Biomass Fast Pyrolysis Oil Research Articles

Electrocatalytic Upgrading of Biomass-Derived Compounds for Biofuel Production

Biomass fast pyrolysis liquid (also known as bio-oil) is considered to be one of the most promising renewable carbon feedstocks. However, fresh pyrolyzed bio-oil is acidic and corrosive and contains large amounts of carbonyl and phenolic compounds produced by polymerization under acidic conditions. This work primarily utilizes an electrochemical conversion strategy using only earth-abundant metal catalysts to achieve the carbonyl hydrogenation process. The results show that upgrading this process produces biofuels with greater stability and higher specific energy. In addition to analyzing the chemical implications of this conversion strategy, this work will also discuss why electrocatalytic conversion is a promising technology path for biofuels and fine chemicals. Reference Huang, S., Lam, C. H.* et al. (2022). "The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural." ACS Catalysis 12(18): 11340-11354.Huang, S., Lam, C. H.* et al. (2022). "MoS2-Catalyzed Selective Electrocatalytic Hydrogenation of Aromatic Aldehydes in an Aqueous Environment." Green Chemistry.Tu, Q., Lam, C. H.* et al. (2021). "Electrocatalysis for Chemical and Fuel Production: Investigating Climate Change Mitigation Potential and Economic Feasibility." Environmental Science & Technology 55(5): 3240-3249.Garedew, M., Lam, C. H.* et al. (2020). "Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production." ChemSusChem 13(17): 4214-4237. Lam, C. H., et al. (2017). "Towards sustainable hydrocarbon fuels with biomass fast pyrolysis oil and electrocatalytic upgrading." Sustainable Energy & Fuels 1(2): 258-266. Figure 1

Efficient catalytic transfer hydrogenation of raw bio-oil over various CuO catalysts

A novel method was proposed for biomass fast pyrolysis oil upgrading using catalytic transfer hydrogenation (CTH) based on various CuO catalysts with methanol as the hydrogen donor. The carbonyl compounds in the bio-oil were hydrogenated to synthesize alcohols using a hydrotalcite-like Cu2Al catalyst at 200℃ for 4 h. The maximum yield of alcohols reached 73.81%. Cu2Al is well applicable to large-scale application in bio-oil CTH for its excellent CTH performance, treating capacity up to 10 vol%, and stable alcohol production during the 5th reuse process. Given the huge range of molecular size of the complex chemical composition of bio-oil, the CTH of raw bio-oil using three catalysts (i.e., CuO/BC, CuO/Al2O3, and Cu2Al) was compared. The CTH performance (71.56%) of CuO/Al2O3 was significantly comparable to that of Cu2Al, and it is also a good choice. The main reason for this outcome was that the average pore size of the two catalysts was high (>5nm), which reduced the possibility of pore blockage during the reaction and improved stability. The reusability of CuO/BC was markedly lower for its small average pore size (∼2nm). Furthermore, the CTH of raw bio-oil over CuO catalyst was discussed in depth, such that a basis is laid for the upgrading and utilization of bio-oil.

Combustion and emission characterization of upgraded biomass fast pyrolysis oil in a swirl burner

Fast pyrolysis oil (FPO, also called bio-oil) is a biofuel made from thermal decomposition of renewable or waste biomass. However, the physiochemical properties of FPO have limited its widespread use in combustion applications. In this study, the impacts of FPO upgrading with multi-stage condensation, catalytic pyrolysis with ZSM-5, and ethanol blending were studied through characterization of physiochemical properties and combustion in a swirl burner. A commercially available FPO sample (COMM) and diesel were used to benchmark the upgraded FPO samples. The non-catalytic FPO (NC) sample produced with multi-stage condensation had 9.0wt% less oxygen and an HHV 2.2 MJ/kg higher than COMM. The FPO produced using ZSM-5 catalyst (CAT) had 19.0wt% less oxygen, an HHV greater by 7.4 MJ/kg, and lower viscosity than COMM. The CAT sample also had fewer low-molecular-weight compounds, showing a peak mass loss rate 70 °C higher than NC. The NC and CAT samples were also blended with 10vol% ethanol, which had minor effects on the measured physiochemical properties aside from improving volatility. Combustion was evaluated by measuring unburned hydrocarbon, CO, NOx, and particulate matter exhaust concentrations from a swirl burner as well as through flame visualization. Combustion of neat NC was stable, although compared to COMM, CO was ∼2-times higher and NOx was ∼2-times lower. In contrast, the CAT flame was unstable, resulting in the highest CO concentrations overall. Blending NC and CAT with 10vol% ethanol resulted in lower CO concentrations (NC: 88% less, CAT: 96% less) and higher NOx (NC: 2-times, CAT: 1.4-times) compared to neat FPO. Although catalytic upgrading and multi-stage condensation improved HHV, oxygen content, and viscosity, changes to these properties did not improve combustion performance. Ethanol blending emphasized the outsize role of volatility in improving furnace combustion relative to other measured physiochemical properties as reflected by the improved flame stability and exhaust composition.

