High-quality Biofuel Research Articles

Microalgae biomass as a sustainable source for biofuel, biochemical and biobased value-added products: An integrated biorefinery concept

Microalgal biomass has been proved to be a sustainable source for biofuels including bio-oil, biodiesel, bioethanol, biomethane, etc. One of the collateral benefits of integrating the use of microalgal technologies in the industry is microalgae’s ability to capture carbon dioxide during the application and biomass production process and consequently reducing carbon dioxide emissions. Although microalgae are a feasible source of biofuel, industrial microalgae applications face energy and cost challenges. To overcome these challenges, researchers have been interested in applying the bio-refinery approach to extract the important components encapsulated in microalgae. This review discusses the key steps of microalgae-based biorefinery including cultivation and harvesting, cell disruption, biofuel and value-added compound extraction along with the detailed technologies associated with each step of biorefinery. This review found that suitable microalgae species are selected based on their carbohydrate, lipid and protein contents and selecting the suitable species are crucial for high-quality biofuel and value-added products production. Microalgae species contain carbohydrates, proteins and lipids in the range of 8% to 69.7%, 5% to 74% and 7% to 65% respectively which proved their ability to be used as a source of value-added commodities in multiple industries including agriculture, animal husbandry, medicine, culinary, and cosmetics. This review suggests that lipid and value-added products from microalgae can be made more economically viable by integrating upstream and downstream processes. Therefore, a systematically integrated genome sequencing and process-scale engineering approach forimproving the extraction of lipids and co-products iscritical in the development of futuremicroalgal biorefineries.

Study on pressurized upgradation of pyrolysis oil for high-value liquid products.

Upgradation of pyrolysis oil is a key process to achieve high-quality biofuel. In this study, the effects of different Ar pressures and H2/Ar ratios in the presence and absence of catalysts on deoxygenation of pyrolysis oil were investigated by autoclaving. When the initial pressure of the reaction is 6MPa and without catalyst addition, the content of carboxylic acid decreases from 51.52 to 41.54%, whereas with the addition of catalyst (10 % Ni/C), the deoxygenation and hydrocarbon content in the product were significantly improved. Hence, 6 MPa was found to be optimum and above which failed to induce such useful changes but can lead to lower high heating value (HHV). However, the presence of hydrogen affects the content of alkanes and olefins in the product.

Full-scale production of high-quality wood pellets assisted by multivariate statistical process control

In order for solid biofuels to be marketable and accessible to stakeholders (e.g., manufacturers, transhippers and customers), they must strictly meet the rigors of international standards and regulatory agencies regarding quality. On this basis, this study assesses the production of high-performance fuel-flexible woody pellets for heating and power, with the assistance of multivariate statistical process control (MSPC). The operational scenarios of industrially pelletizing pinewood sawdust are POSI (150 MPa and no pre-heating) and POSII (250 MPa and no pre-heating) as references, and POSIII (150 MPa and pre-heating) and POSIV (250 MPa and pre-heating) as alternatives to regularize the workflow on the machine. The stream-monitoring techniques of MSPC are the exponential moving average (EMA) and Hotelling's T2. The EMA-Hotelling system accurately tracks non-random errors and predicts the operationally finest scenario for developing high-quality pellets. Pre-heating the compressing channel of the machine regularizes the feeding and thus produces type I pellets (class A1/A2, European standard) with excellent bulk density (1227.55 kg m−3), durability (98.10%) and hydrophobicity (96.65%), without points outside the specific critical ranges. Clear evidence of improved pellet quality with the assistance of MSPC is found. The high-fidelity concept of MSPC captures the advantages of EMA and Hotelling's T2 into an immersive single framework; hence, it can compensate for the potential bias and misinformation-to-information overlapping of outcomes from monitoring latently multivariable flow on classical quality control charts. The major findings and innovations of this study can assist with rolling-out fine-scale pelletization and thus fulfill the increasing global demand for high-quality biofuels.

