Hydrodeoxygenation Process Research Articles

Controlled hydrodeoxygenation of lignin-derived anisole over supported Pt on UiO-66 based-catalysts through defect engineering approach

Herein, we report a series of Platinum (Pt) phase loading on the highly porous channels of the metal-organic framework (MOF) introduces open Lewis acid sites through a defective-effect, which are crucial for selective hydrodeoxygenation (HDO) process of anisole. Thereby, UiO-66 (University of Oslo) based-supports were synthesized by a microwave-assisted solvothermal method using isophthalic acid (IPA) as a mixed linker at different concentrations. The total amount of acid sites in the defective UiO-66 samples was 1.5–2.5 times higher than that of pristine UiO-66, with the corresponding linker deficiency increasing to 1.94 as the concentration of the mixed linker was increased to 30% in the starting material. Consequently, the 3Pt/defective UiO-66 catalysts achieved better catalytic performance for the anisole HDO process, with a turn-over frequency (TOF) value of the Pt site being 2–3 times higher than that of the pristine 3Pt/UiO-66. Notably, the reaction pathway shifted from producing cyclohexane to producing benzene through the demethoxylation of anisole. This resulted in an increase in the TOF value based on the benzene yield by over 10 times as the defective linker content increased from 0 to 20%. The catalytic stability was also investigated using a series of Pt/defective UiO-66 catalysts.

Biomass Fast Pyrolysis Vapor Upgrading over γ-Alumina, Hydrotalcite, Dolomite and Effect of Na2CO3 Loading: A Pyro Probe GCMS Study

The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dolomite on fast pyrolysis vapor upgrading of beechwood was investigated using an analytical pyro probe-gas chromatography/mass spectrometry instrument (Py-GC/MS) at a temperature of 500 °C. Overall, this research showcased that these catalysts can deoxygenate biomass pyrolysis vapors into a mixture of intermediate compounds which have substantially lower oxygen content. The intermediate compounds are deemed to be suitable for downstream hydrodeoxygenation processes and it also means that hydrogen consumption will be reduced as a result of moderate in-situ deoxygenation. Among the support catalysts, the application of hydrotalcite yielded the best results with the formation of moderately deoxygenated compounds such as light phenols, mono-oxy ketones, light furans and hydrocarbons with a TIC area % of 7.5, 44.8, 9.8 and 9.8, respectively. In addition, acids were considerably reduced. Dolomite was the next most effective catalyst as γ-alumina retained most of the acids and other oxygenates. Na2CO3 loading on γ-alumina had a noticeable effect on eliminating more or less all the acids, enhancing the mono-oxy-ketones and producing lighter furans. In contrast, Na2CO3 loading on dolomite and hydrotalcite did not show a major impact on the composition except for further enhancing the mono-oxy-ketones (e.g., acetone and cyclopentenones). Additionally, in the case of hydrotalcite and γ-alumina, Na2CO3 loading suppressed the formation of hydrocarbons. In this research, the composition of pyrolytic vapors as a result of catalysis is elaborated further under the specific oxygenate groups such as acids, phenolics, furanics, ketones and acids. Further the catalysts were also characterized by BET, XRD and TGA analysis.

Ab initio investigation of the adsorption of phenolic compounds, CO, and H[formula omitted]O over metallic cluster/silica catalysts for hydrodeoxygenation process

The catalytic hydrodeoxygenation (HDO) of lignin is an important route to produce green aromatics. Herein we study the adsorption of key phenolic molecules (phenol, catechol, guaiacol, anisole) over various metallic nanoparticles (NP) (Ni, Cu, Co, Fe) supported over amorphous silica, by the periodic spin polarized density functional theory (DFT). CO and water are potential inhibiting molecules present in the lignin pyrolysis gas. Therefore their competing adsorption is also studied in details. Our calculations show that the oxygenated compounds have a stronger interaction at the interface between the NP cluster and the silica for all the studied metals. By comparing the resulting adsorption energies, we found that the Ni13@silica catalyst is the most attractive one for oxygenated molecules. The most stable configuration is a phenol adsorption at the interface through the OH group with the silica surface and the aromatic ring with the transition metal cluster. In addition, we show that the adsorption of the oxygenated compounds is not impacted by the presence of inhibiting molecules on Fe13@silica, Co13@silica and Ni13@silica catalysts. This type of DFT investigation appears to be useful to suggest suitable formulations for an optimal HDO of lignin.

