Heavy Bio-oil Research Articles

Beneficial synergistic effect on bio-oil production from co-liquefaction of sewage sludge and lignocellulosic biomass

Co-liquefaction of municipal sewage sludge (MSS) and lignocellulosic biomass such as rice straw or wood sawdust at different mixing ratios and the characterization of the obtained bio-oil and bio-char were investigated. Synergistic effects were found during co-processing of MSS with biomass for production of bio-oil with higher yield and better fuel properties than those from individual feedstock. The co-liquefaction of MSS/rice straw (4/4, wt) increased the bio-oil yield from 22.74% (bio-oil yield from liquefaction of MSS individually) or 23.67% (rice straw) to 32.45%. Comparable increase on bio-oil yield was also observed for MSS/wood sawdust mixtures (2/6, wt). The bio-oils produced from MSS/biomass mixtures were mainly composed of esters and phenols with lower boiling points (degradation temperatures) than those from individual feedstock (identified with higher heavy bio-oil fractions). These synergistic effects were probably resulted from the interactions between the intermittent products of MSS and those of biomass during processing.

Determination of volatile organic compounds in eucalyptus fast pyrolysis bio-oil by full evaporation headspace gas chromatography

This paper reports a full evaporation (FE) headspace gas chromatographic (HS-GC) method for the determination of the volatile organic compounds (VOCs) in bio-oil (i.e. methanol, ethanol, acetone, acetic acid and furfural). The method uses a 4μL sample of bio-oil in a headspace vial (ca. 20mL). Complete evaporation of the compounds was achieved after seven minutes at 90°C. The method showed good precision and accuracy for methanol, ethanol, acetone and acetic acid. The recovery of furfural was low (74.3%). The results showed that the protocol can be applied for the determination of methanol, ethanol, acetone and acetic acid in bio-oil. Detection limits ranged from 0.13 to 0.16μg. Acetic acid was the dominant analyte in the heavy bio-oil and light bio-oil analysis (113. 3 and 85.1µgmg−1, respectively), followed by methanol, ethanol, and acetone. The polymerisation of furfural was suspected as the cause of its poor quantification.

Bio-oil production from hydrothermal liquefaction of waste Cyanophyta biomass: Influence of process variables and their interactions on the product distributions

Hydrothermal liquefaction (HTL) of waste Cyanophyta biomass at different temperatures (factor A, 260–420 °C), times (factor B, 5–75 min) and algae/water (a/w) ratios (factor C, 0.02–0.3) by single reaction condition and Response Surface Method (RSM) experiments was investigated. By single reaction condition runs, maximum total bio-oil yield (29.24%) was obtained at 350 °C, 60 min and 0.25 a/w ratio. Maximum bio-oil HHV of 40.04 MJ/kg and energy recovery of 51.09% was achieved at 350 °C, 30 min, 0.1 a/w ratio and 350 °C, 60 min, 0.25 a/w ratio, respectively. RSM results indicate that effect of AB interaction was significant on light bio-oil yield. Both AC and AB had more remarkable influence than BC on heavy bio-oil yield and aqueous total organic carbon (TOC) recovery whereas BC was noticeable on ammonia nitrogen (NH3N) recovery in aqueous products. By model-based optimization of highest bio-oil yield, the highest bio-oil yield reached 31.79%, increasing by 8.72% after RSM optimization, and light and heavy bio-oil yield was 17.44% and 14.35%, respectively. Long-chain alkanes, alkenes, ketones, fatty acids, phenols, benzenes, amides, naphthalenes were the main components in light bio-oil. Some alcohols, phenols and aromatics were primarily found in heavy bio-oil. Solid residue after HTL consisted of numerous microparticles (∼5 μm) observed by Scanning Electron Microscopy (SEM). Energy Dispersive Spectrometer (EDS) analysis shows these particles primarily contained C, O, Mg, P and microelements, derived from Cyanophyta cells.

