar) over Ru/CaCO 3 at 250 °C, and the yields of compounds with no oxygen atoms (0-O) and one oxygen atom (1-O) were determined as 25.5 and 48.2%, respectively. X-ray photoelectron spectroscopy revealed that the improved hydrodeoxygenation activity could be ascribed to the increased electron density of catalytically active Ru species because of electron donation from the support. Unlabelled Image • Ru/CaCO 3 as a base-supported metal catalyst for the upgrading of bio-oil. • Improvement of HDO performance by the presence of CaCO 3. • Electron rich Ru particles formed by CaCO 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • High carbon number fuels were produced from furan by one-pot reaction. • Multifunctional catalysts were used for each step by manipulating reaction conditions. • Selective production of fuels was achieved depending Pd, Ni, and Ru. The multifunctionality of tungstate-zirconia-supported metal catalysts was demonstrated in a three-step conversion of 2-methylfuran (2-MF) into deoxygenated C 10-15 hydrocarbon fuels in a one-pot reactor, with condensation, hydrogenation, and hydrodeoxygenation performed using single tungstate-zirconia-supported metal catalysts. Manipulation of the reaction conditions, in particular, the reaction temperature and feeding reactant for each reaction step, enabled different catalytic functions of the tungstate-zirconia-supported metals at different reaction stages. Among the metals, Ni favored the production of C 10 hydrocarbons by suppressing further condensation to C 15 compounds, whereas Ru favored the trimerization of 2-MF during the condensation step to produce C 15 hydrocarbons. The superior hydrogenation of 2-MF on Pd reduced the formation of C 10-15 compounds. The acidity and hydrogenation activity of the catalysts were investigated to demonstrate the multifunctionality of tungstate-zirconia-supported metals. The catalysts were characterized using H 2 temperature programmed reduction, H 2 temperature programmed desorption, X-ray diffraction, transmission electron microscopy, and nuclear magnetic resonance; the results confirmed the variations in their activity among the different reactions. [ABSTRACT FROM AUTHOR]

Abstract: The oxidative coupling of methane (OCM) to produce ethane and ethylene, valuable hydrocarbons, was scaled-up using differential, mid-scale, and bench-scale reactors with 0.030, 2.73, and 40g of packed catalysts, respectively. Organic and inorganic binders, such as methylcellulose, Al2O3, MgO, and TiO2, were mixed with Na2WO4/Mn/SiO2 catalyst powder to produce catalyst pellets, and TiO2-mixed catalyst pellets exhibited the highest C2 hydrocarbon yield despite the lowest active catalyst content. The formation of hot spots, which suppressed the selective conversion to C2 hydrocarbons by further oxidation to CO and CO2, was observed in the mid- and bench-scale reactors because of poor heat transfer. Inert-gas-diluted reactants and lower O2 flow may inhibit the formation of hot spots and allow the development of industry-feasible OCM processes. [Copyright &y& Elsevier]

Abstract: For hydrogenolysis of butyl butyrate (BB), a series of Cu/ZnO/Al2O3 catalysts with different metal compositions were prepared, and characterized by N2O chemisorption for measuring Cu surface area and by chromatographic experiment for determining the heat of BB adsorption. As a result, the presence of ZnO in Cu-based catalysts was found to enhance the catalytic activity of Cu due to dual function of ZnO. The Cu surface area was linearly correlated with the butanol productivity, demonstrating that ZnO exerts the structural function in Cu/ZnO/Al2O3 catalysts. Additionally, the role of ZnO as a chemical contributor was revealed such that its presence leads to lower activation energy of the surface reaction, thus resulting in higher Cu catalytic activity obtained at a low temperature such as 200°C. Consequently, optimizing the Cu/Zn ratio in Cu/ZnO/Al2O3 catalyst is required to tune its structural and chemical characteristics of Cu metals, and thus to obtain a higher activity on the hydrogenolysis reaction. [Copyright &y& Elsevier]

Abstract: The catalytic oxidative coupling of methane (OCM) on transition metal-doped TiO2 nanowire catalysts was performed and the effects of metal dopants were studied. With transition metal doping, the electric and optical properties of nanowires were adjusted, which seemed to improve the catalytic activity and selectivity of the OCM reaction. A Mn-doped TiO2 nanowire catalyst exhibited the highest C2 yield with the highest (ethylene)/(ethane) ratio because of its moderate oxidation activity, while a highly active Rh-doped TiO2 nanowire catalyst converted methane into fully oxidized CO and CO2. The electric conductivity assessed by UV–vis absorption represented the oxidation activity of the nanowire catalysts. [Copyright &y& Elsevier]

Highlights: [•] Oxidative coupling of methane (OCM) on the Mg–Ti mixed oxide-supported catalysts. [•] High catalytic activity at the lower reaction temperature for the development of energy-saving processes. [•] Improved catalytic activity by the active surface lattice oxygen atoms. [Copyright &y& Elsevier]

Highlights: [•] Design and synthesis of highly dispersed Cu nanoparticle catalyst. [•] The high Cu surface area of 45.5m2/g obtained by the modified co-precipitation method. [•] Increased catalytic water-gas-shift reaction activity by increased Cu surface. [Copyright &y& Elsevier]

Abstract: Hydrodeoxygenation of the lignin monomer guaiacol was performed on the bifunctional catalysts of noble-metals supported on acidic matrices. The catalytic roles of metal nanoparticles and acidic supports were elucidated using the acid-site-measurement-dependent catalysis results, which demonstrated that metals were responsible for the hydrogenation of aromatic rings while metal-deposited acidic supports were indispensable to the deoxygenation of oxygenates. Among various combinations of metals and supports, Rh/SiO2-Al2O3 and Ru/SiO2-Al2O3 exhibited the highest cyclohexane yields. [Copyright &y& Elsevier]