Bio-oil Fraction Research Articles

Wheat straw/HDPE co-reaction synergy and enriched production of aromatics and light olefins via catalytic co-pyrolysis over Mn, Ni, and Zn metal modified HZSM-5

The co-reaction synergy of wheat straw (WS) and high-density polyethylene (HDPE) plastic waste with varying mass ratios were evaluated at 550 °C in a fixed bed pyrolyzer reactor. Ex-situ catalytic co-pyrolysis of WS and HDPE feed mix (3:1) at a high feed to catalyst ratio (10:1) was performed over Mn, Ni, and Zn (1, 5, and 10 wt%) metal-modified HZSM-5 at 550 °C to study the effect of metal promotors variations on the production of aromatics and light olefins. The prepared catalysts were characterized by employing XRD, N2 physisorption, NH3-TPD, H2-TPR, and UV-Vis analytical techniques. The results obtained in the present work indicated that 1%-Zn modified HZSM-5 produced a more relative proportion of aromatics (25.12%) in the co-pyrolysis oil organic phase, followed by 5% Ni and 5%-Zn-loaded HZSM-5 at 16.22% and 15.76% respectively. Furthermore, 5% Ni-HZSM-5 has shown higher deoxygenation ability (58.43%) in reducing the oxygenates formed, followed by 5% Mn (40.96%) and 1% Zn (35.37%) respectively. While, 5% Mn-HZSM-5 generated pyrolytic gases with higher volumetric compositions of (C2-C4) light olefins at 15.84%, followed by 1% Mn (13.97%) and 10% Ni (13.61%) respectively and these volumetric yields were strongly correlated with intermediate acidity of catalysts. The physical properties (e.g. HHV ~ 41–43 MJ/kg) of the resultant organic fraction of catalytic co-pyrolysis bio-oil are almost analogous to conventional fuels such as diesel and light fuel oil (LFO). Additionally, the resultant catalytic pyrolytic gases possessed excellent calorific value (LHV ~ 30–31 MJ/Nm3) and are comparable to natural gas. Overall, the present study has successfully demonstrated the promising nature of the catalytic co-pyrolysis process for the conversion of biomass and waste plastic into useful chemicals and fuels.

Fractionation by flash chromatography and molecular characterization of bio-oil by ultra-high-resolution mass spectrometry and NMR spectroscopy

Bio-oils obtained from the pyrolysis of lignocellulosic biomass are highly complex matrices with tens of thousands of organic compounds covering a wide polarity and mass range. Their upgrading into greener fuel or value-added chemicals requires an in-depth knowledge of their molecular composition prior and after valorization treatment, which can be obtained by different analytical techniques. Here, flash chromatography was employed as an efficient way to fractionate a bio-oil vacuum residue into four distinct fractions. This process was repeatable at both gravimetric and chromatographic levels and provided information about the weight contribution of each fraction to bio-oil composition. Achieved fractions were then characterized by ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy. These two techniques ensured the good repeatability of bio-oil fractionation at the molecular level and also highlighted molecular specificities of each fraction. Thus, flash chromatography provided quantitative information that was complementary to FT-ICR MS results. It also simplifies the bio-oil compositional analysis, making it possible to detect more compounds. Eventually, this fractionation process can also be used to target fraction or compounds of interest for bio-oil upgrading.

Efficient hydrodeoxygenation of lignin-derived bio-oil to hydrocarbon fuels over bifunctional RuCoWx/NC catalysts

Efficient hydrodeoxygenation of lignin-derived bio-oils to cycloalkanes was achieved over bifunctional RuCoWx/NC catalyst prepared by in situ pyrolysis method. The performance of RuCoWx/NC was investigated in HDO of 4-propylguaiacol, considering the influences of catalysts, initial H2 pressure, and reaction temperature. Catalyst screening reveals that RuCoW0.03/NC afforded the highest propylcyclohexane yield of 71.3% from 4-propylguaiacol at 220 ℃. At 240 ℃, the yield of propylcyclohexane increased to 95.2 %. The heavy fraction of rice husk bio-oil, primarily composed of lignin-derived phenolic compounds, could be upgraded to 98.3% hydrocarbons at 280 ℃ over RuCoW0.03/NC. The synergistic interaction between highly dispersed Co and Ru metal sites and WOx acidic sites is responsible for the excellent HDO activity of RuCoW0.03/NC. Besides, RuCoW0.03/NC exhibited high stability after four cycles.

