Simultaneous catalytic esterification of carboxylic acids and acetalisation of aldehydes in a fast pyrolysis bio-oil from mallee biomass

This paper reports the simultaneous catalytic esterification and acetalisation of a bio-oil with methanol using a commercial Amberlyst-70 catalyst at temperatures between 70 and 170 °C. The bio-oil was prepared from the pyrolysis of mallee woody biomass in a fluidised-bed pyrolysis reactor under the fast heating rate conditions. Our results show that the conversion of light organic acids and aldehydes to esters and acetals rises significantly with increasing temperature, reaction time and catalysts loading. However, some acetals (e.g. dimethoxymethane) could decompose at higher operating temperatures (>110 °C) and catalyst loadings (>6 wt.%). The medium and heavy fractions of bio-oil also reacted with methanol to result in increases in their volatility (or decreases in boiling points) when their reactive O-containing functional groups were stabilised. The acid-catalysed reactions between bio-oil and methanol also decreased the coking propensity of the bio-oil reaction products.     

Mallee wood fast pyrolysis: Effects of alkali and alkaline earth metallic species on the yield and composition of bio-oil

The purpose of this study was to investigate the effects of inorganic species in biomass, especially the alkali and alkaline earth metallic (AAEM) species (K, Na, Mg and Ca), on the yield and properties of bio-oil from the pyrolysis of biomass. A mallee wood sample from Western Australia was washed with water and a dilute acid solution to remove its AAEM species. The water-washed and acid-washed mallee wood samples were then pyrolysed in a fluidised-bed reactor at 500 °C under fast heating rate conditions. The removal of AAEM species did not result in significant changes in the yields of bio-oil and bio-char. However, the bio-oil properties, e.g. viscosity, were drastically affected by the removal of AAEM species. Our results indicate that the water-soluble AAEM species were not as important as the water-insoluble but acid-soluble AAEM species in influencing the bio-oil composition and properties. It is believed that the acid-soluble AAEM species (especially Ca) were more closely linked with the organic matter in biomass and thus were closely involved in the reactions during pyrolysis. The removal of AAEM species, especially the acid-soluble AAEM species, led to very significant increases in the yields of sugars and lignin-derived oligomers, accompanied by decreases in the yields of water and light organic compounds in the bio-oil.     

Catalytic Pyrolysis of Pine Wood Sawdust to Produce Bio-oil: Effect of Temperature and Catalyst Additives

In this work, non-catalytic pyrolysis of Turkish pine (Pinus brutia Ten.) wood sawdust was performed in a fixed-bed reactor at various temperatures to obtain the optimum conditions to achieve a maximum bio-oil yield. The highest yield of bio-oil was obtained about 46 wt% at 550°C for non-catalytic pyrolysis. At the optimum conditions, the effects of different catalyst types (KOH, ZnCl₂, and ZnO) and amount of catalyst (5, 10, 15, and 20 wt%) on the pyrolysis product yields and bio-oil properties were investigated. The presence of catalysts changed the product distribution considerably. Increasing the amount of catalyst led to a decrease in the yield of liquid product, while the gas and char yields increased compared to non-catalytic pyrolysis. The chemical compositions of bio-oil were determined with GC-MS analyses. It was determined that bio-oils contain a large variety of organic compounds, such as furans, aldehydes, ketones, phenols, acids, benzenes, alcohols, alkanes, and polycyclic aromatic hydrocarbons (PAHs). The catalysis by KOH significantly increased the levels of phenols, while it reduced the formation of acids and aldehydes. ZnCl₂ produced bio-oil with high percentages of aldehydes. Moreover, ZnO reduced the proportion of PAH in the bio-oil. These results demonstrated that bio-oils could improve with a catalyst. Therefore, catalyst selection for high bio-oil quality is crucial in industrial applications.     

