Pyrolysis Bio-oil Research Articles

Advances in upgradation of pyrolysis bio-oil and biochar towards improvement in bio-refinery economics: A comprehensive review

Depletion of fossil fuel reserves and ever-increasing energy demands necessitates exploring green and renewable biofuels. Though biomass-based fuels have the potential to replace fossil fuels but the low quality of fuels along with high process economics limits direct application. Concept of integrated bio-refinery is the unparalleled solution to this problem which involves the production of hydrocarbon grade fuels along with valuable chemicals from the pyrolysis derived bio-oil. This paper reviews recent advances in upgradation techniques of bio-oil along with moisture removal techniques and recovery of valuable chemicals from bio-oil. It also reviews current advances in the utilization of co-product such as biochar to increase the overall economics of the process. It also elucidates the challenges encountered as well as scope for future work. The current review is peculiarly based on pyrolysis based bio-refinery with detailed literature on the techniques of conversion of pyrolysis derived bio-oil into valuable biofuels and industrial grade chemicals with a view to improve the overall economics of the process through biochar utilization, which is not covered in other reviews. As compared to other published studies, this work provides more comprehensive information on the topic, which will give better understanding to a new researcher as well as help to plan and develop new techniques on bio-refinery for attaining the aim of cleaner and sustainable future.

Electrometric bromine number as a suitable method for the quantitative determination of phenols and olefins in hydrotreated pyrolysis bio-oils

Bio-oils after hydrotreatment can still contain significant amount of phenols and cyclic olefins as the products of an incomplete deoxygenation. The removal of these compounds would be necessary to produce suitable components for automotive fuels. However, no routine method currently exists for the reliable determination of these groups in hydrotreated bio-oils (HBOs). In this paper, we analyzed 140 different pure oxygenates as model compounds using the bromine number method (ASTM D1159) observing that most compounds present in HBOs react with one equivalent of bromine. The determination of phenols using bromine number method in crude bio-oil is complicated especially by the presence of guaiacols and syringols that react with more than one equivalent of bromine and, thus, the obtained result is significantly overestimated. Further we optimized the chromatographic separation of hydrocarbons from HBOs for the selective determination of olefins content. As no other reactive compounds under the conditions of the method, besides phenols and olefins, were observed in HBOs, the difference between HBO bromine number (before hydrocarbons separation) and olefins content correspond to the total amount of phenols. The method was finally applied to 11 HBOs with different content of oxygen, providing a good correlation between phenols and oxygen content.

Selective production of furfural and phenols from rice husk: the influence of synergetic pretreatments with different order

The subject of this study was to upgrade the pyrolysis bio-oil by torrefaction combined with different order of acid washing. The pyrolysis behavior of biochar obtained from different pretreatments were investigated by a thermogravimetric analyzer (TGA) and fixed furnace. Moreover, the composition of bio-oil was systematically analyzed by GC-MS. The results showed that torrefaction promoted the aggregation of phenols in bio-oil through removing the hemicellulose and part of cellulose. In addition, aldehydes had increased significantly after acid washing. The acid washing combined with torrefaction could reduce the formation of acids, alcohols and other organic substances except for phenols, aldehydes and ketones. Compared with the pyrolysis bio-oil obtained by directly torrefaction pretreatment, the absolute content of phenols in the pyrolysis bio-oil was slightly reduced from 74 mg/gRH to 63 mg/gRH after first inorganic acid washing and then torrefaction, while the absolute content of furfural increased from 2.8 mg/gRH to 16 mg/gRH. The mechanism showed that the furfural was selected by the catalysis of acid and the torrefaction promoted the cellulose to convert to 1-hydroxy-2-propanone by cracking reaction. This study provided a simple and practical method for the selective production of furfural and phenol from rice husk.

