Production and detailed characterization of bio-oil from fast pyrolysis of palm kernel shell

Bio-oil has been produced from palm kernel shell in a fluidized bed reactor. The process conditions were optimized and the detailed characteristics of bio-oil were carried out. The higher feeding rate and higher gas flow rate attributed to higher bio-oil yield. The maximum mass fraction of biomass (57%) converted to bio-oil at 550 °C when 2 L min⁻¹ of gas and 10 g min⁻¹ of biomass were fed. The bio-oil produced up to 500 °C existed in two distinct phases, while it formed one homogeneous phase when it was produced above 500 °C. The higher heating value of bio-oil produced at 550 °C was found to be 23.48 MJ kg⁻¹. As GC–MS data shows, the area ratio of phenol is the maximum among the area ratio of identified compounds in 550 °C bio-oil. The UV–Fluorescence absorption, which is the indication of aromatic content, is also the highest in 550 °C bio-oil.     

Study of bio-oil and bio-char production from algae by slow pyrolysis

This study examined bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. A thermogravimetric analyser (TGA) was used to investigate the pyrolytic characteristics and essential components of algae. It was found that the temperature for the maximum degradation, 322 °C, is lower than that of other biomass. With our fixed-bed reactor, 125 g of dried Spirulina Sp. algae was fed under a nitrogen atmosphere until the temperature reached a set temperature between 450 and 600 °C. It was found that the suitable temperature to obtain bio-char and bio-oil were at approximately 500 and 550 °C respectively. The bio-oil components were identified by a gas chromatography/mass spectrometry (GC–MS). The saturated functional carbon of the bio-oil was in a range of heavy naphtha, kerosene and diesel oil. The energy consumption ratio (ECR) of bio-oil and bio-char was calculated, and the net energy output was positive. The ECR had an average value of 0.49.     

Hydrothermal liquefaction of spent coffee grounds in water medium for bio-oil production

Spent coffee grounds (SCG) were liquefied in hot-compressed water to produce crude bio-oil via hydrothermal liquefaction (HTL) in a 100 cm³ stainless-steel autoclave reactor in N₂ atmosphere. We investigated the effects of operating parameters such as retention times (5 min, 10 min, 15 min, 20 min and 25 min), reaction temperatures (200 °C, 225 °C, 250 °C, 275 °C and 300 °C), and water/feedstock mass ratios (5:1, 10:1, 15:1 and 20:1) and initial pressure of process gas (2.0 MPa and 0.5 MPa) on the yield and properties of the resulting crude bio-oil. The highest yield of the crude bio-oil (47.3% mass fraction) was obtained at conditions of 275 °C, 10 min retention time and water/feedstock mass ratio of 20:1 with an initial pressure of 2.0 MPa. The elemental analysis of the produced crude bio-oil revealed that the oil product had a higher heating value (HHV) of 31.0 MJ kg⁻¹, much higher than that of the raw material (20.2 MJ kg⁻¹). GC–MS and FT-IR measurements showed that the main volatile compounds in the crude bio-oil were long chain aliphatic acids and esters.     

Bio-oil production from hydrothermal liquefaction of waste Cyanophyta biomass: Influence of process variables and their interactions on the product distributions

Hydrothermal liquefaction (HTL) of waste Cyanophyta biomass at different temperatures (factor A, 260–420 °C), times (factor B, 5–75 min) and algae/water (a/w) ratios (factor C, 0.02–0.3) by single reaction condition and Response Surface Method (RSM) experiments was investigated. By single reaction condition runs, maximum total bio-oil yield (29.24%) was obtained at 350 °C, 60 min and 0.25 a/w ratio. Maximum bio-oil HHV of 40.04 MJ/kg and energy recovery of 51.09% was achieved at 350 °C, 30 min, 0.1 a/w ratio and 350 °C, 60 min, 0.25 a/w ratio, respectively. RSM results indicate that effect of AB interaction was significant on light bio-oil yield. Both AC and AB had more remarkable influence than BC on heavy bio-oil yield and aqueous total organic carbon (TOC) recovery whereas BC was noticeable on ammonia nitrogen (NH₃N) recovery in aqueous products. By model-based optimization of highest bio-oil yield, the highest bio-oil yield reached 31.79%, increasing by 8.72% after RSM optimization, and light and heavy bio-oil yield was 17.44% and 14.35%, respectively. Long-chain alkanes, alkenes, ketones, fatty acids, phenols, benzenes, amides, naphthalenes were the main components in light bio-oil. Some alcohols, phenols and aromatics were primarily found in heavy bio-oil. Solid residue after HTL consisted of numerous microparticles (～5 μm) observed by Scanning Electron Microscopy (SEM). Energy Dispersive Spectrometer (EDS) analysis shows these particles primarily contained C, O, Mg, P and microelements, derived from Cyanophyta cells.     

