Defect-engineered Ru/NbCeO x -assisted photocatalysis under visible light enables the selective conversion of lignin model compounds and native lignin into value-added aromatic monomers and fuel precursors.

Abstract Developing sustainable and hydrogen-efficient catalytic strategies for lignin valorization remains a significant challenge for renewable energy and environmental applications. Herein, we report a defect-engineered, oxygen vacancy–rich Ni–Ru/HO–TiOx catalyst for selective catalytic transfer hydrogenolysis (CTH) of β-O-4 lignin model compounds and native hardwood lignin into value-added chemicals and fuels. Surface hydroxyl enrichment and oxygen vacancies are proposed to enhance metal–support interactions, hydrogen spillover, and C–O bond activation over the optimized 3Ni1Ru/HO–TiOx catalyst. Using isopropanol as both solvent and hydrogen donor, the catalyst achieved >99% conversion of 2-phenoxy-1-phenylethanol at 160 °C, with tunable selectivity toward aromatic and cyclic hydrocarbons in the absence of externally supplied molecular hydrogen. Mechanistic and kinetic studies suggest that in situ alcohol dehydrogenation, defect-rich interfaces, and modulated surface acidity facilitate hydrogen transfer, selective ether bond cleavage, and controlled hydrogenation. The catalyst showed good stability, recyclability, and minimal metal leaching. Furthermore, the catalytic system upgraded organosolv hardwood lignin into C6–C9 cyclic hydrocarbons. CHEM21 green metrics analysis indicated improved material efficiency and reduced environmental impact under optimized conditions. These findings demonstrate the potential of defect-engineered catalysts for sustainable lignin upgrading using catalytic transfer hydrogenolysis pathways.

Biomass conversion requires catalysts that remain active under severe thermal and chemical conditions. Conventional supported catalysts suffer from deactivation due to sintering, coking, and leaching. Metal exsolution, the redox-driven migration of metal ions from oxide lattices to the surface, offers a transformative approach for designing durable, regenerable catalysts. The resulting socketed nanoparticles exhibit strong metal-support coupling, enhanced redox reversibility, and exceptional resistance to deactivation. This Conceptual review establishes a framework linking exsolution fundamentals with catalytic performance in biomass valorization. By integrating defect engineering, dopant selection, and lattice control, exsolved catalysts achieve tuneable activity, selectivity, and self-regeneration. Their structural robustness and adaptive functionality position them as key materials for the next-generation biorefineries and sustainable chemical manufacturing.

The exsolution of metal nanoparticles from solid lattices provides a strategy for designing efficient catalysts in catalytic transfer hydrodeoxygenation (CTHDO). This approach allows precise control over key catalytic properties, including nanoparticle density, surface acidity, and oxygen vacancies, which are crucial for the optimization of CTHDO reactions. We report a NiAl2O4-550 catalyst for the selective CTHDO of furfural (FUR) to 2-methylfuran (2-MF) with high selectivity. Using isopropyl alcohol (IPA) as a hydrogen donor, NiAl2O4-550 exhibited a high performance under favorable reaction conditions. Characterization (PXRD, Raman, TEM, XPS, NH3-TPD, Pyridine-FTIR, and H2-TPR/TPD) highlights the role of surface oxygen vacancies and exsolved Ni-metal in enhancing catalytic activity. XPS, O2-TPD, and EPR confirm their contributions to FUR conversion. DFT calculations reveal that oxygen-deficient sites improve substrate-catalyst interactions, lowering the energy barrier for FUR to 2-MF conversion. Under mild conditions (180 degrees C, 2 MPa of N2), NiAl2O4-550 afforded similar to 99% FUR conversion with a 98.1% 2-MF selectivity, surpassing that of reported catalysts. The combination of oxygen vacancies and metal exsolution enables controlled transfer hydrodeoxygenation, offering an effective strategy for biofuel production. This study establishes a versatile platform for next-generation catalysts in environmentally conscious catalysis, contributing to advancements in catalyst design.

