Hydrocarbon Biofuel Research Articles

Pyrolysis of macroalgae: Insight into product yields and biochar morphology and stability

Pyrolysis of biomass residues into biochar is seen as a feasible way to mitigate climate change by biological carbon storage (carbon dioxide removal, CDR) and to substitute fossil fuel with sustainable biofuel. This study applies a combination of flash and ramp heating pyrolysis, and organic petrography to investigate the hydrocarbon (biofuel) potential and biochar stability and morphotypes of eight brown, red, and green macroalgal species of different tissue complexity. The carbon stability of biochar derived from macroalgae has not previously been assessed using organic petrography (reflectance measurements) and evaluated in the context of the geological carbon cycle. The biochar, hydrocarbon, and CO + CO2 yields vary due to different chemical composition of the macroalgal species, but the product yield variations are not related to the brown, red, or green macroalgal groups. The total biofuel yield shows an inverse trend with biochar yield. A slower heating rate produces more biochar and higher CO + CO2 and lower biofuel yields than the combined flash pyrolysis and faster heating rate. The morphotype composition of the biochar was qualitatively examined by reflected light microscopy while carbon stability was assessed by random reflectance (Ro) measurements. The diverse morphotype compositions observed in biochar formed under similar pyrolysis conditions likely stem from variations in the original algal composition. While some biochar samples show morphologies resembling the original macroalgal structure, porous morphotypes predominantly characterize the biochar samples overall. Despite a maximum pyrolysis production temperature (PT) of 650 °C, the highest mean Ro value among all biochar samples is 2.91%, corresponding to a carbonization temperature (CT) of 526 °C. This observation is tentatively related to the less lignocellulosic structure of the macroalgae compared to terrigenous biomass. Four biochar samples have their entire Ro distribution range above the inertinite benchmark (IBRo2%) of Ro = 2% indicating high carbon stability. Conversely, the remaining four biochar samples exhibit Ro distributions extending below IBRo2%, indicating the presence of a carbon fraction with lower long-term stability in soil. The statistically significant inverse relationship observed between the mean Ro values and the peak hydrocarbon generation temperature (Tmax) can be attributed to the behavior of residual macromolecules within the biochar. When these macromolecules reach peak biofuel generation at a lower temperature, they undergo carbonization over a more extended time interval during pyrolysis. Consequently, this prolonged exposure to the pyrolysis process leads to higher degrees of carbonization, as reflected by higher Ro values. In conclusion, the findings from pyrolysis and organic petrography reveal: (1) Macroalgae demonstrate potential for biofuel production, although biofuel yields contingent upon both the species of macroalgal and the heating rate employed, and (2) This study documents for the first time that flash+ramp pyrolysis of macroalgae yields biochar suitable for long-term carbon storage. However, both the carbon stability inferred from Ro frequency distributions and biochar yields show variations across different macroalgal species and heating rate.

Production of Renewable Hydrocarbon Biofuels with Lignocellulose and Its Derivatives over Heterogeneous Catalysts.

In recent years, the issues of global warming and CO2 emission reduction have garnered increasing global attention. In the 21st Conference of the Parties (convened in Paris in 2015), 179 nations and the European Union signed a pivotal agreement to limit the global temperature increase of this century to well below 2 K above preindustrial levels. To fulfill this objective, extensive research has been conducted to use renewable energy sources as potential replacements for traditional fossil fuels. Among them, the production of hydrocarbon transportation fuels from CO2-neutral and renewable biomass has proven to be a particularly promising solution due to its compatibility with existing infrastructure. This review systematically summarizes research progress in the synthesis of liquid hydrocarbon biofuels from lignocellulose during the past two decades. Based on the chemical structure (including n-paraffins, iso-paraffins, aromatics, and cycloalkanes) of hydrocarbon transportation fuels, the synthesis pathways of these biofuels are discussed in four separate sections. Furthermore, this review proposes three guiding principles for the design of practical hydrocarbon biofuels, providing insights into future directions for the development of viable biomass-derived liquid fuels.