Low Loading of CoRe/TiO2 for Efficient Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone

CoRe bimetallic catalysts with low loading were designed for hydrodeoxygenation of levulinic acid to γ-valerolactone. Results show that the 1 wt % Co0.5Re0.5/TiO2 catalyst achieved the highest yield of γ-valerolactone (>99%) at 220 °C, 3 h, a 1,4-dioxane solvent and Co/levulinic acid molar ratio of 1:1760, with a turnover frequency (TOF) of 1328 h–1. The catalyst can be reused four times with only slight activity loss. The catalyst was characterized with various physicochemical measurements, and its adsorption styles with H2 and levulinic acid were calculated by density functional theory. The results reveal that four main factors are related to its excellent catalytic performance. First, the Re oxides synergize with Co by spillover of the dissociated H atoms, which increases the apparent dispersion of Co and promotes the reaction. Second, the low loading of 1 wt % allowed the metal nanoparticles to be well dispersed with a very fine size of ca. 1.24 nm, which may expose more active sites to the substrate and result in a higher catalytic efficiency. Third, CoRe formed an amorphous alloy with the formula Co-ReO1.6, which showed a synergistic effect during the reaction. Finally, the TiO2 support was nonporous and hydrophilic, which would be beneficial for the mass diffusion of the reaction components to be adsorbed/desorbed onto the vicinity of the metallic active sites and lead to a high TOF in the hydrodeoxygenation process.

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Enhanced production of hydrocarbons from lignin isolated from sugarcane bagasse using formic acid induced supercritical ethanol liquefaction followed by hydrodeoxygenation

This study involves the production of hydrocarbons from lignin extracted from sugarcane bagasse using Hydrothermal Liquefaction (HTL) followed by Hydrodeoxygenation (HDO). HTL of the lignin was studied under different solvents-methanol, ethanol and isopropanol in the presence of formic acid as an effective H-donor under varying lignin to solvent ratios (L:S = 1:15,1:30,1:40 g/mL), reaction temperatures (200 °C - 320 °C), reaction times (15, 30, 45,60 min) and ZnCl2 catalyst concentrations (30, 40, 50, 60 wt%). A maximum of 86% lignin derived phenolics was obtained when ethanol was used as solvent at 250 °C under L:S = 1:30 at 30 min reaction time with 60 wt% ZnCl2. The lignin-oil was upgraded by HDO process in the presence of Ni/Al2O3 catalyst and a maximum hydrocarbon yield of 73.5% was obtained with a HHV value of 48 MJ/kg. The hydrocarbons had excellent properties with a carbon range of C6–C12 with a purity of 51.2%.

Techno-economic and life cycle analysis of biofuel production via hydrothermal liquefaction of microalgae in a methanol-water system and catalytic hydrotreatment using hydrochar as a catalyst support

The hydrochar, a by-product of hydrothermal liquefaction (HTL) of algal biomass, was utilized through two methods; combustion and activation, for its usage as a source of heat and a catalyst support for hydrodeoxygenation (HDO) process in the production of algal biofuels. In this study, techno-economic analysis (TEA) and life cycle assessment (LCA) of algal biofuels production in a two-stage process (HTL and HDO) were investigated. Aspen plus simulation and SimaPro software were used to analyze process economics and greenhouse gas (GHG) emissions. Microalgae at 200 dry metric tonnes day−1 was the basis for its conversion to biocrude oil through HTL in the methanol-water system followed by catalytic upgrading to produce biofuels. According to HTL experimental results, maximum biocrude oil yield of 57.8 wt% was obtained using microalgae-solvent mass ratio and methanol-water mass ratio of 1:5 and 3:1, respectively. Produced biocrude oil contained 14.5 wt% of oxygen and HHV of 33.4 MJ kgbiocrude oil−1 which required upgrading to be utilized as a transportation fuel. HDO was employed to enhance the quality of biocrude oil with decrease in oxygen content (3.1 wt%) and increase in HHV (42 MJ kgbiofuel−1). The minimum fuel selling price (MFSP) for using method #2 (activation) was 2.2 $ L−1 to breakeven the cost of operation, which was about 10% lower than that from method #1 (combustion). The GHG emissions performance was estimated at −1.13 gCO2-eq MJ−1 indicating the significant GHG emissions reduction compared to petroleum-based fuels production.