Insight into Catalytic Hydrothermal Liquefaction of Cardboard for Biofuels Production

Catalytic hydrothermal liquefaction (HTL) of cardboard was carried out in a 300 mL Parr batch reactor using 5 wt % Ni(NO3)2, Ca(NO3)2, and NiCl2 in a temperature range of 225–300 °C for H2, biocrude, and bio-oil production. A slurry with cardboard to water weight ratio of 1:30, 1:10, 1:4, or 1:1.5 was loaded in the reactor and pressurized with N2 (40 or 200 psi). HTL was performed at various temperatures for 120 min. While HTL was in progress, gas samples were withdrawn periodically and analyzed by GC. The maximum H2 yield of 11.46 mL/g of cardboard was obtained using Ni(NO3)2 at 300 °C in 30 min. The percent liquefaction of biomass was quantified by TOC. The liquefaction yields were found to be dependent on reaction temperature, residence time, cardboard to water ratio, and operating pressure. The highest biocrude yield of 47.14% was observed at 275 °C in 30 min. Light bio-oil (LBO) and heavy bio-oil (HBO) were extracted by dichloromethane and acetone, respectively, and characterized by GC/MS and element...

Oxidative fast pyrolysis of banana leaves in fluidized bed reactor

Dried banana leaves were previously chopped, characterized by proximate and elemental chemical analyses, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and higher and lower heating value and submitted to oxidative fast pyrolysis in an auto-thermal fluidized bed reactor. The pyrolysis products were gases, bio-char and bio-oil (heavy and light phase). The gases were burnt in a combustion chamber and the energy was used for to heat the fluidization air in the reactor. The light bio-oil was analyzed by gas chromatography-mass spectrometry (GC/MS); the heavy bio-oil by infrared spectroscopy (FTIR/ATR) and higher and lower heating value; and the bio-char by elemental and proximate analysis, TGA, DTA and scanning electron microscopy (SEM). The mass yield and energy efficiency of the process were determined by mass and energy balances. The process produced 49.6% gases, 27.0% bio-oil and 23.3% bio-char. The light and heavy bio-oil presented complex chemical compounds and phenolic and acid nature. The heavy bio-oil showed elevated higher heating value of 25 MJ/kg. The bio-char released high energy under combustion, enabling it to be used as fuel. The results suggest potential for generating fuel products and chemical inputs from fast pyrolysis of dried banana leaves.

Pyrolysis of Sedum plumbizincicola, a zinc and cadmium hyperaccumulator: pyrolysis kinetics, heavy metal behaviour and bio-oil production

Appropriate disposal of hyperaccumulator biomass is a problem inhibiting the widespread use of phytoremediation technology. In the present study, kinetic analysis of the pyrolysis process of Sedum plumbizincicola, the behaviour of heavy metals and bio-oil composition were studied. The kinetic analysis of the pyrolysis process shows that activation energy (E) changed from 150 to 186 kJ mol−1 and the frequency factor (A) changed from 1.34 × 1011 to 8.99 × 1015 s−1. At temperatures of 450–750 °C more than 66.3 % of zinc (Zn) remained in the char. More than 87.6 % of the cadmium (Cd) was found in the bio-oil. Pyrolysis at 650 °C led to the highest yield of alkanes with low-oxygen compounds found in the bio-oil. Pyrolysis at 650 °C can likely offer a valuable processing method for S. plumbizincicola and recovery of Zn from the char and recovery of Cd from the bio-oil will be attempted in future research.

Polymerization and cracking during the hydrotreatment of bio-oil and heavy fractions obtained by fractional condensation using Ru/C and NiMo/Al2O3 catalyst

Two-step hydrotreatment experiments were performed using three completely different bio-oil fractions namely: whole bio-oil, heavy bio-oil obtained after fractional condensation of pyrolysis vapours and pyrolytic lignin obtained by cold water precipitation of the bio-oil. The aim is to study the de-oxygenation and in addition SEC and UV-fluorescence analysis was used to identify the importance of cracking, polymerization and hydrogenation reactions of the three different bio-oil feedstocks. In the first step hydrotreatment, Ru/C was used at 250 or 300°C with reaction time of 2h. In the second step hydrotreatment, Ni-Mo/Al2O3 catalyst was used at 375 or 400°C, with reaction time of 2 or 4h. During stabilization in the first step, pyrolytic lignin was hydrogenated to a large extent accompanied by cracking reactions. In the second step, unsulphided Ni-Mo/Al2O3 catalyst was active enough to effectively crack pyrolytic lignin into smaller molecules. High molecular weight compounds including large aromatic ring structures were formed from the reactive sugar rich fraction in both first step stabilization and second step hydrotreatment. The newly formed polymerization products were difficult to crack even at extended reaction times of 4h at 400°C. Importantly, the presence of water (and light oxygenates) could significantly supress the polymerization reactions.