Ni–Mo nanoparticles stabilized by ether functionalized ionic polymer: A novel and efficient catalyst for hydrodeoxygenation of 4-methylanisole as a representative of lignin-derived pyrolysis bio-oils

In the present study, nickel-molybdenum nanoparticles stabilized with ether functionalized ionic polymer were synthesized and utilized as a novel and efficient catalyst for hydrodeoxygenation of 4-methylanisole as a representative of lignin-derived bio-oil. The catalytic upgrading process was performed in the presence of hydrogen with a batch reactor at temperature of 80–200 °C, hydrogen pressure of 10–50 bar, reaction time of 0.5–15 h and catalyst loading of 1–5 mol%. The major reaction classes during 4-methylanisole upgrading were hydrodeoxygenation and hydrogenolysis which resulted in production of 4-methylphenol, toluene, phenol and benzene as the main products. The experimental results indicated that the catalytic activity of Ni–Mo (20%–80%) nanoparticles stabilized with ionic polymer is superior to that with low Mo content. Also, it is observed that the selectivity of deoxygenated products including toluene and benzene improves with increasing the Mo content of the catalyst. Finally, regarding to the excellent catalytic activity of synthesized nanocatalyst during upgrading process of bio-oil at mild operating condition, ether functionalized ionic polymer was introduced as an applicable and effective stabilizers for nickel-molybdenum nanoparticles.

A Combined Experimental and DFT Investigation of Selective Hydrodeoxygenation of Guaiacol over Bimetallic Carbides

Catalytic hydrodeoxygenation of fast pyrolysis bio-oils is a potential approach for producing green fuels. This process requires active and inexpensive catalysts with bifunctionality favoring C–O b...

Evaluation of the potential of pyrolytic bio-oil from aquatic macrophytes to generate a new biofuel

Evaluation of the potential of pyrolytic bio-oil from aquatic macrophytes to generate a new biofuel

The effect of thermo-catalytic reforming of a pyrolysis bio-oil on its performance in a micro-gas turbine burner

The combustion performance and pollutant emissions of a pyrolysis bio-oil (also called pyrolysis oil) upgraded with a thermo-catalytic reforming process were investigated experimentally in a micro-gas turbine burner and compared with those of a conventional bio-oil, ethanol (EtOH), and diesel fuel. The upgraded intermediate pyrolysis bio-oil called thermo-catalytic reforming bio-oil (TCRBO) has lower water and oxygen contents, suspended solid particulates, and non-volatile residue, along with higher carbon content, physical and chemical stability, and compatibility with fossil oils compared to the conventional fast pyrolysis bio-oil (FPBO). A stable flame with 100% TCRBO was possible in the present burner, whereas 50% by volume fraction EtOH had to be added to FPBO to improve its ignition and combustion characteristics. The original externally-mixed twin-fluid nozzle of the micro-gas turbine was replaced with an internally-mixed one which exhibited a superior performance with bio-oils. Over the practical range of air-to-liquid mass flow ratio for bio-oils, 0.3<ALR<0.7, the spray Sauter mean diameter (SMD) of TCRBO was estimated larger than that of FPBO/EtOH blend for the both nozzles. However, most of the measured emissions from TCRBO spray flame were lower than those of FPBO/EtOH blend, owing to its improved combustion related properties, except nitrogen oxides (NO) which originated from the high nitrogen biomass feedstocks used for TCRBO production. Furthermore, contrary to FPBO, no flame instability due to the coke formation on the premixer tube of the burner was observed when using TCRBO. Conducting combustion investigations of the bio-oils in the present burner revealed that the thermo-catalytic reforming of bio-oil can greatly improve its ignition, combustion and pollutant emissions compared to conventional bio-oils.

Environmental and Economic Assessments and Uncertainties of Multiple Lignocellulosic Biomass Utilization for Bioenergy Products: Case Studies

