Bio-aviation Fuels Research Articles

Production of high-carbon-number naphthenes for bio-aviation fuels from bio-crude prepared by fast pyrolysis of lignocellulose

Lignocellulose has been suggested as a cost-effective, environmentally sustainable substitute for paraffins, aromatics, and naphthenes in aviation fuel. However, bio-crude derived from the fast pyrolysis of lignocellulose poses challenges because of its high acidity and viscosity arising from oxygenates and water; in addition, the low-carbon-number hydrocarbons obtained from lignocellulose-derived sugars and phenols are unsuitable for aviation fuels. In this investigation, high-carbon-number hydrocarbon fuels are generated from bio-crude through condensation reactions between phenols and saturated cyclic alcohols, achieving a heavy fraction similar to that of aviation fuels. The one-pass, four-step continuous-flow reaction of bio-crude is conducted using a catalysis reactor equipped with carbon-supported palladium, titania-supported nickel–iron, hydrogen-form zeolite Y, and tungstate–zirconia-supported ruthenium. In contrast with conventional two-step hydrodeoxygenation methods yielding 1.1% dimeric cycloalkanes, the suggested multi-step reaction produced 4.5 to 4.7% yields of heavier naphthenes containing twelve or more carbon atoms.

Production of high-carbon-number bio-aviation fuels from furans using sulfated zirconia and silica-alumina aerogel catalysts

Lignocellulose can help produce fuels in biorefineries through its fractionated components such as cellulose, hemicelluloses, and lignin. For instance, hemicellulose-derived xylose has been studied for obtaining petroleum-substituting fuels. Therefore, in this study, catalytic hydroalkylation/alkylation (HAA) of xylose-derived 2-methylfuran (2-MF) with butanal was targeted to selectively produce high-carbon-number diesel fuels. To that end, silica–alumina (SiAl) aerogels with different Si/Al ratios and a series of sulfated zirconia (SZ) compounds calcined at various temperatures were prepared as catalysts to overcome the limitations of conventional hazardous homogeneous acid catalysts. The activity of the SiAl catalysts in forming the desired HAA product, 5,5-bissylvylbutane (denoted as BB), was found to be directly related to the number of acid sites and acid density. Moreover, increasing the Si/Al molar ratio, which reduced the acid density and number of acid sites, led to lower 2-MF conversions and BB yields. The optimal 2-MF conversion and BB yield with the SiAl catalysts (67 % and 45 %, respectively) were achieved using a Si/Al ratio of 8:2 mol/mol. Furthermore, SZ calcined at 700 °C (denoted as SZ-700) exhibited the highest activity among the SZ catalysts (72 % 2-MF conversion, 63 % BB yield), despite having the fewest acid sites and lowest acid density. This was presumably because of the physical structure of SZ-700, which featured mixed monoclinic and tetragonal phases, many oxygen vacancies, and a large accessible external surface area, which facilitated the HAA reactions. Hydrogenation and hydrodeoxygenation (HDO) of BB were performed thereafter using Pd/C and Ru/SiO2–Al2O3 catalysts, respectively. The resulting deoxygenated hydrocarbons comprised 15.1 % light hydrocarbons (C4–C8) and 83.1 % heavier hydrocarbons (C9–C20). Simulated distillation analysis of the post-HDO product distribution indicated that the liquid-phase product contained 70 % high-carbon-number bio-aviation fuels.

Photo-driven enzymatic decarboxylation of fatty acids for bio-aviation fuels production in a continuous microfluidic reactor