Catalytic conversion of bio-oil in supercritical water: Influence of RuO2/γ-Al2O3 catalysts on gasification efficiencies and bio-methane production

Catalytic supercritical water gasification of heavy (dewatered) bio-oil has been investigated in a batch reactor in the presence of ruthenium catalysts in the form of RuO2 on γ-Al2O3 support. The reactions were carried out at temperatures of 400°C, 450°C and 500°C and reaction times of up to 60min using 15wt% of bio-oil feed. Increased ruthenium oxide loading led to increased carbon gasification efficiencies (CGE) and bio-methane production. Hence, using the 20wt% RuO2/γ-Al2O3 catalyst, CGE was 97.4wt% at 500°C and methane yield reached nearly 30wt% of the bio-oil feed, which gave a CH4/CO2 molar ratio of 1.28. There was evidence that the RuO2 was involved in the initial conversion of the bio-oil to carbon oxides and hydrogen as well as the reduction of the CO2 to methane via CO methanation. However, competition for CO consumption via the water-gas shift reaction was also possible due to the large presence of water as the reaction medium. This work therefore demonstrates that high concentrations of heavy fraction of bio-oil can be catalytically converted to a methane-rich gas product under hydrothermal conditions at moderate temperatures. The calorific values of the gas product reached up to 54MJkg−1, which is nearly 3 times the HHV of the bio-oil feed.

A kinetic model for thermal cracking of waste cooking oil based on chemical lumps

Thermal cracking or fast pyrolysis of waste cooking oil (WCO) was performed in a continuous pilot plant operating under isothermal conditions. The experiments were carried out varying the temperature (475, 500 and 525°C) and the residence time (5–70s) to obtain experimental data in order to construct a kinetic model based on chemical lumps. The kinetic model of the waste cooking oil is based on four lumps, defined according to the number of carbon atoms in the carbon chain, determined by gas chromatography, distributed as: waste cooking oil (WCO) (>C18); heavy bio-oil (HBO) (C12–C18); light bio-oil (LBO) (C4–C11); and bio-gas (BG) (<C4). The dependence of the kinetic rates on the composition and temperature considering the proposed mechanism was subjected to regression and the kinetic parameters (reaction order, frequency factor and activation energy) were determined and good agreement was observed. The proposed kinetic model could be used for future scaling-up studies and process development, aimed at the industrial application of the thermal cracking of waste cooking oil for the production of biofuels and renewable chemicals.

Hydrothermal liquefaction of pinewood (Pinus ponderosa) for H2, biocrude and bio-oil generation

This study reports hydrothermal liquefaction (HTL) of pinewood at 200–275°C for H2, biocrude and bio-oil production in presence of a nitrate salt catalyst: Ni(NO3)2, Ca(NO3)2, Co(NO3)2 and Fe(NO3)3. Among these catalysts, Ni(NO3)2 showed higher selectivity towards H2 and biocrude generation. To generate H2 and biocrude, a slurry of pinewood was prepared with different biomass to solvent (B:S) ratios of 1:10, 1:30, and 1:75 and loaded in the SS316 PARR reactor and heated to different temperatures. While the reaction was in progress, gas samples were withdrawn and analyzed using GC equipped with Chrompack capillary column and thermal conductivity detector. The analysis of product gas revealed the presence of H2, CO2, CO and CH4. The liquid samples collected during the reaction were centrifuged to separate residue and analyzed using TOC analyzer, HPLC and GC–MS. Among different homogeneous catalysts used, Ni(NO3)2 yielded 12.26mol% H2 at 275°C and a maximum biocrude of 55wt% at 250°C using 200psi N2 partial pressure. The biocrude was found to contain sugars, C1-C3 carboxylic acids such as lactic, propionic, acetic and formic, HMF/furfural and other oxygenated compounds, which were thoroughly analyzed by GC–MS. Among different C1-C3 acids, lactic acid was observed in the major amount of 83.92wt% using B:S of 1:75 at 250°C. The biocrude obtained was further processed to recover light bio-oil (LBO), heavy bio-oil (HBO) and residue which were found to have higher heating value (HHV) as compared with original pinewood.

