Alcohol Fuels Research Articles

Hysteresis in the Vaporization-Controlled Inertial Regime of Nonpremixed Counterflow Spray Combustion

ABSTRACTThis numerical study uses a Lagrangian–Eulerian formulation employing the point-source approximation to investigate nonpremixed axisymmetric spray diffusion flames stabilized between a stream of hot air and a stream of nitrogen carrying a monodisperse spray of fuel droplets injected at a distance zl from the stagnation plane. The computations consider moderately large values of the relevant thermal Peclet number, such that the thickness of the mixing layer separating both streams is much smaller than zl. A one-step irreversible reaction is assumed between the fuel vapor and the oxygen of the air. Most of the computations consider the thermochemical, vaporization, and transport properties of dodecane, with additional results for the properties of methanol used to assess effects of higher fuel volatility. The analysis considers moderately small values of the liquid mass loading ratio at the injection plane, consistent with the stoichiometric value of the fuel-to-air mass ratio of the global oxidation reaction of typical hydrocarbon and alcohol fuels. Attention is mainly focused on inertial droplets with associated Stokes numbers St of order unity or larger, for which the droplets penetrate far into the oxidizer stream, vaporizing over distances of order zl and leading to combustion occurring outside the mixing layer. In this inertial regime, besides solutions involving a diffusion flame separating the fuel and oxygen with a well-defined peak temperature of the order of the adiabatic flame temperature, the analysis reveals, for the first time, the existence of flameless solutions with distributed combustion and small temperature increments from the air-side value. The two solutions are found to exist for the same sets of boundary conditions. Integrations for increasing values of St identify a value of the Stokes number St2 above which the vaporization rate is too small to support a diffusion-flame solution, while integrations for decreasing St lead to the identification of another value of the Stokes number St1 < St2 below which a distributed reaction cannot occur. In the intermediate hysteretic range St1 ≤ St ≤ St2 where two different steady solutions may exist, the type of solution encountered depends on the initial conditions imposed. The preliminary results suggest that future efforts targeting quantification of the flameless regime, which is found to be relevant in applications with larger droplets, would benefit from consideration of different possible gas-phase chemical kinetics, including cool-flame chemistry.

Coupling Ultrafine Pt Nanocrystals over the Fe2P Surface as a Robust Catalyst for Alcohol Fuel Electro-Oxidation.

Ultrafine Pt nanocrystals with an average particle size of 2.2 ± 1 nm coupled over the petaloid Fe2P surface are proposed as a novel, efficient, and robust catalyst for alcohol fuel electro-oxidation. The strong coupling effect of metal-support imparts a strong electronic interaction between the Fe2P and Pt interface that can weaken the adsorption of poisoning CO species according to the d-band theory. Defects and increased surface area of the petaloid Fe2P are beneficial to the Pt nanoparticle anchoring and dispersion as well as the charge transfer and reactant transportation during the electrochemical reaction. These features make the Pt-Fe2P catalyst system exhibit excellent catalytic activity, antipoisoning ability, and catalytic stability for alcohol fuel of methanol and ethanol electro-oxidation compared with a controlled Pt/C catalyst. The high catalytic efficiency is proposed to come from the strong coupling effect of Pt and petaloid Fe2P interface that can maintain the mechanical and chemical stability of the catalyst system. This kind of phosphide-supported ultrafine Pt nanocrystals will be a promising catalyst in fuel cells.

Study on Sensitivity Differences of Critical Spontaneous Ignition Temperature between Alcohol and Hydrocarbon Fuels Based on Reaction Pathway