Hydrogenation of biomass pyrolysis oil using enhanced reduction catalytic capacity cellular by expressing excavated carbonyl reductase

A biocatalytic method to achieve the hydromodification of biomass fast pyrolysis oil was implemented. Two carbonyl reductases SDR-1 and SDR-8 were excavated in the genome of Bacillus coagulans NL01, enhanced Escherichia coli ability to tolerate and reduce various toxic ketone aldehydes. 10 g/L furfural and 8 g/L acetoin as bio-oil model compounds could be transformed by the recombinant E. coli SDR-1 and E. coli SDR-8 respectively. The biphasic catalysis system was constructed to convert the keto-aldehyde compounds in bio-oil to the corresponding alcohol at 30 °C. Recombinant E. coli SDR-8 could completely consume 20 g/L glucose and consume 60% 20 g/L glucose in the diluted 50-fold and 30-fold bio-oil catalytic system, respectively. This provided a new pathway for the hydrogenation of bio-oil by biocatalytic method and laid the foundation for the low-temperature esterification in the later stage.

Coprocessing Biomass Fast Pyrolysis and Catalytic Fast Pyrolysis Oils with Vacuum Gas Oil in Refinery Hydroprocessing

Coprocessing Biomass Fast Pyrolysis and Catalytic Fast Pyrolysis Oils with Vacuum Gas Oil in Refinery Hydroprocessing

Electrocatalytic Upgrading of Biomass Fast Pyrolysis Oil

Attempts to electrocatalytically upgrade bio-oil have been made in recent years. Mostly, the ECH (Electrocatalytic Hydrogenation) experiments of bio-oil were done using fixed bed electrode configurations at room temperatures and low current densities (<100 cm-2). The main goal was to demonstrate the viability of ECH as a bio-oil stabilization strategy, mainly through reduction of carbonyl contents (aldehydes and ketones) which could cause polymerization. High temperature may promote condensation polymerization of fast pyrolysis oil, low-temperature ECH is therefore considered a promising approach to stabilize pyrolysis oil. However, recent advances in ECH of fast pyrolysis oil have shown the limited reductive upgrading chemistry (hydrogenation, hydrogenolysis, or hydrodeoxygenation) through this approach. This was mainly attributed to the complexity of fast pyrolysis oil and the restricted electrolysis operating conditions. Most of the published works in ECH of pyrolysis oil reported the reduction of carbonyl content into alcohols in the substrate rather than the hydrodeoxygenation of aromatics or phenolics. In this study, ECH of fast pyrolysis oil (FPO) in acidic electrolytes using SSER (Stirred Slurry Electrocatalytic Reactor) configuration was conducted for the first time. A compositional analysis suggested that the FPO sample contained water (29 wt.%) and detected monomers (38.5 wt.%), which comprise of carbohydrate derivatives (35.2 wt.%) and lignin derivatives (3.3 wt.%). Balance of water and monomers must be oligomers. Three polar organic solvents (e.g., ethanol, isopropanol, and acetone) were tested in a mixed aqueous and organic electrolyte with MSA solution. The electrolysis experiments were carried out for 4–30 h at constant cathodic current densities (I = -218 to -255 mA cm-2) and temperatures (50–60 oC). In all cases, decreases in the weight average molecular weight (Mw) and the number average molecular weight (Mn) were observed with prolonged reaction times. Temperature and catalyst loading contributed to faster depolymerization of the oligomers. Using different organic solvents (e.g., ethanol, isopropanol, acetone), the degree of depolymerization was about 33–37% after nearly 20 h reactions. Color changes in the catholyte FPO samples were observed in all cases after 18–25 h, turning from dark brown to light yellow. This observation supports the GPC results showing the molecular weight reduction after the ECH. In this study, compound distributions were determined based on ten functional groups, such as acids, alcohols, aldehydes, ketones, esters, furans, alkanes, aromatics, phenols, and guaiacols. In all cases, the reduction of ketones, aromatics, and guaiacols was noticed, while the alkanes content slightly increased. The most dramatic increases in esters content were observed when ethanol (17–25%) or isopropanol (19–32%) was used. This was attributed to esterification of carboxylic acids (mainly acetic acid) in the FPO with alcohols in the presence of MSA, which catalyzed the reaction. Reduction of p-eugenol to cerulignol (4-propylguaiacol) was the most noticeable in all cases, implying that the unsaturated bond in the allyl group is easily reduced under the ECH conditions. Significant increases in the cerulignol contents were achieved with all the different solvents: ethanol (0.5–4.9%), isopropanol (1.4–6.9%), and acetone (1.4–5.4%), based on the composition calculation normalized by the lignin-relevant compounds detected in the catholyte samples. ECH of FPO in SSER with organic solvents addition has demonstrated mild depolymerization of FPO oligomers, esterification, and reduction of carbohydrate and lignin derivative monomers which could potentially upgrade the quality of FPO for synthesis of hydrocarbon fuels.

