Comparative study by GC×GC-TOFMS on the composition of crude and composite-additives bio-oil before and after accelerated aging treatment

In this study, compositions of bio-oil and bio-oil with composite additives before and after accelerated aging treatment were analyzed by two-dimensional gas chromatography with time flight mass spectrometry detector (GC × GC-TOFMS) in order to evaluate the effect of the composite additives on the characteristics of bio-oil. The effects of composite additives on bio-oil components and the changes of the components of the bio-oil with or without accelerated aging treatment were compared. A structured distribution of compounds of classification groups was observed in the two-dimensional space. At a signal-to-noise ratio of 1000, more than 3000 peaks were detected by GC × GC-TOFMS, and more than 340 peaks (relative content > 0.02%) were identified after further analysis. After accelerated aging, the content of various compounds in bio-oil decreased. The content of the classification group and the total content of compounds in the bio-oil with composite additives changed less than that of the crude bio-oil. Before aging, the most abundant substance in bio-oil was 2(5H)-furanone. After aging, the largest content in crude bio-oil is 2(5H)-furanone, and the most abundant substance in the bio-oil with composite additives is Hydroxyacetone. Regardless of whether composite additives are added or not, the component with the highest content before and after aging of bio-oil is ketones. In crude bio-oil, the substance with the most reduced content was phenols, whose content was reduced by 0.51 wt%. The contents of alcohols, esters, furanones, furans and sugars in the bio-oil with composite additives were increased after aging. The maximum increase in content was furanones, whose content was increased by 0.15 wt%. Analysis of bio-oil components showed that high added value compounds existed in bio-oil such as 2(5H)-furanone, Hydroxyacetone and (S)-(+)-2′,3′-Dideoxyribonolactone. The research can provide detailed information on bio-oil composition.     

Experimental investigation on improvement of storage stability of bio-oil derived from intermediate pyrolysis of Calophyllum inophyllum seed cake

Due to the unstable nature of bio-oil, it becomes mandatory to analyze the changes in physical and chemical properties of the bio-oil during storage to appreciate its chemical instability, for developing stabilization strategies. The present study aims to investigate the oxidative and thermal stability of bio-oil extracted from pyrolyzing Calophyllum inophyllum (CI) deoiled seed cake in a fixed bed reactor at 500 °C under the constant heating rate of 30 °C/min. Each stability analysis method involve an accelerated aging procedure based on standards established by ASTM (D5304 and E2009) and European standard (EN 14112). Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry were employed to analytically characterize the un-aged and aged bio-oil samples. The results clearly depict that stabilizing Calophyllum inophyllum bio-oil with 10% (w/w) methanol improved its stability than that of the crude sample. Addition of methanol reduced the change in viscosity of bio-oil by 38.55% during accelerated aging process. The oxidation stability index of bio-oil stabilized with methanol was found to be 3.97 h which is in accordance with ASTM D6751. FT-IR and GC-MS results showed an increase in the relative concentration of C-O (carboxylic acids, ethers and esters) and C=O (carbonyl) functional groups in aged bio-oil samples.     

Evaluation of esterified pyrolysis bio-oil as a diesel alternative

Refined pyrolysis bio-oil was produced via the pretreatment and esterification of pyrolysis bio-oil over 732-type ion-exchange resin. The main parameters of fuel property such as components, low calorific value and viscosity of refined pyrolysis bio-oil were analyzed. Different volume fractions of refined pyrolysis bio-oil were added to neat diesel to prepare bio-fuel blends. Combustion performances and emission characteristics of engine fueled with bio-fuel blends were analyzed at various loads. The results show that after esterification, the amount of esters and ketones in the crude pyrolysis bio-oil was significantly increased while the contents of acids, phenols and ethers were reduced. Compared with crude pyrolysis bio-oil, the pH value of refined pyrolysis bio-oil was improved to 5.6, the low calorific value increased by 14.89%, and the kinematic viscosity decreased by 10.13%. At the same load, the equivalent brake specific fuel consumption (BSFC) of bio-fuel blends was increased, the maximum cylinder pressures and the brake thermal efficiency (BTE) were both decreased but the peak of instantaneous heat release was increased slightly, and the exhaust gas temperatures also rose up. With the increase of refined pyrolysis bio-oil in bio-fuel blends, the difference between bio-fuel blends and neat diesel in the above indicators was more obvious. Besides, bio-fuel blends produced more HC, CO and smoke emissions but less NO_x emissions than neat diesel.     