In this article, the critical spontaneous ignition temperature of both hydrocarbon and alcohol fuel was acquired on a constant volume combustion bomb platform by slowly heating the inner charges, and then followed by using the CHEMKIN-PRO software to simulate the auto-ignition-dominated characteristic and parameter sensitivity of the two kinds of fuels. Results revealed that in different conditions, the critical spontaneous ignition temperature of methanol changed dramatically, with a maximum temperature of 50 K, while the counterpart temperature of n-heptane remained an invariable value of 553 K within a large changeable scope of temperature, and only a maximum temperature of 10 K was observed. The maximum difference of spontaneous ignition temperature between methanol and n-heptane reached 270 K. At the same time, a minimum difference of 170 K was obtained as well. The complete reaction of methanol requires 5 steps, involving 6 components and 11 elementary reactions. However, for the comparative part-n-heptane, more than 20 main self-ignition reactions were involved, which indicated that the whole reaction process of n-heptane has more reaction pathway branches and it was much more complicated compared to methanol. The differences of the reaction pathways triggered a considerable distinction of critical self-ignition temperature between the two charges, making a “step-by-step” spontaneous ignition combustion mode possible. In this way, a further high-efficient and clean combustion can be available to cater to much more stringent emission regulations in the future.

Hydrothermal conversion of biomass to higher alcohol fuels for compression ignition engine

Abstract Higher alcohol (C5/C6 alcohol) blended with diesel or bio-diesel is a promising alternative clean fuel for the compression ignition engine. The most important puzzle is the technology development of biomass to higher alcohol fuels. In this paper, a novel approach of hydrothermal conversion of biomass into C5/C6 higher alcohol fuels was proposed. High yield of higher alcohol fuels was obtained from the real biomass with the C5/C6 alcohol selectivity of 77% under the mild hydrothermal conditions. The properties of the produced higher alcohol fuels are similar to that of 0# diesel. The exhaust emission of compression ignition engine decreased vigorously by blending the higher alcohol fuels with diesel at weight ratio of 20/80.

Core–shell structured PtRu nanoparticles@FeP promoter with an efficient nanointerface for alcohol fuel electrooxidation

In this study, a bottleneck was overcome for direct alcohol fuel cells using state-of-the-art PtRu catalysts for alcohol fuel oxidation. Herein, a core-shell structured PtRu catalyst system based on the emerging promoter FeP was developed that showed excellent catalytic performance for the oxidation of alcohol fuels. The surface spectrometric analysis and morphology observation confirmed the formation of a nanointerface of the PtRu shell and FeP core hybrid catalyst (PtRu@FeP), and efficient ligand effects and electronic effects were found to result from the noble metal active sites and adjacent promoter in the core-shell structure. The facile formation of oxygen-containing species and the strong electronic effects could activate the Pt active sites, leading to high catalytic performance. High anti-CO poisoning ability was found for this catalyst system when compared with the case of the benchmark commercial PtRu/C catalyst (110 mV less and 60 mV less as evaluated by the peak and onset potentials for CO oxidation, respectively). The PtRu@FeP catalysts also exhibited much higher catalytic activity and stability when compared with commercial and home-made PtRu/C catalysts; specifically, the peak current density of the PtRu@FeP 1 : 1 catalyst was about 2 and 3 times higher than those of the commercial PtRu/C catalyst and home-made PtRu/C for the oxidation of the alcohol fuels methanol and ethanol; moreover, high catalytic efficiency, improved by 2 times, was found, as expressed by the specific activity. Excellent catalytic stability as evaluated by 1000 cycles of cyclic voltammetry measurements was also demonstrated for the PtRu@FeP catalysts. The high catalytic performance could be attributed to the intimate nanointerface contact of the core-shell structured PtRu shell over the FeP core via a bi-functional catalytic mechanism and electronic effects based on the ligand effect in this catalyst system. The current study is a significant step to increase the PtRu catalytic performance via nanointerface construction by a core-shell structure on a novel promoter for direct alcohol fuel cells.

The influence of mixing ratio of low carbon mixed alcohols on knock combustion of spark ignition engines

Alcohol fuels, owing to the characteristics of oxygen-containing and high octane number, are considered as one potential alternative fuel additive in spark ignition (SI) engines. In this paper, the ethanol and n-butanol are blended with gasoline to form the new low-carbon mixed alcohols-gasoline blended fuels. The effect of different mixing proportions of ethanol and n-butanol in gasoline on knock combustion and fuel economy of SI engine was studied by experiment and simulation. The results showed that with the increase of n-butanol ratio, brake specific fuel consumption (BSFC) increase, but knock index (KI) and knock intensity decrease. Moreover, crank angle delays under the same knocking condition when the engine fueled with E5-Bx and B5-Ey fuel, and the crank angle is delayed more significantly with the increase of engine speed. In addition, when the ethanol and n-butanol are blended as the same proportion in gasoline (i.e. x = y), the KI and knock intensity of E5-Bx fuel is lower than that of B5-Ey, which indicates that the B5-Ey fuel has better antiknock property. But the BSFC of B5-Ey is slightly greater than that of E5-Bx under the same operating condition, that is, the B5-Ey fuel has higher fuel consumption.