The conversion of lignocellulosic biomass into lignin bio-oil and its subsequent upgrading into saturated cyclic products holds considerable promise for applications in the aviation industry. This study reports the synthesis of a defect-enriched monometallic CoOx/Co-350-30 catalyst, which is utilized for hydrogenating lignin-derived molecules and lignin bio-oil obtained via reductive catalytic fractionation (RCF) of wheat straw. Under optimized conditions (180 °C, 2 MPa H2, 2 h), benzyl phenyl ether (BPE) affords complete conversion, yielding ≈99% cyclohexanol and ≈98% methylcyclohexane. RCF of wheat straw (conducted at 230 °C and 3 MPa H2 for 6 h) affords lignin bio-oil containing ≈43% alkyl-substituted phenols. Hydrogenation of the bio-oil using the CoOx/Co-350-30 catalyst (at 250 °C for 2 h at 3 MPa H2) results in ≈98% yield of cyclic aliphatic alcohols. Comparative studies with commercial 5%Ru/C reveal that the CoOx/Co-350-30 catalyst produced products with lower oxygen functionalities and fewer native lignin linkages. Comprehensive catalyst characterizations and activity tests were conducted to propose a plausible reaction mechanism for BPE hydrogenation. The cobalt-based catalyst, devoid of noble metals, provides a sustainable and cost-effective method for biomass conversion into fuel-range products, addressing the growing industry demand for more efficient catalytic processes.

Lignin valorization offers a sustainable route to biofuel production, addressing global energy demands and environmental concerns. In this study, Ru-decorated cerium phosphate (CePO4) catalysts with distinct crystalline phases (hexagonal, monoclinic, and mixed) were synthesized to investigate the influence of phase-dependent properties on catalytic transfer hydrogenation (CTH) of phenethyl phenyl ether (PPE), a lignin model compound, and catalytic hydrogenation of lignin bio-oil derived from softwood biomass into cycloalkanes. The hexagonal phase (CePO4-H) emerged as the most effective support, offering superior Lewis/Bronsted acidity, redox activity (Ce3+/Ce4+), and Ru nanoparticles dispersion. The Ru(2%)/CePO4-H offered 99% conversion under CTH conditions, selectively cleaving beta-O-4 ether linkages in PPE to produce ethylbenzene and cyclohexanol as the sole products under mild conditions (150 degrees C, 6 h, 1 MPa N2). The catalyst afforded a near-quantitative yield of saturated cyclic hydrocarbons from PPE under catalytic hydrogenation conditions (150 degrees C, 6 h, 1 MPa H2). Furthermore, Ru(2%)/CePO4-H offered nearly complete conversion (99%) of lignin bio-oil into fully saturated cyclic C6-C9 products (suitable for aviation fuel applications) with up to 99% selectivity under catalytic hydrogenation conditions (220 degrees C, 3 MPa H2). Mechanistic insights revealed that the enhanced catalytic performance arises from phase-dependent surface acidity, electron-enriched Ru0 sites, and strong metal-support interactions, facilitating efficient C-O bond cleavage and hydrodeoxygenation/hydrogenation of PPE. The green chemistry metrics further substantiate the reduced environmental impact of this catalytic process. This work highlights the transformative potential of phase-engineered Ru(2%)/CePO4-H catalysts for lignin bio-oil upgrading. It provides a blueprint for designing robust catalysts with tunable properties for scalable, sustainable biofuel production.

The sustainable synthesis of nitrogen‐containing compounds from biomass‐derived platform molecules offers a viable route toward green chemical production. Herein, we report a selective and efficient strategy for the reductive amination of furfural (FUR) to furfurylamine (FAM) using a Ni(5%)/TiO 2 catalyst under mild conditions. The catalyst was prepared via the wet impregnation method and comprehensively characterized using powder X‐ray diffraction (PXRD), Raman spectroscopy, electron paramagnetic resonance (EPR), H 2 ‐TPR, NH 3 ‐TPD, field‐emission scanning electron microscopy (FE‐SEM), high‐resolution transmission electron microscopy (HR‐TEM), and X‐ray photoelectron spectroscopy (XPS) techniques. These analyses confirmed the successful dispersion of Ni nanoparticles on TiO 2 and revealed strong metal–support interaction (SMSI), modulated surface acidity, and oxygen vacancies that facilitate the reductive amination of FUR. Catalytic evaluation demonstrated an exceptional FAM yield of 98.6% at 90°C in a NH 3 (aq.):CH 3 OH solvent system, with NH 3 (aq.) serving as the nitrogen source. The superior performance is attributed to the synergistic interplay between metallic Ni sites, surface oxygen defects, and tailored acidity, which enhance imine formation and subsequent hydrogenation. The catalyst also exhibited excellent reusability over multiple cycles with negligible activity loss. Furthermore, a qualitative and quantitative assessment using the CHEM21 toolkit indicated that the process has a low environmental impact. Overall, this work identifies Ni(5%)/TiO 2 as an efficient, cost‐effective, and environmentally benign non‐noble metal catalyst for the selective synthesis of FAM from renewable FUR, offering a promising pathway for valorizing biomass into value‐added nitrogenated chemicals.