Life-cycle assessment (LCA) and techno-economic analysis (TEA) were applied to assess the economic feasibility and environmental benefits of utilizing multiple biomass feedstocks for bioenergy products under three different technological pathways with consideration of uncertainties. Three cases were studied for the production of pellets, biomass-based electricity, and pyrolysis bio-oil. A Monte Carlo simulation was used to examine the uncertainties of fossil energy consumption, bioenergy conversion efficiency, stochastic production rate, etc. The cradle-to-gate LCA results showed that pellet production had the lowest greenhouse gas (GHG) emissions, water and fossil fuels consumption (8.29 kg CO2 eq (equivalent), 0.46 kg, and 105.42 MJ, respectively). The conversion process presented a greater environmental impact for all three bioenergy products. When producing 46,929 Mg of pellets, 223,380 MWh of electricity, and 78,000 barrels of pyrolysis oil, the net present values (NPV) indicated that only pellet and electricity production were profitable with NPVs of $1.20 million for pellets, and $5.59 million for biopower. Uncertainty analysis indicated that pellet production showed the highest uncertainty in GHG emission, and bio-oil production had the least uncertainty in GHG emission but had risks producing greater-than-normal amounts of GHG. Biopower production had the highest probability to be a profitable investment with 85.23%.

Catalytic Hydroprocessing of White Pine Pyrolysis Bio-Oil over Cobalt-Molybdenum Carbide in a Continuous Packed-Bed Reactor

Catalytic hydroprocessing of white pine pyrolysis bio-oil over cobalt-molybdenum (CoMo) carbide supported on biochar was carried out in a continuous fixed-bed reactor at a temperature between 350 and 425 °C, hydrogen pressure between 7 and 12.5 MPa, and liquid hourly space velocity (LHSV) of 0.1–1.0 h−1 with a hydrogen flow rate of 500 mL/min. The results showed that the CoMo carbide catalyst can effectively improve the yield and qualities of hydrotreated bio-oil. Under the preferred reaction conditions of 400–425 °C, 10 MPa H2, and LHSV 0.3 h−1, the yield, the carbon content, the carbon recovery ratio, and the higher heating value of the upgraded bio-oil reached 24.2–25.7% of the feed, 86.5–87.4%, 48.1–52.1%, and 41.8–43.9 MJ/kg, respectively. The oxygen content, total acid number, and moisture of the hydrotreated bio-oil decreased to 0.1–1.6 wt%, aromatics > olefins > paraffins > naphthenes.

Low-temperature catalytic conversion of alkaline sewage sludge bio-oil to biodiesel: Product characteristics and reaction mechanisms

Sewage sludge is a promising biomass alternative for the production of liquid biofuels. In this study, bio-oil derived from the fast pyrolysis of domestic sewage sludge was upgraded in a micro Robinson–Mahoneyreactor at 4 MPa and 260 °C, and in the presence of hybridized Ni/HZSM-5 catalyst and ethanol. Fourier transform infrared and gas chromatography-mass spectrometry analyses were used to identify the functional groups and chemical components of raw and upgraded sewage sludge bio-oil. Results showed that catalytic upgrading reduced the relative content of acids, aldehydes, phenols, ketones, and nitrogenated compounds in the pyrolytic bio-oil. Thus, the main components of the upgraded bio-oil product included esters (48.59%), alkanes (10.12%), aromatics (9.38%), and alkenes (5.08%). Water and nitriles in the raw pyrolytic bio-oil together with in-situ-produced carbon oxides helped in the esterification of raw bio-oil. Reaction mechanisms such as nitrile hydrolysis, hydrogenation, and esterification were proposed to elucidate the conversion of the non-acidic pyrolytic bio-oil into ester-dominating upgraded bio-oil. Overall, upgrading sewage sludge pyrolytic oil is crucial to produce high-quality diesel-range biofuel.

Kinetic study of carbonaceous deposit formation and catalyst deactivation in hydrotreating of fast pyrolysis bio-oil

Fast pyrolysis of biomass followed by hydrotreating of bio-oil is considered to be a promising thermochemical conversion process of biomass to liquid fuel. Catalytic hydrotreating converts the crude bio-oil from biomass pyrolysis into liquid intermediates with reduced oxygen content, and low viscosity and acidity. However, effective lifetime of catalyst can be significantly reduced by coking which has been recognized as the main cause of catalyst deactivation during the hydrotreating process. In this study, similar phenomenon has been observed but the catalyst deposit was different from the reported coke and thus a new term of carbonaceous deposit is introduced. Kinetics of the carbonaceous deposit formation and its characteristics have been investigated for hydrotreating of bio-oil derived from fast pyrolysis of rice husk using commercial HTB-45 Ni-based catalyst. A mathematical model for the hydrotreating process, which is based on key chemical reactions and consists of ordinary differential equations (ODEs), has been developed and solved with the kinetic parameters being obtained from the experiments. Results of this study are helpful for better understanding and optimization of the catalytic upgrading of fast pyrolysis bio-oil.

