Crude Bio-oil Research Articles

A comparison of bio-crude oil production from five marine microalgae – Using life cycle analysis

Marine microalgae biomass could offer a viable feedstock for sustainably producing biofuel by hydrothermal liquefaction. In this study, five promising marine microalgae (i.e., Tetraselmis, Picochlorum, Synechococcus, Chroococcidiopsis, and Dunaliella), having different characteristics, were studied for biocrude oil production. The overall microalgal biocrude oil production process was divided into six unit operations: water supply, CO2 supply, nutrient supply, cultivation, harvesting, and HTL process. Models were developed for these unit processes such that once the key parameters of any unit process are known, the corresponding energy consumption could be determined. While the selection of the cultivation site influenced the energy requirements for sourcing seawater and CO2, the characteristics of the strain influenced energy requirements for the other four-unit operations. A cradle-to-grave concept was assumed to compare the life cycle assessment of the five strains. Among these strains, Tetraselmis sp. provided the most favorable energy balance with a net energy gain of 1.77 GJ/barrel of biocrude, an energy return on investment value of 2.81, and GHG reduction potential of 129 kg CO2 equivalent/barrel of biocrude. Further investigation with sensitivity analysis confirmed that the net energy yield for Tetraselmis sp. was least affected by a ±10% variation of the parameters of the unit processes.

Bioenergy characteristics of microalgae under elevated carbon dioxide

Nowadays, biological mitigation of carbon dioxide (CO2) by means of microalgae is one of the promising approaches, as biomass can be used to produce renewable fuels such as biodiesel and crude bio-oil. In this study, the growth ofDesmodesmussp. in response to different CO2levels (ambient air, 5%, 10%, 15%, 20%, 25%, 30%, and 35% CO2) was studied, and then the suitability of the biomass for bio-oil and biodiesel production was evaluated. The studied strain was able to grow efficiently in a broad range of elevated CO2(5–30%,v/v), suggesting its suitability for CO2mitigation. The highest specific growth rate (0.769 d−1) and biomass productivity (0.033 g L−1d−1) were achieved at 15% CO2; therefore, the concentration of 15% CO2was selected as the optimum. Alpha-Linolenic acid (ALA) was the dominant polyunsaturated fatty acids (PUFAs) in studiedDesmodesmusstrain, and its content increased from 31.82% under ambient air to 41.94% and 50.11% under 15% CO and 30% CO2, respectively, suggesting a key role of ALA in response to CO2elevation. Using fatty acid methyl ester (FAME) profiles of cultures in different CO2conditions, biodiesel parameters such as cetane number (CN), saponification value (SV), iodine value (IV), long chain saturation factor (LCSF), oxidative stability (OS), higher heating value (HHV) and degree of unsaturation (DU) were estimated. Overall, the lipid extract was not suitable for biodiesel production due to high PUFA content ranging between 52.91% and 71.14%. Under optimum CO2(15%), saturated fatty acids (SFAs) content increased to 31.91% and PUFA content reduced to 52.91%. This could significantly improve the CN to 38.07, which was 11% and 13% higher than theair and 30% CO2. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was used to analyze the potential of microalgal biomass for bio-oil production upon CO2changes. The pyrolysate contained 40–47% acid content due to the high content of fatty acids. The pyrolysate quality declined under 15% CO2due to the higher accumulation of acidic and nitrogen-containing compounds and reduced hydrocarbon proportion.In conclusion, the optimum CO2could enhance biodiesel parameters such as CN, but demonstrated negative effects on bio-oil quality.

Plasma-electrolytic liquefaction of human waste for biofuels production and recovery of ammonium, chlorine and metals

Sustainable production of value-added fuels and chemicals from biomass faces enormous challenges for integration in zero-carbon-emissions technologies and circular economy. In this work, green and renewable solvents, polyethylene glycol 200 and glycerol, were used in a plasma-electrolytic liquefaction (PEL) system to electrically liquefy human feces in the absence of a catalyst. It is demonstrated that the plasma ignition during the liquefaction accelerated the conversion of feces (85.67% liquefaction yield within 12 min), and the intrinsic heating features of the PEL greatly reduced the energy consumption. The obtained biocrude oil at the optimized conditions contained 10.53% aldehydes, 5.39% ketones, 18.48% cyclic oxygen-containing compounds and others, with a high heating value of 28.10 MJ/kg. Further analysis of the PEL-converted products reveals that most of the chlorine in the feces was gasified, the metals were extracted into the solid residue, while ammonia was released. An evaluation of the developed plasma electrolytic feces liquefaction process was carried out and favorably compared with common liquefaction methods. Overall, the proposed approach may provide a new avenue for clean chemical production and sustainable resource recovery from human waste under benign process conditions.