Replacing All Fossil Fuels With Nuclear-Enabled Hydrogen, Cellulosic Hydrocarbon Biofuels, and Dispatchable Electricity

Abstract We describe a roadmap using three sets of technologies to enable base-load nuclear reactors to replace all fossil fuels in a low-carbon world. The technologies integrate nuclear, wind, solar, hydroelectricity and biomass energy sources. Base-load nuclear reactors with large-scale heat storage enable dispatchable electricity to the grid. The low-cost heat storage enables buying excess wind and solar electricity to charge heat storage for later electricity production while providing assured generating capacity. Nuclear hydrogen production facilities at the scale of global oil refineries produce hydrogen to replace natural gas (gaseous fuel) as a chemical feedstock and heat source. Single sites may have tens of modular reactors produced in a local factory to lower costs by converting to a manufacturing model for reactor construction. Nuclear heat and hydrogen convert cellulosic biomass into drop-in liquid hydrocarbon biofuels to replace fossil-fuel gasoline, diesel, jet fuel, and hydrocarbon feed stocks for the chemical industry. External heat and hydrogen inputs increase the quantities of biofuels that can be produced per unit of cellulosic feedstock, thus assuring sufficient biomass feed stocks to replace all crude oil without major impacts on food and fiber prices. The biofuel production system enables the removal of large quantities of carbon dioxide from the atmosphere that is sequestered as carbon char in the soil while recycling plant nutrients (potassium, phosphorous, etc.) to assure agricultural and forest sustainability.

Fuel-range liquid hydrocarbon products from catalytic deoxygenation of mixtures of fatty acids obtained from the hydrolysis of rapeseed oil

The combined hydrolysis–deoxygenation method reported here demonstrates the efficiency of hydrogen-free catalytic conversion of lipid-derived multi-fatty acids into renewable drop-in hydrocarbon biofuels.

The economic and environmental sustainability of converting Miscanthus to hydrocarbon biofuel by pyrolysis and catalytic hydrotreatment

Utilization of high-quality biomass resources such as Miscanthus is considered an effective way to alleviate energy shortages and develop a low-carbon energy economy. In this work, the economic benefits and environmental impacts of producing hydrocarbon biofuel by fast pyrolysis and catalytic hydrotreatment from Miscanthus were investigated, along with the differences in the utilization of biochar: combustion for heat supply (HS), soil amendment (SA) and upgrading to activated carbon (AC). The hydrocarbon biofuel mass yields of up to 23.3 % for all scenarios. The SA scenario had the lowest selling price of 6.89 Chinese Yuan (CNY) per liter. The HS scenario had the lowest total GHG emissions and fossil energy requirement (FED) of 19.2 gCO2e/MJ and 0.615 MJ/MJ, respectively. The AC scenario had the best net GHG emissions of −46.2 gCO2/MJ due to the replacement of the coal-based activated carbon pathway, but the higher energy consumption and capital investment limit its economic performance. Sensitivity analysis showed that fuel output had the most significant economic and environmental impacts. Optimizing the financing cost and system energy supply was a feasible and effective way to improve the economic and environmental sustainability of the bio-energy plant.

Electrolyte dependence for the electrochemical decarboxylation of medium-chain fatty acids (n-octanoic acid) into fuel on Pt electrode

The deoxygenation of organic acids, important biomass feedstocks and derivatives, to synthesize hydrocarbon products under mild electrochemical conditions, holds significant importance for the production of carbon-neutral biofuels. There is still limited research on the influential factors of the electrochemical decarboxylation reaction of medium-chain fatty acids. In this study, n-octanoic acid (OA) was chosen as the research subject to investigate the electrochemical decarboxylation behavior of OA on a platinum electrode, focusing on the influence of different alkali metal cations (Li+, Na+, K+), common anions (SO42−, Cl−), and electrolyte pH. It was found that KOH as an electrolyte exhibited the best performance for OA. Possibly, the larger size of K+ increased the alkalinity of the electrode surface, facilitating OA deprotonation. LiOH electrolyte reduced the solubility of OA, thereby inhibiting the decarboxylation reaction. SO42− exhibited a weak promoting effect on the decarboxylation reaction of OA, while Cl− showed no adverse effect although Cl− may adsorb on the electrode surface. Furthermore, unlike short-chain fatty acids, medium-chain OA can only achieve efficient decarboxylation under alkaline conditions due to its solubility properties. This study provides references and foundations for future efforts to enhance the efficiency of electrochemical decarboxylation synthesis of hydrocarbon biofuels from medium-chain fatty acids.

