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.     

Economic tradeoff between biochar and bio-oil production via pyrolysis

This paper examines some of the economic tradeoffs in the joint production of biochar and bio-oil from cellulosic biomass. The pyrolysis process can be performed at different final temperatures, and with different heating rates. While most carbonization technologies operating at low heating rates (large biomass particles) result in higher yields of charcoal, fast pyrolysis (which processes small biomass particles) is the preferred technology to produce bio-oils. Varying operational and design parameters can change the relative quantity and quality of biochar and bio-oil produced for a given feedstock. These changes in quantity and quality of both products affect the potential revenue from their production and sale. We estimate quadratic production functions for biochar and bio-oil. The results are then used to calculate a product transformation curve that characterizes the yields of bio-oil and biochar that can be produced for a given amount of feedstock, movement along the curve corresponds to changes in temperatures, and it can be used to infer optimal pyrolysis temperature settings for a given ratio of biochar and bio-oil prices.     

Impact of a pressurized hot water treatment on the quality of bio-oil produced from aspen

The bio-oil produced by fast pyrolysis is a genuine alternative to fossil resources. However an improvement of its quality is required in order to improve its application.To upgrade the quality of bio-oil, Pressurized Hot Water Treatment (PHWT) has been applied on trembling aspen whole wood chips prior to fast pyrolysis process. The pyrolysis was then performed in an auger reactor at the temperature of 723 K. The effects of PHWT on yields, physicochemical properties, and composition of bio-oils were investigated.Although PHWT does not seem to influence the bio-oil yield, which remains around 56% for both untreated and pre-treated wood, it does improve its quality. The main effect of pre-treatment is the lower water content of the oil obtained from pre-treated wood, which is thus meeting the requirements of ASTM D7544 Standard. Moreover, PHWT appeared to favor the levoglucosan production and to decrease the syringol derivatives content of the bio-oil. The elementary composition revealed an increase of the C/O ratio when the biomass was pre-treated. This is in agreement with the heating value of bio-oil from pre-treated biomass which was found to be higher than that of bio-oil from untreated biomass.     

Production of synthesis gas by partial oxidation and steam reforming of biomass pyrolysis oils

As the lowest cost biomass-derived liquids, pyrolysis oils (also called bio-oils) represent a promising vector for biomass to fuels conversion. However, bio-oils require upgrading to interface with existing infrastructure. A potential pathway for producing fuels from pyrolysis oils proceeds through gasification, the conversion to synthesis gas. In this work, the conversion of bio-oils to syngas via catalytic partial oxidation over Rh–Ce is evaluated using two reactor configurations. In one instance, pyrolysis oils are oxidized in excess steam in a freeboard and passed over the catalyst in a second zone. In the second instance, bio-oils are introduced directly to the catalyst. Coke formation is avoided in both configurations due to rapid oxidation. H₂ and CO can be produced autothermally over Rh–Ce catalysts with millisecond contact times. Co-processing of bio-oil with methane or methanol improved the reactor operation stability.     

Catalytic pyrolysis of biomass: Effects of pyrolysis temperature,sweeping gas flow rate and MgO catalyst

Cotton seed, as a biomass source, is pyrolysed in a tubular fixed-bed reactor under various sweeping gas (N₂) flow rates at different pyrolysis temperatures. In the non-catalytic work, the maximum bio-oil yield was attained as 48.30% at 550 °C with a sweeping gas flow rate of 200 mL min⁻¹. At the optimum conditions, catalytic pyrolysis of biomass samples was performed with various amounts of MgO catalyst (5, 10, 15, and 20 wt.% of raw material). Catalyst addition decreased the quantity of bio-oil yet increased the quality of bio-oil in terms of calorific value, hydrocarbon distribution and removal of oxygenated groups. It was observed that increasing the amount of catalyst used, decreased the oil yields while increased the gas and char yields. Bio-oils obtained at the optimum conditions were separated into aliphatic, aromatic and polar sub-fractions. After the application of column chromatography, bio-oils were subjected into elemental, FT-IR and ¹H NMR analyses. Aliphatic sub-fractions of bio-oils were analyzed by GC–MS. It was deduced that the fuel obtained via catalytic pyrolysis mainly consisted of lower weight hydrocarbons in the diesel range. Finally, obtained results were compared with petroleum fractions and evaluated as a potential source for liquid fuels.     

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.     

