Methanol Gas Research Articles

Modeling Analysis of Different Renewable Fuels in an Anode Supported SOFC

It is expected that fuel cells will play a significant role in a future sustainable energy system due to their high energy efficiency and possibility to use as renewable fuels. Fuels, such as biogas, can be produced locally close to the customers. The improvement for fuel cells during the past years has been fast, but the technology is still in the early phases of development; however, the potential is enormous. A computational fluid dynamics (CFD) approach (COMSOL MULTIPHYSICS) is employed to investigate effects of different fuels such as biogas, prereformed methanol, ethanol, and natural gas. The effects of fuel inlet composition and temperature are studied in terms of temperature distribution, molar fraction distribution, and reforming reaction rates within a singe cell for an intermediate temperature solid oxide fuel cell. The developed model is based on the governing equations of heat, mass, and momentum transport, which are solved together with global reforming reaction kinetics. The result shows that the heat generation within the cell depends mainly on the initial fuel composition and the inlet temperature. This means that the choice of internal or external reforming has a significant effect on the operating performance. The anode structure and catalytic characteristic have a major impact on the reforming reaction rates and also on the cell performance. It is concluded that biogas, methanol, and ethanol are suitable fuels in a solid oxide fuel cell system, while more complex fuels need to be externally reformed.

Anhydrous proton exchange membrane operated at 200 °C and a well-aligned anode catalyst

To elevate the operating temperature of proton exchange membranes (PEMs) to 200 °C under anhydrous conditions, in the current work, the protic ionic liquid, 1-methylimidazolium trifluoromethanesulfonate ([MIm][Tfo]), was used as an anhydrous proton conductor and integrated with a superabsorbent host polyacrylamide/polyethylene glycol interpenetrated polymer network (PAM/PEG IPN) by doping and adsorbing methods. The resultant membranes could be operated up to 200 °C under nonhumidified conditions, showing a proton conductivity of 17.02 and 10.37 mS cm−1 at 150 °C for [MIm][Tfo] doped and adsorbed PAM/PEG IPN membranes, respectively. Because of the intrinsic nature of the PAM/PEG IPN superabsorbent, the loaded [MIm][Tfo] could not leak from the PEM systems even under high temperatures and pressures. A percolation phenomenon was observed because of the formation of proton-conducting channels for proton transfer. The new PEM presented a maximum tensile strength of 12.4 MPa and elongation of 1068% and 10.0 MPa and 1594% for the membranes by doping and adsorbing methods, respectively. To increase the electrocatalytic activity and decrease the cost of the catalyst, we also developed a well-aligned low-Pt anode catalyst using a fir template, exhibiting high activity for methanol oxidation reaction. When the methanol gas was bubbled into [MIm][Tfo] around the anode catalyst parallel to its channels, the oxidation current density at 200 °C was 8.7 times larger than that at 25 °C, whereas it was 5.4 times larger at 200 °C than that at 25 °C perpendicular to its channels. The membranes and efficient catalysts are possible candidates for direct methanol fuel cells that operate at high temperature and anhydrous conditions. The use of superabsorbents opens up a new route to high-temperature PEMs.

A comparative study of carbon dioxide capture capabilities between methanol solvent and aqueous monoethanol amine solution

Simulations have been performed to compare the performance of CO2 capture power between 98.5 wt% methanol solvent and 30 wt% MEA aqueous solution. A general purpose chemical process simulator, PRO/II with PROVISION release 8.3 was used for the modeling of CO2 capture process. For the simulation of CO2 capture process using methanol as a solvent, NRTL liquid activity coefficient model was used for the estimation of the liquid phase non-idealities, Peng-Robinson equation of state model was selected for the prediction of vapor phase non-idealities, and Henry’s law option was chosen for the prediction of the solubilities of light gases in methanol and water solvents. Amine special thermodynamic package built-in PRO/II with PROVISION release 8.3 was used for the modeling of CO2 capture process using MEA aqueous solution. We could conclude that the 30 wt% of MEA aqueous solution showed better performance than the 98.5 wt% methanol solvent in CO2 capture capability. Through this study, we tried to compare the differences between the two processes from the aspects of capital and operating costs using a commercial process simulator. This will guide the optimal process design in the carbon dioxide capture process.

