Real Bio-oil Research Articles

Production of Valuable Aromatics from the Hydrodeoxygenation of Guaiacol and Real Bio-Oil over Ni–Nb/HZSM-5 under Supercritical Ethanol

Production of Valuable Aromatics from the Hydrodeoxygenation of Guaiacol and Real Bio-Oil over Ni–Nb/HZSM-5 under Supercritical Ethanol

Hydrodeoxygenation of Oxygenates Derived from Biomass Pyrolysis Using Titanium Dioxide-Supported Cobalt Catalysts.

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.

The in-situ formation of supported hydrous ruthenium oxide in aqueous phase during HDO of lignin-derived fractions

The in-situ formation of supported hydrous ruthenium oxide (HRO) from RuO2 over micro-mesoporous materials is reported for the selective hydrogenation of bio-oil under mild reaction conditions (200 °C, 20 bar H2) in an aqueous medium. For the first time, the phase composition of HRO was determined using a variety of characterization techniques. Using synchrotron radiation and in-situ X-ray absorption spectroscopy (XAS), we demonstrated that HRO was generated during the hydrodeoxygenation process. The hydrodeoxygenation (HDO) of real bio-oil was successfully performed at 200 °C, 20 bar H2 on RuO2-containing catalysts. The approximate composition of HRO after 3 h of catalytic hydrogenation, consisted of in approximately equal ratios metallic Ru, RuO2, and RuOOH phases.

Sorption enhanced steam reforming (SESR) of raw bio-oil with Ni based catalysts: Effect of sorbent type, catalyst support and sorbent/catalyst mass ratio

This work analyzes the effect of sorbent type (dolomite or CaO/mayenite), catalyst type (Ni/Al2O3 obtained upon reduction of a NiAl2O4 spinel or Ni/CeO2 prepared by wet-impregnation) and sorbent/catalyst ratio (4, 10 and 20) in the sorption enhanced steam reforming (SESR) of a real raw bio-oil. The experiments were performed in a continuous reaction system with two units: a thermal treatment unit at 500 °C for real bio-oil volatilization and controlled deposition of pyrolytic lignin, and a fixed-bed reactor for the SESR on line of the remaining oxygenates at 600 °C with steam-to‑carbon (S/C) ratio of 2.6. Furthermore, the causes of the unavoidable catalyst deactivation have been determined by several techniques. The sorbent activity for oxygenates decomposition/cracking reactions competes with the catalyst activity for reforming reactions and affects the morphology and location of the coke, thus affecting the catalyst stability. The combination of dolomite (less active for oxygenates decomposition than CaO/mayenite) and Ni/Al2O3 catalyst (with higher activity for real bio-oil reforming than Ni/CeO2) is the better choice. With space time of 0.15 gcatalyst·h/goxygenates, a dolomite/NiAl2O4 mass ratio of 10 allows producing a gas stream with almost 100% H2 for 30 min with high stability.

Bioh2, Heat and Power from Palm Empty Fruit Bunch via Pyrolysis-Autothermal Reforming: Plant Simulation, Experiments, and CO2 Mitigation

Empty fruit bunch, a significant by-product of the palm oil industry, represents a tremendous and hitherto neglected renewable energy resource for many countries in South East Asia and Sub-Saharan Africa. The design and simulation of a plant producing pure hydrogen through autothermal reforming (ATR) of palm empty fruit bunch (PEFB) was carried out based on successful laboratory experiments of the core process. The bio-oil feed to the ATR stage was represented in the experiments and in the simulation by a surrogate bio-oil mixture of 11 organic compounds shown to be main constituents of PEFB oil from previous work, and whose combined elemental composition and volatility was determined to be as close as possible to that of the real PEFB bio-oil. The experiments confirmed that H2 yields close to equilibrium predictions were achievable using an in-house synthetised Rh-Al2O3 catalyst in a packed bed reactor. Initial sensitivity analysis on the plant revealed that feed molar steam to carbon ratio should not exceed 3 for the optimal design of the ATR hydrogen production plant. An overall plant efficiency of 39.4% was obtained for the initial design, this value was improved to 67.5% by applying pinch analysis to enhance the integration of heat in the design. The proposed design renders CO2 savings of about 0.56 kg per kg of raw PEFB processed. The proposed design and accompanying experimental studies together make a strong case on the possibility of polygeneration of H2, heat, and power from an otherwise discarded agricultural waste.

