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Herein, a Ru-decorated carbon material bearing unique surface chemistry (Brønsted acidic phosphate groups, Lewis basic N-groups and oxygen functional groups) is shown to exhibit exceptional activity, selectivity and stability upon direct hydrogenation of aqueous levulinic acid (LA) (0.47 M and 0.95 M) to γ-valerolactone (GVL) under mild conditions (25–95 °C and 3.5–5 bar). The multifunctional Ru/carbon catalyst outperformed the bifunctional Ru/NbOPO4, and blended (physically mixed) catalytic systems comprising of commercial Ru/carbon (hydrogenation catalyst) and NbOPO4/Amberlyst 15 (acid promoter/co-catalyst). The material also demonstrated remarkable stability for energy efficient GVL production in a fixed-bed reactor under continuous flow conditions, maintaining stable GVL productivity during 52-day time on stream operating at 3.5–5 bar, 80–95 °C and low H2/LA ratio (4–17:1 mol/mol). The exceptional catalytic performance and long term stability of the multifunctional carbocatalyst was attributed to the presence of highly active Ru(0) nanoparticles stabilized on N-doped carbon framework and acidic phosphates and RuOx/RuO2 sites, which promote LA hydrogenation and intramolecular esterification of 4-hydroxypenatonnic (4-HPA) in tandem, affording a high GVL selectivity. The catalyst's combination of high productivity, long-term stability, and ability work under intensified setting in mid conditions highlight its potential for energy efficient GVL production at large scale.

NbOPO4 supported TiO2 materials were demonstrated to be excellent catalysts for selective conversion of C6-carbohydrates to 5-hydroxymethylfurfural in an environmentally benign dimethyl carbonate-water solvent system. The materials presented high activity and excellent stability in sub-critical water conditions (upto 180 °C and 20 bar), enabling continuous 5-hydroxymethylfurfural production from highly concentrated sugars (35 wt% fructose, glucose and glucose:fructose mixtures) in a micro fixed-bed reactor. The high catalytic activity (6–27.3 KgHMFKgCat−1day−1) and good-to-excellent HMF selectivity (55–91 %) and exceptional hydrolytic stability and regenerability observed under process conditions was attributed to a highly crystalline NbOPO4 phase with Q2 and Q3 phosphates stabilized on a TiO2 framework with tunable acidity (0.11–0.52 mmolH+g−1 and Brønsted/Lewis ratio) and acidic strength comparable to bulk-NbOPO4. Furthermore, our experiments also revealed the importance of organic solvents in modulating catalyst acidic properties, particularly the strength of Brønsted acid sites which, in turn, influenced the HMF productivity.

Triglycerides or vegetable oils as fuels is an old idea that can be traced back to the early days of diesel engine development. In this chapter, an overview of the fuel properties of triglycerides and their various upgrading technologies (physical and chemical; catalytic or non-catalytic) are discussed. Moreover, the composition of various feedstocks, the various catalyst materials employed in triglyceride upgrading, and the influence of the support materials, as well as sulfide and other promoters or feed impurities, are briefly discussed. Finally, a number of important large-scale, commercial processes in renewable-diesel production are reviewed and general operating strategies are discussed. In general, it can be concluded that deoxygenative transformation of triglycerides seems to be the most effective, enabling direct production of drop-in hydrocarbon fuels (green diesel or green jet fuels). In summary, significant possibilities still exist for further development of improved deoxygenation technologies that aim to improve the commercial feasibility of processing triglycerides into green hydrocarbon fuels of tomorrow.

The transition to sustainable energy systems requires efficient catalysts capable of upgrading biomass into liquid fuels and platform chemicals to meet future energy demands. Metal oxides, as supports in bifunctional catalysts, are pivotal due to their ability to provide active sites, create oxygen vacancy defects, and facilitate electron transfer. While these properties are well-studied in the presence of metal nanoparticles, the intrinsic activity and surface properties of stand-alone oxide supports remain underexplored.