Hydrodeoxygenation of Anisole and Benzaldehyde Over Bifunctional CoMo/USY Catalyst

Hydrodeoxygenation (HDO) of anisole and Benzaldehyde over bifunctional zeolite USY (ultra-stable Y) supported CoMo catalysts has been studied. The catalyst consisted of metals that Co and Mo were loaded at three different sequences; Co loaded first (Co-Mo/USY), Mo loaded first (Mo-Co/USY), and simultaneously loaded (CoMo/USY). The experiments were conducted in a flow reactor within a temperature of 350 °C for an hour. The oxygen-free products from the HDO process were benzene and toluene compounds. CoMo/USY catalyst exhibited the best catalytic activity of anisole towards the total production of aromatic hydrocarbons yield by 9.17%. It was also found that Mo-Co/USY catalyst exhibited the best catalytic activity of Benzaldehyde with aromatic hydrocarbons yield by 10.46%.

Structure-tunable pompon-like RuCo catalysts: Insight into the roles of atomically dispersed Ru-Co sites and crystallographic structures for guaiacol hydrodeoxygenation

Currently, the highly efficient conversion of biomass resources into highly valuable chemicals and biofuels is one of the most prospective approaches to reduce greenhouse gases emission and environmental pollution caused by excess consumption of fossil fuels. Herein, three-dimensional pompon-like well-defined RuCo particles with tunable crystallographic structures and surface atomically dispersed Ru atoms were constructed and intensively investigated as support-free metal catalysts in the hydrodeoxygenation (HDO) of lignin-derived guaiacol. It was demonstrated that the 300 °C-reduced RuCo sample possessed the hexagonal close-packed (hcp) crystallographic structure with surface abundant atomically dispersed Ru atoms, whereas 600 °C-reduced RuCo sample presented the face-centered cubic phase with lower surface Ru concentration. The as-fabricated RuCo-300 sample showed excellent catalytic HDO activity with a high cyclohexane yield of 85.3%. Comprehensive structural characterizations unveiled that the introduction of atomically dispersed Ru atoms into the RuCo-300 favored the formation of abundant surface Ru-Co sites, as well as electron-rich Ru0, and such-constructed Ru-Co sites were highly beneficial to the hydrogen dissociation on single Ru0 atoms and the further hydrogen spillover to adjacent Co0 atoms to promote the HDO process. Moreover, density functional theory (DFT) calculations revealed that the hcp structure of RuCo catalysts benefited the adsorption of guaiacol. The unique pompon-like microstructure of RuCo catalysts was conducive to the exposure of active sites and provided more open channels for the easy diffusion of reactants and products. Over the RuCo-300 catalyst, the guaiacol HDO could proceed rapidly via an initial demethoxylation reaction. The present Ru-Co synergetic catalysis in the structure of RuCo catalysts would provide a new strategy for constructing robust heterogeneous bimetal catalysts applied in practical HDO processes of a variety of lignin-derived phenolic compounds.

Sulfonic Mesostructured SBA-15 Silicas for the Solvent-Free Production of Bio-Jet Fuel Precursors via Aldol Dimerization of Levulinic Acid

Sulfonic acid-functionalized mesostructured silicas have been evaluated in the solvent-free aldol dimerization of biomass-derived levulinic acid into bio-jet fuel precursors. These compounds produce branched alkanes in a subsequent hydrodeoxygenation process, with suitable properties for being a renewable alternative to conventional fossil aviation fuels. The combination of activity and selectivity toward the desired condensation products achieved over sulfonic acid-functionalized SBA-15 materials is superior to those displayed by other commercial solid acid catalysts. Enhanced textural properties provided by the mesoporous SBA-15 support contribute to such improved catalytic performance. The strength and loading of the mesoporous silica-supported sulfonic acid moieties are also important factors affecting the catalytic performance of the materials. Reaction conditions (temperature, time, and catalyst loading) have been optimized for propylsulfonic acid-functionalized mesostructured silica (Pr-SBA-15) by means of a response surface methodology, leading to a maximum yield to levulinic acid dimerization products of 58.4% (145 °C, 0.15 g of catalyst, 24 h, no solvent). Under these reaction conditions, conversion of levulinic acid is 61.1%, indicating excellent selectivity toward bio-jet fuel precursors. A small catalytic activity decay has been detected in reutilization experiments, attributed to the formation of organic deposits onto the catalyst surface. A mild acid washing of the catalyst allowed a significant recovery of the initial activity.