Preparation of rich hydrocarbon biofuels from cracking of waste cooking oil by CaO@Zn-KIT-6

The preparation of biofuel from bio-oils is of great importance to the development of renewable energy and to alleviate environmental pollution problems. In this work, acidic mesoporous silica Me-KIT-6 (Me = Zn, Al, Zr, Sn, Mn) were prepared and coated with basic metal oxides, and the CaO@Me-KIT-6 catalyst was obtained, and tested in the catalytic cracking reaction of waste oils and fats. The structure of the catalyst was characterized by X-ray diffraction, N2 physical adsorption and transmission electron microscopy (TEM), the acidity/basicity was characterized by chemisorption (NH3-TPD/CO2-TPD), and the structure-performance relationship in waste cooking oil catalytic cracking was investigated in detail. The results showed that CaO@Zn-KIT-6 catalyst had a good catalytic performance with a liquid biofuel yield of 66.30% and an acid value of about 23.35 mg KOH/g. The carbon distribution of the liquid biofuel concentrated in the range of C13-C18 with 67.80% of hydrocarbon products. The synthesized core-shell catalysts displayed multifunctional role resulting from tailored acid-base synergy.

Hydrogel-based heterogeneous-acid-catalysts for converting carbohydrates into the platform chemical: 5-hydroxymethylfurfural

Background5-hydroxymethylfurfural (5-HMF) is a significant platform chemical with the potential to be converted into hydrocarbon biofuels. Herein, a facile and reusable catalyst was investigated to synthesize 5-HMF from monosaccharides in a green solvent medium following eight green chemistry principles. MethodsA hydrogel-based heterogeneous acid catalyst was synthesized through photoreaction to determine its ability to dehydrate fructose in the invert sugar syrup into 5-HMF. The main structure of the hydrogel catalyst was formed with polyethylene glycol diacrylate (PEGDA), and this backbone structure was modified by 3-sulfopropyl methacrylate potassium salt (3SMP) and further acidified by 3M HCl to form PEGDA-3SMP-H with 32.54 mmole/g of H+ amount on the catalyst. Significant findingsWith the PEGDA-3SMP-H catalyst, fructose conversion of 85.80% with a 5-HMF yield of 46.99% could be attained at 120°C for a 24 h reaction time in an aqueous medium with the co-solvent gamma-butyrolactone (GBL), which is considered a green solvent medium. PEGDA-3SMP-M (M=metal) hydrogel catalyst was synthesized using 8 different metal ions fixed on the 3SMP through ion exchange. The catalytic ability sequence for synthesized hydrogel catalysts followed H+> Cr3+> Cu2+> Al3+> Ni2+> Co2+ > Cu+> Fe3+> Fe2+ for 5-HMF formation. The 5-HMF yield was improved with consecutive cycles of using a regenerated PEGDA-3SMP-H catalyst. In the first cycle, the 5-HMF yield was 36.86%; in the second and third cycles, it was 39.39% and 41.49%, respectively. The prepared heterogeneous catalyst is preferred in terms of industrial applications owing to its facile synthesis, recyclability, stability, simple separation method, low equipment corrosion, and minimization of final product contamination with acid catalysts.

What is the long-term demand for liquid hydrocarbon fuels and feedstocks?

Liquid hydrocarbons made from crude oil serve many functions: (1) a dense, easy-to-store, easy-to-transport energy source, (2) a method for daily-to-seasonal energy storage, (3) a chemical feedstock, (4) a chemical reducing agent and (5) a method to enhance high-temperature heat transfer in many furnaces and industrial processes. Liquid hydrocarbons can be produced and used without increasing atmospheric carbon dioxide levels if made from non-fossil feedstocks such as carbon dioxide or biomass. Understanding future liquid hydrocarbon demand is the starting point in assessing the viability of such options. Our assessment is that U.S. demand for liquid hydrocarbons is unlikely to go below the equivalent of 10 million barrels per day of crude oil but could be as high as 20 million barrels per day. The costs to replace liquid hydrocarbons increases rapidly at lower liquid hydrocarbon consumption rates. Hydrocarbon biofuels from cellulosic feedstocks can meet such demands if produced with large external inputs of heat and hydrogen. Options based on more limited feedstocks (starches, plant oils, sugars, etc.) can’t meet such demands.