Preparation and characterization of bio-oil by microwave pyrolysis of biomass

A low temperature method was used to produce bio-oil from fir sawdust by means of microwave pyrolysis. Effects of reaction temperature, ratios of the microwave absorption medium to sawdust, and reaction time on the yield of bio-oil were investigated. The results show that an optimized yield of 21.22% is achieved. Bio-oil obtained was analyzed by gas chromatography-mass spectrometry and Fourier transform infrared, and the result reveals that the product mainly consists of phenolic compounds with esteric compounds as the minor components. Thermal weight loss curves of bio-oil were determined by thermogravimetry-differential thermal analysis in the oxygen atmosphere at different super-heating rates, and combustion kinetic parameters were calculated.     

Upgrading of fast pyrolysis bio-oil to drop-in fuel over Ru catalysts

Catalyst plays a key role in the upgrading of fast pyrolysis bio-oil to advanced drop-in fuel, while the selectivity and deactivation of catalyst still remain the biggest challenge. In this study, three Ru catalysts with activated carbon, Al₂O₃ and ZSM-5 as supports were prepared and tested in bio-oil hydrotreating process. The physical properties and components of upgraded bio-oil were detected to identify the difference in catalytic performance of three catalysts. The results showed that furan, phenols and their derivatives in fast pyrolysis bio-oil could be hydrogenated to alkanes, alkenes and benzenes over Ru catalysts. The different components of oil phase over three catalysts may be resulted from the surface properties of three supports. Activated carbon supported Ru catalyst showed the best catalytic performance and was suggested to be the most promising catalyst for pyrolysis bio-oil upgrading.     

Bio-oil production from cotton stalk

Cotton stalk was fast pyrolyzed at temperatures between 480 °C and 530 °C in a fluidized bed, and the main product of bio-oil is obtained. The experimental result shows that the highest bio-oil yield of 55 wt% was obtained at 510 °C for cotton stalk. The chemical composition of the bio-oil acquired was analyzed by GC–MS, and its heat value, stability, miscibility and corrosion characteristics were determined. These results showed that the bio-oil obtained can be directly used as a fuel oil for combustion in a boiler or a furnace without any upgrading. Alternatively, the fuel can be refined to be used by vehicles. Furthermore, the energy performance of the pyrolysis process was analyzed. In the pyrolysis system used in our experiment, some improvements to former pyrolysis systems are done. Two screw feeders were used to prevent jamming the feeding system, and the condenser is equipped with some nozzles and a heat exchanger to cool quickly the cleaned hot gas into bio-oil.     

Fractional characterization of a bio-oil derived from rice husk

Bio-oils usually contain many types of compounds with various chemical properties. A bio-oil sample derived from rice husk through rapid pyrolysis was fractioned using solvent- or solid-extraction techniques based on their various properties. Ultraviolet-visible spectroscopy, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform infrared spectroscopy were used to characterize their various spectral properties for further understanding the characteristics of the bio-oil. Bio-oil mostly contains many aromatic ring components, acidic polar fractions, few weak- and non-polar components. The results all show that the main compounds and functional groups in the various bio-oil fractions were different and depended on the fractionation methods. The compositions of the bio-oil fractions were also analyzed with a gas chromatography/mass spectrometry (GC/MS) method. The consistency of the results obtained from the spectrometric methods with the GC/MS method indicates that the spectrometric methods have a good potential for rapid and effective characterization of bio-oils.     

Pyrolysis characteristics of bio-oil fractions separated by molecular distillation

Molecular distillation was used to separate bio-oil into a light fraction, a middle fraction and a heavy fraction. The chemical composition of the three fractions and the crude bio-oil was analyzed by gas chromatography coupled with mass spectrometry (GC–MS). The diversity of the components reflected the complexity of the bio-oil and the necessity for fractionation. The pyrolysis characteristics of the bio-oil fractions were determined with a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG–FTIR). The weight loss of components was in agreement with the chemical composition. The light fraction evaporated fastest with the formation of water, CO₂, hydrocarbons and alcohols. The heavy fraction had the slowest rate of decomposition and the highest char residue yield due to the presence of phenols and saccharides, and the pyrolysis products included CO₂ and alcohols or phenols, which was similar to the middle fraction except the formation of water and formic acid. The release of CO or methane, evidence of a secondary reaction, began at ∼450 °C in the pyrolysis of the light and middle fractions.     

