Species In Bio-oil Research Articles

Past to Future: Application of Gel Permeation Chromatography from Petroleomics and Metallopetroleomics to New Energies Applications: A Minireview

In the field of petroleomics and metallopetroleomics, the gel permeation chromatography (GPC) technique coupled with high-resolution detection technologies has made significant contributions as an analytical and preparative tool for over five decades. This bibliographic minireview highlights the study of the supramolecular and structural behavior of heavy crude oil and its fractions, as well as their reactivity to various processes by use of GPC. The preferred mobile phase is tetrahydrofuran (THF), whereas the stationary phase is polystyrene–divinylbenzene copolymer to avoid compound retention in the column. Other techniques such as HPTLC, RPLC, and NPHPLC have been used to provide multidimensional separations complementary to GPC. The high molecular weight (HMW) fraction, due to its greater polarity, reactivity to polymerization, and resistance to hydrodemetallization processes, has been the focus of interest for years. GPC coupled with high-resolution techniques has proven to be reliable for the detection of organic and inorganic species in bio-oils, making it a valuable tool for researchers and industry professionals in the context of feedstocks changes and new energy production.

Effects of Surface Hydrophobicity on Catalytic Transfer Hydrogenation of Styrene with Formic Acid in a Biphasic Mixture.

Transfer hydrogenation (TH) of unsaturated hydrocarbons with formic acid (FA) is an attractive processing pathway for the reduction of lignocellulosic pyrolysis oils. The low solubility of hydrophobic bio-oil species in water and FA in oil necessitates the use of a biphasic system as the reaction environment. Here, we report the effects of Pd/silica catalyst surface wettability on the TH reaction rate. Modification of the surface with short chain (C1-C4) alkyl silanes resulted in an increase in the reaction rate as compared to the unmodified catalyst. In contrast, modification of the surface with sulfonate (hydrophilic) and C18 alkyl silanes (hydrophobic) resulted in a decrease in the reaction rate as compared to the unmodified catalyst. The results are discussed in terms of the catalyst interfacial activity and relative affinity of the reagents to the Pd active sites. An observed change in the apparent reaction order in styrene for a hydrophilic catalyst suggests that changing catalyst surface wettability from hydrophilic to hydrophobic resulted in a switch from a transport-limited to a kinetic-limited reaction regime.

Beneficial use of Fe-impregnated bentonite as a catalyst for pyrolysis of grass cut into syngas, bio-oil and biochar

Fe-impregnated bentonite was employed in CO2-assisted pyrolysis of grass cut as a catalyst to improve syngas production, bio-oil quality, and biochar sorptive property. The gas analysis revealed that H2 and CO production was enhanced by 332 and 7,110%, respectively, by applying Fe-impregnated bentonite in pyrolysis of grass cut while untreated bentonite had a limited influence on syngas production. Bio-oil produced from Fe-impregnated bentonite and grass cut (Fe-BG) had more homogenized chemical species in bio-oil as compared to that produced from pyrolysis of grass cut, and contained methyl 1,1-methyl-dodecanoate (C14H28O2), one of the major components in biodiesel. The produced biochar had high surface area (69.2 m2 g−1) and possessed Fe0 and graphitic carbon structure, which was deemed to arise from reduction of Fe-oxides by syngas. Biochar also showed high As(V) adsorption capacity. The overall results of this work demonstrated the beneficial utility of Fe-impregnated bentonite in pyrolysis of biomass to improve syngas production as well as the quality of pyrogenic products.