Converting lignin, a key sustainable biopolymer, into valuable oxygen-containing compounds is a significant challenge. To address such a challenge, photocatalytic self-transfer hydrogenolysis strategy is employed utilizing a CdS(x%)/TiO2 heterojunction photocatalyst, with minimal CdS loading on TiO2. The CdS(3 %)/TiO2 catalyst, under blue light, dehydrogenates HCa-OH groups, transferring hydrogen to C beta-O bonds, cleaving beta-O-4 ether bonds in lignin model compounds yielding over 95 % phenols and acetophenones. It utilizes glyceryl moieties as a hydrogen source, yielding similar to 24 % of diverse lignin monomer derivatives from teak lignin. Improved charge separation in the CdS(3 %)/TiO2 catalyst is revealed by electrochemical and spectral analyses and exhibits delayed charge carrier recombination. Scavenging studies confirm a type II charge transfer mechanism and support visible-light-driven lignin fragmentation. The present photocatalytic process offers a promising, costeffective approach for converting lignin into valuable aromatic compounds, advancing renewable biomassderived chemicals.

The targeted catalytic transfer hydrodeoxygenation (CTHDO) of vanillin (VAN) to 2-methoxy-4-methylphenol (MMP) holds promise as a noteworthy subject in the domain of bio-oil utilization, offering potential as a future biofuel and finding versatile use in fragrances and pharmaceutical industry. In this study, stable, cost-effective Ni nanoparticles supported on montmorillonite (MMT) clay was synthesized for eco-friendly, alcohol-mediated CTHDO of VAN to MMP. The Ni(10 %)/MMT catalyst achieved >99 % VAN conversion and 95.2 % MMP selectivity using isopropanol (IPA) as a solvent and hydrogen donor. Characterization encompassing PXRD, SEM, TEM, and XPS confirmed successful Ni integration onto MMT. NH3-TPD, pyridine-IR, and H-2-TPR analysis evaluated catalyst surface acidity and reducibility. The synergy between surface-modulated acidity of MMT and Ni nanoparticles collectively facilitated IPA and VAN activation, driving CTHDO performance. The Ni(10 %)/MMT catalyst displayed sustained activity over five recycles. Its exceptional stability and performance underscore its potential as an eco-friendly, sustainable, non-noble transition metal-based catalyst for the hydrogenating lignin bio-oil model compounds, contributing to greener catalytic advancements.

The Cover Feature illustrates the conversion of lignocellulosic biomass-derived, lignin bio-oil compound, Vanillin (VAN), to 2-methoxy-4-methylphenol (MMP), a promising candidate for future biofuel applications for its use in fragrances and intermediate in pharmaceutical synthesis, via transfer hydrodeoxygenation. In their Research Article, R. Srivastava et al. reveal Ni nanoparticle (NP)-loaded montmorillonite (MMT) clay catalysts in catalytic transfer hydrodeoxygenation of lignin bio-oil compounds with isopropanol as a hydrogen source under mild conditions. Ni(10%)/MMT yields MMP with high conversions and selectivity, showcasing impressive recyclability, stability, and efficacy. Optimal Ni NPs and MMT acidity balance influences catalysis. The Ni(10%)/MMT catalyst outperforms reported Ni NP-based catalysts in VAN conversion and MMP selectivity, offering a greener approach to chemical production and advancing eco-friendly catalytic technologies. More information can be found in the Research Article by R. Srivastava et al.

Bulk materials are the oldest in heterogeneous catalysis, but with the resurgence of recent interest, it has emerged as one of the best catalytic tools to unlock their full potential. Boehmite-derived alumina materials are widely studied for catalytic organic transformations. Despite the progress, understanding the mechanistic insights of its catalytic behaviour has remained obscure. Here, we demonstrate the catalytic performance of a boehmite-derived alumina material to a highly selective catalytic process for the preparation of dihydropyran compounds. The catalytic material displayed excellent activity in terms of conversion (up to 99%) and selectivity (up to 99%). The material was characterized using different techniques and observed that the γ-alumina phase with inherent mild acidic character are key feature for the catalytic activity. Based on NMR and in situ FT-IR spectroscopic investigations a probable mechanism is proposed. This study expands the application of robust material for the preparation of industrially important fragrance compounds. The scope of the catalytic study encompasses a range of substrates and scale-up activities.

Ru NPs incorporated nanocrystalline HZSM-5 selectively break C–O bonds in diphenyl ether, a lignin model compound, via a sustainable catalytic transfer hydrogenolysis pathway, transforming it into valuable fuels and fuel additives.

