Stability Of Bio-oil Research Articles

Harnessing palladium-decorated g-C3N4 nanosheets for selective catalytic benzyl alcohol synthesis

The selective reduction of benzaldehyde to benzyl alcohol (a pivotal model reaction for the low-temperature stabilization of bio-oil) was meticulously investigated. This study delved into the catalytic prowess of Pd-modified g-C3N4 nanosheets (PdxCN) within a liquid-phase environment, utilizing H2 as the reducing agent under benign conditions. A series of photocatalysts were synthesized by impregnating graphitic carbon nitride nanosheets (NS-CN) with varying weight percent loadings of Pd nanoparticles. In the context of this selective hydrogenation, the catalytic activity of Pd2CN catalysts outshone that of pure NS-CN and other reference catalysts, exhibiting remarkable efficacy with benzyl alcohol yields nearing perfection at approximately 99%. Moreover, these catalysts demonstrated enduring catalytic reusability and reproducibility. The optimization of experimental parameters, encompassing weight percent loading of co-catalyst, catalyst quantity, temperature, and reaction duration, was systematically undertaken to achieve optimal benzyl alcohol yield.

Unveiling sustainable synergy and ageing stability of bio-oils from cotton gin trash and plastic waste co-liquefaction for an integrated waste-to-energy solution

Co-liquefaction is an emerging technology aimed at enhancing bio-oil yield and quality, compensating for decrease in feedstock, increasing productivity, and adding revenue to bio-refineries. This study delves into the influence of plastic waste (PW) types during co-liquefaction with cotton gin trash (CGT) on the yield and quality of the produced crude oil. Various plastics, including PLA (polylactic acid), PVA (polyvinyl alcohol), PET (polyethylene terephthalate), LDPE (low-density polyethylene), HDPE (high-density polyethylene), PP (polypropylene), and PS (polystyrene), were investigated in a mixing ratio of 2:1 (CGT/plastic waste) at 320 °C and 2 hours in supercritical ethanol (ScEtOH), without catalyst, to produce energy-dense bio-oil under optimised conditions. The study presents the suitability of different types of plastic waste for co-feeding with CGT, along with their synergistic and antagonistic effects on product fraction yield (oil, solid, and gas), and oil energy yield. High bio-oil yields of 54.5 wt%, 53.7 wt%, and 43.1 wt% were achieved during co-liquefaction of CGT with PLA, PET and PVA, respectively. Bio-oil with the highest Higher Heating Values (HHV) was achieved through the co-liquefaction of CGT with PVA (30.6 MJ/kg) and PS (31.5 MJ/kg). The solid fractions obtained from co-liquefying CGT with PLA and PVA contained 46.9 wt% and 55.1 wt% carbon, respectively, making them potential sustainable sources for soil amendment. Furthermore, the bio-oils were characterised using gas chromatography-mass spectroscopy (GC-MS), two-dimensional nuclear magnetic spectroscopy-heteronuclear single quantum coherence (2D‐NMR-HSQC), elemental analysis, fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to assess their quality and stability. Solid residues were characterised to understand the extent of plastic degradation and their suitable applications. The results indicate that the co-liquefaction of lignocellulosic biomass with plastics represents a viable and promising approach for improving bio-oil quality and extending its shelf life.

The effect of citric acid pretreatment on composition and stability of bio-oil from sugar cane residues using a continuous lab-scale pyrolysis reactor