Analyzing esterification kinetics of model bio-oil with ethanol catalyzed by a green catalyst

Fast pyrolysis of biomass is a potential method for the production of bio-oils as a renewable liquid fuel. Bio-oils contain a large number of organic compounds, particularly carboxylic acids, which cause corrosiveness and instability that are troublesome for storage and for the transportation of fuel. Upgrading is an important process to transform bio-oils into high-quality biofuels. Contained organic acids are treated with alcohol to convert them into esters by esterification which may be considered as a good intermediate bio-oil upgrading method. This work presents a kinetic study for 12-tungstosilicic acid (a type of heteropoly acid, HPA) catalyzed esterification of a model bio-oil with ethanol. The main compound of the agro-residue-derived bio-oil was illustrated by oleic acid. The kinetic study was investigated under the molar ratio between ethanol to oleic acid of 9.11:1 and catalyst loading of 10 wt% condition with the varied reaction temperature in the range of 35-75°C. The result showed that a pseudo-first-order was suitable to represent the kinetic model for esterification of the model bio-oil. By fitting between the experimental results and kinetic model, the activation energy (Ea) and the pre-exponential factor (A) were found to be 31.5 kJ/mol and 432 min−1, respectively. This comparatively low activation energy equated to other catalytic esterification proved that the HPA catalyst (12-tungstosilicic acid) considered here was an assured green catalyst for esterification in the bio-oil upgrading process.

Feasibility Analysis of Brewers’ Spent Grain for Energy Use: Waste and Experimental Pellets

Waste production is increasing every day as a consequence of human activities; thus, its valorization is becoming more important. For this purpose, the usage of wastes as biofuels is one of the most important aspects of sustainable strategies. This is the case of the main waste generated in brewing industries: brewers’ spent grain (BSG). In this sector, microbreweries are not able to properly manage the wastes that they generate due to lack of space. Consequently, the transformation of BSG to a high-quality biofuel might be an interesting option for this kind of small industry. In this work, we carried out a physical-energy characterization of BSG, as well as pellets from this waste. The initial characterization showed slightly unfavorable results concerning N and ash, with values of 3.76% and 3.37% db, respectively. Nevertheless, the physical characterization of the pellets was very good, with acceptable bulk density (662.96 kg·m−3 wb) and low heating value (LHV; 17.65 MJ·kg−1 wb), among others. This situation is very favorable for any of the intended uses (for energy use or animal feed, among others).

Mixotrophic cultivation of Chlorella vulgaris in sugarcane molasses preceding nitrogen starvation: Biomass productivity, lipid content, and fatty acid analyses

AbstractIn the present study, a precharacterized oleaginous microalgal species (Chlorella vulgaris) was exploited for its biomass productivity, lipid yield, and fatty acid analysis under mixotrophic and photoautotrophic conditions. For the purpose, the microalgal biomass was raised mixotrophically as well photoautotrophically. For mixotrophic cultivation, molasses was used as additional source of carbon and energy, while for photoautotrophic cultivation, atmospheric CO2 was the sole source of carbon and energy. The microalgal biomass raised thus was then harvested following 5 days of nitrogen starvation. Mixotrophic cultivation depicted remarkably higher biomass productivity (137.43 ± 13.3 mg L−1 day−1) than that of photoautotrophic cultivation (91.57 ± 7.9 mg L−1 day−1). About 39% (w/w) of total lipid content was obtained from the dried biomass raised mixotrophically. Lipidomic analysis of the extracted oil depicted higher concentrations of polyunsaturated fatty acids (palmitic and oleic acids). The significant availability of polyunsaturated fatty acids (60 mg g−1 of dried algal biomass) ensured the production of high quality biofuel.

Catalytic role of metals supported on SBA-16 in hydrodeoxygenation of chemical compounds derived from biomass processing.

