Palm-based transformer oil exhibits significant potential as an environmentally sustainable dielectric fluid. Accelerated thermal aging experiments were conducted under a sealed system with a nitrogen headspace to study its degradation mechanism and compared with those of mineral oil. The physicochemical, electrical, and mechanical properties of both the oil and the associated insulating paper were systematically analyzed. The results demonstrated that increased aging temperature and prolonged aging period facilitated the formation of moisture, carboxylic acids, and dissolved decay products, which critically contributed to the deterioration of oil-paper insulation systems. Notably, the degree of polymerization of insulating papers aged in mineral oil reached end-of-life criteria, whereas this phenomenon was not observed for palm-based oil. This finding suggests that transformers utilizing palm-based oil may exhibit enhanced longevity compared to those using mineral oil. Comparative assessments of structural degradation and property deterioration elucidated the impact of different oil types on insulation paper aging mechanisms. This study provides insight into the thermal stress-induced degradation pathways of palm-based transformer oil and its consequent effects on insulating paper stability, reinforcing its viability as an eco-friendly alternative for transformer applications.

This study explores the thermal and catalytic pyrolysis of palm oil empty fruit bunches (PEFB) using a tandem micro-reactor integrated with gas chromatography/mass spectrometry. The focus is on transforming lignocellulosic biomass into high-value bio-based chemicals using zeolite catalysts, HZSM-5, HUSY, and HBETA, with varying pore structures and acidity. Thermal pyrolysis (400-600 degrees C) predominantly produced phenolics, light and heavy oxygenates at lower temperatures, while increasing the temperature favored hydrocarbons such as aromatics and aliphatics via dehydration, deoxygenation, and cracking reactions. Catalytic pyrolysis conducted at 300-500 degrees C significantly altered product distribution, enhancing the yield of monobenzenes, polyaromatics, and bicyclic compounds. ZSM-5 promoted aromatic hydrocarbon formation due to its strong acidity and shape selectivity, while HUSY favored larger aromatics and cyclics compound, and BETA facilitated bicyclic compound. This one-step catalytic strategy demonstrates a promising route for the selective valorization of agricultural residues into valuable chemical feedstocks, supporting sustainable biorefinery development.

The increasing demand for sustainability in the tire and rubber industries has driven the development of eco-friendly rubber process oils to replace petroleum-derived aromatic extracts restricted for their high polycyclic aromatic hydrocarbon content. In this study, palm oil–derived fatty acid methyl ester (FAME) was epoxidized to produce epoxidized FAME (EFAME) as a green rubber process oil. Titanium-based catalysts with varying silica/titanium (Si/Ti) molar ratios were synthesized via hydrothermal method and compared with commercial titanium dioxide (TiO2-C). Comprehensive characterization revealed that hydrothermal TiO2 (TiO2-H, Si/Ti = 0) possessed a mesoporous, channel-like morphology with moderate surface area and exposed multiple Ti species, enhancing accessibility for bulky FAME molecules. In FAME epoxidation with hydrogen peroxide (H2O2) and tert-butanol, TiO2-H exhibited the best performance, achieving 71% FAME conversion, 1.9 wt% oxirane oxygen content, and 68% relative conversion to oxirane under the optimized conditions (70 °C, 24 h, 4 wt% catalyst). In contrast, titanium silicalite-1 (TS-1) catalyst suffered from diffusion limitations, while TiO2-C was limited by its low surface area. Studies on reaction parameters highlighted the importance of balancing conversion and selectivity to suppress epoxide ring-opening. Application tests showed that EFAME provided cure behavior and mechanical properties in nitrile rubber (NBR) and styrene-butadiene rubber (SBR)/butadiene rubber (BR) blends comparable to petroleum-based plasticizers, offering a sustainable alternative. This work provides both catalytic and application insights for bio-based rubber process oils, contributing to the development of greener tire and rubber technologies.