This study outlines the effect of citric acid leaching on the quality and stability of fast pyrolysis bio-oils from sugarcane bagasse (SCB) and sugarcane trash (SCT). The quality of bio-oil was probed by GC-MS analysis, elemental composition, higher heating value, water and solids content, pH, dynamic viscosity and stability (ageing). Pyrolysis was performed at 500 °C in a fully controlled, continuously operated plant with a biomass throughput of ca. 300 g.hr−1. While citric acid leaching causes a decrease of the average bio-oil yield with 5%, it does not lead to a bio-oil with improved fuel-related properties. However, the bio-oil composition became more advantageous in light of its biorefining. Indeed, citric acid leaching led to an increased levoglucosan concentration – a promising platform chemical – of 17% for SCB and of to 35% for SCT (based on relative abundance in GC-MS). In tandem, the concentration of carboxylic acids and phenols in the bio-oil decreased after citric acid leaching, which is beneficial for downstream purification of levoglucosan. Regarding the non-condensable gases, CO and CO2 represented between 88% and 91% by weight of the total non-condensable gases produced in pyrolysis. Therefore, the results of this study demonstrate that optimized biomass demineralization pretreatment with citric acid could produce bio-oil at high yield and rich in high-value chemical compounds like levoglucosan. Biomass demineralization pretreatment however, does not result in bio-oil with improved quality for fuel purposes, nor does it necessarily lead to bio-oil having higher stability.

Developing alternatives to hydrocarbon via pyrolysis and gasification of industry residual biomass

<p>Pyrolysis and gasification are thermal treatment processes using biomass to produce biofuels that can replace fossil fuels in industrial boilers and furnaces. This paper discusses the potential utilization of four types of residual biomass highly produced in the Argentina Northeast (NEA) region, i.e., rice husk, an agricultural waste rich in cotton husk, carob sawdust, and spent red quebracho sawdust, as raw material. Pyrolysis liquid product yields were 34–51 wt% and char yields were 29–40 wt%; tar represented 16–23 wt%. For gasification, gas yields were between 45.6 wt% and 65.7 wt%; as for tar, it represented 2.4–14.1 wt% of initial biomass, and char yields were 31.4–40.3 wt%. Characterization of all products was performed to clarify their potential applications. Bio-oils, i.e., aqueous fractions of pyrolysis liquid products, have high water content (77–88 wt%), that is why they have lower density and viscosity than tars, oil fractions of pyrolysis liquids. However, chemical stability of bio-oils may vary, and their heating values are much lower than the heating values from tars. Based on these, it is possible to concluded that tar is the product with increased added value and higher energy properties. Efficiency of gasification and heating values of the gases obtained were high for waste rich in cotton husk and spent red quebracho sawdust, suggesting a good potential for the utilization in gasification processes. Additionally, char composition and properties for all biomasses, from both process, show that it is feasible to use them in several new applications.<strong></strong></p>

Stabilization of bio-oil from simulated pyrolysis oil using sulfided NiMo/Al2O3 catalyst

Pyrolysis oil comprises compounds with a broad range of functional groups making its thermal/catalytic upgrading challenging due to the formation of undesired char. In this context, the current contribution addresses the thermal and catalytic hydrotreatment of a simulated pyrolysis oil containing all the representative groups of compounds under bio-oil stabilization conditions (180–300 °C, 60 bar, 4 h) using sulfided NiMo/Al2O3. The effect of reaction conditions and different oxygenated organic compounds on the yields and properties of products was compared thoroughly. Interestingly, a correlation between the presence/absence of oxygenated furan and sugar compounds was found to significantly affect the yield of liquid product containing stabilized compounds. The presence of such compound groups significantly enhances the solid formation via oligomerization and polymerization reactions. To gain further insight, the solid products were analyzed/characterized in detail to elucidate their characteristics by extracting them into a dimethyl sulfoxide (DMSO) soluble and insoluble solid fraction. It was found that in the presence of NiMo/Al2O3, increasing temperature from 180 to 300 °C enhances the formation of liquid product due to transformation of some of the soluble solids, while for experiments without the catalyst, the formation of solids was significantly higher. Oppositely, during heating up to 180 °C, no solids were found in the case without the catalyst, however the presence of the catalyst during heating resulted in solid formation due to various catalytic reactions that promoted char formation. Analysis of solids revealed that the structure of soluble solids at lower temperatures (180 °C) using the catalyst was closely related to sugar derivatives, whereas the corresponding insoluble solids with higher molecular weight were not fully char-like developed. However, at higher temperatures, the soluble and insoluble solid compositions were found to contain aliphatic compounds and fully developed char, respectively. Therefore, the stabilization of furan particularly with attached carbonyl groups and sugars derivatives in pyrolysis oil is of great importance to improve upgrading efficiency.