This study investigates the role of bare metal oxides (TiO2, ZrO2, and Al2O3) in the direct vapor upgrading of beechwood biomass vapors via a two-stage process comprising a non-catalytic hydropyrolysis step followed by ex-situ catalytic upgrading. The performance of metal oxides was compared with non-metal oxide such as SiO2. Through extensive characterization (H2-TPR, NH3-TPD, O2-TPD, CO2-TPD, BET, XRD, and Pyridine-FTIR), we establish that the combination of high weak acidity, low strong basicity, and reducibility of TiO2 results in superior catalytic performance. Ex-situ upgrading over TiO2 achieves the lowest oxygen-to-carbon ratio (O/C = 0.09) in bio-oil, the highest C2+ fraction (98.7 %), and the largest C8-C16 fraction (49.9 %), while minimizing light molecule formation (16.5 %). Binding energy analyses further reveal that weak adsorption of model compounds (acetone, acetic acid, guaiacol) occurs on the TiO2 (101) surface compared to other oxide surfaces, highlighting its exceptional properties for deoxygenation and C–C coupling. This work establishes the first comprehensive correlation between the catalytic performance of oxide supports and their surface properties using actual biomass feedstock, thus offering valuable insights for designing advanced catalysts for biomass upgrading.

Catalytic conversion of carbon dioxide (CO2) into useful chemicals such as methane (CH4) is a promising carbon utilization method that effectively mitigates CO2 and partially meets energy needs. The characteristics of commonly used nickel (Ni) supported meso/microporous catalysts for CO2 methanation can be tailored by tuning the structural properties of the support and adding promoters. This work investigated the Ni supported over hierarchical zeolite 13X (h13X) and incorporated with different promoters (Mg, Ca, Ce, and La) developed using the wet-impregnation method. The catalysts were thoroughly characterized using SEM, EDS, XRD, H2-TPR, CO2-TPD, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and N2 sorption and desorption techniques and evaluated for CO2 methanation. The impact of promoters on the characteristics of the catalysts was observed with improved surface basicity in CO2-TPD and metal-support interaction in H2-TPR analysis. Among the promoted catalysts, the NiLa/h13X catalyst exhibited the highest catalytic activity with a maximum conversion of 76% and CH4 selectivity of 98.5% at 400 degrees C and 20 bar at GHSV of 60,000 mL gcat-1 h-1, respectively. Regarding stability, the Mg-promoted catalyst exhibited better stability during 24 h of reaction than other catalysts, demonstrating better resilience against deactivation. The enhanced performance of the NiLa/h13X catalyst could be credited to the increased surface basicity, high surface area, and dispersion. This study highlights the potential of hierarchical porous zeolites for CO2 methanation and other heterogeneous reactions.

Lignin valorization has attracted significant attention in recent years due to its abundance and potential as a renewable organic carbon resource to produce a variety of value-added chemicals and fuel additives. Catalytic upgrading of lignin faces challenges due to its complex structure and an active catalyst with selective surface properties is needed to break the stable C–O and C–C interunit linkages. In the present work, we developed a series of multifunctional Ru/NbOPO₄/TiO₂ catalysts with varying surface acidic properties and explored their potential upon hydrogenolysis of lignin model compound eugenol. Textural and surface acidic properties of the prepared materials were studied by means of different techniques such as N₂-physisorption, NH₃-TPD, XRD, SEM-EDS, Raman spectra, FT-IR, and TEM. Our catalytic results revealed synergistic role of acid and metal sites upon catalyst performance, whereupon high yields of hydrocarbons (86.9–100 wt.%) were obtained with selective cleavage of the methoxy and hydroxy groups under milder conditions. A kinetic study further identified the reaction mechanism and determined a rate law and partial reaction orders. This research advances the understanding of catalyst design for upgrading of the lignin or lignin monomers into value added chemicals. and on the other hand, contributes to sustainable development by maximizing biomass usage and providing environmentally friendly alternatives in renewable energy.