生物质热解液化技术研究与发展趋势

介绍了生物质热解液化技术,总结了该项技术在原料预处理、热解工艺和生物油分离精制3个方面的最新研究成果。在原料预处理方面,介绍了微波干燥、烘焙和酸洗3种方法;在热解工艺方面,介绍了催化热解和混合热解两种新工艺;在生物油分离精制方面,介绍了催化加氢、催化裂解、催化酯化、乳化燃油和分离提纯5种新技术,并分析展望了生物质热解液化技术的产业化发展趋势。     

Effect of phenols extraction on the behavior of Ni-spinel derived catalyst for raw bio-oil steam reforming

Alkyl-phenols and hydroxy- or methoxy-phenols (e.g., catechols, guaiacols and syringols) tend to polymerize into carbonaceous structures, causing clogging of reaction equipment and high coke deposition during bio-oil steam reforming (SR). In this work, removal of these phenolic compounds from raw bio-oil was addressed by accelerated aging and liquid-liquid extraction methods. The solvent-anti-solvent extraction with dichloromethane and water was suitable for obtaining a treated bio-oil appropriate for SR. The effect that phenols extraction has on the stability and regenerability of a NiAl₂O₄ spinel catalyst was studied by conducting reaction-regeneration cycles. Operating conditions were: 700 °C; S/C, 6; space-time, 0.15 g_catalysth/g_bio-oil (reaction step), and in situ coke combustion at 850 °C for 4 h (regeneration step). Fresh, deactivated and regenerated catalyst samples were analyzed by temperature programmed oxidation (TPO), temperature programmed reduction (TPR) and X-ray diffraction (XRD). Stability of the Ni-spinel derived catalyst was significantly improved by removing phenols due to attenuation of both coke deposition and Ni sintering. Regenerability of this catalyst was also slightly improved when reforming the treated bio-oil.     

Biosurfactant rhamnolipid assisted microemulsification of bio-oil components in diesel

The use of model bio-oil from pyrolysis biomass as a fuel was improved by forming diesel microemulsion using rhamnolipid (RL) as the surfactant. After microemulsification, synthetic bio-oil components were solubilized in different positions of the microemulsion. Water and some hydrophilic substances were solubilized in the hydrophilic core of the microemulsion, glyoxal, and vanillin in the palisade layer, and guaiacol in the diesel continuous phase. The bio-oil components species and their solubilization positions in the microemulsion fuel system had considerable effect on properties of the fuel, e.g., degradation/combustion characteristics as determined by thermogravimetric analysis.     

Study of bio-oil and bio-char production from algae by slow pyrolysis

This study examined bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. A thermogravimetric analyser (TGA) was used to investigate the pyrolytic characteristics and essential components of algae. It was found that the temperature for the maximum degradation, 322 °C, is lower than that of other biomass. With our fixed-bed reactor, 125 g of dried Spirulina Sp. algae was fed under a nitrogen atmosphere until the temperature reached a set temperature between 450 and 600 °C. It was found that the suitable temperature to obtain bio-char and bio-oil were at approximately 500 and 550 °C respectively. The bio-oil components were identified by a gas chromatography/mass spectrometry (GC–MS). The saturated functional carbon of the bio-oil was in a range of heavy naphtha, kerosene and diesel oil. The energy consumption ratio (ECR) of bio-oil and bio-char was calculated, and the net energy output was positive. The ECR had an average value of 0.49.     

Rice husk bio-oil upgrading by means of phase separation and the production of esters from the water phase,and novolac resins from the insoluble phase

A new method of utilization of original bio-oil was developed in this paper. The procedure chosen was based on the fractionation of the bio-oils with water into water soluble and insoluble fractions. After oxidizing the aldehydes to acids by hydrogen peroxide, water soluble fraction was used to obtain upgraded bio-oil (light oil) with ethanol through reactive rectification. The yield of light oil was 20.6% (account to original bio-oil) and the components of upgraded bio-oil were characterized by HPLC and FT-IR. The analysis showed that the main components were ethyl acetate, ethyl formate, methyl acetate and methyl formate. Using water insoluble fractions as starting materials in synthesis of novolac resins was also studied. The water insoluble fraction was used as a substitute of phenol at different ratio to prepare novolac resins. Main properties of obtained resin such as cure time and soft point were characterized. The novolac property of resins was determined by DSC.     