Fatty acid photodecarboxylase derived from Chlorella variabilis NC64A (CvFAP) is a novel enzyme that can convert fatty acids to corresponding C1-shortened alkanes under blue light illumination, which provides an alternative approach for the production of bio-aviation fuels under mild conditions. To date, the production of bio-aviation fuel using CvFAP is severely limited by an inefficient reactor. Microfluidic reactors have attracted significant attention owing to their high mass-transfer efficiency and low light attenuation in continuous photobiocatalysis. In this study, a microfluidic photobioreactor was proposed for the continuous photoenzymatic decarboxylation of palmitic acid for the first time. The optimal palmitic acid conversion of 96.7% was obtained at a flow rate of 10 μL/min, a blue light intensity of 200 μmol/(m2 s), a reaction temperature of 30 °C, a catalyst concentration of 2.4 mg/mL, a substrate concentration of 12 mM, and a cosolvent volume ratio of 30%. The maximum pentadecane production rate of 59.8 mM/h was achieved. The highest turnover frequency of CvFAP up to 19,186/h, as ever reported, was obtained at a flow rate of 40 μL/min. Meanwhile, the energy yield of 33.6 kJ/g and energy production rate of 533.5 kJ/L/h were achieved in continuous bio-aviation fuels production. Taken together, the continuous photoenzymatic decarboxylation of fatty acids in a microfluidic photobioreactor is a promising approach for bio-aviation fuels production.

Hydrocracking optimization of palm oil to bio-gasoline and bio-aviation fuels using molybdenum nitride-bentonite catalyst.

In this study, molybdenum nitride-bentonite was successfully employed for the reaction of hydrocracking of palm oil to produce a bio-gasoline and bio-aviation fuel. The prepared catalyst was characterized using XRD, FT-IR, and SEM-EDX. The acidity of the catalyst was determined using the pyridine gravimetric method. The result showed that the acidity of bentonite was increased after modification using molybdenum nitride. The hydrocracking study showed that the highest conversion and product fraction of bio-gasoline and bio-aviation fuel were exhibited by molybdenum nitride-bentonite 8 mEq g−1. The catalyst was later used to optimize the hydrocracking process using RSM-CCD. The effects of the process variables such as temperature, contact time, and catalyst to feed ratio, on the response variables, such as conversion, oil, gas, and coke yield, were investigated. The analysis of variance showed that the proposed quadratic model was statistically significant with adequate precision to estimate the responses. The optimum conditions in the hydrocracking process were achieved at a temperature of 731.94 K, contact time of 0.12 h, and a catalyst to feed ratio of 0.12 w/v with a conversion of 78.33%, an oil yield of 50.32%, gas yield of 44.00% and coke yield of 5.73%. The RSM-CCD was demonstrated as a suitable method for estimating the hydrocracking process of palm oil using a MoN-bentonite catalyst due to its closeness to the optimal value of the expected yield. This study provided a potential catalyst of based on bentonite modified using molybdenum nitride for the hydrocracking of palm oil.

Bio-aviation fuel via catalytic hydrocracking of waste cooking oils

BackgroundBiomass fuels (bio-jet fuel) have recently attracted considerable attention as alternatives to conventional jet fuel. They have become the focus of aircraft manufacturers, engines, oil companies, governments and researchers alike. This study is concerned with the production of biojet fuel using waste cooking oil (WCO). Batch reactor is used for running the experimental study. The catalytic cracking products are investigated by GC mass spectra. Final products from different reaction conditions are subjected to fractional distillation. The (Bio kerosene) fraction was compared with the conventional jet A-1 and showed that it met the basic jet fuel specifications. Optimum reaction conditions are obtained at (450 °C), pressure of (120 bars), catalyst dose (2.5% w/v), reaction time (60 min) and hydrogen pressure 4 atmosphere. The aim of this study is to produce bio aviation fuel according to specifications and with a low freezing point from waste cooking oil in one step using a laboratory prepared catalyst and with a low percentage of hydrogen to complete the process of cracking and deoxygenation in one reactor, which is naturally reflected positively on the price of the final product of bio aviation fuel.ResultsThe results indicated that the product obtained from WCO shows promising potential bio aviation fuels, having a low freezing point (− 55 °C) and that all bio kerosene’s specifications obtained at these conditions follow the international standard specifications of aviation turbine fuel.ConclusionBiojet fuel obtained from WCO has fairly acceptable physico-chemical properties compared to those of petroleum-based fuel. Adjustment of the hydro catalytic cracking reaction conditions was used to control quantities and characteristics of produced bio aviation fuel. Taking into consideration the economic evaluation WCO is preferable as raw material for bio aviation fuel production due to its low cost and its contribution in environmental pollution abatement. Blend of 5% bio aviation with jet A-1 (by volume) can be used in the engine without any modifications and a successful test of blended aviation fuel with 10% bio aviation has been achieved on Jet-Cat 80/120 engine.