A new insight into high quality syngas production from co-pyrolysis of light bio-oil leached bamboo and heavy bio-oil using response surface methodology

Syngas, bio-oil, and biochar are three-phase products yielded from biomass pyrolysis. As a clean fuel, syngas has great potential value within the background of carbon neutrality. However, little attention has been paid to syngas compared with other pyrolysis products. In this study, a novel method for high yield production of syngas with high calorific value production has been proposed, in the context of light bio-oil (LB) leached bamboo and heavy bio-oil (HB) co-pyrolysis. The effects of three experimental variables (mass ratio, pyrolysis temperature, and residence time) on the yield and properties of syngas were investigated using response surface methodology. Results showed that under the typical experimental conditions (mass ratio 1:1, 550 °C, and residence time of 17.5 min), the experimental gas yield (23.14 wt%) and H2 + CO content (41.18 vol%) of HB and raw bamboo co-pyrolysis were 4.87 wt% and 2.24 vol% higher than the theoretical value, respectively. Notably, LB leaching pretreatment effectively removed biomass ash and changed the pyrolysis pathway. A more significant synergistic effect was observed during the co-pyrolysis of HB and LB leached bamboo, leading to a higher gas yield and a higher combustible gases content. High-quality syngas enriched in H2 and CO was obtained. Under the optimal conditions (mass ratio 1:3.09, 700 °C, and residence time of 19 min), the yield of syngas was up to 42.92 wt% with a high HHV of 19.26 MJ/Nm3, and the H2 + CO content was 63.74 vol%. Eventually, the regression equations between syngas properties and variable values were obtained. The method proposed in this study could herein provide a basis for the utilization of different fractions of bio-oil, as well as the co-pyrolysis for high quality syngas production.

Production of aromatic hydrocarbons by co-cracking of bio-oil and ethanol over Ga2O3/HZSM-5 catalysts

• The activity of Ga 2 O 3 /HZSM-5 was significantly affected by the preparation method. • Weak Brønsted acidity was detrimental to deoxygenation and aromatization reactions. • The catalyst prepared by impregnation showed high activity at a Si/Al ratio of 25. The catalytic cracking of bio-oil is important to produce aromatic hydrocarbons, which can partially replace gasoline or diesel to greatly reduce carbon emissions from transportation. To further promote the formation of aromatic hydrocarbons, this work studied the effects of the preparation method and the acid strength of Ga 2 O 3 /HZSM-5 on catalytic cracking of the bio-oil distilled fraction systematically. The preparation method of Ga 2 O 3 /HZSM-5 had an important effect on its catalytic activity: the Ga 2 O 3 /HZSM-5 prepared by physical mixing showed the low dispersion of active phases and poor pore structure, resulting in its insufficient activity and severe coke deposition; the Ga 2 O 3 /HZSM-5 prepared by precipitation exhibited the higher activity, while many polycyclic aromatic hydrocarbons unfavorable for the subsequent utilization were in the oil phase; the Ga 2 O 3 /HZSM-5 prepared by impregnation showed the highest activity and 35.5% (mass) selectivity of the oil phase, including 80.3% monocyclic aromatic hydrocarbons and 12.0% polycyclic aromatic hydrocarbons. The Brønsted acidity of Ga 2 O 3 /HZSM-5 decreased with Si/Al ratio, leading to the decline in reactant conversion, oil phase selectivity and quality. Meanwhile, the polymerization between monocyclic aromatic hydrocarbons and oxygenates was promoted to produce many polycyclic aromatic hydrocarbons and even coke, causing catalyst deactivation.