Production and fuel properties of fast pyrolysis oil/bio-diesel blends

This paper describes the production and fuel properties of fast pyrolysis oil/bio-diesel blends. The bio-oils used in this study were produced from the fast pyrolysis of woody biomasses, oil mallee and pine. The bio-diesel employed was derived from canola vegetable oil. The conditions used to prepare the bio-oil/bio-diesel blends, as well as some of the fuel properties of the resulting bio-diesel rich phase, are reported. The experimental results show that the solubility of fast pyrolysis oils in bio-diesel is not as high as was previously reported for decanted oils obtained by Auger pyrolysis. The carboxylic acids, mono-phenols, furans and lignin derived oligomers were the compounds most soluble in bio-diesel, while the sugars, on the other hand, showed poor solubility. Although the presence of phenols enhances the oxidation stability of the bio-diesel rich phases, other fuel properties deteriorate. For example, the content of solid residues increased primarily because of the solubilisation of lignin derived oligomers, which were quantified by UV-fluorescence. Concentrations as high as 3.5 mass % of these compounds were observed in the bio-diesel rich phase. The solubility of bio-oil in bio-diesel was enhanced by using ethyl acetate/bio-diesel blends. Some fuel properties of the bio-diesel rich phase, after the removal of ethyl acetate, are reported.     

Pyrolysis of cellulose, xylan and lignin with the K2CO3 and ZnCl2 addition for bio-oil production

The chemical structure of liquid products of the wood biopolymers, i.e. cellulose, xylan and lignin pyrolysis at 450 °C with and without the 10 wt.% addition of potassium carbonate or zinc chloride was investigated. The yield of liquid products of pyrolysis was in the range of 24-44 wt.% and their form was depending on the chemical structure of pyrolyzed material. The potassium carbonate and zinc chloride addition to biopolymers has also influenced the temperature range of samples decomposition as well as the structure of resulted bio-oils. All bio-oils from biopolymer were dark-brown water-oil emulsions. Contrarily, bio-oils obtained from biopolymer with K₂CO₃ or ZnCl₂ addition were orange liquids with well-separated water and oil phases. All analyses proved that the composition and the quality of bio-oil strongly depends on both the nature of the starting sample and the presence of the additive. The FT-IR analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the type of biopolymer. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds due to the zinc chloride and potassium carbonate presence during pyrolysis process.     

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol, ethanol and isopropanol as solvent and hydrogen donor. Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content, elemental content, pH, heating value, gas chromatography-mass spectrometry (GCMS), Fourier transform infrared radiation, ¹³C nuclear magnetic resonance spectroscopy, and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions. The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction. The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value. Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content, reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^‒1 in the crude bio-oil. After the supercritical isopropanol reaction, the heating value of the liquid product slightly further increased to 28.85 MJ·kg^‒1.     

Pyrolysis of microalgae biomass over carbonate catalysts

Microalgae are seen as potential biomass to be used in a biorefinery concept. Several technologies can be used to convert microalgal biomass, but pyrolysis is viewed as a unique pathway to obtain valuable chemicals distributed in three phases: liquid (bio-oil), gas (bio-gas) and solid (bio-char). The liquid phase, bio-oil, usually presents higher heating value than raw biomass, but acidity and oxygen content are major drawbacks. In situ catalyzed pyrolysis can help to decrease the oxygen content and acidity of pyrolytic bio-oils. Chlorella vulgaris and Scenedesmus obliquus were pyrolyzed in a fixed-bed reactor using commercial carbonate catalysts (Li₂CO₃, Na₂CO₃, K₂CO₃, MgCO₃, SrCO₃ and MnCO₃). The catalysis pyrolysis temperature (375 °C) was selected from thermal degradation profiles obtained using thermogravimetry under nitrogen flow and corresponds to the maximum degradation rate for both microalgae. In spite of similar volatile and fixed carbon contents, microalgae performed differentially during pyrolysis mainly due to the different contents of carbohydrates, oils and proteins. Chlorella vulgaris and Scenedesmus obliquus showed bio-oil yield in the range 26–38 and 28–50 wt%, respectively. Only sodium carbonate was able to decrease the bio-char yield, confirming that carbonate catalysts prompt simultaneously gasification and carbonization reactions. Fourier transform infrared spectra of produced bio-oils showed a net decrease of acidity, associated with carbonyl species when carbonate catalysts were used. Bio-char morphology, for both microalgae, showed evidence of melting and resolidification of cell structures, which might be due to the lower melting points of the pyrolysis products obtained from proteins and lipids. © 2020 Society of Chemical Industry     