Perlaksanaan Sifat-Sifat Minyak Alkohol dalam Sistem Gasoline Enjin: Tinjauan

Rapid depletion of petroleum resources had raised the awareness of reducing the dependency on the fossil fuels by means of alternative fuels. Alcohols had emerged as the most competitive candidate among the well-known alternative fuels because it can be produced from renewable resources such as waste material. Some of the examples of alcohols are methanol, ethanol, and butanol. Each of these alcohols has the capability for its utilization in vehicles due to its cheap price than the other alcohol and has similar chemical properties to gasoline and diesel. Currently, only few research papers had discussed the alcohol fuel properties in the collective form of information including adverse effect of alcohol fuel usages and its responses in spark ignition engine performance and emissions. Therefore, this paper is focusing on the physical and chemical properties of alcohol fuels with recent literature data specifically for spark ignition engines. In addition, the usages on the properties of alcohol fuel to the current available spark ignition engine will also be review in this paper. Advantages and disadvantages of alcohol fuel usages are also summarized. This review indicates that continuous research and development still need to be done especially on alcohol fuel properties as it will give greater engine performance and better emissions.

Copper nanocavities confine intermediates for efficient electrosynthesis of C3 alcohol fuels from carbon monoxide

The electrosynthesis of higher-order alcohols from carbon dioxide and carbon monoxide addresses the need for the long-term storage of renewable electricity; unfortunately, the present-day performance remains below what is needed for practical applications. Here we report a catalyst design strategy that promotes C3 formation via the nanoconfinement of C2 intermediates, and thereby promotes C2:C1 coupling inside a reactive nanocavity. We first employed finite-element method simulations to assess the potential for the retention and binding of C2 intermediates as a function of cavity structure. We then developed a method of synthesizing open Cu nanocavity structures with a tunable geometry via the electroreduction of Cu2O cavities formed through acidic etching. The nanocavities showed a morphology-driven shift in selectivity from C2 to C3 products during the carbon monoxide electroreduction, to reach a propanol Faradaic efficiency of 21 ± 1% at a conversion rate of 7.8 ± 0.5 mA cm−2 at −0.56 V versus a reversible hydrogen electrode. The production of higher alcohols is very valuable because of their high volumetric energy density. Now, Sargent, Sinton and co-workers report the design of copper nanoparticles with tailored nanocavities that promote n-propanol formation by the coupling of C2 and C1 intermediates inside the cavity.

Understanding spray and atomization characteristics of butanol isomers and isooctane under engine like hot injector body conditions

Spray characterization of GDI injectors is of significant importance as it influences the overall engine performance and its emissions. Spray morphology under various engine like conditions influences engine design. Vapor bubbles are formed inside liquid droplets when hot fuel is injected into the sub-saturation pressure conditions leading to flash boiling of GDI sprays. This dramatically alters the spray morphology and therefore needs to be understood thoroughly. A spray undergoing flash boiling experiences catastrophic breakup of the liquid jet resulting in fine atomization which in turn enhances droplet evaporation. However, spray structure is significantly altered under such conditions. In the present work, effect of hot injector body was studied to understand flash boiling behaviour of alcohol fuels and which were then compared to isooctane spray characteristics under similar conditions. Experiments were performed at five different injector temperatures: 298 K, 373 K, 423 K, 473 K and 523 K. Significant difference in spray morphology was observed when the fuel temperature was increased. Reduction in overall spray cone angle was observed with increase in temperature for all the fuels considered in this study. Vapour penetration lengths increased with increase in temperature, whereas liquid penetration initially increased and then decreased significantly due to higher evaporation rate. PDPA data showed significant reduction in SMD and AMD when the temperature was raised from 298 K to 423 K. SMD for n-butanol, isobutanol and isooctane reduced by 58.45%, 54.51% and 64.87%, respectively. Similarly, AMD reduced by 65.58%, 57.12% and 74.24%, respectively.