Characterization of bio-oils from the fast pyrolysis of white oak and sweetgum

Conversion of lignocellulosic biomass into bio-oil through fast pyrolysis process is considered one of the promising routes to supplement conventional fossil oil. Future bio-refineries require production large amounts of bio-oil from several biomass types. Characterization of the produced bio-oils is important to determine their suitability as bio-refinery feedstock. In this study, bio-oils were produced from white oak and sweetgum woods in an auger reactor at 450°C. The yields of char, liquid, and gas were calculated. The physical characterization of bio-oils was performed based on the investigation of different properties, such as pH, density, viscosity, water content, acid value, and molecular weight distribution of bio-oil components. The chemical compositions of the bio-oils were also investigated by gas chromatography/mass spectrometry and Fourier transform infra-red analyses. The physicochemical properties of the produced bio-oils were comparable to those obtained from similar woody biomass and the oils were suitable for fuel production.     

Research on Non-Thermal Plasma assisted HZSM-5 online catalytic upgrading bio-oil

In order to improve the quality of bio-oil and reduce the coking and deactivation of HZSM-5 molecular sieve catalyst in the catalytic cracking of bio-oil upgrading process, Non-Thermal Plasma (NTP) assisted HZSM-5 technical scheme was proposed, online upgrading of rape straw vacuum pyrolytic vapors were conducted in a fixed bed reactor to verify the effectiveness of the technology. In the research, the influence of catalyzing temperature, catalyst bed height, discharge power on the physicochemical properties of refined bio-oil were studied, and the yield of refined bio-oil was regarded as evaluation index, response surface methodology was adopted to optimize upgrading processing parameters. Chemical composition of the refined bio-oil which was obtained under optimized parameters was analyzed by GC–MS, and using thermogravimetric analysis, the impact of NTP on catalyst anti-coking property was evaluated. Research results indicates that catalyzing temperature, catalyst bed height and discharge power have significance effect on yield and physicochemical properties of refined bio-oil. With the optimized processing parameters of 392 °C catalyzing temperature, 34 mm catalyst bed height and 23.7 W discharge power, the oxygen content, high heating value and pH of refined bio-oil were respectively 19.79%, 33.14 MJ/kg and 4.98. Compared with original HZSM-5 catalytic upgrading method, the quality of refined bio-oil was improved obviously, and the amount of catalyst coke deposit reduced from 5.88% to 2.14%, the feasibility of NTP assisted HZSM-5 online upgrading bio-oil was confirmed.     

Upgrading the lubricity of bio-oil via homogeneous catalytic esterification under vacuum distillation conditions

In order to accelerate the application of bio-oil in the internal combustion engines, homogeneous catalytic esterification technology under vacuum distillation conditions was used to upgrade the crude bio-oil. The lubricities of the crude bio-oil (BO) and refined bio-oil with homogeneous catalytic esterification (RBO_hce) or refined bio-oil without catalyst but with distillation operation (RBO_wc) were evaluated by a high frequency reciprocating test rig according to the ASTM D 6079 standard. The basic physiochemical properties and components of the bio-oils were analyzed. The surface morphology, contents and chemical valence of active elements on the worn surfaces were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy, respectively. The results show that RBO_hce has better lubricities than those of BO, but RBO_wc has worse lubricities than those of BO. The tribological mechanisms of the bio-oils are attributed to the combined actions of lubricating films and factors that will break the film. Compared with BO, plenty of phenols in RBO_wc results in corrosion of the substrate and destroys the integrity of the lubricating films, which is responsible for its corrosive wear. However, more esters and alkanes in RBO_hce contribute to forming a complete boundary lubricating film on the rubbed surfaces which result in its excellent antifriction and antiwear properties.     