Development of a Mesoporous Silica-Supported Layered Double Hydroxide Catalyst for the Reduction of Oxygenated Compounds in E. grandis Fast Pyrolysis Oils

Biomass fast pyrolysis oil is a potential renewable alternative to fossil fuels, but its viability is constrained by its corrosiveness, low higher heating value and instability, caused by high oxygenate concentrations. A few studies have outlined layered double hydroxides (LDHs) as possible catalysts for the improvement of biomass pyrolysis oil characteristics. In this study, the goal was to reduce the concentration of oxygen-rich compounds in E. grandis fast pyrolysis oils using CaAl- and MgAl- LDHs. The LDHs were supported by mesoporous silica, synthesised at different pHs to obtain different pore sizes (3.3 to 4.8 nm) and surface areas (up to 600 m2/g). The effects of the support pore sizes and use of LDHs were investigated. GC/MS results revealed that MgAl-LDH significantly reduced the concentrations of ketones and oxygenated aromatics in the electrostatic precipitator oils and increased the concentration of aliphatics. CaAl-LDH had the opposite effect. There was little effect on the oxygenate concentrations of the heat exchanger oils, suggesting that there was a greater extent of conversion of the lighter oil compounds. Bomb calorimetry also showed a marked increase in higher heating values (16.2 to 22.5 MJ/kg) in the electrostatic precipitator oils when using MgAl-LDH. It was also found that the mesoporous silica support synthesised at a pH of 7 was the most effective, likely due to the intermediate average pore width (4 nm).

Measuring inorganics in biomass fast pyrolysis oils

Measurement of inorganics present in biomass fast pyrolysis liquids has been scarcely investigated in the literature. In this work several analytical methods based on different sample preparations were investigated and applied on a set of nine biomass fast pyrolysis liquids covering a wide range of inorganics contents that have been measured using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) analyser. Several required mineralisation first steps were studied to completely dissolve the samples. Our results show that the ISO 16967 method, initially developed for solid biomasses and adapted here for bio-oils, was the most interesting one to quantify three major inorganics (i.e. potassium, magnesium and sodium), measurement of calcium contents remaining a challenge when applied to bio-oils, while good results were obtained for reference materials.