Electrochemical and Operando Spectroscopic Studies of Sr2Fe1.5Mo0.5O6‐δ Anode Catalysts in Solid Oxide Fuel Cells Operating with Direct Alcohol Fuels

AbstractThe front cover artwork is provided by the Eigenbrodt (Villanova University, USA) and Walker (Montana State University, USA) research groups. The cover picture shows a background image of the operando spectroscopy apparatus focusing the Raman laser onto the solid oxide fuel cell's Sr2Fe1.5Mo0.5O6‐δ anode catalyst at 800 °C. The forefront of this cover photo showcases Raman spectra that reveal that the anode catalyst has the ability to resists detrimental graphite deposits during fuel cell operation with direct alcohol fuels. Read the full text of the Article at 10.1002/celc.201800827.

Theoretical Study of the Formation Methane in the Reaction of Methyl Radical with Propanol-2

Theoretical Study of the Formation Methane in the Reaction of Methyl Radical with Propanol-2

Biofuel Powering of Internal Combustion Engines: Production Routes, Effect on Performance and CFD Modeling of Combustion

The use of liquid or gaseous biofuels in reciprocating internal combustion engines (ICEs) is today a relevant issue as these systems are largely diffused for both steady power generation and transportation due to their flexibility and easiness of use. The improvement and perfect control of the combustion process under non-conventional fuelling is mandatory to achieve high-energy efficiency without substantial changes to the architecture or the fuel supply system. In this perspective, the detailed characterization of multiphase reacting systems achievable though computational fluid dynamics (CFD) may give a decisive contribution. However, the assessed combustion models used for fossil fuels (diesel oil, gasoline, methane), tuned on the ground of a massive amount of experimental data, often results poor in predicting the actual behaviour of renewable fuels whose composition and properties may change also according to technology for their production. Present work aims at filling some existing gaps in biofuel combustion modeling by performing investigations on two representative engine cases, for their characterization and performance enhancement. Two approaches are followed, namely through reduced chemical kinetics coupled with turbulence within a coherent flame schematization, and through a turbulent species transport approach with detailed kinetics. Simulations are first carried out on a compression ignition (CI) ICE. The formulation of a 3D CFD model is described to reproduce the performance of this engine in a dual-fuel mode with premixed syngas from biomass gasification and a biodiesel pilot injection leading to self-ignition. Pollutants formation and energy efficiency are calculated as syngas amount and the biodiesel start of injection (SOI) are varied. Attention is then focused on the implementation of renewable alcohol fuels (ethanol and butanol), as these lasts are receiving large interest due to low production costs. A validated reduced kinetic mechanism for PRF-ethanol-butanol combustion performs well in multi-component oxidation conditions, as well as in neat fuel oxidation conditions, in terms of ignition delay time, laminar flame speed and HCCI combustion conditions. The paper shows that CFD, even at different level of approximation, may describe into detail the combustion process and provide important guidelines for the design of new generation ICEs fuelled by biofuels.

Surface‐Roughened Pt‐Decorated Pd Nanoparticles as Efficient Electrocatalysts for Direct Alcohol Fuel Cells

Platinum‐decorated Pd nanoparticles (NPs) of Pd100–xPtx (x = 30, 40 and 50) are synthesised by galvanic replacement of Ag by Pt using a Pd@Ag core–shell structure as a template. The Pd@Ag core–shell material is prepared by chemical reduction of Ag+ over Pd NPs, with further Ag being galvanically replaced by Pt to form Pd100–xPtx NPs. The Pd100–xPtx NPs are characterised using optical absorption spectroscopy with surface plasmon resonance (SPR), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The NPs are adsorbed onto vulcan carbon (Pd100–xPtx/C) for further characterisation and electrochemical studies. The materials are characterised using powder X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) studies. The CV studies indicate the absence of silver in the synthesised materials. The electrochemical oxidation of methanol and ethanol are carried out by cyclic voltammetry studies. The results show that Pd100–xPtx/C materials are good catalysts for methanol oxidation reactions (MORs) and ethanol oxidation reactions (EORs), with lower oxidation potentials and higher mass activities than commercial Pt/C catalysts. Among these materials, Pd50Pt50/C has a methanol oxidation potential of 0.18 V, with good mass activity, and the Pd70Pt30/C material is an efficient EOR catalyst, with higher mass activity than commercial Pt/C catalysts.