The effect of oyster shell powder and rice husk ash on the pyrolysis of rice husk for bio-oil

The aim of this study was to investigate the effect of oyster shell powder (OSP) and rice husk ash (RHA) on the pyrolysis of rice husk (RH) for bio-oil. The present study focuses on the effect of catalysts on pyrolysis of RH for bio-oil and the quantity of bio-oil produced. The results showed that both OSP and RHA could improve the yield and quality of bio-oil, and the catalytic effect of OSP was better than that of RHA. With the content of the two catalysts increased, the net increase range of bio-oil yield decreased gradually. With 3 wt.% of OSP or 2 wt.% of RHA, the yield of bio-oil achieved to 57.06% and 56.07% respectively, which increased by 6.03% and 4.20% compared to that of single pyrolysis of rice husk. Both OSP and RHA can increase the bio-oil heating value and decrease the acid value. With the presence of 1–5 wt.% of OSP or RHA in the RH pyrolysis process, the heating value of the bio-oil can be increased by 5.04–10.25% and 4.32–5.78%, the acid value of the bio-oil can be decreased by 5.30–13.54% and 9.81–33.01%, respectively. OSP was better than RHA on the heating value improvement, while RHA was superior to OSP in decreasing the acid value. The gas chromatography/mass spectrometry (GC-MS) analysis of bio-oil composition indicated that the formation of phenols, acids and ketones compounds were inhibited and alcohols and furan compounds were promoted with the addition of OSP and RHA catalysts. The study made the catalytic pyrolysis process more favorable for the production of high heating value fuel.     

基于化工流程模拟平台的生物质移动床热解多联产系统模拟研究

在Aspen Plus平台上构建生物质移动床热解多联产系统模型,通过对秸秆热解过程的模拟,研究了生物炭、生物油和生物燃气三态热解产物特性,以及热解温度对系统燃料投入、水耗和电耗的影响。结果表明,随热解温度升高,生物炭热值逐渐增大。生物油和生物燃气的产率分别在450℃和650℃附近达到最大值。当热解温度为450℃时,生物油重质组分主要由糖衍生类和脂肪酸类物质构成,而轻质组分主要包括醛类、醇类和水;当热解温度为650℃时,生物燃气则主要由CO₂和CO构成。生产过程中,系统的燃料消耗和电耗均随着热解温度的升高而增大,冷却水消耗量则经历先减少后增加的过程,并在450℃附近达到最小值。     

Liquefaction of palm kernel shell in sub- and supercritical water for bio-oil production

The heavy palm oil industry in Malaysia has generated various oil palm biomass residues. These residues can be converted into liquids (bio-oil) for replacing fossil-based fuels and chemicals. Studies on the conversion of these residues to bio-oil via pyrolysis technology are widely available in the literature. However, thermochemical liquefaction of oil palm biomass for bio-oil production is rarely studied and reported. In this study, palm kernel shell (PKS) was hydrothermally liquefied under subcritical and supercritical conditions to produce bio-oil. Effects of reaction temperature, pressure and biomass-to-water ratio on the characteristics of bio-oil were investigated. The bio-oils were analyzed for their chemical compositions (by GC–MS and FT-IR) and higher heating values (HHV). It was found that phenolic compounds were the main constituents of bio-oils derived from PKS for all reaction conditions investigated. Based on the chemical composition of the bio-oil, a general reaction pathway of hydrothermal liquefaction of PKS was postulated. The HHV of the bio-oils ranged from 10.5 to 16.1 MJ/kg, which were comparable to the findings reported in the literature.     

Low energy consumption and high quality bio-fuels production via in-situ fast pyrolysis of reed straw by adding metallic particles in an induction heating reactor

An in-situ fast pyrolysis of biomass by adding metallic particles in an induction heating reactor was proposed to produce high quality bio-fuels. After adding metallic particles into biomass, the times required to reach complete pyrolysis during reed straw pyrolysis process were significantly reduced up to 28.9%. The yields of combustible gas and bio-oil products were significantly increased. Furthermore, higher-quality combustible gas and bio-oil products were obtained with the LHV of gas products and HHV of bio-oil (dry basis) increased by 14.2%–19.1% and 4.16%–16.35%, respectively, under 400–600 °C. The lower oxygen content and higher yields of aromatics, alkenes and alkanes contents in bio-oil were obtained after metallic particles addition. More importantly, up to 26.5% of the total energy consumption during pyrolysis process was reduced after adding metallic particles into biomass in an induction heating reactor. The results indicate that adding metallic particles into biomass in an induction heating reactor can significantly enhance the heat transfer, decomposition reaction intensity and energy utilization efficiency of biomass pyrolysis process with lower energy consumption and higher-quality bio-fuel production.