Isobaric Vapor–Liquid Equilibria of Binary Systems Containing Cyclohexane for the Separation of Phenolic Compounds from Biomass Fast Pyrolysis Oils

Isobaric Vapor–Liquid Equilibria of Binary Systems Containing Cyclohexane for the Separation of Phenolic Compounds from Biomass Fast Pyrolysis Oils

CFD modeling of pyrolysis oil combustion using finite rate chemistry

This paper reports the first Computational Fluid Dynamics (CFD) model developed for biomass pyrolysis oil spray combustion using Finite-Rate Chemistry (FRC) approach. To make the CFD calculations feasible, a reduced mechanism for modeling the combustion of biomass Fast Pyrolysis Oil (FPO) based on the POLIMI 1412 mechanism and a model for eugenol oxidation was developed. The reduced mechanism consisted of 200 reactions and 71 species. This level of complexity was found to be a good tradeoff between predictive power and computational cost such that the reduced model could be used in CFD modeling. The predictive power of the reduced mechanism was demonstrated via 0D (adiabatic, premixed, constant pressure reactor), 1D (laminar counterflow flame) and 3D (CFD of a methane-air flat-flame piloted FPO spray flame) calculations. Results from CFD were compared against experimental data from non-intrusive optical diagnostics. The reduced model was successfully used in CFD calculations—the computational cost was approximately 2 orders of magnitude higher than that of a simplified model. Using the reduced mechanism, the concentration of pollutants, minor combustion products, and flame radicals could be predicted—this is added capability compared to already existing models. The CFD model using the reduced mechanism showed quantitative predictive power for major combustion products, flame temperature, some pollutants and temperature, and qualitative predictive power for flame radicals and soot.

Hydrodeoxygenation of phenol and biomass fast pyrolysis oil (bio-oil) over Ni/WO3-ZrO2 catalyst

The hydrodeoxygenation of pure phenol in hexane solution and of catalytic biomass fast pyrolysis oil (bio-oil) over 10 %Ni/ZrO2 and 10 %Ni/WO3-ZrO2 catalysts was investigated in the present study, at relatively mild conditions (ca. 50−250 °C, 30 bar H2) in a continuous flow high-pressure fixed bed reactor. The catalysts were characterized for their structural, porosity, redox and acidic/basic properties which were used to rationalize the observed catalytic performance. The 10 %Ni/ZrO2 catalyst was very active and selective towards cyclohexanol in the phenol HDO experiments (100 % conversion and selectivity at 110 °C) but the enhanced acidity offered by the addition WO3 in ZrO2 was necessary to succeed a complete hydrodeoxygenation of phenol to cyclohexane at the low temperature of 150 °C with the 10 %Ni/WO3-ZrO2 catalyst. This catalyst was also proven very active in the hydrodeoxygenation of the catalytic bio-oil which consisted of mono-aromatics (i.e. alkyl-benzenes) and PAHs (mainly naphthalenes and indenes), and fewer oxygenated compounds (i.e. alkyl-phenols and benzofurans), providing a product oil containing mainly alkyl-cycloalkanes and fewer alkyl-benzenes, at the mild conditions of 210 °C and 30 bar H2.

Molecular characterisation of biomass pyrolysis oil and petroleum fraction blends

Mixing biomass pyrolysis oil with existing petroleum fractions is one potential option for integration of renewable sources into the oil refinery. To achieve such optimal integration, it is first important to conduct detailed molecular-level characterisation of the blended streams such as biomass fast pyrolysis oil (FPO), vacuum gas oil (VGO), and FPO-VGO mixture. Existing molecular-level characterisation method based on Molecular Type and Homologous Series (MTHS) matrix approach is extended to allow for characterisation of oxygenated molecules in bio oil. The group contribution method is introduced into the transformation methodology in order to calculate bulk properties of oxygenated homologous series within the representation matrix. Different constraints strategies proposed in the existing literature are applied to reduce the degrees of freedom and solution space of the optimisation problem. The computational results show a good agreement between measured and model-predicted results.

Multi-step separation of different chemical groups from the heavy fraction in biomass fast pyrolysis oil

The heterogeneity of the heavy fraction in bio-oil (HBO) causes serious problem for its downstream utilization. A multi-step method is thus proposed to separate different chemical groups from HBO. In this study, HBO from fast pyrolysis of poplar wood was collected and the characteristics of the HBO were investigated. A series of separation experiments was conducted on HBO, whose chemical groups were analyzed by chromatography coupled with mass spectrometry. The results show that through primary pH adjustment and CH2Cl2 extraction, HBO is divided into two fractions with fewer types of chemicals. After further distillation, HBO is separated into four fractions, whose primary chemical groups and their peak area percentages are ketones (89.5%), esters (49.9%), aromatic hydrocarbons (63.8%) and phenols (39.2%), respectively. These fractions can be used efficiently for either upgrading towards fuels or purification towards valuable chemicals. The findings in this paper is hoped to shed a light on solving the heterogeneity problem of bio-oil.