Direct Alcohol‐Fueled Low‐Temperature Solid Oxide Fuel Cells: A Review

AbstractLow‐temperature solid oxide fuel cells (LT‐SOFCs, operating temperature≤600 °C) are advantageous in potential applicability, affordability, and durability compared to conventional SOFCs (operating temperature: 800–1000 °C). Direct operation of LT‐SOFCs on liquid alcohol fuels can further improve their portability as well as accessibility to the fuel. In this review, we overview the results of LT‐SOFCs directly fueled by liquid alcohols that operate at 600 °C and below. Fundamentals regarding operation principles, losses, as well as reactions associated with liquid alcohol‐fueled LT‐SOFCs are presented. The materials, structures, and fabrication processes of cell components, namely anode, electrolyte, and cathode, are mainly reviewed. The electrochemical performances of alcohol‐fueled LT‐SOFCs are also summarized and compared with those of H2‐fueled LT‐SOFCs.

Electrochemical Synthesis of an Alcohol-Tolerant Platinum-Based Material for the Oxygen Reduction Reaction

A prevalent problem in direct alcohol fuel cells (DAFCs) is the crossover of alcohol, which usually floods the cathode compartment and its effects reflect in the decrease of cell performance in terms of efficiency. This is due to the interference of alcohol molecules on the electrocatalyst surface during the oxygen reduction reaction (ORR), causing a competition between them. As this consequence is directly related to the low selectivity of catalyst, an alcohol-tolerant material is necessary; in order to inhibit its deactivation because of oxidized species on the electrode surface. Some approaches to avoid such decrease in activity consists in the incorporation of a secondary metal in the electrocatalyst with the aim of promoting selectivity. Furthermore, the implementation of bimetallic materials leads to the decrease in the Pt loading, as it represents a higher cost of the catalyst; in summary, the best option consists in preparing bimetallic mixtures. In the present work, Pt and Pt/Ag materials were synthesized by cyclic voltammetry (VC) and its behavior in basic medium was evaluated for the oxygen reduction reaction (ORR) in absence and in presence of 0.1 M of methanol, ethanol, ethylene glycol and glycerol. The results demonstrated that the use of PtAg as cathode electrode achieved higher selectivity and better performance compared with Pt catalyst in the presence of alcohol fuels. While Pt preferred to oxidize these fuels instead of taking the ORR, PtAg only carried out the ORR. The activity of PtAg catalyst towards oxygen reduction reaction resulted in an overpotential of 90 mV compared with pure Pt, after the electrochemical activation. Pt showed no tolerance to any tested alcohol-based fuels but, PtAg exhibited excellent tolerance to methanol, ethanol and ethylene glycol.

Characterization of New Biological Membranes for Their Possible Application in Electrolytic and FUEL CELLS at Low Temperature