A review of bio-oil upgrading by catalytic hydrotreatment: Advances, challenges, and prospects

• Two most common biofuels production techniques including fast pyrolysis and HTL arecovered. • The proposed crude bio-oil upgrading approaches are discussed. • Effects of various upgrading parameters on bio-oil HDO are described. • The mechanism for catalyst deactivation and possible solutions are provided. • Chemistry of major bio-oil model compounds during HDO is thoroughly reviewed. Fast pyrolysis and hydrothermal liquefaction (HTL) have been regarded as the most promising thermochemical conversion technologies for liquid bio-fuels production. However, the poor quality of generated crude bio-oils, such as high O and water contents, low thermal stability, and high corrosivity, limits their direct applications as the alternative transportation fuels. Thus, a number of upgrading techniques mainly including chemical and physical methods have been developed. Among them, hydrotreatment like hydrodeoxygenation (HDO) as a well-established technology at petroleum refinery plants has been widely adopted for upgrading of the crude oil obtained from pyrolysis or HTL. In this review, the effects of various upgrading reaction conditions (temperature, H 2 pressure, solvents, residence time, and catalyst) of HDO treatment of real bio-oil and its mode compounds are thoroughly reviewed. In which, the underlying mechanisms for bio-oil HDO are elucidated with a wide range of its model compounds (lignin-derived oxygenates and carbohydrates-derived oxygenates) and the interaction between these model compounds. Moreover, a discussion regarding the HDO of real bio-oil from pyrolysis and HTL is provided, and the technical/operating problems for the catalytic HDO and the possible solutions are presented. Finally, the important knowledge gaps and future directions are addressed for further investigations.

Benzene, toluene and xylene (BTX) from in-situ gas phase hydrodeoxygenation of guaiacol with liquid hydrogen donor over bifunctional non-noble-metal zeolite catalysts

Hydrogen donors were employed to replace pure hydrogen as a hydrogen source for in-situ gas phase HDO due to their low storage and transportation cost. A series of catalysts have been prepared by modifying the zeolite HZSM-5 with polymetallic and multi-carriers. Gas-phase hydrodeoxygenation (HDO) of guaiacol was conducted under a pressure 2 MPa and a temperature at 350 °C. The effect of polymetallic and multi-carrier modification on HDO activity was investigated. The physicochemical properties of catalysts were characterized by BET, XRD, SEM, H2-TPR, XPS and NH3-TPD. The characterization results showed that when La was loaded, the catalyst Ni/HZSM-5&La obtained a stronger medium-strong acidity. The electronic transfer of the elemental nickel was promoted. After HDO, the catalyst Ni/HZSM-5&La exhibited the highest HDO rate and BTX selectivity, reaching 97.79% and 34.25%, respectively. The real bio-oil HDO under a hydrogen donor were also analyzed. The results showed the content of the hydrocarbon compound were over 95%. The reaction mechanism was discussed through the distribution of liquid product species. Direct demethoxylation pathway (DMO) and methylation pathway (ME) were considered as the main pathways.

Approaches to investigate the role of chelation in the corrosivity of biomass-derived oils

The need to provide the U.S. market with a renewable liquid fuel energy source from a non-food feedstock stream has gained considerable traction due to benefits such as improved energy efficiency, reduced environmental impacts, and enhanced national security. Practical achievement of these goals via biomass and bio-waste utilization involves production of liquid intermediates containing corrosive, reactive species like carboxylic acids, ketones, aldehydes, and hydroxyaldehydes. Such mixtures challenge materials of containment, processing, and transport. It is widely recognized that the smaller organic acids, such as acetic and formic, are corrosive and can remove protective surface oxides on alloys used in bio-oil processing infrastructure, and ketones can swell sealing polymers. However, literature shows, and findings herein confirm, larger carboxylic acids and bidentate alcohols are present. This highlights the potential for synergistic, detrimental effects of constituents in bio-oil corrosion, including direct reactivity of small acids compounded with the possibility of mobilization of protective metal oxide layers via chelation by larger acids and oxygenates. The question of whether species beyond small acids can significantly contribute to corrosion requires analytical approaches previously not applied to bio-oil corrosion studies and certainly not previously applied corroboratively. This work introduces a combination of optical, mass spectral, and electrochemical impedance spectroscopies with an incubation approach to study metal mobilization, to facilitate elucidating chelation's role in bio-oil corrosive pathways. To enable systematic study of these oxygenates' material compatibility individually and in combination, a model matrix of bio-oil constituents was also developed based on identification of key components of real bio-oils.