Oily Products from Mosses and Algae via Pyrolysis

In this study, the fuel properties of mosses and algae, and the effect of pyrolysis temperature on the yield of bio-oil from moss and alga samples, were investigated. The yield of bio-oil from pyrolysis of the samples increased with temperature. The yields were increased up to 750 K in order to reach the plateau values at 775 K. The maximum yields were 39.1, 34.3, 33.6, 37.0, 35.4, 48.2 and 55.3% of the sample for Polytrichum commune, Dicranum scoparium, Thuidium tamarascinum, Sphagnum palustre, Drepanocladus revolvens, Cladophora fracta and Chlorella protothecoides, respectively. The bio-oil yield for Chlorella protothecoides (a microalga sample) rose from 5.7 to 55.3% as the temperature rose from 525 to 775 K, and then gradually decreased to 51.8% and was obtained at 875 K with a heating rate of 10 K/s. Formulas can be developed to calculate higher heating value (HHV) of different moss and alga samples. The calculated HHV using these new correlations showed mean differences ranging from ?2.3% to +0.06%. The equation developed in this study showed good agreement with experimental results on moss and algae samples. The HHVs for bio-oils from mosses 21.5–24.8 MJ/kg and the HHVs for bio-oils from algae and microalga 32.5 and 39.7 MJ/kg, respectively, were obtained at temperature ranging from 775 to 825 K. In general, algae bio-oils are of higher quality than bio-oils from mosses. In general, microalgae bio-oils are higher quality than bio-oil from wood.     

Non-catalytic and catalytic pyrolysis of Ulva prolifera macroalgae for production of quality bio-oil

Pyrolysis of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in a fixed-bed reactor in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different catalyst to biomass ratio. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite and Mordenite catalyst in the conversion of UM showed that is affected by properties of zeolites. Bio-oil yield was increased in the presence of Y-Zeolite while decreased with ZSM-5 and Mordenite catalyst. Maximum bio-oil yield for non-catalytic pyrolysis was (38.5 wt%) and with Y-Zeolite catalyst (41.3 wt%) was obtained at 400 °C respectively. All catalyst showed a higher gas yield. The higher gas yield might be attributed to that catalytic pyrolysis did the secondary cracking of pyrolytic volatiles and promoted the larger small molecules. The chemical components and functional groups present in the pyrolytic bio-oils are identified by GC–MS, FT-IR, ¹H-NMR and elemental analysis techniques. Phenol observed very less percentage in the case of non-catalytic pyrolysis bio-oil (9.9%), whereas catalytic pyrolysis bio-oil showed a higher percentage (16.1%). The higher amount of oxygen present in raw biomass reduced significantly when used catalyst due to the oxygen reacts with carbon and produce (CO and CO₂) and water.     

Production of a hydrogen-rich gas from fast pyrolysis bio-oils: Comparison between homogeneous and catalytic steam reforming routes

The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: catalytic and non-catalytic steam reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final steam reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the steam reforming experiments, catalytic and non-catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different catalytic reactors were tested in the catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H₂ yields were as follows: catalytic steam reforming of the aqueous fractions in fixed bed (0.17 g H₂/g organics) > non-catalytic steam reforming of the bio-oils (0.14 g H₂/g organics) > non-catalytic steam reforming of the aqueous fractions (0.13 g H₂/g organics) > catalytic steam reforming of the aqueous fractions in fluidized bed (0.07 g H₂/g organics). These different H₂ yields are a consequence of the different temperatures used in the reforming processes (650 °C and 1400 °C for the catalytic and the non-catalytic, respectively) as well as the high spatial velocity employed in the catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.     

Production and detailed characterization of bio-oil from fast pyrolysis of palm kernel shell

Bio-oil has been produced from palm kernel shell in a fluidized bed reactor. The process conditions were optimized and the detailed characteristics of bio-oil were carried out. The higher feeding rate and higher gas flow rate attributed to higher bio-oil yield. The maximum mass fraction of biomass (57%) converted to bio-oil at 550 °C when 2 L min⁻¹ of gas and 10 g min⁻¹ of biomass were fed. The bio-oil produced up to 500 °C existed in two distinct phases, while it formed one homogeneous phase when it was produced above 500 °C. The higher heating value of bio-oil produced at 550 °C was found to be 23.48 MJ kg⁻¹. As GC–MS data shows, the area ratio of phenol is the maximum among the area ratio of identified compounds in 550 °C bio-oil. The UV–Fluorescence absorption, which is the indication of aromatic content, is also the highest in 550 °C bio-oil.     

An overview of empty fruit bunch from oil palm as feedstock for bio-oil production

Empty fruit bunch (EFB) from oil palm is one of the potential biomass to produce biofuels like bio-oil due to its abundant supply and favorable physicochemical characteristics. Confirming the assertion, this paper presents an overview of EFB as a feedstock for bio-oil production. The fundamental characteristics of EFB in terms of proximate analysis, ultimate analysis and chemical composition, as well as the recent advances in EFB conversion processes for bio-oil production like pyrolysis and solvolysis are outlined and discussed. A comparison of properties in terms of proximate analysis, ultimate analysis and fuel properties between the bio-oil from EFB and petroleum fuel oil is included. The major challenges and future prospects towards the utilization of EFB as a useful resource for bio-oil production are also addressed.     