The present work describes the characterization of new protonic exchange biological membranes, using “maguey” as raw material, with the aim of providing a new alternative due to the fact that, over the past few years, Nafion (perfluorinated polymer) has been the most commonly utilized as polymer membrane in various application: Direct Alcohol Fuel Cell, Methanol and hydrogen [1], as well as electrolysers. In this sense, has been development different modifications to the Nafion [2] membrane without replacing it completely. The organic membrane was based on the use of the “penca” cuticle. The cutine, the main component of the cuticle, is a polymer that consists of long chain fatty acids by ester-type bonds [3]. The epidermis of the plant is mainly responsible for gas exchanging through stomata which allows the cuticle to act as an interface between the cell and the external environment, thus allowing the proton exchange in the electrochemical process. There were various types of treatments to the organic membranes, such as: mechanical activations, acidic, alkaline, polymeric coatings, electrical and thermal. With the purpose of obtaining hydrogen and oxygen in an electrolyzer. It was noted that the viable treatments for activation are both the mechanical and thermal, highlighting the thermal treatment as ideal due to the higher average life span and obtaining current intensity, in comparison with the mechanical treatment, which represents a lower average life span. In addition, the bio-membrane is coupling in a methanol fuel cell results competitive with commercial Nafion membrane, as shown in Table 1. There were different techniques to know the morphology of the membrane, as well as their functional groups (SEM, Infrared, Raman), so the incorporation in an electrolytic cell and fuel show similar results to the Nafion membrane, which is a viable alternative to replace the Nafion.

Synthesis and Caracterization of ZrO2/PANI Composite As Electrocaltalyst Support for Direct Alcohol Fuel Cells

Carbon Vulcan has been widely used as electrocatalyst support despite its susceptibility to electrochemical corrosion. Zirconium oxides are a promising alternative due to its corrosion resistance in acid and alkaline media, the main drawback of these materials are their low conductivity and surface area. Therefore, an alternative to overcome this is, to develop a composite with conducting polymers (CPs) like polyaniline. conducting polymers fulfill the main requirements for fuel cell application: high surface area, to obtain high metal dispersion, suitable porosity, high electrical conductivity, and high stability under fuel cell operational conditions. In this work Pt as electrocatalyst was supported by chemical reduction onto nanostructured ZrO2 followed by chemical deposition of PAni. Every element of the composite was characterized individually. Zirconium oxide was synthesized by sol-gel technique, using different calcination temperatures (300 and 350 °C), TEM analysis shows that zirconia has a particle size between 100 and 1000nm in a disperse pattern with some agglomerates, the X ray diffraction pattern correspond to an amorphous structure. The surface area was determined by nitrogen adsorption and goes from 60 and 160m2/g depending on calcination temperatures. PAni was synthetized by chemical method and showed different morphology depending on incubation temperature and with different corresponding conductivity capacities. When the bath temperature was at -16°C a notorious microfibrillar pattern could be seen by SEM analysis, but the sample color was not characteristic of emeraldine (conductor PAni salt). However, when bath temperature was 2 and 20°C, the color allowed to confirm that emeraldine was the PAni phase presented but with porous nanoparticular morphology. From previous experimental work it is clear that Pt/ZrO2 has a superior performance towards methanol oxidation reaction than Pt/C (20%), especially on alkaline conditions. In this work, the synthesis of PAni over Pt/ZrO2 does not affect the electrocatalytic activity neither in acid or alkaline conditions. Therefore, the low surface area of zirconium could be properly compensated with this conductive polymer. However, stability tests are necessary to consider this composite as adequate substitute for carbon based electrocatalysts supports in direct alcohol fuel cells.

Alcohol dehydrogenase as bioanode for methanol and ethanol oxidation in a microfluidic fuel cell

In this work, an enzymatic bioanode was developed using functionalized carbon nanofibers for the immobilization of alcohol dehydrogenase enzyme, using Nafion, tetrabutylammonium bromide and glutaraldehyde onto Toray carbon paper. Two alcoholic fuels, methanol (MeOH) and ethanol (EtOH) were used to demonstrate the oxidation versatility of the electrode created as well as being able to convert energy from these fuels using an air-breathing microfluidic device. Commercial Pt/C (30% E-TEK) onto carbon nanofoam (Marketech Inc) was using as inorganic cathode. Carbon nanofibers were previously treated with nitric acid to produce oxygen-containing functional groups in order to facilitate the enzyme immobilization. A phosphates buffer solution pH 8.86 was used as electrolyte. The use of ethanol as fuel shows a better performance obtaining 8.643mAcm−2 and 0.847 V as current density and open circuit voltage respectively, compared to that use methanol as fuel (2.655 mAcm−2 and 0.567V).