The success of integrated biorefinery relies on developing robust and economical catalytic processes to produce liquid fuels and value‐added chemicals from the waste lignocellulose biomass. Platform chemicals obtained from biomass are multifunctional molecules, and their upgrading via various catalytic processes requires active and selective catalysts. Supported transition metal nanoparticles have been used extensively to catalyze the upgrading of biomass‐derived platform chemicals. Recent literature studies have focused on understanding the size‐dependent catalytic performances of supported transition metal nanoparticles and single atoms in biomass‐related chemical transformations. The catalytic behavior of transition metals depends on their size‐dependent geometric and electronic structures, and by controlling the size, the catalytic behavior can be optimized. Herein, we have reviewed the synthesis methodologies and characterization techniques of supported metal nanoparticles of different sizes and supported single atoms and have summarized several literature examples employing these catalysts to upgrade biomass‐derived platform chemicals such as; 5‐hydroxymethylfurfural, furfural, and levulinic acid, into liquid fuels and value‐added chemicals.

Selective transfer hydrogenolysis of lignin-derivedaromatic ethers by the utilization of hydrogen donor solventwithout hydrogenation of aromatic rings is a crucial strategy for theselective production of mono-aromatics. The use of non-noblemetal-based catalysts toward transfer hydrogenolysis of anaromatic ether bond with high activity and selectivity is still tobe achieved. Herein, we report the synthesis of a non-noble metal-based nanostructured NiO(x%)/SnO2catalyst for the catalytictransfer hydrogenolysis of benzyl phenyl ether and its homologuesether. The developed catalyst afforded >95% reactant conversionand 100% selectivity toward the aromatic compounds using 2-propanol as a hydrogen source at 250 degrees C and 4 h in the N2atmosphere. The catalyst was thoroughly characterized by severalphysicochemical analytical techniques. The oxygen vacancy was analyzed by Raman and FT-IR spectroscopies & XPS analysis, andacidity was analyzed by the temperature-programmed desorption and pyridine-adsorbed FT-IR spectroscopy. The synergisticparticipation of NiO and SnO2nanoparticles in NiO/SnO2, reducing ability, and interface formation were confirmed usingtemperature-programmed reduction, several physicochemical characterization techniques, and control reactions. Based on thecatalytic activity data, it is concluded that the appropriate NiO loading (10 wt %) was the dominant factor for controlling thearomatic selectivity. The catalyst was efficiently recycled after a simple calcination process with no substantial loss in the catalyticactivity. An in-depth study on the change in the catalyst chemical composition and their regeneration using various characterizationtechniques was conducted. A simple, cost-effective non-noble catalyst and straightforward eco-friendly transfer-hydrogenolysiscatalytic process involving 2-propanol to produce aromatic platform chemicals would attract significant attention from catalysisresearchers and industrialists.

Multiple reduction sites in furfural require suitable metal sites and reaction conditions to achieve a desired reduced product in high yield. Herein, Ni(x%)/CePO4 catalyst has been synthesized for the selective hydroge-nation of furfural to tetrahydrofurfuryl alcohol. Experiments show that the Ni(10%)/CePO4 catalyst exhibits the highest selectivity and yield of similar to 89% for the tetrahydrofurfuryl alcohol at 423 K and 20 bar H-2 pressure. The structure-activity relation has been established using physical properties such as XRD, BET, HR-TEM, and chemical properties such as XPS, NH3-TPD, pyridine FT-IR, and TPR techniques. Finally, based on the catalytic activity data, control reactions, literature reports, physicochemical properties, and furfural adsorption study, the reaction mechanism has been proposed for the formation of tetrahydrofurfuryl alcohol on Ni(10%)/CePO4 catalyst. The attractive feature of this work lies in the development of a cheap Ni decorated CePO4 for the se-lective production of valuable tetrahydrofurfuryl alcohol from furfural.

A library of halogen-substituted azobenzenes (ABs) have been synthesized and structurally characterized by single crystal X-ray diffraction technique. Azobenzenes studied herein display fast photo switching properties. Kinetics of cis- -> trans- isomerization has been studied using UV-VIS spectroscopy and the rate constant for this transformation were determined. Optimization of probable conformers of the cis- isomer and the corresponding transition state (TS) were carried out to determine the energy of activation. The Time-Dependent Density Functional Theory (TD-DFT) calculations were also performed to gain insight into the photo-isomerization. Our results indicate that the fluorinated compounds display better kinetic stability of the cis- isomer compared to the corresponding chloro and bromo analogues.