Currently, bio-transformer oil (BTO) is in high demand due to the increasing demand for electrical power and environmental policy considerations. Hence, this research aimed to produce BTO with high oxidation tolerance via partial hydrogenation of trimethylolpropane triester derived from sunflower seed oil (SF-TMPTE) over Pt/KIT-6 catalyst. The results revealed that as-prepared Pt/KIT-6 catalysts with various Pt loadings exhibited a high mesopore surface area with a uniform pore size distribution. The importance of studied reaction parameters on iodine value, reflecting the degree of unsaturation of hydrogenated BTO (H-BTO), was investigated using a univariate experiment and a 2k-factorial experimental design. The reaction condition was then optimized to obtain the H-BTO having the acceptable pour point (-10 degrees C) following IEC 62770 specification and high oxidation stability (14 h), which was the same levels as commercial BTO (FR3 (R)). The obtained results indicated that the system operated using 0.25 wt% catalyst content consisting of 0.25 wt% Pt loading under 15 bar initial H2 pressure and 1250 rpm stirring rate at 70 degrees C for 20 min was optimal to provide H-BTO having iodine value (IV) of 87 giodine/100 goil, which reached the desired pour point and oxidation stability of-10 degrees C and 14 h, respectively. Additionally, the H-BTO obtained under this optimal condition exhibited physical and electrical properties that conformed to the IEC 62770 standard. The Pt/KIT-6 catalyst with an appropriate platinum loading also demonstrated excellent reusability, maintaining high performance over four consecutive cycles. This indicates that the production of H-BTO with high oxidation stability via catalytic hydrogenation over Pt/KIT-6 catalyst is a promising process with strong potential for future BTO manufacturing.

The aim of this research was to investigate the syngas production from dry reforming of methane (DRM) in a planar plate dielectric barrier discharge (DBD) plasma reactor packed with Ni-based catalyst on SiO2 fiber (SF) and SiO2 porous (SP) supports. The SiO2 fiber support was synthesized by sol-gel and electrospinning techniques. Fresh Ni/SiO2 catalysts were characterized by XRD, N2 adsorption-desorption, SEM-EDS, TEM-EDS and XPS. The effects of full and partial packing configurations of the catalyst, Ni loading on SF and SP supports, and applied voltage were investigated on the DBD plasma-catalytic DRM performance. The results showed the partial packing configuration of the catalyst into this studied DBD plasma reactor and the increasing applied voltage gave a positive effect in improving performance. Moreover, the Ni loading and SiO2 support type (SF and SP) had a significant role on the overall system performance. The conditions with partial packing of the 10%Ni/SF catalyst and an applied voltage of 15 kV exhibited good results based on CH4 and CO2 conversions, syngas yield, hydrogen-to-carbon monoxide molar ratio and energy efficiency.

The transition to sustainable aviation fuel (SAF) requires efficient catalytic technologies to convert oxygenated lipid-derived feedstocks into hydrocarbon fuels that comply with stringent aviation fuel specifications. Motivated by the relatively low cost of nickel (Ni)-based catalysts and their suitability for large-scale commercial applications, a series of Ni-based catalysts supported on a modified beta zeolite (m-beta) were synthesized to investigate the effects of gallium (Ga) incorporation and the addition of a cerium (Ce) promoter on hydroconversion of palm oil-derived biodiesel. Based on catalyst characterization, the incorporation of Ga improved Ni dispersion and reduced Ni particle size, while Ce further modified Ni electronic states, enhanced H2 consumption, and introduced additional Brønsted acid sites through OH-bridging Ce species. Among the studied catalysts under a central condition, the bimetallic 5Ni5Ga/m-beta catalyst exhibited the highest liquid biofuel yield at 75.9 wt %, with 35.1 wt % biojet fuel-range hydrocarbons, and a high iso-/n-alkane ratio (1.14), attributable to its enhanced Ni active sites and alkane dehydrogenation and aromatization. For the effect of reaction parameters, both the reaction temperature and weight hourly space velocity (WHSV) played critical roles in overcoming limitations in oxygen-removal reactions. Although higher reaction temperatures and lower WHSV enhanced the biojet fuel fraction in the resulting liquid biofuels, these conditions should be carefully optimized to minimize undesirable aromatization. The addition of an appropriate Ce loading to the 5Ni5Ga/m-beta catalyst (5Ni5Ga-5Ce/m-beta) could further improve oxygen removal and alter the reaction pathway, thereby increasing iso-alkane selectivity over aromatic and cyclic compounds. A blend of oil between commercial Jet A-1 and the resulting liquid biofuel from 5Ni5Ga-5Ce/m-beta at 90/10 (v/v) had a heating value comparable to that of Jet A-1 (43.0 MJ/kg) and a freezing point of -54.9 °C. These results highlight the potential of NiGaCe/m-beta catalysts as cost-effective systems for producing SAF-compatible hydrocarbons from biodiesel, expanding strategies for sustainable aviation applications.