Fast and catalytic pyrolysis of pistacia khinjuk seed in a well-swept fixed bed reactor

The pyrolysis of pistacia khinjuk seed was investigated with the aim to study the product distribution and their chemical compositions and to identify optimum process conditions for maximizing the bio-oil yield. Fast and catalytic pyrolysis of biomass sample with two selected commercial catalyst, namely BP 3189 and Criterion-424 have been conducted in a well-swept resistively heated fixed bed reactor under nitrogen atmosphere. The maximum bio-oil yield of 66.5% with the use of Criterion-424 and 69.2% with the use of BP 3189 were obtained at the catalytic pyrolysis conditions, while it was only 57.6% without catalyst. The bio-oils were investigated, using chromatographic and spectroscopic techniques.     

The influence of temperature on the yields of compounds existing in bio-oils obtained from biomass samples via pyrolysis

The influence of temperature on the compounds existing in liquid products obtained from biomass samples via pyrolysis were examined in relation to the yield and composition of the product bio-oils. The product liquids were analysed by a gas chromatography mass spectrometry combined system. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiacol and their alkylated phenol derivatives. Thermal depolymerization and decomposition of biomass structural components, such as cellulose, hemicelluloses, lignin form liquids and gas products as well as a solid residue of charcoal. The structural components of the biomass samples mainly affect the pyrolytic degradation products. A reaction mechanism is proposed which describes a possible reaction route for the formation of the characteristic compounds found in the oils. The supercritical water extraction and liquefaction partial reactions also occur during the pyrolysis. Acetic acid is formed in the thermal decomposition of all three main components of biomass. In the pyrolysis reactions of biomass: water is formed by dehydration; acetic acid comes from the elimination of acetyl groups originally linked to the xylose unit; furfural is formed by dehydration of the xylose unit; formic acid proceeds from carboxylic groups of uronic acid; and methanol arises from methoxyl groups of uronic acid     

Wood/plastic copyrolysis in an auger reactor: Chemical and physical analysis of the products

Previous studies observed that slow copyrolysis of wood and plastic in enclosed autoclaves produced an upgraded raw bio-oil with increased hydrogen content. We now demonstrate that fast simultaneous pyrolyses of 50:50, w/w, pine wood/waste plastics in a 2 kg/h lab scale auger-fed reactor at 1 atm, with a short vapor residence time, generates higher heating value upgraded bio-oils. Three plastics: polystyrene (PS), high density polyethylene (HDPE) and polypropylene (PP) were individually copyrolyzed with southern yellow pine wood at 525, 450 and 450 °C, respectively, to generate modified bio-oils upon condensation. These liquids exhibited higher carbon and hydrogen contents, significantly lower oxygen contents, higher heats of combustion and lower water contents, acid values and viscosities than pine bio-oil. The formation of cross-over wood/plastic reaction products was negligible in the oils. Simultaneous pyrolysis process design requires using a temperature at which the plastic’s thermal decomposition kinetics produce vapors rapidly enough to prevent vaporized plastic from condensing on wood chars and exiting the reactor.     

Copyrolysis of block polypropylene with waste wood chip

In this study, the copyrolysis of waste wood chip (WC) and block polypropylene (PP) was studied to investigate how the characteristics of bio-oils are affected by copyrolysis. The thermogravimetric analysis performed with a temperature rise of 20 °C/min, from room temperature to 600 °C, showed that the decomposition temperature of PP was a little higher via copyrolysis than the single-component pyrolysis. This result suggests that the characteristics of the pyrolysis of PP were affected by the pyrolysis products of WC. The Py-GC/MS analysis of the copyrolysis products detected some new compounds that had not been detected in the single-component pyrolysis products, indicating interactions between the products of WC and PP pyrolyses. The results of the experiments using a fixed bed reactor showed improved properties of the bio-oil obtained from the copyrolysis compared to those of the bio-oil obtained from the single-component pyrolysis: increased carbon and hydrogen contents, decreased water content and a significantly increased heating value.     