Hydrodeoxygenation (HDO) carried out at high temperatures and high hydrogen pressures is one of the alternative methods of upgrading pyrolytic oils from biomass, leading to high quality biofuels. To save energy, it is important to carry out catalytic processes under the mildest possible experimental conditions. The aim of our research was the synthesis of ordered mesoporous SBA-16 type silica materials modified with transition metal atoms (Ir, Ru, Pd, Pt), their physicochemical characterization and use as catalysts in hydrodeoxygenation of model chemicals (guaiacol, syringol, creosol). The HDO process was carried out under mild experimental conditions at temperatures in the range from 90 to 130 °C and hydrogen pressures in the range from 25 to 60 bar. The catalytic tests revealed differences in the catalytic properties of the samples studied. The catalytic systems used assured highly efficient transformations of the examined molecules as well as high selectivity towards chemical compounds with lower O/C ratio and higher H/C ratio as compared to those in the initial substrates. High activity of the catalysts containing precious metals in the experimental conditions applied suggests their potential to improve bio-oil production for biofuels.

Economic and Environmental Assessment of Catalytic and Thermal Pyrolysis Routes for Fuel Production from Lignocellulosic Biomass

Meeting the transport needs of a growing world population makes it imperative to develop renewable and sustainable routes to production of liquid fuels. With a market-driven economic structure and pressing environmental issues, it is essential that these new routes provide environmental benefits while being economically viable. Conversion of second-generation lignocellulosic biomass resources to fuels via pyrolysis represents an important technological route. In this article, we report comparative assessment of the economic and lifecycle environmental aspects for catalytic and thermal pyrolysis. The goal of this assessment is two-fold: one is to understand the potential of this conversion route via the catalytic and thermal processes and second is to provide feedback for further development of catalysts for various stages of this conversion. The complete assessment is interdisciplinary in nature and connects the laboratory experiments with contextual sustainability assessment. Three catalytic and one thermal pyrolysis processes are analyzed using this assessment approach. Subject to the model choices and data inputs, the results, which consider quality of the oil product, show that biofuels produced using catalytic and thermal routes are rather expensive compared to gasoline. But at the same time, they provide significant greenhouse gas emission savings and can lead to lower CO2 abatement costs compared to the first-generation ethanol that is used currently. With one of the product scenarios of hydrotreated (HT) oil, the abatements costs are estimated to be 51% of those associated with first-generation ethanol. Additional product scenarios with developments in catalysts show potential to further reduce abatement costs significantly to below 100 EUR per metric tonne of CO2 equivalents. Using scenario analysis, the results help us to understand specific areas for development of novel catalysts. At the same time, the results demonstrate the trade-offs associated with the variety and complexity of technical factors associated with the pyrolysis routes. The study highlights the challenges and the promises of catalytic and thermal pyrolysis for production of high-quality biofuels produced via a sustainable production route.

Kinetic model for esterification of oleic acid catalyzed by a green catalyst in ethanol

Bio-oil produced from biomass fast pyrolysis process is an organic liquid that can be transformed into high quality biofuel through upgrading process. Bio-oil comprises a large amount of carboxylic acids, which cause its corrosiveness, hence, difficulty for storage and utilization. Esterification may be considered as an intermediate upgrading method to convert the acids in bio-oil into esters by reacting with alcohol. This work presents kinetic studies of the esterification of a bio-oil model compound in ethanol catalyzed by 12-tungstosilicic acid. Oleic acid was used to represent the main component of bio-oil derived from agro-residues. Conditions considered were the molar ratio of ethanol to oleic acid of 9.11:1, catalyst loading of 10 wt%, and reaction temperatures in the range of 35-75 °C. It was found that the pseudo-homogeneous kinetic model was suitable to represent the esterification of the bio-oil model compound. Average reaction order n = 1.9, activation energy Ea=50.1 kJ/mol, and pre-exponential factor A = 11.11×103 min−1 were obtained by fitting the kinetic model with experimental results.