Fabricating effective reusable catalysts for biomass deoxygenation is essential for sustainable fuel production. In this study, Ni nanoparticles (15-25 wt%) were incorporated into UiO-66 through solvothermal synthesis, followed by partial carbonization at 300 degrees C to improve thermal stability, dispersion and catalytic efficiency in palm fatty acid distillate deoxygenation. Structural analysis confirmed that the UiO-66 framework remained intact after Ni incorporation, with X-ray photoelectron spectroscopy indicating well-dispersed Ni species (Ni2p(3/2) at 855.6-856.7 eV). The acid-base characteristics and high surface area supported the cleavage of C-O and C-C bonds. Among the catalysts tested, C-UiO-66@Ni-20wt% showed the best performance, achieving an 87.65% hydrocarbon yield under conditions (3.14 h, 3.28 wt% catalyst, 340 degrees C) optimized by response surface methodology. The reliability of the model was confirmed by a high R-2 value (99.47%) and statistical significance (p < 0.0001). The catalyst maintained stable activity over seven cycles, with only a 2-7% yield reduction per cycle, before significant deactivation occurred in the eighth cycle owing to pore blockage and active site agglomeration. This study illustrates that Ni-doped UiO-66, with its balanced acidity, structural integrity and efficiency at low temperatures, is a promising catalyst for scalable biofuel production, offering both high reactivity and reusability.

According to rising electrical power consumption, attention to bio-transformer oil (BTO) is increasing due to higher environmental and ecological concerns. Thus, this research aimed to identify the appropriate plant-based oils and polyols to prepare BTO synthesized via two-step transesterification involving the transformation of plant-based oils into fatty acid methyl ester (FAME) with methanol and then reacting with polyols to produce polyolesters (POEs). The plant-based oils—palm kernel oil (PK), refined palm oil (RFP), high olein palm oil (HOP), sunflower oil (SF), and soybean oil (SB)—were reacted with various polyols, neopentyl glycol (NPG), trimethylolpropane (TMP), and di-trimethylolpropane (Di-TMP), to produce BTO in forms of neopentyl glycol diester (NPGDE), trimethylolpropane triester (TMPTE), and di-trimethylolpropane tetraester (Di-TMPTTE), respectively. Among these POEs, BTO with TMPTE structure had appropriate properties in terms of dielectric breakdown voltage, kinematic viscosity at 40 °C, and flash point following IEC 62770 specification. However, the pour point and oxidation stability of BTO derived from each FAME (PK-TMPTE: − 7 °C, 22 h/RFP-TMPTE: 19 °C, 35 h/HOP-TMPTE: 17 °C, 30 h/SF-TMPTE: − 14 °C, 3 h and SB-TMPTE: − 10 °C, 4 h, respectively) failed to meet specified standard requirements (≤ − 10 °C and ≥ 13 h). The balance between steric hindrance and unsaturation level generated from the polyols and plant-based oils was crucial in achieving BTO with the desired properties. A 70/30 (w/w) PK-TMPTE/SF-TMPTE blend ratio was observed as an optimal formulation to provide BTO having a low pour point (− 10 °C) and high oxidation stability (15 h), following the standard specification for transformer oil.

This study investigated the catalytic performance of Ni-based catalysts supported on micromesoporous composites derived from the incorporation of SBA-15 with USY-(SBA-15-xUSY) or Hbeta-(SBA-15-xHbeta) zeolites (where x is wt percentage of zeolite fraction in the composite) for palm oil hydroisomerization to produce biojet fuel range. The hydroisomerization was conducted in a fixed-bed reactor under 25 bar of H2 pressure at 40 mL/min, 425 °C, 0.1 mL/min palm oil feed rate, and 5 g of catalyst. It was observed that the support materials significantly influenced catalytic activity and product selectivity. In the case of zeolite supports, the Ni-based catalysts supported by USY zeolite showed the highest liquid product yield (54.3 wt %) and iso-to-normal (i-/n-) alkane ratio of 1.43, whereas those supported on Hbeta zeolite provide the lower yield of liquid biofuel with high gasoline fraction (25.5%) and i-/n-alkane ratio of 2.58. The micromesoporous composite supports enhanced specific surface area and pore size to decrease the mass transfer limitation, resulting in better catalytic performance. The Ni/SBA-15-50USY and Ni/SBA-15-50Hbeta catalysts exhibited the highest selectivity to biojet fuel-range hydrocarbons, reaching 78.8 and 76.7 wt %, respectively. Moreover, the Ni/SBA-15-xHbeta catalyst promoted significantly higher selectivity to the iso-alkanes fraction in the obtained liquid biofuels than Ni/SBA-15-xUSY catalysts. The maximum i-/n-alkanes ratio at 3.45 was achieved for the system using Ni/SBA-15-30Hbeta catalyst, demonstrating the beneficial role of SBA-15 in boosting diffusion and catalytic efficiency. This result suggested that the integration of BEA zeolite crystals into the mesoporous SBA-15 structure allowed the closer proximity between the Ni-metal and Brønsted acid sites to optimize the hydrocracking efficiency for biojet fuel production.