Catalytic upgrade for pyrolysis of food waste in a bubbling fluidized-bed reactor.

Biofuel production via pyrolysis has received increasing interest as a promising solution for utilization of now wasted food residue. In this study, the fast pyrolysis of mixed food waste (MFW) was performed in a bubbling fluidized-bed reactor. This was done under different operating conditions (reaction temperatures and carrier gas flow rate) that influence product distribution and bio-oil composition. The highest liquid yield (49.05wt%) was observed at a pyrolysis temperature of 475°C. It was also found that the quality of pyrolysis bio-oils (POs) could be improved using catalysts. The catalytic fast pyrolysis of MFW was studied to upgrade the pyrolysis vapor, using dolomite, red mud, and HZSM-5. The higher heating values (HHVs) of the catalytic pyrolysis bio-oils (CPOs) ranged between 30.47 and 35.69MJ/kg, which are higher than the HHVs of non-catalytic pyrolysis bio-oils (27.69-31.58MJ/kg). The major components of the bio-oils were fatty acids, N-containing compounds, and derivatives of phenol. The selectivity for bio-oil components varied depending on the catalysts. In the presence of the catalysts, the oxygen was removed from oxygenates via moisture, CO2, and CO. The CPOs contained aliphatic hydrocarbons, polycyclic aromatic compounds (such as naphthalene), pyridine derivatives, and light oxygenates (cyclic alkenes and ketones).

Microwave-Assisted Pyrolysis of Pine Wood Sawdust Mixed with Activated Carbon for Bio-Oil and Bio-Char Production

Pyrolysis of pine wood sawdust was carried out using microwave-heating technology in the presence of activated carbon (AC). Experimental conditions were of 20 min processing time, 10 wt.% of AC, and a microwave power varying from 100 to 800 W. The results obtained showed that the microwave absorber allowed increasing the bio-oil yield up to 2 folds by reducing the charcoal fraction. The maximum temperature reached was 505 °C at 800 W. The higher heating values (HHV) of the solid residues ranged from 17.6 to 30.3 MJ/kg. The highest HHV was obtained for the sample heated at 800 W with 10 wt.% of AC, which was 33% higher than the non-charged sample heated at the same power. Furthermore, the addition of AC allowed showing the probable catalytic effect of the AC in the charged sample pyrolysis bio-oils.

Sunflower seed hulls waste as a novel source of insecticidal product: Pyrolysis bio-oil bioactivity on insect pests of stored grains and products

The edible oil industry produces abundant sunflower seed hulls (SSH) as waste. Pyrolysis offers a sustainable method for producing high-value bioproducts from this lignocellulosic residue. This paper reports on the bioefficacy of SHH pyrolysis bio-oils from raw SSH (named SSH bio-oil) and acid pretreated hulls (named PTH bio-oil) as bioinsecticides against Sitophilus oryzae, Lasioderma serricorne and Tribolium castaneum. Raw SSH and pretreated hulls with 10% H3PO4 were subjected to fast pyrolysis in a vertical reactor at 450 °C. Results show that PTH bio-oil is a furfural enriched bio-liquid with storage stability and a yield of 33%. SSH bio-oil was unsuitable for evaluating biological activity since it produce high variability in mortality data. In contrast, PTH bio-oil produces high insecticidal activity in S. oryzae (LC50 = 0.51 mg cm−2) by contact toxicity bioassay, followed by L. serricorne and T. castaneum. In behavioral assays, PTH bio-oil shows a slight repellent effect and mobility reduction. Moreover, PTH bio-oil affects the nutritional physiology of S. oryzae and T. castaneum producing a modification of nutritional indices and antifeedant effects. Our study provides information on the potential of fast pyrolysis bio-oils from SSH waste to develop novel bioinsecticides as an alternative to the use of conventional synthetic pesticides.