Towards understanding the chemical reactions between KOH and oxygen-containing groups during KOH-catalyzed pyrolysis of biomass

In this study, the effect of KOH/biomass ratios and pyrolysis temperatures on products distribution, the evolution of oxygen-containing groups in pyrolytic tri-state products and the possible chemical reactions between oxygen-containing groups and KOH were investigated. The results indicated that KOH can react with oxygen-containing groups in biomass to facilitate gas generation at lower ratios (≤1:2) or higher temperature (∼800 °C). When at higher ratios (>1:2) and 600 °C, KOH has an inhibitory effect on gas production. With a significant decreased in the oxygen-containing species and acids, the phenols and hydrocarbons became the main species in bio-oil. Moreover, KOH facilitates methoxyphenol conversion and has high selectivity for alkyl phenol generation. For biochar, at lower ratios (<1:2), K can attack the oxygen sites of phenolic hydroxyl groups, forming dangling bonds and promoting the formation of aromatic rings with anhydride groups. However, at higher ratios (>1:2), the oxygen-containing groups on the surface of biochar gradually changed from anhydride groups to quinone groups, and finally form a biochar with large aromatic ring and rich in quinone groups. As analyzed above, a possible chemical reaction between KOH and oxygen-containing groups during KOH-catalyzed pyrolysis of biomass was proposed.

Numerical modeling of biomass fast pyrolysis by using an improved comprehensive reaction scheme for energy analysis

In this study, we developed an improved comprehensive pyrolysis scheme by modifying the bio-oil species and gas species fractions, increasing the carbon fraction in the char, and combining and changing the metaplastic decompositions for energy analysis. The two-fluid model (TFM) framework was used to simulate pyrolysis in a two-dimensional tubular reactor, and 10 g of 1500-μm-sized pinewood particles was used as biomass feedstock. Pyrolysis was performed at 400 °C−600 °C with an average heating rate of 115 °C/min. The improved scheme was evaluated against recent comprehensive pyrolysis schemes with respect to decomposition characteristics. The pyrolysis product yields and compositions predicted by the improved model accorded with experimental results. Moreover, the energy contents and distributions of pyrolysis products were successfully estimated, and the relative errors of bio-oil, gas, and char energies were 0.61%, 9.54%, and −3.76%, respectively. The energy distributions were more dominant influenced by the pyrolysis product yields than by the energy density.

Towards Understanding the Chemical Reactions Between KOH and Oxygen-Containing Groups During KOH-Catalyzed Pyrolysis of Biomass

In this study, the effect of KOH/biomass ratios and pyrolysis temperatures on products distribution, the evolution of oxygen-containing groups in pyrolytic tri-state products and the possible chemical reactions between oxygen-containing groups and KOH were investigated. The results indicated that KOH can react with oxygen-containing groups in biomass to facilitate gas generation at lower ratios (≤ 1:2) or higher temperature (~800 o C). When at higher ratios (> 1:2) and 600 o C, KOH has an inhibitory effect on gas production. With a significant decreased in the oxygen-containing species and acids, the phenols and hydrocarbons became the main species in bio-oil. Moreover, KOH facilitates methoxyphenol conversion and has high selectivity for alkyl phenol generation. For biochar, at lower ratios ( 1:2), the oxygen-containing groups on the surface of biochar gradually changed from anhydride groups to quinone groups, and finally form a biochar with large aromatic ring and rich in quinone groups. As analyzed above, a possible chemical reactions between KOH and oxygen-containing groups during KOH-catalyzed pyrolysis of biomass was proposed.

Effect of Bio-Oil Species on Rheological Behaviors and Gasification Characteristics of Coal Bio-Oil Slurry Fuels

Bio-oil is a promising fuel as one of the main products from biomass fast pyrolysis for improving energy density and reducing transportation cost, but high acidity and low calorific value limit its direct application. It can be used to prepare coal bio-oil slurry as partial green fuels for potential feeds for synthesis gas production via gasification with the advantages over traditional coal-water slurries of calorific values and being additives-free. In the present work, three bio-oils were blended with lignite to prepare slurry fuels for the investigation of the effect of bio-oil species on rheological behaviors and gasification characteristics of coal bio-oil slurry fuels. Results show that slurry prepared with bio-oil from fruit tree pyrolysis is highly viscous and has higher activation energy in gasification. Slurries prepared with bio-oils from straw pyrolysis and pyroligneous acid from wood pyrolysis exhibited an acceptably lower viscosity, and the gasification temperatures were lower than for coal. The activation energy decreased by 15.98 KJ/mol and 2.77 KJ/mol, respectively, which indicates these bio-oils are more suitable with lignite for slurries preparation.