This study demonstrates a sustainable and integrated method for the co-production of carbon quantum dots (CQDs) and activated carbon (AC) using natural rubber (NR) latex, which is a renewable and widely available biomass. CQDs were synthesized via a hydrothermal method using cetyltrimethylammonium bromide and nitric acid as nitrogen dopants. The as-formed product comprised uniform amorphous nanoparticles (3.5-11.0 nm) that exhibited intense blue photoluminescence and abundant surface amino and oxygen-containing groups. The CQDs exhibited excellent antimicrobial and antiviral activities, achieving >99.9% inactivation of Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Candida albicans, Aspergillus niger, and influenza A virus (H3N2) within 5 min of exposure at a concentration of 15 µg mL-1. Moreover, they demonstrated negligible cytotoxicity toward HaCaT keratinocytes. Furthermore, the hydrochar obtained as a by-product of hydrothermal synthesis was subsequently converted into AC via physical and chemical activation, yielding a large-surface-area adsorbent (up to 1167 m2 g-1) featuring a diclofenac uptake capacity of 126.82 mg g-1 at 25 °C. The adsorption process followed pseudo-second-order kinetics and a Langmuir-type monolayer adsorption mechanism. Adsorption mainly proceeded via π-π interactions, hydrogen bonding, and electrostatic attraction between diclofenac molecules and heteroatom-rich surface sites. This dual-function valorization of NR latex simultaneously addresses microbial and pharmaceutical pollution, advancing circular bioeconomy principles and offering sustainable solutions for water treatment and healthcare applications.

A highly efficient and cost-effective Ni-Mo/Zr-SBA-15 catalyst was developed for the selective hydrogenation of biomass-derived oleic acid to octadecanol, a high-value fatty alcohol. By systematically optimizing the Ni/Mo weight ratio and varying the ZrO x content, the 10Ni-10Mo/10Zr-SBA-15 catalyst exhibited excellent performance, achieving 100% conversion and 93.5% selectivity to octadecanol at 220 degrees C and 3.0 MPa of H2. Characterization results revealed that Mo species enhanced Ni dispersion, while the synergistic Ni-MoO x interfacial sites contributed to the high catalytic performance. Metallic Ni is the main active site for H2 activation/dissociation. The incorporation of Mo species in the 10Ni/10Zr-SBA-15 catalyst increased the density of oxygen vacancies and enhanced the amount of Lewis acid sites. Additionally, ZrO x species contributed to the properties of the SBA-15 support, introducing more Lewis acid sites to the catalyst. The combined effect of metallic sites, oxygen vacancy/redox centers, and Lewis acidity facilitated the hydrogenation process, C-O/C = O bond activation, and strengthened oleic acid adsorption, which was crucial for octadecanol production. Moreover, the 10Ni-10Mo/10Zr-SBA-15 catalyst demonstrated high stability and reusability, maintaining its activity over four consecutive reaction cycles without significant deactivation.

Currently, biotransformer oil (BTO) is in high demand due to the increasing level of electrical power consumption and environmental policy. Hence, this research aimed to prepare a highly stable BTO via basic transesterification of palm oil methyl ester (POME) and ditrimethylolpropane (Di-TMP) catalyzed by sodium methoxide (NaOCH3). Under the optimal conditions (POME/Di-TMP molar ratio = 5.0/1.0, NaOCH3 loading = 8 mol % based on the Di-TMP content under 3.5 mbar, and 300 rpm at 160 degrees C for 2 h), the POME conversion level and POME-Di-TMPTTE selectivity reached 90.3% and 96.6%, respectively. The obtained BTO with a high POME-Di-TMPTTE portion exhibited greater oxidation stability with a higher flash point and breakdown voltage in accordance with the IEC 62770 specification. A techno-economic analysis revealed the possibility of POME-Di-TMPTTE as a commercial BTO for its competitive cost and profit based on the current commercial price of BTO.