A step change towards sustainable aviation fuel from sewage sludge

Sewage sludge, an abundant and problematic organic waste, was successfully converted into sustainable jet fuel range hydrocarbons (C8-C16). Sewage sludge was pre-conditioned and processed through a Thermo-Catalytic Reforming (TCR) system (2 Kg/h) at 450 ºC pyrolysis and 700 ºC post-reforming temperature to produce a biocrude oil. The bio-crude oil was subsequently conditioned and upgraded via consecutive two-step hydroprocessing, comprising hydrodeoxygenation and hydrocracking as two separate unit operations. The two-step hydroprocessing was carried out in a bench-scale batch high-pressure reactor (autoclave). The process parameters such as temperature, feed volume, catalyst loading, and batch time were held constant, whilst the H2 pressure was varied. The effect of H2 pressure across 30 – 60 bar on the quality of the hydroprocessed oil was evaluated in terms of elemental composition, chemical compound distribution, and fuel properties. Hydroprocessing at 60 bar H2 resulted in better fuel properties compared to hydroprocessing at 30 bar H2. Hence, approximately 25% by weight jet fuel fraction, including normal, cyclo and iso-paraffins and aromatics in the C8–C16 range, was recovered via atmospheric distillation of the hydroprocessed oil at 60 bar H2. Sewage sludge derived jet fuel range fraction met the majority of the jet fuel specifications for calorific value, viscosity, density, and freeze point under the ASTM D7566 standard. Some parameters such as smoke, flash point and total acid number slightly fell out of specifications. The process also produced green naphtha and diesel as by-products. In addition, the process was further tested for catalyst reusability and regeneration potential that showed promising results for future research.

Targeted conversion of model phenolics in pyrolysis bio-oils to arenes via hydrodeoxygenation over MoOx/BaO@SBA-15 catalyst

The bio-oils derived from fast pyrolysis of lignin contain large amount of phenolic components. Owing to the high oxygen content, these bio-oils could not be used as traffic liquid fuels. Hydrodeoxygenation (HDO) was an effective strategy to upgrade these phenolics into high value-added chemicals such as arenes. However, the challenge of upgrading phenolics into arenes lies in selective hydrogenolysis of the oxygen-containing groups (e.g. –OCH3 and –OH) while keeping the unsaturated aromatic rings intact. However, the competitive adsorption behavior of produced intermediates likely inhibits the further HDO of phenol to arenes. In this work, MoOx/SBA-15 with rich oxygen defects was synthesized, which is capable of inducing phenolics adsorbed in a “nonplanar” manner, weakening the intensity of CAr-OR (R = CH3 or H) bonds and preventing the excessive hydrogenation of aromatic rings. In addition, BaO coating was decorated on MoOx/SBA-15 to tune the surface acid-base properties so as to promote the adsorption of phenol and consume MeOH via alkylation reaction with phenol, enhancing guaiacol one-step HDO into benzene and toluene. Based on catalyst evaluation and characterization as well as density functional theory (DFT) calculations, the catalytic mechanism of phenolics HDO reaction over MoOx/BaO@SBA-15 was analyzed and discussed. Current work helps not only gain deep insights into the competitive interaction for mixed phenolics HDO reaction, but also shed light on the design and synthesis of high-efficient HDO catalysts for upgrading crude bio-oils into arenes.