P.775 Worms from the brain: treatment challenges in delusional parasitosis - a case report

As one of the major products from cellulose pyrolysis, levoglucosan (LG) is highly oxygenated and stubborn, causing serious problems to bio-oil utilization. In this study, catalytic ketonization of LG over nano-CeO2 was performed in a pyrolyzer-gas chromatography/ mass spectrometry (PY-GC/MS) system to prepare hydrocarbon precursors (principally ketones). Nano-CeO2 has been proven effective to convert LG into ketones, with the highest selectivity (71.2 %) obtained when CeO2 to LG ratio was 15:1 (mm3: mg) at 700 °C. When 5% ZrO2 was loaded on CeO2 (5% Zr/CeO2), the selectivity of ketones further increased to 76.0 %, and that of linear compounds in all the ketone products reached 53.9 %. Results from catalyst characterization revealed that 5% Zr/CeO2 contained an abundance of basic surface sites and redox capacity, thus leading to high ketonization activity. Ketonization of LG possesses significant potential in facilitating the conversion of cellulose into high-quality biofuels in a sustainable way.

Catalytic ketonization of levoglucosan over nano-CeO2 for production of hydrocarbon precursors

As one of the major products from cellulose pyrolysis, levoglucosan (LG) is highly oxygenated and stubborn, causing serious problems to bio-oil utilization. In this study, catalytic ketonization of LG over nano-CeO2 was performed in a pyrolyzer-gas chromatography/ mass spectrometry (PY-GC/MS) system to prepare hydrocarbon precursors (principally ketones). Nano-CeO2 has been proven effective to convert LG into ketones, with the highest selectivity (71.2 %) obtained when CeO2 to LG ratio was 15:1 (mm3: mg) at 700 °C. When 5% ZrO2 was loaded on CeO2 (5% Zr/CeO2), the selectivity of ketones further increased to 76.0 %, and that of linear compounds in all the ketone products reached 53.9 %. Results from catalyst characterization revealed that 5% Zr/CeO2 contained an abundance of basic surface sites and redox capacity, thus leading to high ketonization activity. Ketonization of LG possesses significant potential in facilitating the conversion of cellulose into high-quality biofuels in a sustainable way.

Near zero-waste biofuel production from bioderived polyhydroxybutyrate

Fuel production from biomass offers a low-carbon strategy to address the global challenge of climate change associated with carbon emission. Novel technique with high carbon- and energy-recovery from biomass has been pursued for decades, but rarely achieved. Here we demonstrate the near zero-waste production of high-quality biofuels from poly(3-hydroxybutyrate), a biofeedstock widely accumulated in microorganisms, under mild temperature (200 °C), with 99% carbon utilization and 91.5% energy recovery. Products are dominated by easy-to-use alkanes, butyrates and butanol. This technique paves the way for green production of biofuels from bioderived feedstocks.

Effect of different ash/organics and C/H/O ratios on characteristics and reaction mechanisms of sludge microwave pyrolysis to generate bio-fuels

To study the effects of different ash/organics and C/H/O ratios on bio-fuel characteristics and energy efficiency, four kinds of sludge with different properties were used for microwave pyrolysis (800 °C). Moreover, the microwave pyrolysis reaction mechanisms of different sludge were also explored. The results showed that high-ash sludge could accelerate the frequency of polar molecule rotation in the microwave field due to the presence of oxides with dielectric properties in ash, thereby achieving faster heating rates and higher temperatures. However, compared with high-organic sludge, high-ash sludge exhibited lower bio-gas yield and higher bio-char yield. As the H/C ratio increased from 0.127 to 0.148, the bio-gas yield increased from 15.41% to 40.01%, and the content of H2 in bio-gas and aliphatics in bio-oil increased to 36.69 vol% and 26.54 wt%, respectively. When the O/C ratio was reduced to 1.31, the content of CO and oxygenated compound in bio-oil increased to 31.25 vol% and 40.04 wt%, which lowered the quality of the bio-oil. Those consequences also determined that a mixture of sludge with different ash/organic ratios could be pyrolyzed to obtain high-quality bio-fuels and high energy efficiency. Differences in C/H/O ratios in the mixed sludge greatly affected the microwave pyrolysis heating process, which affected the pyrolysis reactions and the quality of the bio-fuels. Therefore, this study provides a theoretical basis to elevate the quality of bio-fuels and reduce microwave pyrolysis costs.