Fractional condensation and aging of pyrolysis oil from cotton stalk

The current study is to investigate a multi-condenser system for separating pyrolytic vapors as a promoting method to produce bio-oils that are more impervious to aging. Bio-oil vapors produced by fast pyrolysis of cotton stalk in a fluidized bed reactor at a temperature of 500 °C and were divided by a fractional condensation system into four fractions. The results showed that the stability of the fractional bio-oil was improved because most of the reactive aliphatic compounds with small molecules involving water rich organic acids, aldehydes and ketones were effectively separated from the other components. It was found out that the stability of bio-oil was affected by the active chemicals derived from fast pyrolysis as well as the aqueous acidic condition of bio-oils because most polymerization, condensation and electrophilic addition substitution reactions need the presence of H+ to be the catalyst. The observation pointed out that the suspended solid particles (SS) in bio-oils can be suppressed by separating conventional bio-oils into different stages by means of concentrating the initial SS in a certain fraction.

Ex Situ Catalytic Pyrolysis of Invasive Pennisetum purpureum Grass with Activated Carbon for Upgrading Bio-Oil

Energy demands keep increasing in this modern world as the world population increases, which leads to a reduction in fossil fuels. To resolve these challenges, Pennisetum purpureum, an invasive grass in Brunei Darussalam, was examined as the feedstock for renewable energy through a catalytic pyrolysis process. The activated carbon was applied as the catalyst for a simple and economical solution. The catalytic pyrolysis was executed at 500 °C (the temperature for the highest biofuel yield) for both reactors to produce the highest amount of upgraded biofuels. The biochar produced from the non-catalytic and catalytic pyrolysis processes showed a consistent yield due to stable operating conditions, from which the activated carbon was generated and used as the catalyst in this work. A significant amount of improvement was found in the production of biofuels, especially bio-oil. It was found that for catalysts, the number of phenolic, alcohol, furans, and ketones was increased by reducing the amount of acidic, aldehyde, miscellaneous oxygenated, and nitrogenous composites in bio-oils. The highest amount of phenolic compounds was produced due to a number of functional groups (-C=O and -OH) in activated carbon. The regenerated activated carbons also showed promising outcomes as catalysts for upgrading the bio-oils. The overall performance of synthesized and regenerated activated carbon as a catalyst in catalytic pyrolysis was highly promising for improving the quality and stability of bio-oil.

Pyrolysis of Delonix regia using metal oxide catalysts and solvent effect on fuel fraction of bio-oil

Delonix regia (DR) lignocellulosic biomass waste contributes to large quantities of daily solid waste which is having high volatile matter that can be utilized for the production of bio-oil by pyrolysis. The pyrolytic raw bio-oil consists of both fuel and non-fuel fractions which can be separated by organic solvents. Further, application of mixed or individual metal oxide catalysts in pyrolysis reactor along with the feed reduces the corrosiveness and improves stability of pyrolytic bio-oil. Therefore, novelty statement includes catalytic pyrolysis of DR carried out in the presence of mixed metal oxide catalysts, TiO2 and ZnO; followed by separation of fuel and non-fuel fractions of pyrolytic bio-oil using dichloromethane and n-hexane solvents. The improvement of product quality was realized by catalytic activity though the yield is almost unaffected compared to that of non-catalytic pyrolysis. Addition of solvents, helped improving quality of bio-oil by separating out non-fuel phase from it. Each experiment repeated thrice to ensure repeatability and reliability. Higher heating value (HHV) of pyrolytic raw liquid oil increased by 16.2% by the use of catalyst compared to that of non-catalytic pyrolytic raw liquid oil whereas the pH enhanced from 3.72 to 4.77, which indicated catalytic bio-oil has become less acidic. In addition, the physical and fuel properties of fuel fraction obtained by n-hexane are found to be superior to those obtained by dichloromethane. For instant, HHV of fuel portion separated with n-hexane is 23% higher than that obtained with dichloromethane. Density of fuel part obtained by n-hexane was found to be 0.74 g/ml (close to that of commercial gasoline) which is much low as compared to that obtained by using dichloromethane that is having density of 1.01 g/ml. Fourier-Transform InfraRed (FTIR) spectroscopy and proton Nuclear Magnetic Resonance (NMR) spectroscopy of fuel fraction of liquid product indicated partial deoxygenation of bio-oil by separating it with n-hexane.