Roles of furfural during the thermal treatment of bio-oil at low temperatures

The reactive O-containing species in bio-oil could induce the polymerization of bio-oil during its thermal treatment, which affects the relevant utilization of bio-oil significantly. Furans, as the highly reactive O-containing species in bio-oil, play important roles during the thermal treatment of bio-oil. In this study, furfural was chosen as the representative of the furans in bio-oil to investigate its roles during the thermal treatment of bio-oil. The raw bio-oil with and without the addition of extra furfural (10 wt% of bio-oil) and pure furfural were pyrolyzed in a fixed-bed reactor at 200–500°C. The results show that the interactions among furfural and bio-oil components can take place prior to the evaporation of furfural (< 140°C) to form the intermediates, then these intermediates could be further polymerized to form large molecular compounds, and coke can be formed via the interactions at temperatures ≥ 300°C. At temperatures ≤ 300°C, furfural mainly interacts with anhydrosugars. As the temperature further increases, the aromatics are involved in the interactions to form coke. The increased percentage of the coke formed via the interactions is in a linear relation with the conversion of furfural during the pyrolysis at 300–500°C (no coke formed at 200°C). Meanwhile, more non-aromatic light components (≤ C6) and less aromatics in the tars could be formed due to the interactions.

Spirulina hydrothermal carbonization: Effect on hydrochar properties and sulfur transformation

The effect of hydrothermal carbonization (Htc) on the hydrochar properties and sulfur conversion for microalgae was investigated. The sulfur species and distribution in solid and aqueous products produced from different temperature (180–300 °C) were evaluated. Results suggested that varying temperature significantly influenced the elemental composition, functional groups of hydrochar, and the sulfur species in the products. With temperature increased, the hydrochar had increased aromatic structure with low H/C and O/C ratio, and more conversion of organic sulfur into liquid as SO42−-S, which acquired the highest concentration (293.31 mg/L) at 300 °C. The thiophene-S, aromatic-S, and thiazole-S accounted for the main sulfur species in bio-oil, while components of thiophene-S and thiazole-S were decreased at high temperature. In addition, elevated temperature resulted in more sulfur forms (i.e. thiophene) in hydrochar and formation of more inorganic-S species like sulfate.

New Magnetic Fe Oxide-Carbon Based Acid Catalyst Prepared from Bio-Oil for Esterification Reactions

In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe3+ salt in bio-oil followed by treatment at 400, 450, 500 or 600 oC in N2 atmosphere. X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM), elemental analysis, thermogravimetric-mass spectrometry (TG-MS), potentiometric titration, Raman and Mossbauer spectroscopies showed that Fe3+ species in bio-oil is reduced to produce magnetic nanoparticles phases: magnetite Fe3O4 and maghemite γ-Fe2O3. At low temperatures, the iron phases were less protected, and the carbon matrix was more reactive, while in temperatures above 500 oC, the iron phases were more stable, however, the carbon matrix was less reactive. Reaction of these magnetic carbon materials with concentrated H2SO4 produced surface sulfonic acidic sites (ca. 1 mmol g-1), especially for the materials obtained at 400 and 450 oC. The materials were used as catalysts on esterification reaction of oleic acid with methanol at 100 oC and conversions of 90% were reached, however, after 2 consecutive uses, the conversion decreased to 30%, being required more studies to improve the material stability.

Density functional study on the thermal stabilities of phenolic bio-oil compounds