Use of an alkaline catalyst with ethanol-water as a co-solvent in the hydrothermal liquefaction of the Korean native kenaf: An analysis of the light oil and heavy oil characteristics

Hydrothermal liquefaction of the Korean native kenaf, with ethanol–water as a co-solvent at 275–350 °C for 30 min with and without 1 wt% of the alkaline catalysts Ca(OH)2, Na2CO3, K2CO3, and KOH, was investigated to identify the effect of the alkaline catalyst addition on the characteristics of the light and heavy oil produced. Component, elemental, ICP-ASE, and GC-MS analyses were conducted to determine the characteristics of the light oil, heavy oil, and solid residue. The highest bio-crude oil yield of 61.81% at 275 °C was found using ethanol–water without an alkaline catalyst. The addition of alkaline catalysts prompted the decomposition of both the heavy oil and light oil fractions, and re-polymerization reactions were suppressed. In addition, there were increases in the area percentages of ketone and phenolics derived from holocellulose and monolignols, respectively. Calcium ion was mainly detected in the aqueous phase, while sodium and potassium existed as solids in the solid residue. The results show that the addition of a calcium-based alkaline catalyst in the hydrothermal liquefaction of kenaf can enhance the energy recovery ratio to 58% and calorific value to 32.27 MJ/kg of the light oil at 350 °C.

One-step catalytic pyrolysis of pre-treated rice straw to biofuel over waste-extracted Ni–H3PW12O40 activated nano-catalyst

ABSTRACT Alternative, renewable and carbon-neutral fuels are an urgent requirement. Pyrolysis has received the most attention in the conversion of biomass into fuel. The main disadvantages of chemical and physical properties of pyrolysis crude bio-oil include its high oxygen content and acidity. Catalytic fast pyrolysis can overcome this problem. Rice straw is an abundant biomass residual that can be of environmental negative impact and is not of proper use. Therefore, this research work introduces the use of this residual in the production of fuel sources by one-step catalytic pyrolysis with the reusability of the employed catalyst. A waste extraction catalyst modified with acidic and nickel sites has been prepared and was utilised for the proposed target in this study. The removal of silica, lignin and minerals by treatment of the rice straw with KOH and then HNO3 in a green terminated process improved the catalytic biomass conversion from 83% to 96% at a catalyst dose of 5%, at 250°C. The pre-treatment of the rice straw enables the reusability of the catalyst in direct catalytic pyrolysis where the employed catalyst exhibits good stability in four consecutive runs. The used KOH and HNO3 were neutralised by mixing to produce KNO3 as a valuable fertiliser.

Catalytic deoxygenation of carboxyl compounds in the hydrothermal liquefaction crude bio-oil via in-situ hydrogen supply by CuO-CeO2/[formula omitted]-Al2O3 catalyst

Hydrothermal liquefaction (HTL) has drawn great attention as a potential method to produce bio-oil from biomass waste. However, bio-crude from HTL shows undesired high-oxygen content and needs further deoxygenation upgrading. Herein, stearic acids as a model carboxylic compounds in HTL bio-crude was employed to investigate catalytic deoxygenation performance. Results showed that (CuO)10-CeO2/γ-Al2O3 had the most superior catalytic deoxygenation performance for the stearic acids. The maximum stearic acid conversion rate (96.36%) and total hydrocarbon yield (88.79%) were obtained at 300°C, 12h, ratio of stearic acid to water 1:4. The main catalytic deoxygenation pathways were proposed: carbon monoxide generation (decarbonylation) – in-situ hydrogen generation (water–gas shift) – short-chain fatty acid generation (hydrogenolysis) – n-alkanes generation (decarboxylation, hydrodeoxygenation and hydrogenation). DFT calculation elucidated that CuO-CeO2 reduced the activation energy from 24.8kcalmol−1 (vacuum) to 15.0kcalmol−1 (catalytic). Thus, deoxygenation via CuO-CeO2/γ-Al2O3 would be an effective method for upgrading HTL bio-crude.