An efficient bifunctional Ru-NbOPO4 catalyst for the hydrodeoxygenation of aromatic ethers, phenols and real bio-oil

An efficient bifunctional NbOPO4 supported Ru catalyst (Ru-NbOPO4) was applied to the hydrodeoxygenation of aromatic ethers and phenols and the upgrading of bio-oil. Characterization results revealed that the Ru-NbOPO4 catalyst possessed strong acidity, including Lewis and Brønsted acids. The Lewis acid sites originated from the NbO bonding structures, including slightly distorted octahedral NbO6, regular tetrahedral NbO4 and highly distorted octahedral NbO6. In combination with the strong acidity of the NbO species and excellent hydrogenation activity of the metallic Ru, the bifunctional Ru-NbOPO4 catalyst exhibited an excellent catalytic activity in the hydrodeoxygenation of aromatic ethers and phenols with different structures, and even real bio-oil to alkanes. The hydrocarbon yield after real bio-oil upgradation was up to 88.2 %. Carbon deposition and enlargement of the Ru nanoparticles resulted in slight deactivation of the catalyst. The catalytic activity could be mostly recovered after being calcined and reduced.

Geminal Coordinatively Unsaturated Sites on MOF-808 for the Selective Uptake of Phenolics from a Real Bio-Oil Mixture.

The capping formate anions of the metal-organic framework (MOF) zirconium benzene-1,3,5-tricarboxylate (MOF-808) were removed by a solvent exchange procedure, resulting in a formate-free MOF-808 sample containing "geminal" defects consisting of six coordinatively unsaturated sites (CUSs) on each of the Zr6 nodes. Adsorption experiments with this material showed that the uptake of 4-methylguaiacol from a bio-oil mixture was proportional to the number of defects and amounted to one mole adsorbed per mole of zirconium. The selective uptake behavior of MOF-808 towards phenolic compounds was further evident from competitive adsorption experiments between furfuryl alcohol and 4-methylguaiacol as well as from the excellent (20 wt % for phenolic compounds and <7 wt % for other compounds) uptake performance for real bio-oil mixtures containing a large concentration and diversity of molecules.

Hydrogen production through steam reforming of bio-oils derived from biomass pyrolysis: Thermodynamic analysis including in situ CO2 and/or H2 separation

A thermodynamic analysis based on the minimization of the Gibbs free energy method was performed in order to study the steam reforming of real bio-oils (obtained from biomass fast pyrolysis) from different sources. For comparison purposes, four types of reactors were used, namely: traditional reactor (TR), membrane reactor (MR) with H2 separation, sorption-enhanced reactor (SER) with CO2 sorption, and sorption-enhanced membrane reactor (SEMR) with both H2 and CO2 separation. The CO2 capture was studied varying the sorbent (CaO) to feed molar ratio (SFR) while the effect of the H2 removal was assessed with the use of a removal fraction (fH2) of 0 to 0.8 (typical recoveries for an H2-selective membrane).The simulated results obtained for the TR showed a good agreement with those reported in literature experimental works at similar operation conditions. The optimum conditions for the production of hydrogen were obtained in the SEMR in which it was possible to obtain 99% of the maximum theoretical yield for spruce bio-oil and 97% of the maximum yield for wheat bio-oil. Furthermore, this reactor configuration minimizes CH4, H2, CO, CO2 and coke yields. In addition, the effect of pressure in a range of 1 to 10 bar was also assessed for the reactor configurations with H2 removal. It was shown that the increase of pressure decreases H2 yield; nevertheless, this can be offset by moderately increasing the WFR.