Anatase TiO₂ (TiO₂-A) has been utilized for biomass upgrading processes such as hydrodeoxygenation (HDO) and Carbon-Carbon (C-C) coupling reactions (ketonisation and aldol condensation), where Ti-O Lewis acid-base pairs (LABPs) serve as active sites. Altering the metal oxide’s reduction state can modify its acid-base properties, yet the effects of oxygen vacancy coverage on TiO₂ during biomass vapor upgrading remain unclear. This study investigates the dynamics between C-C coupling and HDO reactions in the ex-situ upgrading of beechwood pyrolysis vapors at 600 °C and 1 atm. LABPs properties were tuned by varying degrees of oxygen vacancy on TiO2, and the catalyst was characterized by BET, XRD, NH₃-TPD, CO2-TPD, H₂-TPR, Raman, UV–vis, SEM-EDX, and FTIR. Our study demonstrated that decreasing the O/Ti ratio (i.e., increasing oxygen vacancies) promotes C–C coupling and HDO reactions. The highest C-C coupling and moderate HDO observed on an O/Ti ratio of 1.7 produced the highest jet-fuel fraction (56.5%) compared to other TiO₂ variants. The C2+ selectivity shifted from 85.2% of hydropyrolysis oil to 99.2 wt%, while the O/C and H/C ratios changed from 0.45 and 1.55 of hydropyrolysis oil to 0.06 and 1.39, respectively, on TiO₂ with an O/Ti ratio of 1.7. The adsorption behavior of the acetone, furan, and guaiacol on LABPs was evaluated on the (1 0 1) plane of A-TiO₂ by DFT, which corroborated the experimental findings. This is the first time a deep correlation has been provided on the influence of oxygen vacancies on the vapor phase upgrading of real biomass feedstock.

Halogenated porous melamine polymers were demonstrated as an efficient catalyst for CO2-epoxide cycloaddition, selectively (>99%) producing C3-C12 cyclic carbonates in excellent yields (upto 99%) under solvent and co-catalyst free conditions. The halogenated polymers outperformed benchmark catalysts incorporating only basic (N-doped carbon, ZIF-8, N-rich melamine polymer) or nucleophilic (TBAB, KI) sites. The superior catalytic performance of these inexpensive polymers was attributed to their unique surface chemistry incorporating abundant, stable basic N sites (amine N and protonated N) and nucleophilic (Cl-, Br- or I-) that enabled simultaneous activation of both epoxide and CO₂ molecule (supported by kinetic and DFT studies). Further, among halogenated polymers a Br- containing material (PMF_Br) presented highest activity owing to its balanced CO₂-philicity and strong nucleophilicity. Most importantly, PMF_Br was robust, reusable and maintained stable performance for continuous production of C3-C4 cyclic carbonate (120 ^oC, 0.3-0.83 h^-1 WHSV_epoxide and 15 bar) in a fixed-bed reactor during 60-190 h TOS.

The present invention provides a method for producing hydrocarbons having 6 to 20 carbon atoms, comprising the steps of: a) providing a feedstock comprising saturated fatty acids, and/or derivatives thereof; b) deoxygenating the feedstock in the presence of a metal free hydrogenation and decarboxylation catalyst under low-pressure hydrothermal conditions, wherein the temperature is in the range 350-400 °C and the pressure is in the range 10-30 bar; and wherein the catalyst is a heteroatom-doped carbon material. Furthermore, there is provided a system for preforming the method in a single reactor (R) system comprises a bed of a carbon catalyst facilitating simultaneous hydrogenation and decarboxylation

For the first time, a tandem catalytic material, 5 wt. % Pd/NbOPO₄, was utilized in the depolymerization of wood in supercritical ethanol under hydrogen atmosphere. The experiments were conducted under various conditions, with fresh, and acetone extracted birch. A comprehensive analysis was performed to elucidate the dissolution efficiency and achieved product distribution. The results indicated that with fresh birch, 34 wt. % of lignin monomer yield with 84 wt. % delignification efficiency were obtained while with extracted wood, 35 wt. % of lignin monomer yield with 78 wt. % delignification efficiency were achieved. The total lignin monomer content extracted from the fresh birch is composed of 76.9 wt. % of dimethoxyphenols and 16.5 wt. % with the guaiacol structure. Major lignin monomer product was homosyringaldehyde (61.9 wt. %). With extracted wood, 93.2 wt. % of dimethoxyphenols (63.6 wt. % homosyringaldehyde) and 6.8 wt. % of guaiacol-monomers were achieved. It was concluded that the depolymerization occurred via breaking of the ether bonds in lignin, including ether hydrolysis by Lewis acid sites over the solid acid catalyst and with subsequent deoxygenation of monophenols over Pd. In addition, an extraction process was proposed to extract the aromatic fraction from the obtained biocrude.