Improving Performance of Phenol-Formaldehyde Resins Modified/Blended with Phenol-Rich Pyrolysis Bio-Oil

Abstract In this study, we compare the panel performance of plywood made with phenol-formaldehyde (PF) resins modified and blended with phenol-rich bio-oil produced from pyrolysis of biomass. The modified PF resins were synthesized with phenol-rich bio-oil at phenol substitutions of 10, 25, 50, and 75 percent. The blended PF resins were prepared by blending control PF resin with phenol-rich bio-oil at 4, 13, 23, and 38 percent by weight. These resins were examined with Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) and evaluated as plywood binders. The results indicated that the apparent viscosities of modified PF resins were similar to those of control PF resin, while the apparent viscosities of blended PF resins increased with the addition of phenol-rich bio-oil. As the amount of phenol-rich bio-oil increased, the gel times of both modified and blended PF resins decreased first and then increased. FTIR results showed that modified PF resins with up to 25 percent substitution had FTIR spectra similar to those of control PF resin, while blended PF resins with a higher amount of added bio-oil had spectra more like those of bio-oil. TGA results showed that at temperatures of 25°C to 400°C, both modified and blended PF resins with high bio-oil content had better thermal stability than the control PF resin. Panel tests showed that modifying or synthesizing PF resin with phenol-rich bio-oil up to 50 percent increased both dry and wet bond strength. Blending PF resin with phenol-rich bio-oil up to 13 percent increased both dry and wet bond strength compared with control PF resin.

Application of Hydroprocessing, Fermentation, and Anaerobic Digestion in a Carbon-Negative Pyrolysis Refinery

This study investigates the economic and environmental benefits of integrating hydroprocessing, fermentation, and anaerobic digestion into a pyrolysis refinery. Two scenarios were developed for upgrading and/or utilizing the primary products of pyrolysis (bio-oil, gas, and char). The first (hydroprocessing) scenario hydroprocesses whole bio-oil into gasoline and diesel. The second (fractionation) scenario fractionates bio-oil into sugars for fermentation to cellulosic ethanol and residual phenolic oil as the primary product. Both scenarios use the gaseous product of pyrolysis for process heat in the plant and employ biochar to enhance anaerobic digestion of manure for power generation. The fast pyrolysis plant processes 2000 ton/day of corn stover while the anaerobic digester employs 430 ton/day of manure to generate power. The hydroprocessing scenario produces gasoline at a minimum fuel-selling price (MFSP) of $2.77 per gallons of gasoline while the fractionation scenario produces ethanol and phenolic oils (diesel) as a transportation fuel for $1.2 per gallon ($1.41 per GGE). Sensitivity analysis indicates that the MFSP for both scenarios is highly sensitive to the fixed capital cost. Fixed capital costs for the hydroprocessing and fractionation scenarios were estimated to be $643 and $288 million, respectively. Fuel production rates for the hydroprocessing and fractionation scenarios are 60.5 and 16 million GGE per year, respectively. Life cycle greenhouse gas emissions were calculated as −9.6 and −16.6 g CO2,eq per MJ for the hydroprocessing and fractionation scenarios, respectively. LCA emissions are sensitive to byproduct credits derived from biochar sequestration and power generation. This study shows that both systems produce transportation fuels at competitive market prices with an additional reduction in atmospheric CO2 levels compared to fossil fuel sources.