Alternating magnetic field initiated catalytic deconstruction of medical waste to produce hydrogen-rich gases and graphite

During the coronavirus 2019 (COVID-19) pandemic, there has been a dramatic increase in the use of medical products and personal protective equipment, such as masks, gowns, and disposable syringes, to treat patients or administer vaccines. However, this may lead to generation of large quantities of biohazardous medical waste. Here, an alternating-magnetic-field-initiated catalytic strategy is proposed to convert disposable syringes into hydrogen-rich gases and high-value graphite. Specifically, in addition to selecting heavy fraction of bio-oil as initiator, disposable syringe needles are used as radio frequency electromagnetic wave receptors to initiate the deconstruction of disposable syringe plastic. The highest H2 yield of 39.9 mmol g-1 is achieved, and 30.1 mmol g-1 is maintained after 10 cycles. Moreover, a high carbon yield of 286 mg g-1 can be obtained. Beyond disposable syringes, this strategy could help to solve the emerging issue for other types of medical waste (e.g., mask and protective clothing) disposal.

Slow pyrolysis of flax straw biomass produced in Kazakhstan: Characterization of enhanced tar and high-quality biochar

In the present study, local flax straw waste biomass samples were studied for their physical and chemical characteristics using a thermogravimetric analyzer (TGA) and thermal properties. Thermochemical conversion of the flax straw samples was performed in an electrically heated horizontal tube furnace from 400 to 600℃. Thermal analysis of the flax straw biomass showed higher calorific value of 18.2 MJ/kg, cellulose (27.4 wt%) and hemicellulose (24.8 wt%) content and lower lignin content (21.2 wt%). Mass balance of pyrolysis products showed 40.3% for bio-oil fraction at temperature of 500 ℃, which resulted in a notable reduction in the biochar yield by 34.6% compared to biochar yield at temperature of 400 ℃. Pyrolysis of flax straw samples further shows a notable reduction in moisture, ash and fixed carbon by 4.4%, 2.9% and 11.4%, respectively. In addition, it was noted that the tar obtained from flax straw is mostly composed of phenolic components, while XRD analysis confirms the degradation of cellulose in biochar fraction. Due to the higher de-volatilization behavior, calorific value, cellulose and hemicellulose content, also lower lignin and ash content, flax straw biomass can be used as a promising feedstock for bioenergy production.

Investigation of cascade valorization of Pistia stratiotes L. by hydrothermal treatment

Aquatic plant Pistia stratiotes L. has widely dispersed around the world and is known for rapid reproduction in water system. However, over reproduction could generate serious issues such as clogging the waterways and results in secondary environmental pollution. Therefore, developing an economical and value-added route to valorize aquatic plants not only solves environmental pollution, but also provides novel utilization values. In this study, Pistia stratiotes L. was hydrothermal treated from 200 to 280℃, which can obtain hydrochar, light bio-oil and supernatant fractions. The surprising results showed that a large amount of alkali calcium (5.50 wt%) was enriched on the surface of hydrochar. And the hydrochar could be used as a catalyst for glucose isomerization to fructose after limited oxygen calcination. The yield of light bio-oil increases with the temperature and the composition contains a large amount of cyclopentene derivatives, which can be further refined to chemicals. The hydrothermal supernatant contains a large amount of calcium, magnesium, iron and other nutrients. The seed germination test showed that the supernatant liquid had certain bioactivity and had the potential of developing liquid fertilizer. This study provides basic reference for comprehensive and novel utilization of aquatic plants with abundant yield.

Polymerization during low-temperature electrochemical upgrading of bio-oil: Effects of interactions among bio-oil fractions

The electrochemical method is becoming a promising approach to deliver the bio-oil upgrading objective at room temperature. However, it still faces the coke formation issue because of the easy polymerization nature of bio-oil. Interactions among components impact the polymerization during the electrochemical upgrading of bio-oil. This study investigates the effects of interactions between the aromatic-rich and aromatic-poor fractions (ARFs and APFs) of the bio-oil on polymerization under various reaction time and current densities. Coke yield differences provide direct evidence of the existence of interactions between ARFs and APFs during the electrochemical upgrading process. Our results indicate that the coke yields and its condensation level are decreased by the interactions. The surface area, pore volume and the functionalities content of the coke are increased by the interactions. In addition to polymerization, more types of reactions including hydrogenation and esterification are induced by the interactions, resulting in more types of products and less coke. The interactions can inhibit polymerization by consuming the coke precursors before their condensation. The interactions can also inhibit the anodic adsorption and oxidation, thus depressing polymerization and coke formation.