Current Technologies for Biomass Conversion into Chemicals and Fuels

Thermal depolymerization and decomposition of woody biomass structural components, such as cellulose, hemicelluloses and lignin, form liquids and gas products as well as a solid residue of charcoal. The direct thermo-chemical conversion technologies that have been developed are classified into two groups: high pressure liquefaction and fast pyrolysis. Bio-oils derived from biomass have been increasingly attracting attention as alternative sources of fuels and chemicals. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiocol and their alkylated phenol derivatives. The structural components of the biomass samples mainly affect pyrolytic degradation products.     

Evaluation of influence of two different catalysts on the pyrolysis of laurel (Laurus nobilis L.) extraction residues

Laurel extraction residues with zeolite and alumina catalysts were pyrolyzed in a fixed-bed reactor with a constant heating rate of 10°C min^–1. The final pyrolysis temperature and sweep gas flow rate were kept constant at 500°C and 100 ml min^–1 in all of the experiments, respectively. The influence of catalysts and their ratio (10, 20, 30, 40, and 50% w/w) on the pyrolysis conversion and product yields were investigated in detail. The physicochemical properties of the catalytic bio-oil were determined and compared to those of non-catalytic bio-oil. The catalytic bio-oils were examined using some spectroscopic and chromatographic techniques.     

Combustion characteristics of bio-oil from swine manure/crude glycerol co-liquefaction by thermogravimetric analysis technology

The thermal analysis and kinetics of bio-oils derived from swine manure/crude glycerol co-liquefaction were studied by thermogravimetric analysis (TGA) in the air. It was found that the combustion processes of bio-oils can be divided into three stages, with most of the materials decomposing between 330 and 370°C. In kinetic calculations, oxidation of the bio-oils was determined using the Coats–Redfern method, considering that bio-oil combustion occurs in three consecutive steps. Four models including more than 12 alpha functions were tested to fit the study’s experimental results. The calculation shows that the diffusion models are the best fit for describing the bio-oil combustion process in the air.     

Mild hydrotreatment of the light fraction of fast-pyrolysis oil produced from straw over nickel-based catalysts

Upgrading bio-oils for the production of transport fuel and chemicals is a challenge that has recently attracted a lot of attention. As one of the most prominent approaches, hydrodeoxygenation (HDO) was used in this work to upgrade the light phase of a pyrolysis oil produced from straw in the bioliq^® pilot plant in Karlsruhe. A mild hydrotreatment was performed in a batch autoclave at 250 °C under hydrogen atmosphere (8.0 MPa at room temperature) in the presence of various nickel-based catalysts using different loadings and supports. Their catalytic performances, measured in term of hydrogen consumption, were similar but inferior to Ru/C (used as benchmark). The oxygen content was significantly decreased in the upgraded oils (20–26 wt%) as result of hydrodeoxygenation reactions and of the repartition of more apolar compounds in the upgraded oil. Using gas chromatography, the typical biomass platform molecules were detected and some reaction trends were identified. The conversion of phenol and the product selectivity was different whether this molecule was investigated in the pyrolytic mixture or as model compounds, indicating that the complex composition of the light phase or the probable deactivation of the catalyst plays a significant role. Quantitative ¹H-NMR analysis was a useful method for gaining an overview about the reactivity of the different molecular functional groups present in the bio-oil.     

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.     

Potential evolution of Turkish agricultural residues as bio-gas,bio-char and bio-oil sources

A study has been conducted to evaluate the potential power production from the pyrolysis for bio-oil and bio-char, and anaerobic digestion (for bio-gas), of agricultural residues in Turkey. Agricultural residues are potential renewable energy resources such as bio-gas from anaerobic digestion, bio-oil from pyrolysis, and bio-char from carbonization and slow pyrolysis processes. Anaerobic bio-gas production is an effective process for conversion of a broad variety of agricultural biomass to methane to substitute natural gas and medium calorific value gases. When the pyrolysis temperature increased the bio-char yield decreased. The bio-char yield increased with increasing particle size of the sample. Thermochemical conversion processes of biomass are the most common and convenient methods for conversion into energy. Among the processes of energy production from biomass, pyrolysis is the most popular thermal conversion process.     

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.     

生物质制燃油流化床反应器工作安全性研究

针对生物质制燃油流化床反应器工作中生物质进料与热解能量补充对连续生产可能带来的不安全因素,分析了其引起不安全的原因,对生物质进料结构上采取了螺旋进料器并辅以流化风实现;对热解反应的能量补充采取了流化气预热与反应器外壁加热相结合的方法,有效地解决存在的技术矛盾,消除了连续生产存在的不安全因素。设备的安全可靠运行,能对低成本、大规模生产生物燃油技术推广应用提供装备上的保障。