Production of bio-jet fuel range hydrocarbons from catalytic HDO of biobased difurfurilydene acetone over Ni/SiO2-ZrO2 catalysts

Biobased difurfurylidene acetone produced by aldol condensation of furfural was used as a renewable feedstock for production of jet fuel range hydrocarbons via the hydrodeoxygenation (HDO) process. The reaction was carried out in a single step at 280° C using Ni/SiO2-ZrO2 (Si/Zr = 1, 3, 5) as catalysts. The influences of Si/Zr ratio as well as Ni content were examined. Excellent results in terms of activity and selectivity towards the formation of bio-jet fuel range hydrocarbons C13-C16 have been obtained. The catalyst's performances were related to the nature and the strength of the support acidity as well as to the metal-support interaction.

Catalytic Process Development of Bio-BTX from Lignocellulose Derived Product: Preliminary Study Using Transition Metal Catalysts

Lately, the increase in biofuel production has simultaneously led to lignocellulose material disposal activities. As a waste produced by the biofuel industry, lignocellulose materials are not utilized fully yet due to their complex polymeric structure. As one compound of lignocellulose, lignin possesses the lowest economic value due to its recalcitrant nature. In this work, guaiacol as one of monomeric substance originated from lignin is used as a representative molecule to be valorized due to the existence of both hydroxyl and methoxy moiety groups in it. One important reaction of lignin monomeric substance (phenolic compounds) valorization is oxygen removal. Aromatic substances such as Benzene and Toluene are produced through oxygen removal from the guaiacol molecule. Hydrodeoxygenation of guaiacol is aimed to remove oxygen atoms from it. Though conventionally hydrogen for the Hydrodeoxygenation process is supplied by external molecular hydrogen, in this work it is supplied from hydrogen atom abstraction of methylcyclohexane. Therefore, in a one-pot catalytic reaction system, methylcyclohexane dehydrogenation is the sole hydrogen provider for subsequent hydrodeoxygenation of guaiacol and this novel concept of a circular hydrogen economy has been proven its feasibility through heterogeneous catalytic reaction schemes conducted in this work. Metal supported on zeolite beta is selected as heterogeneous catalysts to evaluate the feasibility of one-pot hydrodeoxygenation and dehydrogenation reaction. Of every catalytic reaction attempt, multiple products consist of alkylated phenol, phenol itself, and toluene are observed proofing the feasibility of this concept. Possible interaction of catalyst surface acidity and metal contents are also probed through the distribution of byproducts. Overall, sequential dehydrogenation and hydrodeoxygenation have been proven through a catalytic reaction catalyzed by metal-supported zeolite beta catalyst and this work can potentially pave the way for further application.

Recent developments in multifunctional catalysts for fatty acid hydrodeoxygenation as a route towards biofuels

Catalytic hydrodeoxygenation (HDO) provides a promising route for upgrading biomass-derived fatty acids to alkanes, which are potential biofuels (e.g. jet fuel (C8–C16) and diesel (C12–C22)) that could reduce our reliance on unsustainable fossil fuels. Currently, catalytic HDO, conducted over catalysts such as molybdenum disulfide, necessitates harsh operating conditions (>300 °C) which is both environmentally and economically unsustainable and promotes unwanted side reactions, e.g. cracking, which compromises product selectivity. Accordingly, the development of novel catalysts, which enable efficient and sustainable HDO, under milder operating conditions, and their translation from lab bench to large-scale production are highly desired. This review discusses the recent development of heterogeneous catalysts for HDO (including reaction pathways, mechanisms, and side reactions) and explores design strategies for the development of new multifunctional catalysts with potential to enable future development of HDO processes under mild conditions. In particular, we consider the sequential cascade transformation of fatty acids into fatty alcohols (via hydrodeoxygenation) and then hydrocarbons (via dehydration and hydrogenation), which requires the coupling of different but complementary catalytic sites, as an attractive alternative mild HDO strategy.