Optimization of Bio-Oil Pyrolysis Product from Palm Empty Fruit Bunches over H-Zeolite Catalyst using Response Surface Methodology (RSM)

Bio-oil pyrolysis product considered as a promising resource of hydrocarbon compound that can be used as alternative fuel or other application. Palm empty fruit bunch (PEFB) based bio-oil converted into hydrocarbon trough pyrolysis over sulfate activation natural zeolite. Here, we reported an optimization process of bio-oil pyrolysis specifically on temperature and catalyst dose variables by using response surface methodology (RSM). Prior conversion process, PEFB was analyzed to determine cellulose, hemicellulose and lignin content. Sulfate activation natural zeolite confirmed its acidity by ammonia and pyridine adsorption calculated by gravimetric method. Two independent variables namely temperature and catalyst weight used in optimization process by RSM whereas response variable is conversion percentage. Analysis result on cellulose, hemicellulose and lignin content are 45.39%, 30.36% and 20.5% respectively. Catalyst acidity determination based on ammonia and pyridine adsorption gave 1.002 mmol/g and 0.1994 mmol/g. Optimum condition of hydrocracking achieved at 568 °C and 2.1088 g catalyst weight with the product obtained at 62.21% conversion. The best product density is 1.086 g/mL obtained at hydrocracking temperature 554 °C and 2.0362 g catalyst. Based on GC-MS analysis, it was confirmed that the product comprises more straight-chain hydrocarbon than cyclic one. RSM calculation able to formulate the feasible model equation to predict the conversion percentage. The equation is; percent conversion = 60.059 + 14.268T + 9.783W – 25.649T2 – 18.809W2 + 3.114TW, whereas model equation for response variable on product density; ρ= 1.09103 – 0.12356T – 0.09744W + 0.11489T2 + 0.28888W2 – 0.00740TW

The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

Combustion-generated fly ash particles in combination with the particles arising from the disintegration of iron-ore pellets, could give rise to the build-up of deposits on the refractory linings of the induration facility. Due to climate change and other environmental issues, there is a desire to cut down on use of fossil fuels. Therefore, it is of interest to investigate the feasibility of replacing coal with less carbon-intensive alternatives such as upgraded biomass, e.g., biochar and pyrolysis bio-oil. While the combustion of biomass can be carbon-neutral, the effects of biomass ash upon slagging during the iron-ore pelletizing process in a grate-kiln setup is unknown. In the present study, the effect of the interaction between the pellet dust and biomass-ash upon melt formation and the viscosity of the resulting melt, which can collectively affect melt-induced slagging, was theoretically assessed. The slagging potential of 15 different biomass fuels, suitable for the pelletizing process, was quantified and compared with one another and a reference high-rank coal using a thermodynamically derived slagging index. The replacement of coal with biomass in the pelletizing process is a cumbersome and challenging task which requires extensive and costly field measurements. Therefore, given the wide-ranging nature of the biomasses investigated in this study, a prescreening theoretical approach, such as the one employed in the present work, could narrow down the list, facilitate the choice of fuel/s, and help reduce the costs of the subsequent experimental investigations.

Fenton pretreatment of lignin to remove methoxy in pyrolytic bio-oil

A Fenton solution with different H2O2 concentrations was used to pretreat an alkali lignin (AL), and combined with fast pyrolysis,the change in the content of phenolic compounds containing methoxy group in light bio-oil was explored, also, the influence of the Fenton solution on the structure of the alkali lignin was also studied. The results show that the peak area of phenolic compounds containing methoxy groups in light bio-oil decreases from 7.3×109 with AL (untreated alkali lignin) to 5.2×109 with 13-FML (pretreated alkali lignin with Fenton solution at a concentration of 13mL/g H2O2), decreasing by about 29%. While the peak area of phenolic compounds containing methyl groups and ethyl groups increases from 3.9×109 with AL to 7.2×109 with 13-FML, increasing by about 1.85 times. At the same time, the yield of light bio-oil increases from 22.4% to 28.7%. Through FT-IR, 1H NMR and13C NMR analysis, it is found that Fenton pretreatment can destroy the condensational structural units of lignin and reduce the content of methoxy, thus providing favorable conditions for subsequent fast pyrolysis to produce bio-oil with low methoxy content.

Efficient One-Stage Bio-Oil Upgrading over Sulfided Catalysts

Efficient upgrading of fast pyrolysis bio-oils into products that can be easily integrated into existing refinery complexes remains to be a challenge particularly from the stability of a catalyst p...