A Biomass Pyrolysis Oil as a Novel Insect Growth Regulator Mimic for a Variety of Stored Product Beetles.

As fumigants face increasing regulatory restrictions, resistance, and consumer pushback, it is vital to expand the integrated pest management (IPM) chemical toolkit for stored products. The production of biomass derived insecticides (e.g., bio-oil fraction) from byproducts of biofuel production may be a promising alternative source of chemistries for controlling stored product insects. These potential insecticidal bio-oils were fractionated based on boiling points (ranging from 115 to 230°C in one series and 245-250°C in another). Fractions were analyzed using GC-MS, and were found to be unique in composition. The lethality of these fractions was tested on Tribolium castaneum, Tribolium confusum, and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Fractions were tested at concentrations ranging from 5-260 mg/ml to screen for efficacy against adults for durations of 2-8 hr sprayed on concrete arenas. In addition, a separate assay evaluated adult emergence of larvae after 6 wk with supplemental food in arenas, while repellency was evaluated against four stored product insect species in a laminar wind tunnel. A greenhouse gas (GHG) emissions life cycle assessment was also performed, which found the use of the bio-oil fraction could reduce GHG emissions associated with the insecticide supply chain by 25-61% relative to a fossil-fuel based insecticide or pyrethroid. While adults were largely unaffected, we found that larval emergence was significantly suppressed compared to controls by roughly half or more. We also determined that there was minimal repellency to most fractions by most species. We conclude that the use of bio-oil fractions is a climate-friendly choice that may support IPM programs.

Synthesis and characterization of phenolic resins based on pyrolysis bio-oil separated by fractional condensation and water extraction

The combination of fractional condensation and water extraction methods is proposed to produce phenol rich beech wood pyrolysis bio-oil fractions, which have great potential to replace petroleum-based phenol in polymerization of novolac resin. The polymerization of model phenol acetaldehyde (MPA) resins, mimic acetaldehyde (mimic) resin which base on the composition of phenol compounds in bio-oil, and bio-oil acetaldehyde (BOA) resins were studied. MPA and mimic resins were used to compare with the BOA resins to determine the feasibility of using bio-oil. Bisphenol A type epoxy resin (DGEBA) was used, for the first time, as a formaldehyde-free cross-linker for bio-oil based novolac resins. The kinetic parameters of the curing reaction with model-free methods were obtained using data from a differential scanning calorimeter (DSC). The BOA resin showed curing activation energy was close to that of the phenol-acetaldehyde (PA) resin (95.5 and 94.9 kJ/mol by Kissinger method). The physicochemical and thermal properties of the novolac resins before and after curing are compared, and the potential of treated bio-oil products to effectively replace commercial phenols is demonstrated.

Acetone reaction pathways as a model bio-oxygenate in a hydrocarbon medium on zeolite Y and ZSM-5 catalysts: Isotope labeling study

• Acetone catalytic conversion in hydrocarbon medium was studied by isotope labeling. • Under studied conditions C 3 -C 5 olefins formed from hexane contain H from acetone. • Obtained results can be explained by acetone addition to carbocations as an enol. In this research the isotope labeling experiments were used to study the reaction pathways of acetone conversion in hydrocarbon medium in the presence Y and ZSM-5 zeolites. Acetone is a model for ketones, which are a considerable fraction of bio-oil. The analysis of the isotope distribution in the conversion products was carried out by 1 H NMR and GC/MS methods; it was shown that the deuterium labels introduced with acetone are distributed mainly in C 3 -C 4 olefins, as well as pentenes and 2-methylpentane. The results obtained correspond with the previously proposed assumption that the catalytic cracking of ketones, capable to transform into enols, in a hydrocarbon medium starts with a nucleophilic attack of the protonated ketone on hydrocarbon intermediates. Additionally, the H/D exchange between deuterated compounds and cracking intermediates or zeolite has been established.