Hydrodeoxygenation of Guaiacol over Pd–Co and Pd–Fe Catalysts: Deactivation and Regeneration

In bio-oil upgrading, the activity and stability of the catalyst are of great importance for the catalytic hydrodeoxygenation (HDO) process. The vapor-phase HDO of guaiacol was investigated to clarify the activity, stability, and regeneration ability of Al-MCM-41 supported Pd, Co, and Fe catalysts in a fixed-bed reactor. The HDO experiment was conducted at 400 °C and 1 atm, while the regeneration of the catalyst was performed with an air flow at 500 °C for 240 min. TGA and XPS techniques were applied to study the coke deposit and metal oxide bond energy of the catalysts before and after HDO reaction. The Co and Pd–Co simultaneously catalyzed the CArO–CH3, CAr–OH, and multiple C–C hydrogenolyses, while the Fe and Pd–Fe principally catalyzed the CAr–OCH3 hydrogenolysis. The bimetallic Pd–Co and Pd–Fe showed a higher HDO yield and stability than monometallic Co and Fe, since the coke formation was reduced. The Pd–Fe catalyst presented a higher stability and regeneration ability than the Pd–Co catalyst, with consistent activity during three HDO cycles.

Upgradation of Nostoc punctriforme under subcritical conditions into liquid hydrocarbons (bio-oil) via hydro-deoxygenation: Optimization and engine tests

In this present study, hydro-deoxygenation (HDO) process was performed to upgrade the liquefied bio-oil of Nostoc punctriforme biomass. The engine performance and emission properties of the enriched bio-oil and blends (with diesel) were evaluated. The HTL resulted in highest bio-oil yield of 47.5 wt% at a temperature of 300 °C at 60 min with calorific value of 32.5 MJ/kg. At 60 min and temperature of 300 °C with 1 wt% of heterogeneous catalyst the upgraded HDO-bio-oil yield reached 38.4 wt% with deoxygenation percentage of 70%. The properties of upgraded bio-oil are HHV of 44.74 MJ/kg, Kinematic viscosity of 6.23 mm2/s and density 923 kg/m3 respectively. The response surface methodology (RSM) was used for modeling and optimizing the upgraded bio-oil yield. The optimized RSM conditions for upgraded bio-oil yield (44.5 wt%) are temperature of 280 °C, catalyst load of 0.6 wt%, and time of 120 min. The physiochemical properties of upgraded bio-oil are in agreement with ASTM standards. Equal proportion of bio-oil to diesel (D50: B50) reduced the brake thermal efficiency to 6.66% with reduced NOx emission and slight increase in CO emission. This study highlights that microalga fuels are better renewable energy resource with reduced greenhouse gas emission.

Synthesis layered material of MnO2 and TiO2 as the support of molybdenum catalyst for bio-crude oil upgrading process

Layered materials are attractive for many applications because of their unique structure consisting of stacked sheets that can be controlled and modified. In this work, various synthetic layered materials (SLMs) i.e., Na-MnO2, H-MnO2, and Cs-TiO2 have been successfully prepared as the support for molybdenum (Mo)-based catalyst and applied for bio-crude oil hydrodeoxygenation (HDO) process. A commercial Mo/Al2O3 catalysts will also be utilized as a benchmark. The physical and chemical properties of the catalysts were characterized by using an X-ray diffractometer, X-ray fluorescence, surface area analyzer, NH3-temperature-programmed desorption, and scanning electron microscopy. The characterization results showed that the interlayer ion exchange of Na+ ions with H+ ions was successful for MnO2 support. The impregnation of the MoO3 into SLMs increased the surface area, pore-volume, average pore size, and total acidity. The HDO of bio-crude oil using MoO3/Na-MnO2 catalyst produced a higher HHV value of 38.75 MJ/Kg and a DOD value of 82.75% compared to other prepared catalysts or even the MoO3 commercial catalyst.