Hydrothermal hydrolysis of grape seeds to produce bio-oil

In the present work, the hydrothermal hydrolysis of grape seeds focused on the production of bio-oil was studied. The grape seeds composition in terms of lignin, sugars, ash, extractives and bio-oil was determined. The composition of grape seeds was: 17.0 wt% of extractives; 36.8 wt% of sugars (hemicellulose and cellulose); 43.8 wt% of lignin and 2.4 wt% of ash. The grape seeds were hydrothermally treated using three different temperatures: 250 °C, 300 °C and 340 °C employing a semi-continuous reactor. The solid residue varied from 25.6–35.8 wt% depending on the hydrolysis temperature. The maximum yields of light (15.7 wt%) and heavy bio-oil (16.2 wt%) were achieved at 340 °C. The Arrhenius parameters for the kinetics of grape seeds hydrolysis in our system were k0 = 0.995 g min−1 and Ea = 13.8 kJ mol−1. The increment of the flow rate favoured the mass transfer in the system and so, the hydrolysis rate. However, the maximum hydrolysis rate was found at a water surface velocity of 2.3 cm min−1.

Upgrade of Biofuels Obtained from Waste Fish Oil Pyrolysis by Reactive Distillation

Bio-oil is classified as second-generation biofuel and it is produced mainly through the pyrolysis of a waste lignocellulosic biomass base. The application of this product is still very limited, due to some of its chemical characteristics. This paper presents a proposal for the reduction of the acidity of bio-oil obtained from waste fish oil, previously produced and characterized as described in the literature, applying the reactive distillation process. This process is primarily based on the conversion of carboxylic acids into their corresponding esters by adding a widely available alcohol and a simple and cheap catalyst in the process for the fractional distillation of crude bio-oil to obtain light and heavy bio-oil, that is, fractions which are equivalent to the fossil fuels gasoline and diesel, respectively. The alcohols tested were methanol and ethanol and the catalysts were H2SO4, H3PO4, NaOH and Na2CO3, in proportions of 10 and 0.5 wt.%, respectively. The light bio-oil was obtained within a temperature range of 42 to 198 oC with yields of 27.0 to 43.1% and the heavy bio-oil was recovered at 93 to 230 oC with yields of 42.6 to 49.2%. The greatest acidity reduction was observed employing methanol+H2SO4 (95% and 43% for light and heavy bio-oils, respectively). The fractions produced were characterized by gas cromatography/mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID), applying the compound classification process PIONA (Paraffins, Iso-paraffins, Olefins, Naphtenes and Aromatics), revealing a homologous series of 1-alkenes and n-alkanes along with some aromatic compounds. The 1H and 13C NMR analysis showed that the process had no significant influence in relation to the carbons and hydrogens associated with the methyl, methylene, methyne and olefinic groups.

An Exploration of Improving the Properties of Heavy Bio-oil

In recent years, much effort has been directed toward the production of bio-oil from biomass and the upgrading of bio-oil to advanced biofuels. However, most research has focused on promoting the yield and quality of raw bio-oil and exploring valid methods for converting raw bio-oil into hydrocarbons that can be directly processed in a petroleum refinery. In practice, raw bio-oil is unstable and easily changes into viscous compounds with high molecular weights (heavy bio-oil) through polymerization as storage time increases. This leads to added difficulty in subsequent pumping/operating because of the high viscosity of heavy bio-oil (more than 5000 cP at 20 °C). Two-stage hydrotreating/cracking experiments were carried out to explore a valid method for improving heavy bio-oil’s properties in an autoclave reactor under different process conditions. Heavy bio-oil was placed in an autoclave along with a combination of metal-based catalyst with zeolite. After a heat treatment at 250 °C for 4 h, the heavy bio-...

Hydrothermal liquefaction of beech wood using a natural calcium borate mineral

This study reports the effects of a natural calcium borate mineral, colemanite, on the hydrothermal liquefaction of beech wood biomass. Hydrothermal liquefaction experiments were performed at 250, 300 and 350°C with and without colemanite. The highest light bio-oil yield (11.1wt%) and the highest heavy bio-oil yield (29.8wt%) were obtained at 300°C with colemanite. The total bio-oil yields were 22wt% and 41wt% ca. at 300°C without and with colemanite, respectively. The highest heating values were obtained from the hydrothermal liquefaction of biomass using colemanite at 350°C: 23.81MJ/kg for LBO and 27.53MJ/kg for HBO. Most of the identified compounds in the light bio-oils were phenols. The light bio-oil obtained without the catalyst at 300°C contained furfurals. However, these compounds were not observed in the run with colemanite at the same temperature. The heavy bio-oils from the runs both without and with colemanite are composed of phenols, aldehydes, ketones, acids, and benzene derivatives. 4-Methyl-3-penten-2-one was the major compound in the heavy bio-oils produced in the catalytic runs.