Reutilization potential of antibiotic wastes via hydrothermal liquefaction (HTL): Bio-oil and aqueous phase characteristics

Hydrothermal liquefaction (HTL) technology was employed to investigate the feasibility of recovering energy from penicillin mycelial waste (PMW) with the help of TG, Py-GC/MS and GC-MS techniques; meanwhile, the nutrients in aqueous phase were also analyzed by spectrophotometry methods. The effects of operating conditions, including hydrothermal temperature (240–300 °C), duration time (20–60 min), total solid ratio (5–15%) and their interactive reactions were concurrently evaluated via response surface methodology. Results demonstrated that operating temperature was found to be the dominant variable affecting the HTL of PMW. Based on the optimal conditions of 298 °C, 60 min and 14.85%, heavy oil derived from PMW was comparable with algal-derived bio-oil as it possessed the highest energy recovery efficiency (42.95%) with a calorie value of 32.84 MJ/kg and a yield of 24.93%. GC/MS results indicated that heavy oil mainly consisted of N-containing compounds (36.73%) and aromatic compounds (31.07%), which might be contributed to the hydrolysis of protein and the aromatization of intermediates, respectively. Besides, more than 65% of nitrogen and 40% of carbon were enriched in aqueous phase, suggesting the possibility of further recycling for algae cultivation, fermentation and anaerobic digestion.     

Understanding the pyrolysis behavior of agriculture,forest and aquatic biomass: Products distribution and characterization

Pyrolysis studies on agricultural (rice straw), forest (pine) and aquatic (Ulva lactuca) biomass were carried out in a fixed bed reactor at different temperature range of 300–550 °C. The product distributions and their characterization of products were compared among these biomasses. The maximum liquid product yield 29.4, 57.5 and 25.6 wt% obtained at 400, 500 and 400 °C respectively from rice straw (RS), pine (PN) and Ulva lactuca (UL) biomass. However, the higher conversion was observed in the case of pine wood biomass 77.0% at 550 °C. From the GC-MS analysis, it is observed that RS and PN bio-oil mostly composed of derivatives of phenolic compounds, while UL bio-oil composed of cyclopentenone derivatives compounds. The highest higher heating value (HHV) was found in pine bio-oil 34.8 MJ/kg. Also PN pyrolytic bio-oil had higher boiling point differences compounds. The bio-char analysis showed that the PN bio-char is a carbon rich and porous in nature as compared to the RS and UL bio-char.     

Production of crude bio-oil via direct liquefaction of spent K-Cups

Spent K-Cups were liquefied into crude bio-oil in a water-ethanol co-solvent mixture and reaction conditions were optimized using response surface methodology (RSM) with a central composite design (CCD). The effects of three independent variables on the yield of crude bio-oil were examined, including the reaction temperature (varied from 255 °C to 350 °C), reaction time (varied from 0 min to 25 min) and solvent/feedstock mass ratio (varied from 2:1 to 12:1). The optimum reaction conditions identified were 276 °C, 3 min, and solvent/feedstock mass ratio of 11:1, giving a mass fraction yield of crude bio-oil of 60.0%. The overall carbon recovery at the optimum conditions was 93% in mass fraction. The effects of catalyst addition (NaOH and H₂SO₄) on the yield of crude bio-oil were also investigated under the optimized reaction conditions. The results revealed that the presence of NaOH promoted the decomposition of feedstock and significantly enhanced the bio-oil production and liquefaction efficiency, whereas the addition of H₂SO₄ resulted in a negative impact on the liquefaction process, decreasing the yield of crude bio-oil.     