Catalytic pyrolysis of Reutealis trisperma oil using raw dolomite for bio-oil production

Conversion of non-edible Reutealis trisperma Oil (RTO) into bio-oil by catalytic pyrolysis was carried out using dolomite as catalysts. Dolomite, a sedimentary carbonate rock mineral, has shown potential as a cheap and eco-friendly catalyst to enhance bio-oil yield by reducing coke formation. Dolomite was directly used in the catalytic pyrolysis of RTO without prior calcination or treatment. Increasing the pyrolysis temperatures from 400 °C to 450 °C, improved bio-oil production from 59.68% to 77.39%, with only 0.11% of carbon char formation. The non-catalytic thermal pyrolysis produced 68.29% liquid bio-oil product and 7.04% carbon char. GC-MS analysis revealed that dolomite also enhanced the composition of heavy hydrocarbon molecules, contributing to a higher flash point and thermal stability of bio-oil. Analysis of the physical properties proved that the use of fresh dolomite decreased the viscosity (3.12 cSt) and increased calorific value (41.61 MJkg−1) and density (0.85 g/cm−3) compared with the bio-oil produced by non-catalytic thermal pyrolysis. Bio-oil quality was further enhanced through esterification reaction that significantly reduced the carboxylic acid content from 55.47% to 3.32%.

Study on the Stability of Bio-Oil Modified Prime Coat Oil Based on Molecular Dynamics

To explore the effect of different emulsifier contents on the stability performance of biomass-emulsified asphalt, three types of emulsified asphalt with 1%, 3%, and 5% anionic emulsifiers were prepared and analyzed by molecular dynamics simulation and macroscopic experiments. Firstly, we used molecular simulation software (Material Studio, MS) to construct a model of biomass-emulsified asphalt with different emulsifier contents and analyzed the microscopic mechanism of the emulsifier to improve the stability of the emulsified asphalt by the radial distribution function, interaction energy, interfacial layer thickness, and solubility parameters of the emulsified asphalt system with different emulsifier contents. The results were validated by macro and micro tests including storage stability, particle size determination, and infrared spectroscopy. The results show that at low emulsifier contents, the emulsifier can reduce the interfacial tension between the oil–water interface and expand the transition region between the two phases (interfacial layer thickness), which will prevent interparticle agglomeration and reduce the emulsion particle size, thus reducing the settling rate and ensuring the stability of the emulsion. When the emulsifier content is further increased beyond the critical micelle concentration, the emulsifiers will agglomerate with each other and show larger peaks in the radial distribution function, and the phenomenon of emulsifier agglomeration will appear in the five-day storage stability test, resulting in a corresponding decrease in the proximity of the infrared absorption peak area ratio in the same wavelength band of the upper and lower layers of the biomass-emulsified asphalt, and the emulsion stability decreases instead.

Effect of FeCl3 combined with biochar as dewatering conditioners on sludge pyrolysis products