Synergistic effect of bimetallic Fe-Ni supported on hexagonal mesoporous silica for production of hydrocarbon-like biofuels via deoxygenation under hydrogen-free condition

The need to explore a sustainable manner to produce hydrocarbon-like biofuel has attracted tremendous interest. A series of bimetallic catalysts comprised of Fe and Ni with different Ni loadings supported on hexagonal mesoporous silica (HMS) were synthesized for the production of hydrocarbon-like biofuel via deoxygenation (DO) reaction without the use of external hydrogen. The bimetallic 10Fe40Ni/HMS catalyst possesses a high conversion (96.1%) and selectivity towards C8-C20 hydrocarbon (91.8%) during the DO reaction. This is because the finely dispersed Fe and Ni consisting of NiO and NiFe2O4 demonstrate strong acidity along with higher amount of Brönsted-Lewis acid properties. The DO reaction of triglycerides with bimetallic Fe and Ni supported on HMS is a sustainable process to produce hydrocarbon biofuel.

A review in redressing challenges to produce sustainable hydrogen from microalgae for aviation industry

The global depletion of fossil fuel reserves and associated environmental crisis have led researchers to explore microalgal biomass which has been proven could be a promising potential as a renewable energy feedstock. Biofuels such as biodiesel, bioethanol and hydrogen can be produced from microalgae. Indeed, microalgae are best employed for hydrogen generation because the microalgal cells have high growth rate, can grow in diverse habitats and non-arable lands, can solve the fuel versus food conflicts as well as can capture and assimilate the atmospheric carbon dioxide. Hydrogen that is produced from microalgae is a clean and sustainable option to replace or complement the fossil fuel demands. The combustion of hydrogen produces only water and no greenhouse gases emission which will assuage the untoward effect on the environment. Moreover, it can also be used directly to generate electricity in fuel cells and engines. Another sector that is looking into hydrogen as a replacement for fossil fuels, is transportation inclusive of the aviation industry. The use of hydrogen as an energy carrier in airplanes offers several advantages, the burning of hydrogen in the jet engines would produce water vapour which will eliminate carbon-related emissions. However, this also comes with limitations such as new designs and larger tanks for hydrogen storage. Besides, the mechanisms of hydrogen production from microalgae are also sporadic and not well documented systematically, pre-empting researchers from exploring this new energy source inclusively. The factors affecting the microalgal hydrogen production are as well essential, but still poorly conceived, leading to the low outputs in terms of hydrogen yields from microalgae. Accordingly, this article reviews various mechanisms and methods employed for producing hydrogen from microalgae as well as the pre-treatment procedures for enhancing the rates of hydrogen production from microalgae. Furthermore, the enhancement of hydrogen yields through state-of-the-art techniques and genetic engineering the microalgal strains are also unveiled to materialize the hydrogen production at an industrial scale. This review intents to shift the paradigm from typical hydrocarbon biofuels to green hydrogen adoption, hastening the carbon neutrality target that benefits the natural environment the most.

Combustion reaction kinetics of biodiesel/n-butanol blends: Experiments in an ultrahigh-pressure rapid compression machine

Burning oxygenated hydrocarbon biofuels in engines is a viable path for saving energy and reducing carbon emissions. N-butanol and biodiesel are two representative biofuels and have attracted widespread interest. In this study, the blends of n-butanol and biodiesel (a waste cooking oil) with different n-butanol ratios (40%, 60%, 80% by volume) were adopted to study their autoignition characteristics in a newly developed ultrahigh-pressure rapid compression machine. The ignition delay times of the blends were precisely measured under wide pressures of 10/20/40/60 bar, equivalence ratios of 0.3/0.5/1.0, and a temperature range of 700–970 K. Experimental results show that the ignition delay time decreases with the increase of pressure and equivalence ratio at the investigated conditions regardless the blending ratios. It is also found that the ignition delay time becomes slightly longer with the increasing n-butanol ratio in the blends at temperatures below 820 K. However, as the temperature further increases, the ignition delay times of different blends get closer and has a crossover tendency. The composition of the biodiesel was quantitively analyzed and a surrogate fuel was developed. An optimized mechanism was proposed based on a documented detailed mechanism with 461 species and 18,217 reactions. Simulation results show that the optimized mechanism better captures the dependence of the measured ignition delay times on temperature, pressure, and blending ratios over the entire temperature range compared to the original mechanism. In the end, species evolution and sensitivity analysis were performed sequentially with the optimized mechanism to give kinetics insight into the chemical interaction between biodiesel and n-butanol. The experimental data and modeling results reported here provide a basis for understanding the combustion reaction kinetics of biodiesel/n-butanol blending fuels.