Characterization of bio-oil and its sub-fractions from pyrolysis of Scenedesmus dimorphus

In the present study, microalgae Scenedesmus dimorphus was reported for pyrolysis in a fixed-bed reactor to determine the effects of temperature on products yield and the chemical compositions of the liquid and solid products. Experiments were carried out at a temperature range of 300–600 °C with heating rate of 40 °C/min and nitrogen flow rate of 100 ml/min. The yield of bio-oil was found to be maximum (39.6%) at the temperature of 500 °C and was further fractionated into n-hexane, toluene, ethyl acetate and methanol sub-fractions by using liquid column chromatography. Various characteristics of bio-oil and its sub-fractions were determined by ¹H NMR, FTIR and GC–MS. The biochar produced as a co-product can be a potential soil amendment with multiple benefits including soil fertility and C-sequestration. The present investigation suggests the suitability of Scenedesmus dimorphus as a potential feedstock for exploitation of energy and biomaterials through pyrolytic conversion.     

Evaluation on hydrothermal gasification of waste tires based on chemical equilibrium analysis

Massive amounts of waste tires are produced globally, which brings great challenges to the disposal and recycling of used tires. Hydrothermal gasification is a promising option for recycling waste tires. The hydrothermal gasification of waste tires was evaluated based on the chemical equilibrium analysis along with the response surface methodology (RSM) in terms of subcritical temperature range (250–300 °C), transition temperature range (350–400 °C), supercritical temperature range (550–600 °C), supercritical pressure (22.5–30.5 MPa) and feedstock concentration (5–20 wt%). CH₄ yield at 350 °C reached a maximum, 41.575 mmol/g. H₂ yield increased from 0.0283 to 53.602 mmol/g with increasing the temperature from 250 °C to 600 °C. CH₄ yield at the supercritical temperature increased with lifting the feedstock concentration, while H₂ yield decreased. The optimal parameters regarding maximum H₂ and CH₄ yields in the subcritical temperature range were 300 °C, 22.5 MPa and 12.5 wt%, respectively, while they in the supercritical temperature range were 550 °C, 30.5 MPa and 5.4 wt%, respectively. RSM was more suitable for predicting H₂ yield in the hydrothermal gasification of waste tires at subcritical and supercritical temperature ranges, but it was available for predicting CH₄ yield in three temperature ranges. This study can provide basic data for the hydrothermal treatment of waste tires.     

Hydrothermal liquefaction of macroalgae: Influence of zeolites based catalyst on products

Hydrothermal liquefaction (HTL) of Ulva prolifera macroalgae (UP) was carried out in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different weight percentage (10–20 wt%) at 260–300 °C for 15–45 min. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite, and Mordenite in the conversion of Ulva prolifera showed that is affected by properties of zeolites. Maximum bio-oil yield for non-catalytic liquefaction was 16.6 wt% at 280 °C for 15 min. The bio-oil yield increased to 29.3 wt% with ZSM-5 catalyst (15.0 wt%) at 280 °C. The chemical components and functional groups present in the bio-oils are identified by GC-MS, FT-IR, ¹H-NMR, and elemental analysis techniques. Higher heating value (HHV) of bio-oil (32.2–34.8 MJ/kg) obtained when catalyst was used compared to the non-catalytic reaction (21.2 MJ/kg). The higher de-oxygenation occurred in the case of ZSM-5 catalytic liquefaction reaction compared to the other catalyst such as Y-zeolite and mordenite. The maximum percentage of the aromatic proton was observed in bio-oil of ZSM-5 (29.7%) catalyzed reaction and minimum (1.4%) was observed in the non-catalyst reaction bio-oil. The use of zeolites catalyst during the liquefaction, the oxygen content in the bio-oil reduced to 17.7%. Aqueous phase analysis exposed that presence of valuables nutrients.     