Molecular Modeling of Coprocessing Biomass Fast Pyrolysis Oil in Fluid Catalytic Cracking Unit

Integration of renewable sources into a transportation fuels production system through FCC units in an oil refinery has gained increased attention. For better understanding of the effect of the reaction conditions, blending ratios, and feed properties on product yields and qualities, kinetic modeling of FCC units is necessary. In this Article, a novel framework for molecular-level modeling of coprocessing biomass fast pyrolysis oil (FPO) with vacuum gas oil (VGO) in an oil refinery FCC unit is developed, which includes molecular-level characterization of biomass pyrolysis oil and VGO feed blends, synthesis of large-scale and complex reaction network, molecular-level kinetic modeling, and parameter estimation. The rule “same type of reactions have similar activation energies” is employed to reduce the number of kinetic parameters. The kinetic parameters in the proposed model are estimated using a hybrid solution algorithm combining deterministic and stochastic optimization methods. The computational results demonstrate an overall good agreement between measured and predicted yields using the developed kinetic model for VGO:FPO blending ratio, C/O ratio, and reaction temperature of 95:5, 5, and 530 °C, respectively. PONA composition in each layer of product stream (e.g., gasoline, diesel, gasoil, etc.) as well as oxygen compounds compositions and oxygen content are also successfully predicted. The proposed framework can be easily extended for modeling of other refinery processes and creates potentials for rigorous simulation and optimization of refinery operations to achieve maximization of refinery profit or better product quality control.

Upgrading of biomass fast pyrolysis oil over a moving bed of coal char

Fast pyrolysis of sawdust (SD) and upgrading of the derived bio-oil* (water-free basis) over Shenmu bituminous coal char (SMC) were conducted in an integrated free fall pyrolyzer and moving bed upgrading reactor. The water soluble and heavy bio-oil* (THF soluble) yields decrease and the content of light bio-oil* (CH2Cl2 soluble) increases significantly compared that without SMC despite the decrease of light bio-oil* yield. Chemical analyses of the light bio-oil* were performed using GC–MS and 1H NMR techniques. The results show that during volatiles-char interaction, the SMC plays important roles in deoxygenation and denitrogenation. The role of SMC in the upgrading process was explored by BET, FT-IR and XRD characterization. The porous structure provides reaction active sites for the bio-oil upgrading. After volatiles-char interaction, the specific surface area of SMC decreases significantly and the carbon crystallite size increases. With increasing the char updating rate from 1 g/min to 4 g/min, the relatively fresh SMC surface leads to the increased active sites, the conversion of heavy bio-oil* is slightly promoted and the removal effects of heteroatoms (O, N) compounds in the light bio-oil* are enhanced. The changes in SMC specific surface area and microcrystalline size are weakened accordingly.

A rational strategy based on experimental designs to optimize parameters of a liquid chromatography-mass spectrometry analysis of complex matrices

A high number of factors controlled by the experimenter has to be optimized to successfully separate, ionize and detect compounds when analyzing complex matrices by liquid chromatography hyphenated to high resolution mass spectrometry (LC-UV/MS). Key steps to manage such hyphenation are focused on desolvation and ionization processes. In this study, a design of experiments approach was used to optimize decisive parameters (i.e. nebulising, drying and sweep gas flow rates, ion transfer capillary voltage and temperature) for electrospray ionization and atmospheric pressure chemical ionization sources both in positive and negative modes. Central composite designs including 131 experiments each were built to cover rationally a sufficiently wide range of operating conditions. Each run was repeated three times to insure stable conditions of ionization and thus a satisfactory repeatability. Extracted ion chromatograms of twelve model oxygenated compounds were integrated and used as responses for experiment designs. Quadratic models for each standard allowed to take into account interactions between factors. Then responses were simultaneously maximized to achieve optimized factors. To illustrate the methodology relevance, optimal conditions were applied to a lignocellulosic biomass fast pyrolysis oil. Thanks to our high sensitivity method, a large number of molecular formulae was identified, as for instance in negative-ion mode electrospray with more than 5500 identified molecular formulae whereas analysis of the same sample by mass spectrometry without any prior chromatographic separation provided less than 2000 molecular formulae. In short, this study proposed a rational methodology to optimize ionization efficiency for LC-UV/MS analysis of complex mixtures.

Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry

The objective of this work was to move towards developing a comprehensible Computational Fluid Dynamics (CFD) model to facilitate the predictive modeling of Fast Pyrolysis Oil (FPO) spray combustion. A CFD model was implemented from the literature and results were compared to 2D data from non-intrusive optical diagnostics involving Planar Laser Induced Fluorescence of the OH radical, Mie scattering imaging and two-color pyrometry using a laboratory-scale, CH4/air flat-flame with an air-assist atomizer. Furthermore, flame radiation and contributions from graybody sources, chemiluminescence and soot were studied experimentally using emission spectroscopy and Laser Induced Incandescence (LII). Reasonable qualitative agreement was found between experimental and model results in terms of flame structure and temperature. Emission spectroscopy and LII results revealed and confirmed earlier observations regarding the low soot concentration of FPO spray flames; furthermore, it was shown that a significant portion of flame radiation originated from graybody char radiation and chemiluminescence from the Na-content of the FPO. These suggest that the treatment of soot formation might not be important in future computational models; however, the description of char formation and Na chemiluminescence will be important for accurately predicting temperature and radiation profiles, important from the point of e.g., large-scale power applications. Confirmed low soot concentrations are promising from an environmental point of view.

Spray combustion of biomass fast pyrolysis oil: Experiments and modeling

In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime.

Centrifugal partition chromatography a first dimension for biomass fast pyrolysis oil analysis

Biomass fast pyrolysis oils contain molecules having a large variety of chemical functions and a wide range of molecular weights (from several tens to several thousand grams per mole). The good knowledge of their complex composition is essential for optimizing the conversion of bio-oils to biofuels, thereby requiring powerful separation techniques. In this work, we investigate the interest of centrifugal partition chromatography (CPC) as a first dimension for the analysis of a bio-oil. A CPC method is proposed to separate oxygen containing compounds according to their partition coefficients in the solvent system. This approach is a powerful and easy-to-use technique that enables fractionation of a bio-oil at a semi-preparative scale, without any sample loss related to adsorption on the stationary phase. Collected fractions are then injected in liquid chromatography as a second dimension of separation. Contour plot representations of the CPC × LC separation are established to discuss the potential of this approach. These representations can be used as a veritable fingerprint in the comparison of different samples or samples at different steps of a conversion process but also as a powerful tool to identify new compounds and describe the entire composition of the bio-oil.

Production of hydrocarbon fuels from heavy fraction of bio-oil through hydrodeoxygenative upgrading with Ru-based catalyst

Heavy fraction of bio-oil, the bottom-layer of biomass fast pyrolysis oil, is hard to be directly used due to its high molecular weight, complex components and deteriorate thermal stability. Here, a novel catalytic hydrotreating process for the heavy fraction of bio-oil, including depolymerization, decarboxylation, decarbonylation, hydrogenation and hydrodeoxygenation (HDO), is proposed with Ru/α-Al2O3 catalyst and super/subcritical ethanol. Results demonstrated that heavy fraction of bio-oil was depolymerized into monomeric phenolic compounds, and then was converted to hydrocarbons by hydrodeoxygenation in one-pot. The average molecular weight (Mw) of upgraded oil decreased drastically from 8941 g/mol to 937 g/mol during the catalytic hydrotreating process, and the formation of coke is suppressed. Under the optimal conditions, the total yield of hydrocarbons, which were comprised of alkyl-substituted cyclohexane and alkyl-substituted benzene, could be up to 23.15%. These hydrocarbons have a high octane number, would be the desirable components for fungible liquid transportation fuel. Furthermore, Ru/α-Al2O3 catalyst can be regenerated by calcination in the presence of O2. These results indicated high quality fuels could be obtained from heavy fraction of bio-oil over suitable catalytic system.