Role of copper- or cerium-promoters on NiMo/γ-Al2O3 catalysts in hydrodeoxygenation of guaiacol and bio-oil

Effect of copper (Cu) or cerium (Ce) as promoters for nickel-molybdenum/γ-alumina (NiMo/γ-Al2O3) catalyst on the hydrodeoxygenation (HDO) of guaiacol (GUA), a model oxygenated compound found in a bio-oil derived from woody biomass, was comparatively investigated. The addition of Cu- or Ce-promoters affected the physicochemical properties of the NiMo catalyst. The NiMo catalyst promoted by Cu showed the higher reducibility, whilst the Ce-promoter (2–8 wt% based on γ-Al2O3 content) provided the NiMo catalyst with a higher distribution of active metals and induced a greater difficulty in the reduction under hydrogen (H2) atmosphere. For the HDO of GUA at a mild reaction condition (10 bar initial H2 pressure and 300 °C) in the absence of solvent, the Cu-promoter enhanced the hydrogenation activity of the NiMo catalyst to convert GUA to phenol and methylphenols, one-atomic oxygen species. Whereas, the addition of Ce obviously inhibited the formation of coke on the catalyst surface after a long reaction period (6 h) and gave a higher GUA conversion level with increasing yield of phenols. For the HDO of real bio-oil obtained from the fast pyrolysis of cassava rhizome, the NiMo catalysts promoted by Cu or Ce at 4 wt% based on the γ-Al2O3 content showed a higher performance at eliminating the oxygenated compounds in the bio-oil, reducing the oxygen/carbon (O/C) molar ratio by over seven-fold from 1.75 to 0.24–0.25. Moreover, the gross heating value of the bio-oil was improved from 21.5 to ca. 29.0 MJ/kg after the HDO process. However, the addition of the Cu or Ce promoter did not inhibit coke deposition, possibly due to the acidic properties of the bio-oil that deteriorated the catalyst performance by metal leaching.

Upgrading phenolic compounds and bio-oil through hydrodeoxygenation using highly dispersed Pt/TiO2 catalyst

Noble metal catalyst has an outstanding catalytic activity on the hydrodeoxygenation (HDO) process, but its high cost limits large-scale application. Herein, we put forward a novel photochemical method to prepare the highly dispersed Pt/TiO2 catalyst with a low metal loading. And it presented an efficient performance on the HDO of phenolic compounds and real bio-oil. Guaiacol could be converted into cyclohexane with 95.1% selectivity at 280 °C under 1 MPa H2 atmosphere. Characterization results revealed that the high Pt dispersion was the critical factor for the high catalytic activity. And the photochemical method preferred to achieve high metal dispersion due to the room temperature condition. Other typical phenolic monomers and dimers were able to transform into hydrocarbons with most yield above 80%, wherein not only the deoxygenation step, but also the cleavage of ether bonds can be realized in one pot. This catalytic system was also effective on the upgrade of bio-oil derived from the pyrolysis of cotton straw. Hydrocarbon content increased to 33.80% from 11.33%. Alkylphenols content increased to 51.38% from 27.86%. These two products can be used as value-added fuels and chemicals, respectively. Guaiacols and syringols were completely converted into alkylphenols and hydrocarbon. The amount of other oxygenated compounds also decreased significantly. This simple and active catalytic system is potential to apply widely for the upgrade of raw bio-oil.

Efficient catalytic hydrodeoxygenation of phenolic compounds and bio-oil over highly dispersed Ru/TiO2