Prospects and perspectives foster enhanced research on bio-aviation fuels

Bio-aviation fuels are a major research and development topic, with strong interests from the aviation sector, the public, lawmakers and potential producers. Yet the development and market penetration in the air-transportation sector is slow, despite proven environmental benefits. Bio-fuels can indeed mitigate the environmental impact of the aviation sector mostly due to their low carbon intensity and favourable chemical structure. Such bio-aviation fuels must have “drop-in” characteristics with specifications and compatibility with the combustion behaviour of kerosene. The ASTM approval procedures are an important guarantee in this respect. Additional emission reductions rely on the production pathways, while optimum flight-related strategies are an additional benefit.An analysis of both the production pathways, and the environmental and Life Cycle Assessment findings delineates important research directions to enhance the production and use of bio-aviation fuels.Towards specific environmental issues, target research topics should include various topics. A better quantification of particulate and soot emissions, condensation contrails and NOx are of primary concern. The impact of geographic parameters on the bio-aviation fuel benefits should be investigated towards using bio-aviation fuels primarily in specific climate zones. Emission prediction models should be further developed. LCA approaches should be extended. More on-flight emission patterns should be measured to provide relevant data for the above considerations; Towards bio-aviation fuel characterization, safety and reliability are major criteria of the ASTM approval. Towards production pathways, the technical viability studies of synthesis pathways should be combined with economic assessments. Towards fuel costs, the reason for the high production cost of bio-aviation fuel is at least partly due to the oxygen-rich bio-polymer nature of biomass with unsuitable carbon chain length. In order to reduce the cost of bio-aviation fuel, several research directions are encouraged and discussed in the paper.

Analysis on Ignition Delay Characteristics of Bio Aviation Fuels Manufactured by HEFA Process

본 연구에서는 서로 다른 원료를 이용하여 HEFA 공정을 통해 제조한 국내외 바이오항공유(Bio-ADD, Bio-6308, Bio-7720)의 점화지연특성을 비교 및 분석하였으며, 이러한 바이오항공유의 실제 시스템에의 적용 가능성을 확인하기 위하여 기존에 사용되고 있는 석유계항공유(Jet A-1) 및 바이오항공유와 석유계항공유를 일정한 비율(50:50, v:v)로 혼합한 연료의 점화지연특성에 대해서도 분석하였다. 각 항공유의 점화지연시간은 CRU 장비를 사용하여 측정하였으며, 결과 해석을 위해 표면장력 측정, GC/MS 및 GC/FID 분석을 수행하였다. 그 결과, 모든 온도 조건에서 Jet A-1의 점화지연시간이 가장 길게 측정되었는데, 이는 aromatic compounds가 약 22.8% 존재하여 분해 과정에서 열적으로 안정하고 주변 산소와도 반응성이 낮은 benzyl radical이 생성되기 때문인 것으로 판단된다. 바이오항공유의 점화지연시간은 모두 비슷하게 측정되었는데, 이는 각 항공유를 구성하는 n-paraffin과 iso-paraffin의 비율(n-/iso-)이 약 0.12로 서로 비슷한 값을 가지며, cycloparaffin의 구성 비율도 약 3% 미만으로 크게 차이가 없기 때문인 것으로 해석된다. 또한, 국내외에서 개발된 바이오항공유(Bio-ADD, Bio-6308)를 석유계항공유와 50:50(v:v)으로 혼합한 연료의 점화지연시간은 혼합하지 않은 Jet A-1과 각 바이오항공유가 갖는 점화지연시간의 사잇값으로 측정되어, 기존에 사용 중인 시스템을 변경하거나 개선하지 않아도 적용이 가능함을 확인하였다.