Catalytic hydrotreatment upgrading of biocrude oil derived from hydrothermal liquefaction of animal carcass

Hydrothermal liquefaction (HTL) is a promising approach converting wet biomass into biocrude oil. However, the high nitrogen and oxygen content in the biocrude oil inhibit its application as a transportation fuel. In this study, HTL of the animal carcass was carried out at 320 °C for 60 min. An average biocrude oil yield of 55.6 wt% was obtained. The biocrude oil was then hydrotreated with commercial catalysts (NiMo/Al2O3 and CoMo/Al2O3), noble metal catalysts (Pt/Al2O3 and Pd/Al2O3), Mo2C, and Mo2S at 400 °C with a catalyst loading of 20 wt% for 4 h in the presence of hydrogen. CoMo/Al2O3 showed better catalytic performance regarding the nitrogen, oxygen removal, and energy recovery. Subsequently, the effect of operating temperature, catalyst loading, and residence time was investigated with CoMo/Al2O3. A maximum degree of deoxygenation and denitrogenation of 86.2% and 64.4% were achieved at 400 °C with a catalyst loading of 20 wt% for 4 h. The higher heating value of the biocrude oil was improved to 46.7 MJ·kg−1. Oil characterization results showed that upgraded biocrude oil was mainly composed of alkanes, with a small number of nitriles. The Sankey diagram shows that 37.8% of the mass, 52.7% of the energy, and 49% of the carbon were incorporated in the upgraded biocrude oil based on the animal carcass feedstock.

Microalgae cultivated in wastewater catalytic hydrothermal liquefaction: Effects of process parameter on products and energy balance

Different harvested process can be decreased the costs of microalgae growth, to remove nutrients and improve the carbon cycle. Promising process for the conversion of biomass to fuel or bio-crude oil has been used for the better quality bio-oil. Hydrothermal liquefaction is promising process for the aquatic biomass conversion, as it has been operated in the presence of high moisture in the biomass. Catalytic hydrothermal liquefaction of ozone-air flotation for harvesting microalgae grown in wastewater was investigated for bio-crude production. The effect different reaction parameters in the catalytic HTL on the distribution of bio-crude and hydrocarbons was experimentally evaluated using microalgae grown in wastewater, and harvested by ozone-air flotation and gravity-sedimentation, respectively. Hydrothermal liquefaction was carried out under water solvent at temperature range of 300–350 °C, reaction times (30–120 min) and ZSM-5 and MCM-41 catalyst with different catalysts amount. The bio-crude yields obtained from non catalytic and catalytic bio-oil yield range of 17.3–39.7 wt%. Maximum bio-oil yield (39.7 wt%) was found with ZSM-5 catalytic hydrothermal liquefaction process. Using ZSM-5 catalysts the production of hydrocarbon yield was doubled compared to the non-catalytic and MCM-41 catalytic HTL reaction. After HTL reaction the obtained bio-oil has been utilization was analyzed to understand Net Energy Ratio value and the carbon footprint. It has been found that harvested microalgae catalytic HTL bio-oil significantly decreased greenhouse gas emissions compared to the conventional grow microalgae HTL bio-oil. The deamination and deoxygenation reactions were observed in the tests without catalyst as the temperature increased and improved with ZSM-5 catalyst, resulted decreasing the content of N and O in the bio-oil.

Hydrothermal liquefaction of green macroalgae Cladophora glomerata: Effect of functional groups on the catalytic performance of graphene oxide/polyurethane composite

This study highlights the challenges and opportunities of Hydrothermal Liquefaction (HTL) of Cladophora glomerata. It suggests functionalized graphene oxide/polyurethane (F-GO-PU) composite as the promising metal-free catalysts for sustainable algae upgrading. The catalysts contained three types of functional groups, including methyl (-CH3), vinyl (-CH=CH2), and amine (-NH2), and were completely analyzed by FTIR, XRD, and SEM-EDS in terms of functional groups, crystalline structure, morphology, and surface elemental distribution, respectively. The results showed that F-GO-PU catalysts efficiently suppressed side reactions that would generate non-desired chemicals. Functionalization with vinyl increased the yield of bio-crude oil by about 54% and showed high selectivity for hydrocarbons with a yield of 15.66 wt%. This catalytic activity was due to the existence of stable and accessible Brønsted acid sites plus the hybrid structure of the composite, which enhanced the accommodation of reaction intermediates on the surface of the catalyst. Thus, as-prepared F-GO-PU composites may hold great promise as metal-free active phase catalysts to develop algae transformation reactions.