Environment-friendly deoxygenation of non-edible Ceiba oil to liquid hydrocarbon biofuel: process parameters and optimization study.

Non-edible Ceiba oil has the potential to be a sustainable biofuel resource in tropical countries that can replace a portion of today's fossil fuels. Catalytic deoxygenation of the Ceiba oil (high O/C ratio) was conducted to produce hydrocarbon biofuel (high H/C ratio) over NiO-CaO5/SiO2-Al2O3 catalyst with aims of high diesel selectivity and catalyst reusability. In the present study, response surface methodology (RSM) technique with Box-Behnken experimental designs (BBD) was used to evaluate and optimize liquid hydrocarbon yield by considering the following deoxygenation parameters: catalyst loading (1-9 wt. %), reaction temperature (300-380°C) and reaction time (30-180min). According to the RSM results, the maximum yield for liquid hydrocarbon n-(C8-C20) was found to be 77% at 340°C within 105min and 5 wt. % catalyst loading. In addition, the deoxygenation model showed that the catalyst loading-reaction time interaction has a major impact on the deoxygenation activity. Based on the product analysis, oxygenated species from Ceiba oil were successfully removed in the form of CO2/CO via decarboxylation/decarbonylation (deCOx) pathways. The NiO-CaO5/SiO2-Al2O3 catalyst rendered stable reusability for five consecutive runs with liquid hydrocarbon yield within the range of 66-75% with n-(C15 + C17) selectivity of 64-72%. Despite this, coke deposition was observed after several times of catalyst usage, which is due to the high deoxygenation temperature (> 300°C) that resulted in unfavourable polymerization side reaction.

Variation in sooting characteristics and cetane number of diesel with the addition of a monoterpene biofuel, α-pinene

Diesel fuel combustion generates soot particles, which are harmful for human health and the environment. To reduce soot emission, various solutions are proposed in the literature such as the use of metal-additives in fuels, fuel blending with biofuels, and the use of diesel particulate filters. This study analyses the effect of the addition of a bicyclic monoterpene hydrocarbon biofuel, α-pinene to diesel in different proportions on the fuel cetane number, sooting propensity, and the physicochemical properties of soot nanoparticles. The addition of 10% α-pinene to diesel exhibited a synergistic effect on sooting tendency and reduced the threshold sooting index of diesel by 21%, even though α-pinene is an unsaturated hydrocarbon, and had a minimal impact on cetane number, which reduced from 63.5 for diesel to 61.5 for the blended fuel. The influence of α-pinene addition to diesel on soot nanostructural characteristics and reactivity is determined through different characterization approaches including HRTEM, TGA, XRD, SEM-EDX, and EELS. The results indicate that α-pinene addition to diesel imposes curvatures in soot nanostructure, creates relatively smaller fringes (PAHs) in soot, and reduces soot aromatic content to improve soot oxidation rate.

Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ∼77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.

Production of jet fuel-range hydrocarbon biofuel by hydroxyalkylation–alkylation of furfural with 2-methylfuran and hydrodeoxygenation of C15 fuel precursor over a Ni/γ-Al2O3 catalyst: a reaction mechanism

A comprehensive reaction mechanism for hydrodeoxygenation of the C15-fuel precursor, which proceeds via ring hydrogenation, ring opening, dehydroformylation, and hydrodeoxygenation reactions.

Green Diesel Production by Catalytic Hydrodeoxygenation of Vegetables Oils.

Non-renewable fossil fuels and the air pollution associated with their combustion have made it necessary to develop fuels that are environmentally friendly and produced from renewable sources. In addition, global warming and climate change have brought to the attention of many countries the need to develop programs and reforms, such as the 2030 Agenda of the United Nations and the European Green Deal, that finance and promote the conversion of all socio-economic activities in favor of sustainable and environmentally friendly development. These major projects include the development of non-polluting biofuels derived from renewable sources. Vegetable oils are a renewable source widely used to produce biofuels due to their high energy density and similar chemical composition to petroleum derivatives, making them the perfect feedstock for biofuel production. Green diesel and other hydrocarbon biofuels, obtained by the catalytic deoxygenation of vegetable oils, represent a sustainable alternative to mineral diesel, as they have physico-chemical properties similar to derived oil fuels. The catalyst, temperature, hydrogen pressure, and the type of vegetable oil can influence the type of biofuel obtained and its properties. The main aspects discussed in this review include the influence of the catalyst and reaction conditions on the catalytic deoxygenation reaction.