Light cycle oil (LCO) is a by-product obtained from the fluid catalytic cracking unit in petroleum refineries. Since LCO has a high content of organosulfurous compounds and polycyclic aromatic hydrocarbons (PAHs), which adversely affect the environment and animals, LCO cannot be directly applied in combustion engines. To utilize LCO as a higher value-added chemical, this work aimed to transform the PAHs in LCO into aromatics with a lower toxicity, such as BTX (benzene, toluene, and xylene), tetralins, and decalins, via hydrogenation over nickel (Ni)–molybdenum (Mo)-based catalysts. The effect of the catalyst’s support on the hydrogenation efficiency was investigated using -alumina ( -Al2O3), KIT-6, and -zeolite. The results showed that the NiMo/KIT-6 catalyst exhibited the highest ability for hydrogenation of PAHs (49.6% removal of PAHs) and produced alkylbenzenes, decalins, and tetralins at 12.0, 0.22, and 36.4% selectivity, respectively, when the reaction was conducted under 40 bar hydrogen pressure at 350 C for 3 h with a stirring rate of 300 rpm. This study proposed an alternative way to produce value-added chemicals from a by-product stream derived from the petroleum refinery process, thereby expanding the options for sustainable development.

Transformation of some oxygenated compounds in bio-oil derived from biomass pyrolysis via hydrodeoxygenation (HDO) generally improves its quality and potentially produces bio-based chemicals. Although alumina (Al₂O₃) supported catalysts are normally applied for HDO, they have certain limitations, such as acidity and high susceptibility to water, which need to be improved. In this research, an Al2O3-incorporated zirconia (ZrO2) composite (AZ) was prepared as a support of nickel (Ni)-molybdenum (Mo) catalysts used for HDO of guaiacol (GUA) and real bio-oil derived from pyrolysis of Leucaena leucocephala trunks to produce phenols. In the absence of water, the NiMo catalyst supported on AZ at 1/1 Al2O3/ZrO2 molar ratio [NiMo/AZ(1/1)] having higher reducibility with a greater number of weak-medium acid sites provided >98% GUA conversion with 87% selectivity to phenols. In the presence of water, the NiMo/AZ(1/1) catalyst maintained its catalytic activity, whereas NiMo/Al2O3 catalyst showed its deactivation to obtain the lowering GUA conversion (27.1% reduction). The FESEM and 27Al-NMR analyses revealed that the addition of ZrO2 improved the water tolerance of the catalyst by protecting the Al2O3 structure and preventing the transformation of Lewis acid-related tetrahedral Al to octahedral Al. Moreover, the NiMo/AZ(1/1) catalyst exhibited the highest HDO activity for real bio-oil without solvents, achieving a maximum oil yield of 25.2 wt% with 75.6% selectivity to phenols and the lowest coke formation.

Long-chain alpha-olefins (& GE; C10) are normally applied in detergents, lubricants, and oil field chemicals. Due to the abundance of palm oil, the derivatives derived from palm oil, such as oleic acid (OA), can be converted to long -chain olefins via oxidative dehydrogenation (ODH) over a series of vanadium oxides (VxOy) incorporated with KIT-6 (nV-KIT-6 catalysts) synthesized by a direct hydrothermal method. Various ammonium metavanadate/ tetraethyl orthosilicate molar ratios (V/Si) were evaluated over the range of 0.01-0.09. The results obtained from X-ray diffractometry, hydrogen-temperature programmed reduction, and X-ray photoelectron spectroscopy an-alyses revealed that the VxOy were mainly in a tetrahedral form when the V/Si molar ratios were lower than 0.05. Above this point, the formation of V2O5 crystallites was observed. The ODH of OA was performed in a continuous flow fixed-bed reactor under atmospheric pressure in the absence of solvent to avoid the interference of by-products generated from solvent oxidation. The results showed that the OA conversion and selectivity towards the desired products strongly depended on the V/Si molar ratio and the reaction temperature. The highest selectivity of olefins (alkenes + dienes) with carbon atoms in the range of C7-17 was 44%. Moreover, the selectivity to aromatics at 24% was observed at a 76% OA conversion level when the ODH was activated using the 0.05 V-KIT-6 catalyst under a 1/1 (v/v) oxygen/nitrogen gas mixture at a flow rate of 100 mL min-1 at 450 C. Although the high selectivity towards alkenes was promoted by a higher dispersion of VxOy species on the catalyst, overdose of V/Si molar ratios produced more oxygenate compounds. The reaction mechanism for the ODH of OA was likely to be decarboxylation and decarbonylation followed by dehydration. The 0.05 V-KIT-6 catalyst also exhibited reusability over two cycles.