Optimisation of bio-oil production by hydrothermal liquefaction of agro-industrial residues: Blackcurrant pomace (Ribes nigrum L.) as an example

This work reports bio-oil production by hydrothermal liquefaction of blackcurrant pomace (Ribes nigrum L.), a fruit residue obtained after berry pressing. The bio-oil has a higher heating value of 35.9 MJ kg⁻¹ and low ash content, which makes it suitable for energy applications. We report the influence of process parameters on yields and carbon distribution between products: temperature (563–608 K), holding time (0–240 min), mass fraction of dry biomass in the slurry (0.05–0.29), and initial pH (3.1–12.8) by adding sodium hydroxide (NaOH). Depending on the experiments, the bio-oil accounts for at least 24% mass fraction of the initial dry biomass, while char yields ranges from 24 to 40%. A temperature of 583 K enhances the bio-oil yield, up to 30%, while holding time does not have a significant influence on the results. Increasing biomass concentrations decreases bio-oil yields from 29% to 24%. Adding sodium hydroxide decreases the char yield from 35% at pH = 3.1 (without NaOH) to 24% at pH = 12.8. It also increases the bio-oil yield and carbon transfer to the aqueous phase. Thermogravimetric analysis shows that a 43% mass fraction of the bio-oil boils in the medium naphtha petroleum fraction range. The bio-oil is highly acidic and unsaturated, and its dynamic viscosity is high (1.7 Pa s at 298 K), underlining the need for further upgrading before any use for fuel applications.     

Selective pyrolysis of paper mill sludge by using pretreatment processes to enhance the quality of bio-oil and biochar products

Paper mill sludge (PMS) is a residual biomass that is generated at paper mills in large quantities. Currently, PMS is commonly disposed in landfills, which causes environmental issues through chemical leaching and greenhouse gas production. In this research, we are exploring the potential of fast pyrolysis process for converting PMS into useful bio-oil and biochar products. We demonstrate that by subjecting PMS to a combination of acid hydrolysis and torrefaction pre-treatment processes it is possible to alter the physicochemical properties and composition of the feedstock material. Fast pyrolysis of pretreated PMS produced bio-oil with significantly higher selectivity to levoglucosenone and significantly reduced the amount of ketone, aldehyde, and organic acid components. Pretreatment of PMS with combined 4% mass fraction phosphoric acid hydrolysis and 220 °C torrefaction processed prior to fast pyrolysis resulted in a 17 times increase of relative selectivity towards levoglucosenone in bio-oil product along with a reduction of acids, ketones, and aldehydes combined from 21 % to 11 %. Biochar, produced in higher yield, has characteristics that potentially make the solid byproduct ideal for soil amendment agent or sorbent material. This work reveals a promising process system to convert PMS waste into useful bio-based products. More in-depth research is required to gather more data information for assessing the economic and sustainability aspects of the process.     

Energy Applications of Biomass: Pyrolysis of Apricot Stone

Apricot stone (Prunus armeniaca L.) was pyrolyzed in a directly heated fixed-bed reactor under nitrogen atmosphere. Effects of sweeping gas flow rates and pyrolysis temperature on the pyrolysis of the biomass were also studied. Pyrolysis runs were performed using reactor temperatures between 400°C and 700°C with heating rate of about 300°C min^?1. As the pyrolysis temperature was increased, the percentage mass of char decreased while gas product increased. The product yields were significantly influenced by the process conditions. The bio-oil obtained at 550°C, at which the liquid product yield was maximum, was analyzed. It was characterized by Fourier transform infrared spectroscopy (FT-IR). In addition, the solid and liquid products were analyzed to determine their elemental composition and calorific value. Chemical fractionation of bio-oil showed that only low quantities of hydrocarbons were present, while oxygenated and polar fractions dominated.     