Elucidating radical-mediated pyrolysis behaviors of preoxidized lignins

Effect of lignin preoxidation on subsequent radical-mediated pyrolysis was discussed in this study. Technical hot-water-extracted lignin was preoxidized by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in diverse degrees and pyrolyzed under different temperatures. Characterizations indicated that preoxidation increased lignin oxygen contents and converted α-hydroxyls to α-carbonyls. These structural modifications caused by preoxidation reduced the thermal stability and pyrolysis reactivity of lignin, shifting lignin thermal decomposition to the low temperature region and inhibiting lignin pyrolysis into bio-oil fractions. However, recognition of species and yields of specific compounds via analytical pyrolysis declared that although preoxidation reduced product yields, it did not alter the reaction pathways. The fixed bed experiments proved the above findings and gave the gas compositions, mainly CO2 derived through decarbonylation. Both radicals in chars and bio-oils were monitored, and char radical concentrations were proportional to the preoxidation degrees. This work sorted out the performances of lignin pyrolysis after preoxidation and determined their negative effects.

Co-pyrolysis of light bio-oil leached bamboo and heavy bio-oil: Effects of mass ratio, pyrolysis temperature, and residence time on the biochar

Light fraction of bio-oil (LB) has high contents of water and organic acids with good liquidity and is a promising leaching agent for deashing of biomass. Heavy fraction of bio-oil (HB) contains more amounts of phenols and pyrolytic lignin, has poor fluidity, and is easy to carbonize when heated. In this study, a novel method for preparation of biochar from co-pyrolysis of HB and LB leached bamboo (LB-bamboo) has been proposed. Effects of three experimental variables, namely, mass ratio (1:0–0:1), pyrolysis temperature (400–700 °C), and residence time (5–30 min), on the mass yield and properties of biochar were investigated, based on response surface methodology. Results showed that co-processing of HB and bamboo by pyrolysis synergistically improved the yield and higher heating value (HHV) of biochar. Under typical co-pyrolysis conditions (mass ratio 1:1, 550 °C, and 17.5 min), the experimentally determined yield (25.97%) and HHV (29.43 MJ/kg) of biochar from co-pyrolysis of HB and raw bamboo were 1.61% and 1.01 MJ/kg higher than the corresponding theoretically predicted values. The ash and metallic species in bamboo were significantly removed by LB leaching pretreatment, leading to a more synergistic effect observed during the subsequent co-pyrolysis. The experimentally determined yield (24.63%) and HHV (30.62 MJ/kg) of biochar from co-pyrolysis of HB and LB-bamboo were 2.40% and 1.57 MJ/kg higher than the corresponding theoretical values. Ultimately, the regression equations between the biochar properties and the three experimental variables were established. The best fitting models for yield and HHV of biochar were quadratic regression equations.

Comprehensive characterization of cattle manure bio-oil for scale-up assessment comparing non-equivalent reactor designs

Microscale pyrolysis reactors are used to predict the properties of pyrolysis products and/or optimize operating conditions. However, a major challenge encountered with these systems concerns reactor scale-up, since the conception of an equivalent large-scale configuration involves a complex step of mathematical analysis of the process. Furthermore, the effect of scale for different reactor configurations, considering the ways that the reactor design can influence pyrolysis, are still unknown parameters in the process. Therefore, this work evaluated the influence of scale, for different pyrolysis reactor configurations, on the composition of the liquid product (bio-oil) obtained by thermoconversion of cattle manure, using comprehensive chemical characterization by GC/MS and UHRMS, followed by statistical analysis. The gravimetric yields of the liquid fractions produced at the micro (R1) and semi-pilot (R2) scales showed a difference of ~10%, while similarity indices of ~90% were found for the volatile constituents of the bio-oils, determined by GC/MS. The ~10% disparity for the GC-analyzable bio-oil fraction was mainly associated with higher production of methoxyphenols in the R2 process. The molecular compositions determined by UHRMS showed degrees of dissimilarity < 18%, mainly reflected in higher formation of basic polar components of the O1 and O2 classes, and acids of the O4 class, in the R2 process. The results obtained in this work suggest that for a conventional pyrolysis process, the influence of scale for reactors of different configurations is less than 20%, with the products obtained showing similar compositions if the same operating conditions are used. Therefore, the challenges encountered in the scale-up phase of the system can be minimized, since changing the scale of the pyrolysis process, even using different reactors, will result in the formation of similar products.