An effective strategy for waste oil deoxygenation and upgrading for hydrocarbon biofuels production: A computational and experimental investigation

Waste oil, like waste cooking and acidic oil, are two promising carboxylic acids feedstocks that can be converted into hydrocarbons by the pyrolytic method, usually through DCO2 and DCO processes. DFT is employed to investigate the deoxygenation mechanism using octanoic acid as a model compound in this work. Additionally, pyrolysis of the above samples was carried out at atmospheric pressure, temperature below 773.15K. GC-MS, GC and TG-FTIR-MS test measures were used to analyze pyrolytic products. The DFT results reveal that pyrolysis conversion of waste oil was a direct and effective deoxygenation method. And high alkene content endowing pyrolytic oil greatly potential to upgrade for high-quality biofuel production. Finally, pyrolytic oil was upgraded by SAPO-11-Pd/C can increase the components of iso-hydrocarbons, further can faction cut to obtain three biofuel fractions. Fraction blending with fuels could decrease the cold filter plugging point of final fuels, dramatically improving the commercial value of pyrolytic oil and effectively solving the waste oil disposal problem.

Multiple-objective optimization in green fuel production via catalytic deoxygenation reaction with NiO-dolomite catalyst

This study investigates the multi-objective optimization of reaction parameters with response surface methodology (RSM) with central composite design (CCD) for the deoxygenation of waste cooking oil (WCO) over low cost-modified local carbonate mineral catalyst (NiO-Malaysian dolomite) into green fuel in the range of gasoline, kerosene and diesel. RSM was performed to study the effect of four operating parameters: temperature (390–430 °C), time (30–120 min), catalyst loading (1–10 wt%) and nitrogen flow rate (50–300 cm3/min). The results indicate that for maximum WCO conversion, deoxygenated oil and product yield, the optimum parameters of the deoxygenation reaction were at 410 °C, 60 min, 5.50 wt% of catalyst loading, and 175 cm3/min of N2. The green fuel properties testing (density, kinematic viscosity, flash point, cloud point, pour point, sulfur, carbon residue, cetane index, oxidation stability, acid value, iodine value and calorific value) and GC–MS analysis show that the product oil meets almost all the requirements of green diesel fuel and hydrocarbon biofuel standards for fuel application while the quadratic model proposed agreed with the experimental data (95% confidence) which indicates that the RSM can adequately predict the reaction products.

Promoting hydrocarbon production from fatty acid pyrolysis using transition metal or phosphorus modified Al-MCM-41 catalyst

Oleaginous biomass conversion to liquid hydrocarbon biofuels has emerged as an effective solution to the energy crisis and environmental problems. In this process, the removal of oxygenated compounds will directly affect the effectiveness of subsequent biofuel applications. Herein, deoxygenation of oleic acid by catalytic cracking was conducted using five various elements (La, Ni, P, Zr and Ce) modified Al-MCM-41. The related characterizations were carried out for these catalysts, including N2 physisorption, XRD, XPS, pyridine-FTIR and NH3-TPD techniques. The results showed the mesoporous structure of Al-MCM-41 was maintained after different modifications, and these catalysts greatly improved the hydrocarbons content and physiochemical properties of biofuels. The modified catalysts tended to facilitate the decarbonylation pathway and showed high selectivity to alkane and aromatic hydrocarbons. Besides, La/Al-MCM-41 presented excellent anti-coking activity. Ni/Al-MCM-41 showed both high dehydrogenation and deoxygenation activities. The Zr modification and Ce modification had a promotion effect in the deoxidizing activity of the catalyst, owing to the formation of oxophilic metal oxides. Noteworthily, P/Al-MCM-41 displayed the best deoxidizing performance due to its high Brönsted acidity, which caused the highest hydrocarbons content (82.30 %) and the lowest fatty acids content (around 0 %) of the biofuel. Moreover, the resulting biofuel had not only low oxygen content (3.88 wt.%) and acid value (5.47 mgKOH g−1) but also a high calorific value (44.50 MJ kg−1), which could be processed into green diesel. Hence, the catalytic cracking of fatty acid over P/Al-MCM-41 has excellent potential to produce high-quality renewable fuels.