Catalytic hydrothermal liquefaction of Spirulina over bifunctional catalyst to produce high-quality biofuel

In this study, five different bifunctional catalysts (NiO/SAPO-34, NiO/ZSM-5, NiO/USY, NiO/γ-Al2O3 and NiO/SiO2) are characterized and applied for the hydrothermal liquefaction (HTL) of Spirulina to produce biofuel. The X-ray diffraction (XRD), ammonia desorption measurement (NH3-TPD) and Brunauer-Emmet-Teller (BET) analysis results show that NiO/SAPO-34 and NiO/USY catalysts have the better physical properties compared to the other three catalysts, resulting in the higher bio-oil yields of 59.85 wt% and 59.12 wt%, respectively. Then the bio-oil samples are characterized by elemental analysis, Gas Chromatography-Mass Spectrometry (GC–MS) and Thermo-gravimetric analysis (TGA). Results indicate that the bio-oil obtained over NiO/USY catalyst has the highest higher heating value (HHV) due to the higher C and H content as well as the lower O and N content. What’s more, it contains the most hydrocarbons (20.58%) and light oil components (72.91%) with NiO/USY catalyst. Consequently, NiO/USY is considered to be the best bifunctional catalyst for the HTL of Spirulina.

Composition and Properties of Rapeseed Oil Hydrotreating Products over CoMo/Al2O3 and NiMo/Al2O3 Catalysts

Currently, there is an effort to achieve a more widespread use of biofuels, which are an alternative to conventional, petroleum-based fuels in mobile and stationary applications. The conversion of vegetable oils via catalytic hydrotreating to hydrotreated vegetable oil (HVO) is one of the most promising alternatives to produce high-quality biofuels. In this work, the composition and properties of rapeseed oil hydrotreating products gained over sulfided CoMo/γ-Al2O3 and NiMo/γ-Al2O3 catalysts were studied. The experiments were carried out in a laboratory trickle bed reactor in a temperature range of 320–380 °C and pressures of 4 and 8 MPa. The mixture of a rapeseed oil and isooctane was hydrotreated to simulate the coprocessing of rapeseed oil and petroleum fractions. Small amounts of aromatic hydrocarbons and, at higher reaction temperatures, considerably high contents of cycloalkanes and isoalkanes were found in the obtained liquid products. These were specifically alkylated cyclopentanes, cyclohexanes, decalines, benzenes, indanes, tetralines, and naphthalenes. The content of isoalkanes and aromatics in the liquid hydrotreating products gained over both catalysts increased with an increasing reaction temperature. A higher total amount of aromatics was found in the products of the NiMo catalyst because of its higher dehydrogenation activity compared with the CoMo catalyst. The liquid products with a high content of n-alkanes had a very high cetane index and cold filter plugging point, which decreased with an increasing reaction temperature due to the increasing content of isoalkanes and aromatics.

Facile Synthesis of Kilogram-Scale Co-Alloyed Pt Single-Atom Catalysts via Ball Milling for Hydrodeoxygenation of 5-Hydroxymethylfurfural

Catalytic conversion of biomass-derived 5-hydroxymethylfurfural (HMF) into high quality biofuel 2,5-dimethylfuran (DMF) is significant for the utilization of biomass but remains a substantial chall...

Deoxygenation of triolein to green diesel in the H2-free condition: Effect of transition metal oxide supported on zeolite Y

H2-free deoxygenation is a very important process in producing high-quality biofuel without the use of H2 gas supply. Considering the costly price of the noble metals, transition metal (TM) based catalysts are more affordable, and the performance is comparable to the noble metal-based catalyst. In this study, TMO supported on zeolite Y catalysts (Ni-, Cu-, Co-, Zn- and Mn-Y) are prepared via wet-impregnation for deoxygenation of triolein, a model compound of non-edible oil under H2-free condition. The deoxygenation activity of TMO supported on zeolite Y is following the order of Ni-Y > Co-Y > Cu-Y > Mn-Y > Zn-Y. The nickel oxide supported on zeolite-Y (Ni-Y) shows the highest conversion up to 76.21 % with 84.28 % hydrocarbon selectivity after reacted at 380 °C for 2 h. Besides, the selectivity toward diesel range hydrocarbon is 92.61 %. The superior deoxygenation activity of Ni-Y can be related to synergistic effect between the reduced B/L and high hydrogenolysis ability of Ni that promote the decarboxylation reaction, suppress the cracking and polymerization of heavy hydrocarbon. Therefore, Ni-Y is a potential catalyst to obtain high quality green diesel from non-edible oil through catalytic deoxygenation without addition of external H2 source.