Channeling Biomass Waste as An Alternative Industrial and Domestic Energy with Pollution Effects Mitigation in Nigeria: An Overview

This write-up provides an in-depth analysis of major anthropogenic activities contributing to environmental pollution in Nigeria. It identifies and discusses environmental problems associated with fossil fuel (petroleum products, gases), heavy metal, dye, domestic and industrial wastes in Nigeria. It describes the world reserve of fossil fuel as being scarce, limited and non-renewable but provided a suitable alternative (biomass) as renewable material with potential of drastically reducing reliance on fossil fuel and removing environmental nuisance in Nigeria. It discusses the models and mechanisms of using biomass waste for environmental remediation. The common demerit of crude bio-oil is its low heating value that limit its use as engine fuel, the write-up discusses methods of upgrading crude bio-oil to be fit as engine fuel. This write-up proffers how one environmental problem (biomass waste) could be used as a cheaper and sustainable solutions for energy generation and pollution control in Nigeria.

Physicochemical Assessment, Pyrolysis and Thermal Characterization of Albizia Zygia Tree Sawdust

Standard methods were used to obtain proximate and ultimate parameters of Albizia zygia tree sawdust. The HHV of 16.01 MJ/ Kg, H/C of 0.127, O/C of 0.96, high volatile matter of 87.85 wt.% and low ash content of 1.55 wt.% Albizia zygia sawdust makes it a good biofuel. Its empirical formula from elemental ratios combination is CH0.127 O0.96 N0.057 . There were insignificant volumes of oxides of nitrogen and sulphur produced during its pyrolysis since %N & %S are relatively low (2.63 & 0) wt.% respectively. Its TG/DTG profile showed devolatilization of sawdust began at 230 o C and the pyrolysis temperature was in the range of 420- 600 o C. Its fixed bed pyrolysis recorded maximum value of bio-oil at 450 o C. FTIR analysis confirmed the presence of oxygenated compounds in the sawdust and its crude bio-oil. The analysis of the obtained bio-oil using GC-FID showed that significant quantity of -OH compounds were produced from the sawdust through pyrolysis though the obtained quantity is not economical. Sintering and slagging-fouling indicators such as; [Na2 O + K2 O] / [SiO2 ]= 0.0695 showed (unlikely sintering inclination); Base/Acid=0.438 (low ash deposition tendency); [SiO2 ]/([Al2 O3 ]=5.44 & [Fe2 O3 ] / [CaO]=0.28 (low ash deposition tendencies respectively); slagging viscosity index= 68.58 (low slagging tendency); %(SiO2 )=55.18 (high); Babcock (Rs)= 4.38x 10-5 & Fouling indices (Fu)= 1.68x10-2 (low deposition tendencies); Total alkalis (TA) =0.0097 ( Low fouling tendency). It can be projected that improvement on pyrolysis process parameters and pre-treatment of sawdust can be used to achieve higher yield of bio-oil then consequently leading to higher quantity of alcohol compounds.

Hydrothermal pretreatment of cotton textile wastes: Biofuel characteristics and biochar electrocatalytic performance

The amount of waste cotton textiles presents an uptrend with the demand for textiles increasing. In this work, hydrothermal pretreatment of waste cotton textiles was conducted at 240 ℃–340 ℃ to obtain bio-crude oil and biochar. The hydrothermal pretreatment at 320 ℃ for 60 min yielded the highest bio-crude oil of 23.3%, in which ketones, diverse oxygen-containing functional group compounds, alcohols, furans, phenols, esters, carboxylic acids, ethers, nitrogencompounds, hydrocarbons and aldehydes were main compounds. Carbon-rich (as high as 76.86%) biochar with low oxygen shows high heating value as high as 30.505 MJ/kg, and lower atomic H/C and O/C ratios, which could be used as alternative solid biofuel. To broaden the utilization of biochar, it was further characterized by SEM, Raman spectra, and XRD. The biochar was the first time to use as electrocatalytic material. It significantly reduced both the overpotential (η10) from 403.6 mV to 247.6 mV and the Tafel slope from 192.5 mV dec-1 to 120.8 mV dec-1. It could speed up charge transfer rate and made H2 release facilely to promote the hydrogen evolution reaction activity with good stability. These results evidence the feasibility of converting waste cotton textiles to high-quality biofuels or even electrocatalytic carbon material via hydrothermal treatment.