Heavy metal removal and crude bio-oil upgrading from Sedum plumbizincicola harvest using hydrothermal upgrading process

The main aim of this study was to separate heavy metals and yield crude bio-oil from a heavy metals hyperaccumulator harvest, Sedum plumbizincicola, through hydrothermal upgrading process. Parameters such as granularity, temperature, pressure, and duration were examined for their effect on the removal efficiency of heavy metals and upgrading efficacy of crude bio-oil. Maximum heavy metal removal efficiency of >99% and crude bio-oil upgrading efficiency of >63% were attained with an 18 mesh (1 mm) granularity, and 22.1 MPa at 370 °C in the presence of 10 mg/L additives for 60 s. Under these optimized conditions, an oil phase (mostly composed of phenolic hydrocarbons and derivatives), a water phase raffinate containing Zn 2+ (0.39 g/L), Pb 2+ (0.10 g/L), Cu 2+ (0.16 g/L), and a solid phase (the hydrothermal upgrading residue, which completely satisfies the limit set by China legislation related to biosolids disposal, were obtained).

Biofuels from waste fish oil pyrolysis: Chemical composition

In a previous study, waste fish oil was converted into bio-oil by a fast pyrolysis process at 525 °C in a continuous pilot plant reactor with 72–73% yield. The bio-oil was distilled to obtain light bio-oil and heavy bio-oil and these biofuels were characterized in terms of their physico-chemical properties. In this study, the chemical composition of light bio-oil and heavy bio-oil was determined using GC-FID, GC–MS, 1H and 13C NMR techniques. The GC–MS analysis of waste fish oil showed the main composition of fatty acids to be the following: C 16:0 (15.87%), C 18:2 (20.96%), C 18:1 (17.29%), C 20:5 (5.11%), C 20:1 (7.59%), C 22:6 (4.53%), C 22:1 (10.42%) and others. The GC-FID analysis of the light bio-oil showed 482 compounds that were PIONA classified as paraffins (4.48%), iso-paraffins (8.31%), olefins (26.56%), naphthenes (6.07%) and aromatics (16.86%). The heavy bio-oil had a similar chromatographic profile as diesel oil, with a high content of carboxylic acids and olefins. These results are in good agreement with those for the gasoline and diesel oil fractions of petroleum.

Effects of particle size on the fast pyrolysis of oil mallee woody biomass

This study aims to investigate the effects of biomass particle size (0.18–5.6 mm) on the yield and composition of bio-oil from the pyrolysis of Australian oil mallee woody biomass in a fluidised-bed reactor at 500 °C. The yield of bio-oil decreased as the average biomass particle size was increased from 0.3 to about 1.5 mm. Further increases in biomass particle size did not result in any further decreases in the bio-oil yield. These results are mainly due to the impact of particle size in the production of lignin-derived compounds. Possible inter-particle interactions between bio-oil vapour and char particles or homogeneous reactions in vapour phases were not responsible for the decreases in the bio-oil yield. The bio-oil samples were characterised with thermogravimetric analysis, UV-fluorescence spectroscopy, Karl–Fischer titration as well as precipitation in cold water. It was found that the yields of light bio-oil fractions increased and those of heavy bio-oil fractions decreased with increasing biomass particle size. The formation of pyrolytic water at low temperatures (<500 °C) is not greatly affected by temperature or particle size. It is believed that decreased heating rates experienced by large particles are a major factor responsible for the lower bio-oil yields from large particles and for the changes in the overall composition of resulting oils. Changes in biomass cell structure during grinding may also influence the yield and composition of bio-oil.

Biofuels from waste fish oil pyrolysis: Continuous production in a pilot plant

Fast pyrolysis of waste fish oil was performed in a continuous pyrolysis pilot plant. The experiment was carried out under steady-state conditions in which 10 kg of biomass was added at a feed rate of 3.2 kg h −1. A bio-oil yield of 72–73% was obtained with a controlled reaction temperature of 525 °C. The bio-oil was distilled to obtain purified products with boiling ranges corresponding to light bio-oil and heavy bio-oil. These biofuels were characterized according to their physico-chemical properties, and compared with the Brazilian-fuel specifications for conventional gasoline and diesel fuels. The results show that the fast pyrolysis process represents an alternative technique for the production of biofuels from waste fish oil with characteristics similar to petroleum fuels.