To overcome mass transfer limitation and adjust zeolite's acidity, the modification of beta zeolite via etching with hydrofluoric acid/ammonium fluoride (HF/NH4F) solution was revealed and the modified beta zeolite was then applied as a support of nickel (Ni) catalysts used for hydroisomerization of palm olein. HF/NH4F solution containing 0.25 M HF concentration was appropriate to enlarge original existing intercrystalline mesopores of beta zeolite (beta-0.25), which resulted to the higher pore volume. The Ni/beta-0.25 catalyst also exhibited the better Ni dispersion and lower acidity. These features suppressed overcracking and provided 43.4 wt% bio-jet fuel yield with 22.1 wt% iso-alkanes fraction when hydroisomerization was operated under 40 bar initial hydrogen (H2) pressure at 340 degrees C for 5 h. At 0.75 M HF concentration, the excessive leaching of aluminum species out of the zeolite framework provided beta-0.75 with very low acidity, which was ineffective to convert molecules of palm olein to bio-jet fuel range. Initial H2 pressure at 40 bar was sufficient to activate the hydroisomerization of palm olein over Ni/beta-0.25 catalyst to produce liquid biofuel containing iso-/n-alkane ratio of 2.61. The liquid biofuel/Jet A-1 blend at 50% (v/v) had freezing point and gross heating value of-58.9 degrees C and 43.7 MJ/kg, respectively.

A multiloop splitter-based non-cryogenic artificial trapping (M-SNAT) modulation technique was established, which applied the first (1D) nonpolar and the second (2D) polar columns, deactivated fused silica (DFS) columns, a microfluidic Deans switch (DS), and splitters located between the 1D column outlet and the DS. The splitters were connected into multiple loops with a progressively doubled perimeter of the next loop. This enabled a duplex splitting mechanism within each loop consisting of splitting of analyte pulses, the pulse delay, and their combination which led to equally split peaks of the same analytes with the number of split peaks (nsplit) equal to 2m (m = number of loops). This system resulted in local profiles of artificially split-and-trapped analytes prior to their selective transfers onto the 2D column by means of periodic multiple heart-cuts (H/C). The developed SNAT approach can be successful, providing that the ratio of modulation period to sampling time (PM/tsamp) is equal to nsplit. The approach with nsplit = 16 was further developed into a single device platform and applied for the modulation of a wide range of compounds in waste tire pyrolysis samples with the RSD of ≤0.01 and <10% for the one-dimensional modulated peak times and peak areas, respectively (n = 50). The method enabled an artificial modulation mechanism without cryogen consumption and enhanced the 2D peak capacity (2nc) and 2D separation by use of a longer 2D column.

Bio-oil upgrading to produce biofuels and chemicals has become an attractive topic over the past decade. However, the design of cost- and performance-effective catalysts for commercial-scale production remains a challenge. Herein, commercial titania (TiO2) was used as the support of cobalt (Co)-based catalysts (Co/TiO2) due to its low cost, high availability, and practicability for commercialization in the future. The Co/TiO2 catalysts were made with two different forms of TiO2 (anatase [TiO2–A] and rutile [TiO2–R]) and comparatively evaluated in the hydrodeoxygenation (HDO) of 4-propylguaicol (4PG), a lignin-derived model compound. Both Co/TiO2 catalysts promoted the HDO of 4PG following a similar pathway, but the Co/TiO2–R catalyst exhibited a higher activity in the early stages of the reaction due to the formation of abundant Ti3+ species, as detected by X-ray photoelectron spectroscopy (XPS) and hydrogen–temperature programed reduction (H2–TPR) analyses. On the other hand, the Co/TiO2–A catalyst possessed a higher acidity that enhanced propylcyclohexane production at prolonged reaction times. In terms of reusability, the Co/TiO2–A catalyst showed a higher stability (less Co leaching) and reusability compared to Co/TiO2–R, as confirmed by transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses. The HDO of the real bio-oil derived from pyrolysis of Leucaena leucocephala revealed that the Co/TiO2–A catalyst could convert high oxygenated aromatics (methoxyphenols, dimethoxyphenols, and benzenediols) to phenols and enhanced the phenols content, hinting at its potential to produce green chemicals from bio-feedstock.