Sustainable alternative fuels in aviation

Abstract In recent years, renewable energy resources have become more important due to the limited number of regions for production of petroleum-based fuels, which are continuously depleting. The aviation sector in terms of commercial and cargo transportation has an increasing need for conventional, as well as, alternative fuels. Derivatives of petroleum fuels used in aviation have negative impacts on air quality. Factors causing greenhouse gas emissions (GHG) in the aviation sector must be reduced. However, such fuels used in the aviation sector are not sustainable. Biofuels which have the potential to replace petroleum fuels and help with emissions are heavily investigated in developed countries for independency, creating a better environment and sustainability. Biofuels which are already used for ground vehicles could also be implemented in the aviation sector to reduce fuel cost and emissions. Overall, aviation fuels made of sustainable resources would also support social and economic development. Numerous industrial initiatives have emerged to find alternative ways to attain bio-aviation fuels. Therefore, there is an increasing level of research with regards to alternative aviation fuels made of biomass in recent years. It is important to obtain basic feedstocks and to develop biofuel production processes in a cost-effective way. This study examines the necessity and the types of biofuels in the aviation sector. By designing unique fuel systems for air vehicles, it is possible to formulate biofuels which can be used for both air and ground vehicle applications. This type of consensus would help with sustainability and a better environment.

Triglycerides Catalytic Hydroconversion into Bio-Aviation Fuels Based on Temperature by One-Step

One-step hydrotreatment of three different vegetable oils have been carried out over Pd loading bi-functional catalyst in batch reactor. Rubber seed oil, Jatropha oil and castor oil have different acid value and constituents, which will influence the hydroprocessing and the quality of products. With temperature rising, several principles have been summarized, and an optimal temperature corresponding to three oils have been determined respectively. At the optimal temperature of Jatropha oil, 300°C, deoxygenation rate was up to 99.29%, C8-16hydrocarbons of products was up to 77.36%; 310°C and 320°C were respectively optimal temperature of rubber seed oil and castor oil, deoxygenation rate were 99.15% and 98.78%, C8-16hydrocarbons were 71.46% and 69.25%. The products quality of Jatropha oil was better than rubber seed oil and castor oil, and rubber seed oil and castor oil can cause the deactivation of catalyst.

Experimental and Modeling Studies of the Oxidation of Surrogate Bio-Aviation Fuels

Jet fuels currently in use in the aviation industry are exclusively kerosene-based. However, potential problems regarding security of supply, climate change, and increasing cost are becoming more significant, exacerbated by the rapidly growing demand from the aviation sector. Biofuels are considered one of the most suitable alternatives to petrochemical-based fuels in the aviation industry in the short to medium term, since blends of biofuel and kerosene provide a good balance of properties currently required from an aviation fuel. Experimental studies at a variety of stoichiometries using a flat flame burner with kerosene and kerosene/biofuel blends have been performed with product analysis by gas sampling and laser-induced fluorescence detection of OH, CO, and CO2. These studies have been complemented by modeling using the PREMIX module of Chemkin to provide insights into and to validate combined models describing the oxidation chemistry of surrogate fuels depicting kerosene, fatty acid methyl ester biofuels, and Fischer-Tropsch derived fuels. Sensitivity analysis has identified important reactions within these schemes, which, where appropriate, have been investigated by molecular modeling techniques available within Gaussian 03.

The influence of the support on the catalytic behavior of ruthenium in [formula omitted] synthesis reactions

As social concerns for the environment have increased owing to the extreme greenhouse gas emissions, the conversion of biomass to renewable bioaviation fuels is drawing attention to replace petroleum-derived aviation fuels. Renewable bioaviation fuel will help reduce CO2 emissions, making it a better substitution than currently available aviation fuels. Renewable biomass is one of the sustainable candidates to consider in the upcoming bio-based industry. Significant efforts have been made to convert lignocellulosic biomass to sugars for aviation fuel synthesis. Genetically modified microbial strains can convert these sugars into a variety of bioproducts, including fatty acid-, 2-keto acid-, and terpene-derived compounds. Further, these compounds are used as precursors for the production of bioaviation fuel. This chapter illustrates biomass pretreatments, biofuel production from sugars obtained after biomass conversion, and metabolic and genetic engineering of suitable microbial strains for enhanced bioaviation fuel production.