Guaiacol hydrodeoxygenation in hydrothermal conditions using N-doped reduced graphene oxide (RGO) supported Pt and Ni catalysts: Seeking for economically viable biomass upgrading alternatives

Herein we present an innovative route for model biomass compounds upgrading via “H2-free” hydrodeoxygenation (HDO) reactions. The underlaying idea is to implement a multifunctional catalyst able to activate water and subsequently use in-situ generated hydrogen for the HDO process. In this sense we have developed a series of effective Ni and Pt based catalysts supported on N-promoted graphene decorated with ceria. The catalyst reached commendable conversion levels and selectivity to mono-oxygenated compounds considering the very challenging reaction conditions. Pt outperforms Ni when the samples are tested as-prepared. However, Ni performance is remarkably boosted upon applying a pre-conditioning reductive treatment. Indeed, our NiCeO2/GOr-N present the best activity/selectivity balance and it is deemed as a promising catalyst to conduct the H2-free HDO reaction. Overall, this “proof-concept” showcases an economically appealing route for bio-compounds upgrading evidencing the key role of advanced catalysts for a low carbon future.

Upgrading of Oils from Biomass and Waste: Catalytic Hydrodeoxygenation

The continuous demand for fossil fuels has directed significant attention to developing new fuel sources to replace nonrenewable fossil fuels. Biomass and waste are suitable resources to produce proper alternative fuels instead of nonrenewable fuels. Upgrading bio-oil produced from biomass and waste pyrolysis is essential to be used as an alternative to nonrenewable fuel. The high oxygen content in the biomass and waste pyrolysis oil creates several undesirable properties in the oil, such as low energy density, instability that leads to polymerization, high viscosity, and corrosion on contact surfaces during storage and transportation. Therefore, various upgrading techniques have been developed for bio-oil upgrading, and several are introduced herein, with a focus on the hydrodeoxygenation (HDO) technique. Different oxygenated compounds were collected in this review, and the main issue caused by the high oxygen contents is discussed. Different groups of catalysts that have been applied in the literature for the HDO are presented. The HDO of various lignin-derived oxygenates and carbohydrate-derived oxygenates from the literature is summarized, and their mechanisms are presented. The catalyst’s deactivation and coke formation are discussed, and the techno-economic analysis of HDO is summarized. A promising technique for the HDO process using the microwave heating technique is proposed. A comparison between microwave heating versus conventional heating shows the benefits of applying the microwave heating technique. Finally, how the microwave can work to enhance the HDO process is presented.

Production of Aromatic Hydrocarbons from Biomass

The results of recent research on the production of aromatic hydrocarbons from biomass are summarized. Alternative types of catalytic fast pyrolysis of lignocellulosic biomass of diverse origin into bio-oil, as well as catalysts and carriers for the bio-oil hydrodeoxygenation process are reviewed. HZSM-5 zeolite is widely used as a catalyst for a biomass pyrolysis process. Oxygen-containing bio-oil compounds are converted into aromatic hydrocarbons with the best performance when noble metal-based catalysts are used, whereas acceptable performance is also achieved with molybdenum oxides and zirconium oxides. Experimental and computational data on the mechanisms of biomass components conversion to aromatic hydrocarbons are discussed.

Ordered mesoporous silica-supported metal catalysts for hydrodeoxygenation of anisole derivatives

The aim of the study presented was a comprehensive analysis of catalytic performance of palladium and platinum catalysts (1 or 3 wt% relative to the support), on SBA-16, in hydrodeoxygenation (HDO) of chemical compounds generated in biomass processing (anisole, 4-methylanisole and 1,3-dimethoxybenzene). HDO of these compounds was carried out in a high pressure reactor for 4 h in temperatures from 90 to 130 °C and under hydrogen pressure of 25–60 bar. The catalytic performance of palladium and platinum modified materials was found to differ considerably. The SBA-16 supported catalyst modified with palladium permitted getting high conversion of the model molecules studied (often 100%), while those modified with platinum showed higher selectivity to the compounds with no oxygen atom in their structures, which allowed a significant reduction of the O/C ratio. Direct impact of the process conditions (temperature, pressure) on the degree of conversion and selectivity of the HDO process was established and characterized. • Pd and Pt catalysts supported on SBA-16 for HDO of anisole derivatives. • Influence of the type of metal on HDO activity was studied. • Influence on the reaction conditions on HDO activity was studied. • HDO reactions conducted under mild experimental conditions.