Upgrading of bio-oils to value-added products through simple and cost-efficient catalytic routes is always a big challenge in the energy utilization field. Herein, we prepared a highly dispersed 2 wt% Ru/TiO2 catalyst using a simple and novel photochemical method at room temperature. The synthetic catalyst exhibited an efficient performance on the HDO of phenolic compounds and real bio-oil, owing to its high Ru dispersion. Guaiacol could be converted into cyclohexane with 91.3% selectivity at 260 °C under 1 MPa H2 atmosphere. Other typical phenolic monomers (phenol, anisole, etc.) and dimers (α-O-4, 4-O-4, etc.) were transformed into cycloalkanes with most yield close to 100%. Results showed that the cleavage of ether bonds and the HDO step can be realized in one pot. This catalytic system was also effective on the upgrade of bio-oil derived from the pyrolysis of cotton straw. A upgraded product composed of 32.4% hydrocarbons and 57.6% alkylphenols was achieved at 280 °C, which can be used as fuels and chemicals respectively. The enhanced reaction temperature (300 °C) enabled hydrocarbon contents increased to 41.4%, leaving the other oxygenated compounds only 4.2%. This work provides a promising reference for the valorization of raw bio-oil.

Nickel based monometallic and bimetallic catalysts for synthetic and real bio-oil steam reforming

Catalysts based on Ni supported on alumina were studied for steam reforming (SR) of a synthetic bio-oil/bio-glycerol mixture and a real bio-oil. Catalyst tests were carried out in a continuous fixed bed reactor at atmospheric pressure and steam to carbon (S/C) ratio of 5.0. In the case of experiments with the bio-oil/bio-glycerol mixture the initial temperature was 1073 K, then it was successively changed to 973 K and 1073 K again to assess catalyst deactivation. Experiments with the bio-oil sample were run at 1073 K. First, the effect of modifications to the alumina support with CeO2 and La2O3 was studied in monometallic catalysts. Ni/CeO2Al2O3 was identified as the catalyst more resistant to deactivation, likely due to its higher oxygen mobility, and selected for further tests. Then, bimetallic catalysts were produced by impregnation of noble metals (Pd, Pt or Rh) on the Ni catalyst supported on CeO2Al2O3. Co-impregnation of Rh and Ni on the CeO2Al2O3 support represented a further improvement in the catalytic activity and stability respect to the monometallic catalyst, leading to stable gas compositions close to thermodynamic equilibrium due to the favourable RhNi interactions. RhNi/CeO2Al2O3 is therefore a promising catalyst to produce a hydrogen-rich gas from bio-oil SR.

Pure hydrogen from lighter fractions of bio-oil by steam-iron process: Effect of composition of bio-oil, temperature and number of cycles

High purity hydrogen has been obtained by “steam-iron” process from lighter fractions of synthetic bio-oils of different compositions in a single fixed bed reactor operating cyclically. This process in closely related to chemical looping producing and purifying hydrogen in a single reactor. The feedstock consisted of a blend of four model compounds representing the lighter fractions of a bio-oil. Acetic acid has been chosen as representative of the acidic fraction, hydroxyacetone of the ketonic/aldehydic, methanol of the alcoholic and finally water of the aqueous one. Content of each model compound in the mixture has been fixed by design of experiments techniques according to composition of real bio-oils found in literature. First step involves the reduction of an iron oxide at several temperatures (650–850°C) by the action of a synthetic bio-oil, which catalytically decomposes into gaseous reductive species (mainly hydrogen and carbon monoxide). Solid carbon was also produced and deposited on the surface of the solid. Once the iron oxide is completely reduced, a second step consists in the oxidation of the metallic iron with steam releasing pure hydrogen. Along this reaction, and due to the low oxidation temperature (550°C), carbon deposited in the previous step was not appreciably gasified, letting the released hydrogen be virtually free of carbon monoxide ([CO]<20ppm). Low proportions of water in the reductive gases have proved to exert a positive effect in the process, diminishing the residual carbon deposited on the solid bed, although decreasing reduction rates. The solid tested along this study, based on an iron oxide with small amounts of alumina and ceria, can produce pure hydrogen following a cyclic process, but exhibits a progressive loss of redox capacity of ca. 3wt% after each cycle.

Catalysts for Steam Reforming of Bio-oil: A Review

Despite extensive studies on the steam reforming of model compounds (e.g., ethanol), steam reforming of real bio-oil is a more practical means for H2 production. This review summarizes recent advances made in steam reforming of real bio-oil, with an emphasis on catalyst development for the process. Among the catalysts investigated, Ni is shown to be promising given its high activity for C–C and C–H bond cleavage. It also has the added advantage of a low cost of production. Strategies to improve catalyst performance include the mitigation of carbon deposition, inhibition of methanation, as well as promotion of water gas shift reactions. In addition, a discussion on current understanding of the reaction mechanism and catalyst deactivation is included in this review, with the aim to provide insight into the relationship between catalyst structure and performance that will give direction toward the development of high performance bio-oil steam reforming catalysts.