Studies on an Ultrasonic Synthesis, Characterization, and Thermodynamic Analysis of New Metal Nanocatalysts Applied Directly to Alcohol Fuel Cells

In this study, for direct methanol fuel cell (DMFC), PtCu and PtOs nanocatalysts were prepared using the ultrasound-assisted method to directly enhance methanol fuel cell (DMFC) performance. Ultrasonic applications are safe from laboratory to industry and from environmental impacts on energy applications. It was aimed to strengthen Pt/Cu and Pt/Os dispersion with platinum nanocatalyst directly stabilized by copper (Cu) and osmium (Os) ligands and to increase active surface area by using ultrasonication method. Then, these prepared monodisperse nanomaterials for characterization techniques have been used as X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and induced paired plasma optical emission spectrometry. The results obtained show that methanol crossover has been found to decrease significantly when reaching the value of the large stable open-circuit voltage of the DMFC under the ultrasound-assisted system. Polarization performance does not change significantly. For this reason, in an ultrasound-assisted process, increased energy density of DMFC in high methanol concentration improves operating performance. The membrane electrode assembly having PtOs and PtCu provided the highest performance with the peak power density of 0.582 and 0.489 $$\hbox {mW/cm}^{2}$$ at a temperature of 120 $$^{\circ }\hbox {C}$$ and concentration methanol of 4 M, respectively. Based on the results of the stability tests, a commercial cathode catalyst was developed from PtCu and PtOs.

On the effects of fuel type, fuel mixing and sulphur content on the performance of a high-temperature membrane reactor adapting liquid fuel: A numerical study

Abstract The study investigates numerically oxygen permeation and combustion and emission characteristics of a button-cell high-temperature membrane reactor (HTMR) handling different grades of liquid fuels including methanol (CH3OH), ethanol (C2H5OH), benzene (C6H6), n-octane (C8H18) and gas oil (C16H29). Effects of mixing different grades of fuels on the HTMR performance are also investigated. A disc-shaped La2NiO4 (LNO) ceramic membrane is used. A plain orifice atomization model is used for numerical calculations of liquid fuel atomization. Fuel is introduced along with CO2 at sweep inlet and air is introduced at fed inlet of the membrane reactor. 2-D axisymmetric mesh was constructed, and simulations were performed using Ansys-Fluent Workbench 15.0. All calculations were performed at fixed inlet gas temperature of 1173 K, fixed inlet fuel temperature of 300 K and fixed molar fuel concentration of 5% in the vapor phase. For single fuel operation, the highly reactive light oxygenated alcohol fuels resulted in stoichiometric combustion with better oxygen flux compared to rich combustion and low oxygen flux for heavier fuels. Gas oil fuel showed poor fuel evaporation, poor mixing with the sweeping gas, and low reaction rate. Trying to improve the performance of the HTMR while burning heavy fuels, three mixtures of three fuels containing gas oil fuel were tested. The compositions of the mixtures 1, 2 and 3 are 2%C6H6/2%C8H18/1% C16H29, 2%CH3OH/2%C8H18/1%C16H29 and 2%CH3OH/2%C6H6/1%C16H29. The results showed better performance of the HTMR when burning gas oil fuel in a mixture than burning it purely. Mixtures 1 and 2 resulted in about three times and mixture 3 resulted in about six times the oxygen flux value when using pure gas oil fuel. The maximum temperature with the reactor has been improved from 1208 K for gas oil fuel to 1383 K, 1372 K and 1557 K for mixtures 1, 2 and 3. Using methanol as fuel additive significantly improve the performance of the HTMR, even better than burning it alone, and enables the use of heavier fuels in HTMR applications. Based on that, the performance of the HTMR was evaluated while burning mixtures of two fuels, one of them is methanol. Three mixtures were considered (mixtures 4, 5 and 6) with the compositions of 4%CH3OH/1%C6H6, 4%CH3OH/1%C8H18 and 4%CH3OH/1%C16H29. Mixing methanol with benzene (mixture 4) resulted in the highest obtained oxygen permeation flux among the tested ranges of pure and mixed fuels. Locations where sulfates compounds are created within the HTMR with respect to the membrane are calculated for proper control of membrane operation while utilizing heavy gas oil fuel with Sulphur content.