Comparison of three accelerated aging procedures to assess bio-oil stability

The current study utilizes three stability ranking methods to compare oxidative and thermal stability of alcohol-stabilized and un-stabilized slow pyrolysis bio-oil. Procedures were based on standard methods established by ASTM (D5304 and E2009) for hydrocarbon fuels and on a widely used method that assesses viscosity change over time. Each method involves an accelerated aging procedure ranging from several minutes to 24 h. Average stability rankings for bio-oils produced from two biomass feedstock (pine and peanut hull) in two pyrolysis units were compared. Bio-oils in order from most to least stable included; methanol-stabilized pine pellet oil, un-stabilized pine pellet oil, ethanol spray-condensed pine pellet oil, methanol-stabilized peanut hull oil, and un-stabilized peanut hull pellet oil. FT-IR spectra from pre- and post-aging showed an increase in the relative concentration of C-O (phenols, carboxylic acids, esters, and ethers) and CO (carbonyl) functional groups for aged samples.     

Thermochemical liquefaction characteristics of microalgae in sub- and supercritical ethanol

Thermochemical liquefaction characteristics of Spirulina, a kind of high-protein microalgae, were investigated with the sub- and supercritical ethanol as solvent in a 1000 mL autoclave. The influences of various liquefaction parameters on the yields of products (bio-oil and residue) from the liquefaction of Spirulina were studied, such as the reaction temperature (T), the S/L ratio (R₁, solid: Spirulina, liquid: ethanol), the solvent filling ratio (R₂) and the type and dosage of catalyst. Without catalyst, the bio-oil yields were in the range of 35.4 wt.% and 45.3 wt.% depending on the changes of T, R₁ and R₂. And the bio-oil yields increased generally with increasing T and R₂, while the bio-oil yields reduced with increasing R₁. The FeS catalyst was certified to be an ideal catalyst for the liquefaction of Spirulina microalgae for its advantages on promoting bio-oil production and suppressing the formation of residue. The optimal dosage of catalyst (FeS) was ranging from 5-7 wt.%. The elemental analyses and FT-IR and GC-MS measurements for the bio-oils revealed that the liquid products have much higher heating values than the crude Spirulina sample and fatty acid ethyl ester compounds were dominant in the bio-oils, irrespective of whether catalyst was used.     

离子液体-催化剂对甲基纤维素微波裂解产物分布的影响

以离子液体1-丁基-3-甲基咪唑氯(IL)为添加剂、考察5A-Ca型分子筛、HNO₃及FeCl₃等催化剂对甲基纤维素(MC)微波裂解过程的影响。实验研究了IL用量、微波功率、作用时间及催化剂对MC裂解的影响,并通过GC-MS联用仪研究了微波裂解液体产物分布的变化。结果表明,不同催化剂导致了不同的液体产物分布,其中5A-Ca型分子筛催化剂可促进小分子物质的形成,同时使生物质油中的含氧量从37.43%降低到了34.82%;HNO₃催化剂促进了醋酸甲酯、正丁醇及苯甲酸甲酯的生成;FeCl₃作为催化剂时,促进了糠醛及5-甲基糠醛的生成。通过比较常规热解与微波裂解,发现微波裂解能在较短的时间内得到高的生物质油产率。     

Liquefaction of giant fennel (Ferula orientalis L.) in supercritical organic solvents: Effects of liquefaction parameters on product yields and character

Ferula orientalis L. stalks were liquefied in an autoclave in supercritical organic solvents (methanol, ethanol, 2-propanol, acetone and 2-butanol) with (NaOH, Na₂CO₃, ZnCl₂) and without catalyst at five different temperatures ranging from 240 °C to 320 °C. The amounts of solid (unconverted raw material), liquid (bio-oil) and gas produced, as well as the composition of the resulting liquid phase, were determined. The effects of various parameters such as temperature, solvent, catalyst and ratio of catalyst on product yields were investigated. The results showed that conversion highly depends on the temperature and catalyst. The highest bio-oil yield (53.97%) was obtained using acetone with 10% zinc chloride at 300 °C. The liquid products were extracted with benzene and diethyl ether. Some of selected liquid products (bio-oils) were analyzed by elemental, FT-IR and GC–MS. 126 different compounds were identified by GC–MS in the liquid products obtained in ethanol at 300 °C.     