Study on the Preparation of Biohydrocarbon Fuel by Catalytic Hydrogenation of Swida wilsoniana Pyrolysis Products

The Ni‐ZSM‐5 catalyst, under four different factors of Swida wilsoniana pyrolysis products of catalytic hydrogenation, GC‐MS, FI‐IR, and elemental analyzers, was used to identify the elements, carbon chain distribution, and composition of the products. The effects of reaction temperature, reaction pressure, and catalyst hydrogenation level on the conversion rate were investigated. The reaction pressure and the amount of catalyst are the main factors that affect the conversion of the pyrolysis products into biofuels. Using 1.05 wt.% Ni‐ZSM‐5 catalyst, the highest conversion rate was 98.10% at 173°C and 2.00 MPa. The results show that Swida wilsoniana‐decomposed products can be converted to high‐quality biofuels by catalytic hydrogenation of Ni‐ZSM‐5 and can be used as an alternative energy source.

Methanation potential: Suitable catalyst and optimized process conditions for upgrading biogas to reach gas grid requirements

Increasing CO2 and greenhouse gas emissions are decreasing the living conditions all around the world and considerable damage is inflicted on our planet. Creating solutions for clean energy, air, water and food is becoming inevitable and urgent. This paper focuses on upgrading biogas to high quality biofuel to meet German gas grid requirements. The Sabatier process has proven that carbon dioxide present in biogas can be converted to methane (>96% -Vol) by adding hydrogen in a stoichiometric ratio. High quality methane yield 98.9%, with CO2 conversion 99.6% is achieved with a Nickel catalyst and with process conditions of temperature (473.15 K), pressure (1000 kpa), H2/CO2 ratio (6), CH4/CO2 ratio (1.52), a flow rate of 1.11 × 10−6 m3 s−1 for the reactor dimensions of a diameter of 0.1 m, a catalyst bed height of 0.14 m, a catalyst amount of 0.01 kg and a reactor volume of 1.099 × 10−3 m3. These experimental laboratory parameters are beneficial as a reference for upscaling Methanation reactors.

Catalytic pyrolysis of biomass with potassium compounds for Co-production of high-quality biofuels and porous carbons

This paper studied the catalytic pyrolysis of rice husk (RH) with different K-compounds (i.e., KOH, K2CO3, and K2C2O4) for co-production of biofuels and porous carbons. The decomposition of biomass occurred at lower temperature ranges due to the catalytic performance of K-compounds, following the order of KOH > K2CO3 > K2C2O4. By fast pyrolysis of RH with the K-compounds, the number of organic compounds was significantly reduced. More hydrocarbons (e.g., benzene, long-chain alkanes) were generated due to the in-situ catalytic upgrading (e.g., deoxygenation) of bio-oil. Pyrolysis of biomass with K-compounds could also accelerate the generation of unsaturated aliphatic hydrocarbons. In particular, pyrolysis of RH with K2C2O4 could result in the bio-oil with high-content of hydrocarbons and with low-content of oxygenated compounds (e.g., acids, phenols). Furthermore, the activated char with hierarchically micro-mesoporous structure was applied for toluene sorption. The pristine biochar had a relatively low adsorption time and capacity. By the chemical activation followed by the washing process, the specific surface area (SBET) of the RH-derived chars was significantly increased. The RHC-K2C2O4 had a maximum SBET of 1347 m2/g due to its mild activation process, which further contributed to a highest breakthrough time (1230 min) and capacity (609.38 mg/g) on toluene adsorption.