Pyrolysis of biomass provides a potential carbon-neutral route to fuels and precursor chemicals through the formation of bio-oil. Lignin accounts for up to 40% of the weight of biomass feedstocks and so the products of lignin deconstruction form a significant portion of the bio-oil. Understanding the thermal stability of bio-oil species is critical for predicting the relationship between product prevalence and pyrolysis temperature, which in turn will allow for greater control of the output of key products. In this work, density functional theory (DFT) was employed to assess the stabilities of key bio-oil compounds by calculating their bond dissociation enthalpies (BDEs). 140 individual bonds across twenty-seven common bio-oil compounds representing eight different bond types were assessed. It was found that the PW6B95 functional can be used as a reliable method for predicting pyrolysis product stability through calculation of functional group BDEs. This is mainly owing to its low mean unsigned error (MUE) (0.5 kcal mol−1 = 2.1 kJ mol−1) in predicting BDEs in a test set of six bonds, as well as correct treatment of aromatic substitution effects for phenolic derivatives. The assessment results reflected that the weakest bonds of phenolic bio-oil species were the O–Me and Ph–O bond of the methoxy groups and the O–H bond of hydroxy groups. The weak bond strength exhibited by methoxy group bonds correlates well with reduced presence of guaiacyl and syringyl type species following higher temperature pyrolysis. Conversely, the hydroxy Ph–O and propenyl Ph–C bonds exhibited high BDEs, which is in agreement with the persistent presence of phenol and styrene type species following high temperature pyrolysis.

A kinetic study of the fast micro-pyrolysis of hybrid poplar

Hybrid poplar from the clone DN34 was studied to determine the rate of production of bio-oil species with respect to time during the fast pyrolysis process. 300–660 ug samples were pyrolyzed using a micropyrolzer at 500°C at very high heating rates and very short vapor residence times. Individual poplar samples were run in triplicate at discrete time points ranging from 1 to 20s in the micropyrolzer. Several bio-oil compounds from each individual sample were analyzed using GC/MS. Select bio-oil compounds, derived from the hemicellulose, cellulose, and lignin fractions of the wood, were used to determine their rates of production from thermal degradation of the biomass. These rates were quantified using standards to determine the weight percent relative to the original raw biomass with respect to time. Pyrolysis kinetic reaction models were fit to this experimental data in order to determine suitability of each model. A first order exponential decay model for degradation of the solid biomass was fit against the data along with a six-step consecutive degradation model previously developed by our group. The experimental data suggests that compounds derived from the hemicellulose are produced at faster rates than that of the lignin or cellulose fractions of the wood, consistent with prior data from thermogravimetric analysis (TGA). When applying the first order exponential decay model, the reaction rates calculated did prove that holocellulose compounds reaction rates were approximately twice that of the lignin compounds reaction rate but did not provide the best fit. The six-step degradation model provided a better fit to all of the biooil compounds and char data, and the stoichiometric parameters derived from the model fit showed that the first three reactions involved mostly the hemicellulose derived compounds while reaction steps 4–6 released cellulose- and lignin-derived compounds.

Adsorption Characteristics of Bio-oil on Biochar in Bioslurry Fuels

This study reports the adsorption characteristics of bio-oil on biochar in biochar/bio-oil slurry (i.e., bioslurry) systems at three biochar loading levels (2.4, 4.8, and 16.7%, respectively). At low biochar loading levels (2.4 or 4.8%), heavy organic compounds (particularly those containing fused aromatic systems) in bio-oil was selectively adsorbed onto the biochar. Such selective adsorption also resulted in reduced concentrations of alkali and alkaline earth metallic (AAEM) species in the adsorbed bio-oil phase compared to that in the bio-oil blank. A comparison between the experimental and calculated distributions of AAEM species in bio-oil indicates that at least part of the AAEM species adsorbed on biochar is associated with heavy organic compounds. Consequently, such selective adsorption results in changes in the unadsorbed bio-oil phase that has decreased viscosity and aromaticity and increased polarity. It is interesting to note that the selective adsorption was weakened with an increasing biocha...

Effects of Lignin Content and Temperature on the Properties of Hybrid Poplar Bio-Oil, Char, and Gas Obtained by Fast Pyrolysis

Eight genetically different hybrid poplar samples with varying lignin content were pyrolyzed at 500 °C using a micropyrolysis unit, which was directly connected to a GC/MS. Four of these hybrid poplar samples with a range of lignin content were then pyrolyzed at temperatures of 550 and 600 °C to determine the effects of pyrolysis temperature on product distribution among bio-oil, char, and gas. At a pyrolysis temperature of 500 °C, an increase in poplar lignin content from 17% to 22% decreased the relative bio-oil yield from 73% to 65%, increased the char yield from 17.5% to 27.2%, and decreased the yield of lignin-derived phenolic species in the bio-oil by 3%. At the higher pyrolysis temperature of 600 °C, there was neither a decrease in the yield of bio-oil nor an increase in the char yield, and there was an increase in the relative abundamnce of bio-oil phenolics compared to the results obtained at 500 °C. According to these results, higher temperatures are needed to increase the yield of bio-oil and the content of phenolic species in bio-oil.