Owing to the rapid development of cities, sewage treatment plants produce an abundance of sewage sludge (SS). As a new sludge treatment technology, pyrolysis has been widely popularized in the disposal of SS. Sludge must be dewatered before pyrolysis, and FeCl3 combined with biochar has been shown to effectively improve SS dewatering performance in previous studies; however, its influence on subsequent SS pyrolysis disposal has not been studied. Based on the sludge conditioning-dewatering-pyrolysis system process, the effect and mechanism of the SS dewatering process on subsequent sludge pyrolysis disposal were elucidated. In this study, the combined effects of FeCl3 and biochar (FB) on sludge pyrolysis products were investigated using thermogravimetric mass spectrometry (TG-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Additionally, the mechanism by which FeCl3 and biochar functioned are separately explained. Results showed that FB reduced the release of C/H/O-containing gases to a certain extent, which was mainly related to the biochar conditioner, promoted the S-containing gases, and reduced the release of N- and Cl-containing gases. Thus, FB is beneficial for improving the calorific value and chemical stability of bio-oil, in which the FeCl3 conditioner played a dominant role. Additionally, FB also moderately reduced the formation of N/S/Cl-containing compounds, mainly through the synergistic action of FeCl3 and biochar. Particularly, FB has the catalytic ability to remove tar. Several reaction kinetics models fitted using the Coats−Redfern method showed that FB was beneficial for reducing the energy required during pyrolysis. The results have important guiding significance to SS pyrolysis for the selection of sludge dewatering conditioners.

Electrocatalytic Upgrading of Biomass Fast Pyrolysis Oil

Attempts to electrocatalytically upgrade bio-oil have been made in recent years. Mostly, the ECH (Electrocatalytic Hydrogenation) experiments of bio-oil were done using fixed bed electrode configurations at room temperatures and low current densities (<100 cm-2). The main goal was to demonstrate the viability of ECH as a bio-oil stabilization strategy, mainly through reduction of carbonyl contents (aldehydes and ketones) which could cause polymerization. High temperature may promote condensation polymerization of fast pyrolysis oil, low-temperature ECH is therefore considered a promising approach to stabilize pyrolysis oil. However, recent advances in ECH of fast pyrolysis oil have shown the limited reductive upgrading chemistry (hydrogenation, hydrogenolysis, or hydrodeoxygenation) through this approach. This was mainly attributed to the complexity of fast pyrolysis oil and the restricted electrolysis operating conditions. Most of the published works in ECH of pyrolysis oil reported the reduction of carbonyl content into alcohols in the substrate rather than the hydrodeoxygenation of aromatics or phenolics. In this study, ECH of fast pyrolysis oil (FPO) in acidic electrolytes using SSER (Stirred Slurry Electrocatalytic Reactor) configuration was conducted for the first time. A compositional analysis suggested that the FPO sample contained water (29 wt.%) and detected monomers (38.5 wt.%), which comprise of carbohydrate derivatives (35.2 wt.%) and lignin derivatives (3.3 wt.%). Balance of water and monomers must be oligomers. Three polar organic solvents (e.g., ethanol, isopropanol, and acetone) were tested in a mixed aqueous and organic electrolyte with MSA solution. The electrolysis experiments were carried out for 4–30 h at constant cathodic current densities (I = -218 to -255 mA cm-2) and temperatures (50–60 oC). In all cases, decreases in the weight average molecular weight (Mw) and the number average molecular weight (Mn) were observed with prolonged reaction times. Temperature and catalyst loading contributed to faster depolymerization of the oligomers. Using different organic solvents (e.g., ethanol, isopropanol, acetone), the degree of depolymerization was about 33–37% after nearly 20 h reactions. Color changes in the catholyte FPO samples were observed in all cases after 18–25 h, turning from dark brown to light yellow. This observation supports the GPC results showing the molecular weight reduction after the ECH. In this study, compound distributions were determined based on ten functional groups, such as acids, alcohols, aldehydes, ketones, esters, furans, alkanes, aromatics, phenols, and guaiacols. In all cases, the reduction of ketones, aromatics, and guaiacols was noticed, while the alkanes content slightly increased. The most dramatic increases in esters content were observed when ethanol (17–25%) or isopropanol (19–32%) was used. This was attributed to esterification of carboxylic acids (mainly acetic acid) in the FPO with alcohols in the presence of MSA, which catalyzed the reaction. Reduction of p-eugenol to cerulignol (4-propylguaiacol) was the most noticeable in all cases, implying that the unsaturated bond in the allyl group is easily reduced under the ECH conditions. Significant increases in the cerulignol contents were achieved with all the different solvents: ethanol (0.5–4.9%), isopropanol (1.4–6.9%), and acetone (1.4–5.4%), based on the composition calculation normalized by the lignin-relevant compounds detected in the catholyte samples. ECH of FPO in SSER with organic solvents addition has demonstrated mild depolymerization of FPO oligomers, esterification, and reduction of carbohydrate and lignin derivative monomers which could potentially upgrade the quality of FPO for synthesis of hydrocarbon fuels.