Experimental study of the pyrolysis of waste bitumen for oil production

This work focuses on bitumen slow pyrolysis. Mass and energy yields of oil, solid and gas were obtained from pyrolysis experiments using a semi-batch reactor in a nitrogen atmosphere, under three non-isothermal conditions (maximum temperature: 450 °C, 500 °C and 550 °C). The effect of temperature on the product yields was discussed. The gas compositions were analysed using gas chromatography (GC) and the heating value of oil and solid residue was also measured. Using a thermo-gravimetric analyser, kinetic parameters were evaluated through Ozawa-Flynn-Wall (OFW) method. Results showed that oil yield is maximum at 500 °C (50%). Moreover, gas yield increased with increasing pyrolysis temperature from 18% to 36%. On the other hand, solid yield showed an opposite trend: it decreased from 39% to 32%. As regard energy yields, they showed a similar trend with the mass ones. H_2, CH₄, C₂H₄, C₂H₆ and C₃H₈ are the main components of the produced gas phase. It has been noticed that the recovery of bitumen to liquid oil through pyrolysis process had a great potential since the oil produced had high calorific value comparable with commercial fuels.     

Non-catalytic and catalytic pyrolysis of Ulva prolifera macroalgae for production of quality bio-oil

Pyrolysis of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in a fixed-bed reactor in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different catalyst to biomass ratio. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite and Mordenite catalyst in the conversion of UM showed that is affected by properties of zeolites. Bio-oil yield was increased in the presence of Y-Zeolite while decreased with ZSM-5 and Mordenite catalyst. Maximum bio-oil yield for non-catalytic pyrolysis was (38.5 wt%) and with Y-Zeolite catalyst (41.3 wt%) was obtained at 400 °C respectively. All catalyst showed a higher gas yield. The higher gas yield might be attributed to that catalytic pyrolysis did the secondary cracking of pyrolytic volatiles and promoted the larger small molecules. The chemical components and functional groups present in the pyrolytic bio-oils are identified by GC–MS, FT-IR, ¹H-NMR and elemental analysis techniques. Phenol observed very less percentage in the case of non-catalytic pyrolysis bio-oil (9.9%), whereas catalytic pyrolysis bio-oil showed a higher percentage (16.1%). The higher amount of oxygen present in raw biomass reduced significantly when used catalyst due to the oxygen reacts with carbon and produce (CO and CO₂) and water.     

Low energy consumption and high quality bio-fuels production via in-situ fast pyrolysis of reed straw by adding metallic particles in an induction heating reactor

An in-situ fast pyrolysis of biomass by adding metallic particles in an induction heating reactor was proposed to produce high quality bio-fuels. After adding metallic particles into biomass, the times required to reach complete pyrolysis during reed straw pyrolysis process were significantly reduced up to 28.9%. The yields of combustible gas and bio-oil products were significantly increased. Furthermore, higher-quality combustible gas and bio-oil products were obtained with the LHV of gas products and HHV of bio-oil (dry basis) increased by 14.2%–19.1% and 4.16%–16.35%, respectively, under 400–600 °C. The lower oxygen content and higher yields of aromatics, alkenes and alkanes contents in bio-oil were obtained after metallic particles addition. More importantly, up to 26.5% of the total energy consumption during pyrolysis process was reduced after adding metallic particles into biomass in an induction heating reactor. The results indicate that adding metallic particles into biomass in an induction heating reactor can significantly enhance the heat transfer, decomposition reaction intensity and energy utilization efficiency of biomass pyrolysis process with lower energy consumption and higher-quality bio-fuel production.     

Characterization of hydrocarbonaceous liquid and solid products derived from thermal defragmentation of Cissus quadrangularis Linn in a fixed bed pyrolysis

Utilization of Cissus quadrangularis Linn (CQ) for producing hydrocarbonaceous bio-oil and biochar in a fixed bed pyrolysis at 550°C was studied. Rapid and progressive thermal decompositions took place between 220 and 550°C. Elemental composition of the biomass shows 12.32% moisture and 67.97% volatiles. Spectroscopic and chromatographic analysis of bio-oil having a calorific value of 26.58 MJ/kg elucidates 15 different chemicals of different functional groups. Two major chemicals (ethanol, pentamethyl, and benzedrex) dominate at around 60% of the chemicals identified in the bio-oil. Biochar could be a possible source of activated carbon for suntan lotion producing industries.     