Analytical Strategies Involved in the Detailed Componential Characterization of Biooil Produced from Lignocellulosic Biomass.

Elucidation of chemical composition of biooil is essentially important to evaluate the process of lignocellulosic biomass (LCBM) conversion and its upgrading and suggest proper value-added utilization like producing fuel and feedstock for fine chemicals. Although the main components of LCBM are cellulose, hemicelluloses, and lignin, the chemicals derived from LCBM differ significantly due to the various feedstock and methods used for the decomposition. Biooil, produced from pyrolysis of LCBM, contains hundreds of organic chemicals with various classes. This review covers the methodologies used for the componential analysis of biooil, including pretreatments and instrumental analysis techniques. The use of chromatographic and spectrometric methods was highlighted, covering the conventional techniques such as gas chromatography, high performance liquid chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance, and mass spectrometry. The combination of preseparation methods and instrumental technologies is a robust pathway for the detailed componential characterization of biooil. The organic species in biooils can be classified into alkanes, alkenes, alkynes, benzene-ring containing hydrocarbons, ethers, alcohols, phenols, aldehydes, ketones, esters, carboxylic acids, and other heteroatomic organic compounds. The recent development of high resolution mass spectrometry and multidimensional hyphenated chromatographic and spectrometric techniques has considerably elucidated the composition of biooils.

Bio-oil Stabilization by Hydrogenation over Reduced Metal Catalysts at Low Temperatures

The thermal and chemical instability of biomass fast pyrolysis oil (bio-oil) presents significant problems when it is being converted to hydrocarbon transportation fuels. Development of effective approaches for stabilizing bio-oils is critical to the success of the biomass fast pyrolysis and bio-oil upgrading technology. Catalytic hydrogenation to remove reactive species in bio-oil has been considered as one of the most efficient ways to stabilize bio-oil. This paper provides a fundamental understanding of hydrogenation of actual bio-oils over a Ru/TiO2 catalyst under conditions relevant to practical bio-oil hydrotreating processes. The results indicated hydrogenation of various components of the bio-oil, including sugars, aldehydes, ketones, alkenes, aromatics, and carboxylic acids, over the Ru/TiO2 catalyst and 120 to 160 °C. Hydrogenation of these species significantly changed the chemical and physical properties of the bio-oil and overall improved its thermal stability, especially by reducing the carb...

Different reaction behaviours of the light and heavy components of bio-oil during the hydrotreatment in a continuous pack-bed reactor

This study aims to investigate the hydrotreatment of bio-oil in a continuous packed-bed reactor at around 375°C and 70bar. The bio-oil was produced from the grinding pyrolysis of mallee wood in a grinding pyrolysis pilot plant. Our results indicate that the lighter and heavier components in the same bio-oil could behave very differently. Their behaviour can be affected very significantly by the overall bio-oil liquid hourly space velocity. While the residence time of the light species that evaporate instantly could be very short, the residence time of heavy species passing through the catalyst bed in the form of liquid could be very long. When a commercial pre-sulphided NiMo/Al2O3 catalyst came into contact with the heavy bio-oil species, significant exothermic reactions would take place, which result in the deactivation of hyperactive sites in the catalyst. The NiMo/Al2O3 catalyst used was less active in hydrotreating the heavier bio-oil species than in hydrotreating the lighter bio-oil species. However, even at very low extents of hydrotreatment, the bio-oil structure and properties, e.g. coking propensity, could be drastically improved.