Characterization of rheological properties and aging performance of bitumen modified by bio-oil from bamboo charcoal production

As a waste stream from charcoal production, the liquid bio-oil has not been properly used, leading to both environmental and economic issues. In this study, this deleterious waste was explored as a promising additive for petroleum-based bitumen. Raw bio-oil was pretreated through distillation under different temperature to remove undesirable components. The resulting medium and heavy bio-oil fractions were blended with petroleum-based bitumen by weight ratios up to 12% to obtain bio-bitumen. The rheological and aging properties of the bio-bitumen were further evaluated with various test means. The results showed that the addition of bio-oil had softening effect on bitumen. Bio-bitumen performed better brittleness resistance with smaller Glover-Rowe parameters and better fatigue crack resistance at shorter crack length than that of base bitumen. The lower non-recoverable creep compliance of the heavy fraction modified bio-bitumen indicated its better rutting resistance, compared to that of the base bitumen. Characterization of the carbonyl and sulfoxide functional groups in the aged bitumen showed comparative aging performance of the bio-bitumen modified with heavy fraction. The findings of this study indicate that the promising potential of bio-oil heavy fraction to replace petroleum-based bitumen for generating sustainable road paving material.

Hydrogen production via steam reforming of small organic compounds present in the aqueous fraction of bio-oil over Ni-La-Me catalysts (Me = Ce, Ti, Zr)

Hydrogen production via steam reforming of small organic compounds present in the aqueous fraction of bio-oil over Ni-La-Me catalysts (Me = Ce, Ti, Zr)

Experimental and modeling investigation on pyrolysis of agricultural biomass residues: Khat stem and coffee husk for bio-oil application

Khat stem and coffee husk are commonly available agricultural residues in Ethiopia and pose serious environmental hazards through the eutrophication of water streams and greenhouse gas emissions. To alleviate these impacts, thermochemical conversion of these residues through fast pyrolysis can be employed. The samples are characterized for their composition, experimental investigation has been carried out using thermogravimetric analysis at different heating rates (10, 20, 30, 40, and 50 °C/min) in the temperature range 30–800 °C under an inert atmosphere to scrutinize the decomposition characteristics. Estimation of pyrolysis kinetic parameters for these materials, which are not widely available in the literature, has been done using different model-free approaches: Kissinger, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose. Empirical models were developed and employed for comparison of experimental data and error analysis. Validation of experimental data has been done and evolved pyrolysis product yields are predicted using the CRECK-S-B model. The effect of biomass characterization parameters and heating rate are examined. From the results, it is possible to perceive that the Kissinger, single first order, and 4-component models can predict with good accuracy but can not predict the residual char evolution that occurs at higher temperatures (> 450 °C) and the derivative of thermogravimetric shoulders, correspondent to the hemicellulose decomposition. The CRECK-S-B model revealed good agreement with the experimental data for both samples, while being capable of capturing the hemicellulose shoulder and the residual decomposition of char at higher temperatures. The yields and composition of gas, bio-oil and char fractions are estimated, for which the biomass characterization and heating rates have influenced the distribution of the products. This study reveals the potential of these residues to promote local sustainable economies and also gives a possible solution to the environmental issue caused by their disposal.

Stabilization of the Aqueous Phase Fraction of Pine Wood Bio-Oil Using Zirconia-Supported Fe/Cu/Pd Nano-Catalysts at Mild Conditions

Stabilization of the Aqueous Phase Fraction of Pine Wood Bio-Oil Using Zirconia-Supported Fe/Cu/Pd Nano-Catalysts at Mild Conditions

Steam Reforming of the Model Compounds in the Aqueous Fraction of Bio-Oil Based on Pre-Reforming Over Dolomite

Steam Reforming of the Model Compounds in the Aqueous Fraction of Bio-Oil Based on Pre-Reforming Over Dolomite