Catalytic supercritical water gasification of aqueous phase directly derived from microalgae hydrothermal liquefaction

Microalgae (N. chlorella) hydrothermal liquefaction (HTL) was conducted at 320 °C for 30 min to directly obtain original aqueous phase with a solvent-free separation method, and then the supercritical water gasification (SCWG) experiments of the aqueous phase were performed at 450 and 500 °C for 10 min with different catalysts (i.e., Pt-Pd/C, Ru/C, Pd/C, Na₂CO₃ and NaOH). The results show that increasing temperature from 450 to 500 °C could improve H₂ yield and TGE (total gasification efficiency), CGE (carbon gasification efficiency), HGE (hydrogen gasification efficiency), TOC (total organic carbon) removal efficiency and tar removal efficiency. The catalytic activity order in improving the H₂ yield was NaOH > Na₂CO₃ > None > Pd/C > Pt-Pd/C > Ru/C. Ru/C produced the highest CH₄ mole fraction, TGE, CGE, TOC removal efficiency and tar removal efficiency, while NaOH led to the highest H₂ mole fraction, H₂ yield and HGE at 500 °C. Increasing temperature and adding proper catalyst could remarkably improve the SCWG process above, but some N-containing compounds were difficult to be gasified. This information is valuable for guiding the treatment of the aqueous phase derived from microalgae HTL.     

Effect of fractional condensers on characteristics,compounds distribution and phenols selection of bio-oil from pine sawdust fast pyrolysis

Bio-oil is a multicomponent mixture of more than 400 types of organic compounds, with high water content. Fractionation of bio-oil may be a more efficient approach for primary separation of bio-oil. In this work, to better understand the effect of fractional condensers on bio-oil yield, physicochemical characteristics, compounds distribution and phenols selection during biomass fast pyrolysis process, a semi-automatic controlled fluidized bed reactor biomass fast pyrolysis system with four-stage condensers was developed. Average temperatures of Condensers 1, 2, 3, 4 were 32.39 °C, 26.74 °C, 24.06 °C and 23.68 °C, respectively. And the bio-oil yields of Condenser 1, 2, 3, and 4 were 26.82%, 7.31%, 1.48% and 9.69%, respectively. Bio-oil collected from Condenser 4 had the lowest water content (9.68 wt%), the lowest acidity (pH = 3.67), and the highest HHV (29.2 MJ/kg). The highest relative contents of compounds collected from Condenser 1, 2, 3 and 4 were 1-(4-hydroxy-3-methoxyphenyl)-2-Propanone (6.95%), trans-Isoeugenol (6.63%), Creosol (5.28%), and trans-Isoeugenol (6.69%), respectively. Fractional condensers affected the compounds distribution, but it has a stronger effect on relative heavy compounds (molar mass > 250) and a weaker effect on relative light compounds (molar mass < 200). Fractional condensers were more conducive to the selection of phenols with relative yield of more than 30%. Phenols, acids and furfurans tended to distribute at higher temperature, while alcohols, ethers and hydrocarbons tended to distribute at relative lower temperature, but the difference was small. The research has provided a reference for the production of bio-oil.     

Utilization possibilities of Albizia amara as a source of biomass energy for bio-oil in pyrolysis process

Pyrolysis is one of the potential routes to harmless energy and useful chemicals from biomass. The pyrolysis of Albizia amara was studied for determining the main characteristics and quantities of liquid products. Particular investigated process variables were temperature from 350 to 550°C, particle size from 0.6 to 1.25 mm, and heating rate from 10 to 30 °C/min. The maximum bio-oil yield of 48.5 wt% at the pyrolysis temperature of 450°C was obtained at the particle size of 1.0 mm and at the heating rate of 30 °C/min. The bio-oil product was analyzed for physical, elemental, and chemical composition using Fourier transform infrared spectroscopy and gas chromatography spectroscopy. The bio-oil contains mostly phenols, alkanes, alkenes, saturated fatty acids and their derivatives. According to the experimental results, the pyrolysis bio-oil can be used as low-grade fuel having heating value of 18.63 MJ/kg and feedstock for chemical industries.