Study of bio-oil production from (Eucalyptus and Plastic) wastes by using the Co-pyrolysis technique: review

This study incorporated the co-pyrolysis of eucalyptus biomass and plastic-wastes for bio-oil production. This study also discussed the advantage and challenges of the used technique for bio-oil production. In conventional pyrolysis process found some drawbacks such as tar content and thermal instability. These issues can be resolved by using the co-pyrolysis technique to meet the modification of the quality and combustion stability of bio-oil. This study also promotes environmental safety by reducing the carbon level from the atmosphere by using solid wastes (eucalyptus wood and plastic-wastes).

Advanced thermochemical conversion of algal biomass to liquid and gaseous biofuels: A comprehensive review of recent advances

Algal biomass is considered to be one of the most promising feedstocks of importance for conversion into biofuels. With their benefits over other biomass feedstocks, such as sustainability, renewability and productivity, microalgae are one of the most promising biomass resources for use in thermochemical conversion processes. With this review, we hope to present the most recent information available on the commonly used thermochemical conversion procedures, which are hydrothermal liquefaction, pyrolysis, and gasification processes. The study evaluated both the quality and yield of liquid products (bio-oil) as well as gaseous products (syngas) derived by thermochemical conversion processes, to truly comprehend the effectiveness and feasibility of each method. It was found that the yield of bio-oil obtained through hydrothermal liquefaction was lower than the yield achieved through pyrolysis. However, the energy density, fuel properties and storage stability of hydrothermal liquefaction bio-oil are superior to those of pyrolysis bio-oil. This study also demonstrated that the gasification process has been the most energy-saving approach for the transformation of microalgae to syngas. Microalgae supercritical water gasification might be a good way to turn microalgae into high-heating-value gas without having to dry it first. Finally, the prospects and obstacles of converting microalgal biomass to biofuels were discussed. Overall, the purpose of this work is to present a comprehensive assessment of the most recent developments in microalgal biomass thermochemical conversion for the production of liquid and gaseous biofuels.

Influence of methanol addition on bio-oil thermal stability and corrosivity

Bio-oil has been considered to be upgraded via co-processing with petroleum intermediates in existing fluid catalytic cracking (FCC) units to produce drop-in fuels. However, the low stability and high corrosivity of bio-oil are two major obstacles preventing further advances in bio-oil upgrading processes. Previously, efforts have been made to improve bio-oil stability through the use of additives, with methanol as a promising candidate. Yet, the effect of these additives on bio-oil corrosivity has not been fully understood. In this study, both the stability and corrosivity of bio-oil with methanol addition are analyzed. Bio-oil was blended with methanol at concentrations of 5–20 wt%. These mixtures were subject to accelerated aging at 50 and 80 °C for up to 168 hours. Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry, and thermogravimetric analysis were conducted to identify functional groups, chemical compounds, and thermal behaviors of bio-oil, respectively. Viscosity, density, water content, and pH were also measured to track the physical and chemical property changes of bio-oil and bio-oil/methanol mixtures during aging. Alongside, immersion experiments with common FCC structural materials such as carbon steel (CS) and stainless steels (SS) 304L and 316L were conducted in bio-oil and bio-oil/methanol mixtures, at 50 and 80 °C for 168 hours. The result of aging experiments showed that the viscosity increasing rate of bio-oil was dramatically lowered by adding methanol, especially at 80 °C, indicating that adding methanol was effective in stabilizing bio-oil. For corrosivity investigation, CS corroded severely in tested bio-oil mixtures. At 50 °C, it was found that CS immersed in bio-oil mixtures with higher methanol concentration corroded at a more significant rate; whereas at 80 °C, the corrosion rate of CS initially increased with methanol concentration in bio-oil and then declined. 304L SS exhibited moderate corrosion rates at 80 °C, while 316L SS showed minimal corrosion at the tested conditions. It has also been observed that CS accelerated the viscosity increasing rate of bio-oil, especially after being aged at 80 °C for 168 hours. After immersion experiments, abnormally high carbon, oxygen, and nitrogen contents were identified on rigorously cleaned metal coupon surfaces. A combination of viscosity measurements and surface characterization suggested that chelation between organic compounds and metal atoms/ions played a significant role in the corrosion of steels in bio-oil. A mechanism was proposed to justify the corrosion behavior of steels in bio-oil/methanol mixtures.