Quantification of real thermal, catalytic, and hydrodeoxygenated bio-oils via comprehensive two-dimensional gas chromatography with mass spectrometry

The elucidation of bio-oil composition is important to evaluate the processes of biomass conversion and its upgrading, and to suggest the proper use for each sample. Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) is a widely applied analytical approach for bio-oil investigation due to the higher separation and resolution capacity from this technique. This work addresses the issue of analytical performance to assess the comprehensive characterization of real bio-oil samples via GC×GC-TOFMS. The approach was applied to the individual quantification of compounds of real thermal (PWT), catalytic process (CPO), and hydrodeoxygenation process (HDO) bio-oils. Quantification was performed with reliability using the analytical curves of oxygenated and hydrocarbon standards as well as the deuterated internal standards. The limit of quantification was set at 1ngµL−1 for major standards, except for hexanoic acid, which was set at 5ngµL−1. The GC×GC-TOFMS method provided good precision (<10%) and excellent accuracy (recovery range of 70–130%) for the quantification of individual hydrocarbons and oxygenated compounds in real bio-oil samples. Sugars, furans, and alcohols appear as the major constituents of the PWT, CPO, and HDO samples, respectively. In order to obtain bio-oils with better quality, the catalytic pyrolysis process may be a better option than hydrogenation due to the effective reduction of oxygenated compound concentrations and the lower cost of the process, when hydrogen is not required to promote deoxygenation in the catalytic pyrolysis process.

Catalytic Hydrodeoxygenation of Bio-oil Model Compounds over Pt/HY Catalyst.

The hydrodeoxygenation of a model compound of lignin-derived bio-oil, guaiacol, which can be obtained from the pyrolysis of biomass to bio-oil, has attracted considerable research attention because of its huge potential as a substitute for conventional fuels. In this study, platinum-loaded HY zeolites (Pt/HY) with different Si/Al molar ratios were used as catalysts for the hydrodeoxygenation of guaiacol, anisole, veratrole, and phenol to a range of hydrocarbons, such as cyclohexane. The cyclohexane (major product) yield increased with increasing number of acid sites. To produce bio-oil with the maximum level of cyclohexane and alkylated cyclohexanes, which would be suitable as a substitute for conventional transportation fuels, the Si/Al molar ratio should be optimized to balance the Pt particle-induced hydrogenation with acid site-induced methyl group transfer. The fuel properties of real bio-oil derived from the fast pyrolysis of cork oak was improved using the Pt/HY catalyst.

Biofuel production using Pd/Zn synergistically catalyzed hydrodeoxygenation applied at bio oil extracted in biomass pyrolysis process

Raw bio oil includes multicomponents. In order to avoid the interference between complex reactions, the model compounds, instead of the real bio oil, have been widely used for the study of raw bio-oil upgrade. In this work, the hydrodeoxygenation (HDO) of raw pine pyrolysis bio oil was investigated at 200 °C using Pd/Zn synergistic catalysis under hydrogen pressures of 200, 300, and 400 psi, separately. The resulting product included gas, liquid, and coke. The gas was characterized using a gas chromatography. The liquid was characterized using a gas chromatography–mass spectrometry. The results showed that the HDO performance achieved promotion to some extent by the Pd/Zn synergistic catalysis compared with use of Pd/C or Zn2+, independently. The HDO also gave rise to improvements on physicochemical properties of bio oils. Notably, the highest water content (13.16 wt%) revealed that deoxygenation reaction could be promoted by Pd/Zn synergistic catalysis compared with use of Pd/C or Zn2+, independently. More importantly, the highest hydrocarbon yield (19.15% on the base of liquid part) could be obtained by the treatment of 300 psi pressure and 200 °C temperature over Zn/Pd/C synergistic catalysis. Copyright © 2016 John Wiley & Sons, Ltd.