Enhancing water repellency and decay resistance of wood by using water-soluble fractions separated from pyrolytic lignin of fast-pyrolysis bio-oil

Biocides with lower environmental and human health impacts have been demanded by the society. Based on bioeconomy concepts, we investigated the potential of water-soluble fractions separated from the pyrolytic lignin of fast-pyrolysis bio-oil for wood protection against physical and biological agents. The high-viscosity crude bio-oil was fractionated in two oil-to-water ratios, 1:50 and 1:100, by separating the pyrolytic lignin and water-soluble fractions. Additionally, exfoliated nanostructures of bentonite were incorporated into water-soluble fractions to form bicomponent systems to improve the protection degree. These materials were then characterized in terms of morphological, chemical, and biological features. The preservative formulations were impregnated into pinewood (Pinus taeda), with subsequent evaluation of the morphology, wettability, thermal aspects, and antifungal activity of treated wood to determine the degree of protection. The water-soluble fractions severely impacted the water repellency of wood with contact angles up to 115°, and normal growth of the decay fungi (Trametes versicolor and Gloeophyllum trabeum). Also, the addition of nanobentonite in the formulations improved the action of the water-soluble fractions against the physical and biological agents, specifically for G. trabeum the decay can be decreased around three times compared to untreated wood. The combined action of water-soluble fraction and nanobentonite supported the wood water repellency with time-dependent stability of the contact angle and excellent antifungal activity, which is partially explained by the chemical composition of the water-soluble fraction and physical barriers formed by the nanobentonite on the surface. Therefore, a single use of water-soluble fractions or in combination with nanobentonite has potential for application as a bio-based wood protection process.

Enhancing faecal sludge derived biocrude quality and productivity using peat biomass through co-hydrothermal liquefaction

Faecal sludge (FS) and drained peatlands have become the hotspots research area in recent years, causing significant environmental pollution and greenhouse gas (GHGs) emissions. Hence, this study explored the co-hydrothermal liquefaction (co-HTL, 300 °C for 60 min) of peat (P) and FS at different ratios (100:0, 25:75, 50:50, 75:25, and 0:100% of P: FS) to produce high-quality biocrude as a “waste to energy” approach. A positive synergistic effect was observed in P and FS co-HTL with higher biocrude yield and enhanced quality than individual HTL. Among the co-HTL ratios, the optimum biocrude yield of 44.58% was observed for the 50-50 ratio (P50FS50) with a conversion rate of 55.8% and energy recovery of 72%. However, the highest HHV was obtained from co-HTL of P75FS25 (35.5 MJ/kg), where biocrude had higher C (70.5%) and H (10.4%) contents with less amount of N (0.01%). The elemental composition of co-HTL indicated that biocrude had potential similarities to petro-crude. FTIR analysis confirmed that biocrude samples had aliphatic hydrocarbons, phenols, and esters, where the oil quality was immature to premature grade oil of kerogen type I (highly oil-prone). GC-FID hydrocarbon fractionation analysis revealed that the optimum lighter fraction crude (35.3%) was produced from co-HTL of the P50FS50 sample. In this context, the findings demonstrated that the co-HTL of P and FS might be an alternative approach for green biocrude oil production.

Primary amines from lignocellulose by direct amination of alcohol intermediates, catalyzed by RANEY® Ni.

Primary amines are crucially important building blocks for the synthesis of a wide range of industrially relevant products. Our comprehensive catalytic strategy presented here allows diverse primary amines from lignocellulosic biomass to be sourced in a straightforward manner and with minimal purification effort. The core of the methodology is the efficient RANEY® Ni-catalyzed hydrogen-borrowing amination (with ammonia) of the alcohol intermediates, namely alkyl-phenol derivatives as well as aliphatic alcohols, obtained through the two-stage LignoFlex process. Hereby the first stage entails the copper-doped porous metal oxide (Cu20PMO) catalyzed reductive catalytic fractionation (RCF) of pine lignocellulose into a crude bio-oil, rich in dihydroconiferyl alcohol (1G), which could be converted into dihydroconiferyl amine (1G amine) in high selectivity using ammonia gas, by applying our selective amination protocol. Notably also, the crude RCF-oil directly afforded 1G amine in a high 4.6 wt% isolated yield (based on lignin content). Finally it was also shown that the here developed Ni-catalysed heterogeneous catalytic procedure was equally capable of transforming a range of aliphatic linear/cyclic primary/secondary alcohols - available from the second stage of the LignoFlex procedure - into their respective primary amines.