The stabilization of bio-oil as an alternative energy source through hydrodeoxygenation using Co and Co-Mo supported on active natural zeolite

In this study, hydrodeoxygenation (HDO) process of bio-oil from coconut shell waste was catalyzed by active Sarulla natural zeolite (ZAS) supported by Co metal and a combination of Co-Mo metal. The resulting bio-oil HDO product is expected to have good physicochemical stability during the storage period so as to increase its potential as an alternative source of hydrocarbon energy. Preparation and activation of ZAS catalyst with 3M HCl and calcination with N2 gas flow. Impregnation of Co and Co-Mo into ZAS was carried out by wet impregnation method followed by oxidation and reduction with O2 and H2 gas flow. Several important properties of the catalyst were characterized by XRD, SEM, FTIR, and BET methods. Bio-oil HDO process is carried out in fixed bed reactor with H2 gas flow at a certain temperature for two hours. Analysis of physicochemical properties and stability of bio-oil products includes analysis of acid number, viscosity, elementary content, HHV, and component analysis using GC-MS. The data obtained showed that the loading of two metals increased the spesific surface area, volume and pore size, but decreased the crystallinity of the catalyst. Based on the distribution of HDO products, it indicates that monometal catalysts tend to produce more liquid phase, coke, and gas while bimetallic catalysts tend to produce more organic phase. Viscosity and acid number of bio-oil catalyzed by Co-Mo/ZAS is lower than that of Co/ZAS. Co/ZAS catalyst showed high selectivity towards the aqueous phase. The bio-oil catalyzed by Co/ZAS has a higher HHV and a higher viscosity and lower oxygen content as a result of the release of hydrogen bound oxygen into water molecules. Thus, it can be assumed that the deposition of Co and Co-Mo on zeolite has a different effect on the characteristics of zeolite and its activity as a catalyst.

Investigation of the combination of fractional condensation and water extraction for improving the storage stability of pyrolysis bio-oil

To improve the storage stability of bio-oils obtained from beech wood intermediate pyrolysis in a drop tube reactor, the combination of three-stage condensation with an additional water extraction system was accomplished to produce separated and purified bio-oil products. The physicochemical properties and composition variation of bio-oil during aging at different storage temperatures (4 °C, room temperature-18 °C, and 50 °C) and different storage times (1, 2, 3, and 4 weeks) were studied and compared to that of fresh bio-oil. The water content of each bio-oil product increased compared to the fresh oil, whereas the pH value decreased slightly. GC chromatography and FT-IR analysis results showed that the chemical composition of the bio-oil changed. All the variations indicate that some reactions, such as polymerization, oxidation, polycondensation, hydrolysis of sugars, and esterification, occurred in the bio-oil samples during storage. Bio-oil products stored at 4 °C and room temperature for 4 weeks had relatively high stability, whereas the accelerated aging of bio-oil stored at 50 °C revealed a significant change in its chemical composition. The additional water extraction step specifically improved the stability of the water-insoluble fractions of the bio-oil products. However, the water-soluble fractions were not as stable as the fractions before water extraction. The high content of acid in the water-soluble fractions made it an appropriate medium for hydrolysis sugar and to produce interesting chemical components, 5-(Hydroxymethyl) furfural (HMF), 2(5H)-furanone, furfural, furan, 2,5-dimethyl- and γ-Valerolactone (GVL).