Pyrolysis of eastern redcedar: Distribution and characteristics of fast and slow pyrolysis products

Eastern redcedar is a problematic plant in Oklahoma due to its extinguished environmental flexibility and rapid expansion. Thermally converting solid biomass polymers into liquid fuel intermediate, solid char and gaseous products through pyrolysis is one promising approach to use redcedar for the production of sustainable fuels. The objective of this study was to investigate effects of eastern redcedar wood zones (heartwood and sapwood), pyrolysis temperature (450 and 500°C) and pyrolysis types (slow at lab-scale and fast at micro-scale) on the distribution and composition of the pyrolysis products. In fast pyrolysis conditions, the products were dominated by anhydrous sugars, phenols and guaiacols. The total yield of lignin-derived compounds from heartwood was higher than that from sapwood at 500°C but the total yields were not significantly different at 450°C. In slow pyrolysis conditions, acetic acid and furfural were the two most abundant species in bio-oil. Slow pyrolysis products consisted of less branched compounds of phenols and guaiacols as compared to fast pyrolysis products. Cedar oil components (alpha/beta-cedrene) were only produced at slow pyrolysis conditions and its maximum yield (21.04±1.08area%) of was obtained from heartwood at 500°C. Heartwood produced significantly more cedrenes than sapwood.

Manipulation of chemical species in bio-oil using in situ catalytic fast pyrolysis in both a bench-scale fluidized bed pyrolyzer and micropyrolyzer

In situ catalytic fast pyrolysis (CFP) of biomass was conducted with base or acid catalysts in a bench-scale fluidized bed pyrolyzer. Complete mass balances were performed, allowing for quantitatively investigating the catalytic impacts on the final bio-oil composition. Acidic catalysts exhibited relatively higher activities for decomposition of sugar and pyrolytic lignin, dehydration, decarbonylation, and coke formation, as relative to base catalysts. Carbon balances revealed that a significant amount of carbon in bio-oil was transformed to coke during CFP. Due to the decrease in the bio-oil yield during CFP, significantly less energy was recovered in CFP products than in control fast pyrolysis products. CFP was also performed in micropyrolyzer and the results were compared with those in the bench-scale reactor to determine the consistency across the experimental systems. Different from the bench-scale pyrolyzer, the basic catalyst more strongly influenced the micropyrolyzer products and the discrepancies suggest a more rapid deactivation of the basic catalyst.

Techno-economic performance analysis of biofuel production and miniature electric power generation from biomass fast pyrolysis and bio-oil upgrading

The techno-economic performance analysis of biofuel production and electric power generation from biomass fast pyrolysis and bio-oil hydroprocessing is explored through process simulation. In this work, a process model of 72 MT/day pine wood fast pyrolysis and bio-oil hydroprocessing plant was developed with rate based chemical reactions using Aspen Plus® process simulator. It was observed from simulation results that 1kgs−1 pine wooddb generate 0.64kgs−1 bio-oil, 0.22kgs−1 gas and 0.14kgs−1 char. Simulation results also show that the energy required for drying and fast pyrolysis operations can be provided from the combustion of pyrolysis by-products, mainly, char and non-condensable gas with sufficient residual energy for miniature electric power generation. The intermediate bio-oil product from the fast pyrolysis process is upgraded into gasoline and diesel via a two-stage hydrotreating process, which was implemented by a pseudo-first order reaction of lumped bio-oil species followed by the hydrocracking process in this work. Simulation results indicate that about 0.24kgs−1 of gasoline and diesel range products and 96W of electric power can be produced from 1kgs−1 pine wooddb. The effect of initial biomass moisture content on the amount of electric power generated and the effect of biomass feed composition on product yields were also reported in this study. Aspen Process Economic Analyser® was used for equipment sizing and cost estimation for an nth plant and the product value was estimated from discounted cash flow analysis assuming the plant operates for 20years at a 10% annual discount rate. Economic analysis indicates that the plant will require £16.6 million of capital investment and product value is estimated at £6.25/GGE. Furthermore, the effect of key process and economic parameters on product value and the impact of electric power generation equipment on capital cost and energy efficiency were also discussed in this study.