生物油储存稳定性的研究进展

保持良好的储存稳定性是生物油作为替代能源进入市场应用的关键之一。本文介绍了生物油的基本特性、储存稳定性的研究现状以及测量评价生物油储存稳定性的参数和方法,并重点介绍了目前提高生物油储存稳定性的方法,分析了不同方法的优缺点以及目前所面临的问题,并提出了深入生物质快速热解机理并制定关于生物油储存稳定性及应用的标准将有助于生物油的市场商业应用。     

Characterization of the liquid and solid products obtained from the oxidative pyrolysis of meat and bone meal in a pilot-scale fluidised bed plant

Pyrolysis of meat and bone meal material has been studied in an auto-thermal pilot scale unit with a fluidised bed reactor based on Bioware Technology. The heating value of the bio-oil samples is around 33-36 MJ/kg, whilst the nitrogen content is between 7.3 wt.% and 9.0 wt.%. Liquid fractionation with solvents of the bio-oil has been carried out. Chemical analyses of the fractions have shown that the main components in the bio-oil samples are alkanes, alkenes, oxygenated components (as alcohols) and nitrogen compounds (as nitriles) which are identified in the water insoluble fraction. Knowing the chemical composition of the bio-oils is important for assessing possible chemical and pharmaceutical applications of these bio-oils. The char samples have a notable ash content (63 wt.% to 77 wt.%) and its high Ca content could make it suitable for use as a catalyst in gasification processes.     

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.     

Influence of temperature and alumina catalyst on pyrolysis of corncob

Corncob has been investigated as an alternative feedstock to obtain fuels and chemicals via pyrolysis in fixed-bed reactor. The influence of pyrolysis temperature in the range 300-800 °C as well as the catalyst effects on the products was investigated in detail and the obtained results were compared. The results indicated that a maximum oil yield of 22.2% was obtained at a moderate temperature of 600 °C. The oil yield was reduced when the temperature was increased from 600 to 800 °C, whereas the gas yield increased.Pyrolysis oils were examined by using instrumental analysis, ¹H NMR spectroscopy and GC/MS. This analysis revealed that the pyrolysis oils were chemically very heterogeneous at all temperatures. It was determined that the most abundant compounds composing the bio-oil were phenolics.It was observed that the catalyst decreased the reaction temperature. Most of the components obtained using a catalyst at moderate temperatures was close to those obtained at high temperatures without using a catalyst. Moreover, the use of a catalyst and the high temperatures of the reactions also decreased the amount of oxygenated compounds produced.According to these results, corncob bio-oils can be used as fuel and constitute a valuable source of chemical raw materials.     

玉米秸秆棒状燃料热解过程和产物特征研究

以玉米秸秆棒状燃料为原料,在固定床反应器上探究热解温度对玉米秸秆棒状燃料热解过程和热解产品性质的影响。研究发现,随着热解温度的升高,热解气体产量增加,固体炭产量逐渐减少,生物油产量先增后减在450℃时达到最大值35.61%。对固体炭进行工业分析,发现其灰分含量较高;FT-IR分析表明:玉米秸秆棒状燃料的热解反应主要发生在650℃之前;SEM图显示断截面表现为蜂窝状的孔结构。生物油的GC-MS分析表明:在250~750℃下生物油的组成主要是呋喃、酮、醛和酚类等含氧化合物,其中酚类和呋喃类化合物是含量最多的物质;而在850~950℃下以多环芳烃类化合物为主。热解气的主要组成是CO₂、CO、CH₄和H₂,同时有少量的C₂H_n化合物,在250~450℃范围内,气体的主要组成是CO和CO₂,随着温度升高,CO、H₂、CH₄和C₂H_n逐渐增加,热解气的热值逐渐增加,在650℃下气体产品的热值已达到13.05 MJ/m³,当温度大于650℃后,热值增加速率变慢。