Fast Hydrothermal Liquefaction Coupled with Homogeneous Catalysis to Valorize Livestock Manure for Enhanced Biocrude Oil and Hydrochar Production

Fast Hydrothermal Liquefaction Coupled with Homogeneous Catalysis to Valorize Livestock Manure for Enhanced Biocrude Oil and Hydrochar Production

Hydrothermal liquefaction of Fucus vesiculosus algae catalyzed by Hβ zeolite catalyst for Biocrude oil production

Low lipid content brown algae (Fucus vesiculosus) are considered an efficient biocrude oil source for their higher productivity rate, adaptation, and ease of cultivation. The hydrothermal liquefaction process can directly utilize algal biomass in the wet state. Hβ zeolite catalyst activity was tested for the hydrothermal liquefaction process of F. vesiculosus algal biomass. Maximum biocrude oil yield (27.6%) from the F. vesiculosus algae feedstock was obtained using catalyst amount of 15 wt%, residence time of 20 min, and temperature of 300 °C. The higher heating value (HHV) of the biocrude oil product was found to be 38.47 kJ/kg. Chemical compounds in the biocrude oil and aqueous phase products were detected using Gas Chromatography-Mass Spectroscopy (GC–MS) showing the main compounds to be ketones, and nitrogen-containing and heterocyclic compounds in biocrude oil, while oxygenated compounds prevail in the aqueous phase. Low amounts of amines and amides due to low protein content and of esters and hydrocarbons because of low lipids content were found in the F. vesiculosus algae feedstock. Biocrude oil energy efficiency was 45.68% compared to the biochar energy efficiency of 16.54%.

Hydrothermal Liquefaction of Cornstalk by Reusing Pyroligneous Acid: Synergistic Effects on Biocrude Oil Formation and Solid Residue Accumulation

The reuse of process wastewater as a reaction medium in hydrothermal liquefaction (HTL) of biomass to enhance biocrude oil (BO) production has been investigated, but the interaction between the biomass and process wastewater has rarely been studied. In the present work, pyroligneous acid (PA) was used as the reaction medium and substrate during the HTL process of cornstalk (CS). Hydrothermal conversion of PA itself, HTL of CS with water, and coliquefaction of CS and PA were carried out in a high-temperature and high-pressure batch reactor. Effects of reaction temperature and PA on the yields and characteristics of products were investigated. The PA itself was hydrothermally converted into BO, solid residue (SR), an aqueous phase, and gases. Reaction temperature had a strong influence on the product distribution during the coliquefaction of CS and PA but little influence on products during PA hydrothermal conversion. The highest BO yield from PA hydrothermal conversion occurred at 300 °C (28.96 wt %). For the coliquefaction of CS and PA, the highest experimental BO yield was 31.29 wt % at 300 °C, exceeding its corresponding theoretical value by 3.28 wt %; the experimental SR yield at 350 °C was 13.01 wt %, with the highest increase of 3.34 wt % compared to its corresponding theoretical value. The synergistic effects of CS and PA occurred at high temperatures (300 and 350 °C), promoting BO formation and strengthening SR accumulation, possibly due to the interactions among the compounds dissolved in PA and the components of CS. The BOs obtained from CS and PA coliquefaction had similar C, H, and O contents and higher heating values (HHVs) than those of HTL of CS, suggesting that the reuse of PA in HTL did not compromise the oil quality. Compared with the HTL of CS with water, CS and PA coliquefaction resulted in reduced concentrations of phenols, N-containing compounds, and organic acids and higher concentrations of ketones, alcohols, and hydrocarbons. Hence, PA clearly affected the distribution of organic components in BOs. In addition, more carbonaceous SRs were produced from coliquefaction with C and O contents of 65.14–70.23 and 23.94–29.89 wt %, respectively, and HHVs of 22.77–26.99 MJ/kg.