Hydrothermal liquefaction of sugarcane bagasse to bio-oils: Effect of liquefaction solvents on bio-oil stability

Bio-oil produced from the hydrothermal liquefaction (HTL) of biomass is unstable and cannot be transported over long distances to a refinery for upgrading to transportation fuel. This study examined the effect of the liquefaction solvent on the stability of bio-oils derived from the HTL of sugarcane bagasse. The accelerated aging test (0–8 days at 80 °C) was used to assess the stability of these oils with the aid of indicators such as water content, molecular weight range, functional groups present, phase separation, thermal stability, and the amount of residue after thermal analysis of the oils. The HTL solvent mixture of ethanol/water was found to produce the most stable bio-oil when compared to crude glycerol/water or water on its own. The light oils fractionated by solvent extraction were more stable than their corresponding bio-oils. The higher heating values (HHVs) of the light oils during the agiging process were relatively stable and were between 33 and 35 MJ/kg. The maximum boiling temperature of the first peak in the DTG thermogram of the aged light oil derived from ethanol/water is 147 °C (cf. diesel of 157 °C), while that of crude glycerol/water light oil is up to 190 °C. The stabilities of the oils derived from either ethanol or crude glycerol are related to alkylation, esterification, and acetalization reactions. This study has demonstrated that the HTL of sugarcane bagasse in the presence of ethanol/water produces oils of good quality that have long shelf-lives and have been projected to be stored for up to 8 years with minor compositional and structural changes.

Rough-surface hydroxyl-group-rich hollow mesoporous silica nanospheres with nanocellulose as a template to improve the oxidation stability of bio-oil

Bio-oils are good substitutes for petrochemical oil, but their high oxygen contents result in poor oxidation stability. Therefore, anti-oxidants are essential to improve the oxidation stability of bio-oils. In this study, quantum chemistry has been used to analyze in detail the relationship between the structure and adsorption properties of bio-oils and silanol groups. A new type of rough-surface hollow mesoporous silica nanospheres (R-nCHMSNs) bearing abundant hydroxyl groups has been prepared using hydroxyl-group-rich nanocellulose as a template. In an evaluation of anti-oxidants for bio-oil, R-nCHMSNs showed excellent anti-oxidant properties. They formed hydrogen or ester bonds with oxygen-containing groups in bio-oil through their surface hydroxyl groups and wide channel structure, thus improving the oxidation stability of the bio-oil. Furthermore, the kinetics of adsorption of bio-oil on the R-nCHMSNs has been found to be in accordance with a second-order model.

Improved bio-oil upgrading due to optimized reactor temperature profile

Production of second-generation biofuels by upgrading of pyrolysis bio-oil from biomass attracted much attention in recent years. Here, we present a study dedicated to the stabilization of pyrolysis bio-oil over NiMo/Al2O3 catalyst in single-stage fixed bed reactor with different temperature profiles (ramp to the 340 °C). Detailed characterisation of the textural properties of the fresh and the spent catalyst and the determination of the changes in physicochemical properties and chemical composition of the liquid and gaseous products have allowed us to discuss the influence of the temperature profile on the catalyst stability during 80 h time on stream of the bio-oil hydrotreatment. We have observed that the lower average temperature in the reactor can yield stabilized bio-oil with physicochemical properties comparable with bio-oil that was hydrogenated at higher temperatures. Moreover, the catalyst long-term stability was higher when using a slower temperature ramp. Thus, the physicochemical properties of the stabilized bio-oil obtained with the lower average temperature in the reactor was maintained uniform with the increasing time on stream, while deterioration of the properties of the hydrotreated liquid products produced under the faster temperature ramp occurred. Additionally, we have shown that no sulfur loss occurred from the NiMo/Al2O3 catalyst during bio-oil hydrotreatment.