Hydrogen production from gas phase photocatalytic decomposition of methanol using Pt‐supported nanocrystalline WO3 films

AbstractNanocrystalline uniform thin films of WO3 were fabricated by polymer assisted deposition (PAD) varying the polymer concentration in the precursor solution and the calcination temperature with controlled heating rate. The precursor solution was prepared using peroxo‐tungstic acid and polyethylene glycol (PEG300) in water. The microstructure and morphology of the WO3 thin films were studied by the XRD, AFM techniques. Nanocrystalline thin films were obtained with 20% of polyethylene glycol (PEG300) and at a calcination temperature of 350 °C. The hydrogen generation process on platinized WO3 specimens was investigated using a six channel quadrupole mass spectrometer at a real‐time scale with gaseous methanol under visible (400‐700 nm), UVA (300‐400 nm), and UVB (240‐300 nm) light illumination. The use of WO3 as photocatalyst opens the way for solar light powered photocatalytic hydrogen production. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Photocatalytic evaluation of TiO 2/nylon systems prepared at different impregnation times

TiO 2/nylon fabrics were investigated for methanol degradation under UV light irradiation. TiO 2 Degussa P-25 was supported on nylon by immersing the nylon in sol–gel TiO 2 and silicone. The TiO 2 layers on the nylon were explored as a function of the time of immersion, impregnation agent and the type of nylon fabric used. The energy diffuse spectroscopy (EDS) and infrared spectroscopy (ATR-FTIR) confirmed the presence of TiO 2 bonded to the nylon fabrics. Optical microscopy (OM) and scanning electron microscopy (SEM) show a more uniform distribution of TiO 2 on nylon fabrics prepared by immersion in sol–gel as compared to the silicone method. The most suitable photodegradation of gaseous methanol by TiO 2/nylon samples was obtained by sol–gel samples prepared by 24 h immersion time.

Terahertz heterodyne spectrometer using a quantum cascade laser

A terahertz (THz) heterodyne spectrometer is demonstrated based on a quantum cascade laser (QCL) as a local oscillator (LO) and an NbN hot electron bolometer as a mixer, and it is used to measure high-resolution molecular spectral lines of methanol (CH3OH) between 2.913–2.918 THz. The spectral lines are taken from a gas cell containing methanol gas and using a single-mode QCL at 2.9156 THz as an LO, which is operated in the free running mode. By increasing the pressure of the gas, line broadening and saturation are observed. The measured spectra showed good agreement with a theoretical model.

Controlled growth of SnO 2 nanorods clusters via Zn doping and its influence on gas-sensing properties

Zn-doped SnO 2 nanorods clusters with controllable size (the length and the diameter of nanorods) are prepared by adjusting the Zn 2+ concentration in the precursor solution using a facile hydrothermal process. The as-synthesized samples are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy (EDS). With an increase of the molar ratio of Zn 2+/Sn 4+ in the solution, the length of the Zn-doped SnO 2 nanorods gradually increases, and the average length of the nanorods reaches the maximum of 239 nm at 0.133. However, when the molar ratio of Zn 2+/Sn 4+ is increased to 0.2, the length of the nanorods decreases accompanied with the generation of Zn 2SnO 4 phase. The Zn-doped SnO 2 nanorods grow along the [1 1 2] direction and the possible growth mechanism is proposed. The gas-sensing properties of the obtained Zn-doped SnO 2 samples are tested towards methanol gas. And, it is found the composition–morphology-performance relationship that the more the doping content of Zn, the longer the length of nanorods and the higher the response to methanol, which is significant for the preparation and the design of gas-sensing materials with the high performance.

Aluminum-mesoporous silicon coplanar type structure for methanol gas sensing

In this paper, we treat gas sensing properties of porous silicon layer (PSL) towards methanol (MeOH) gas. For this purpose an Al/meso-PS/c-Si/meso-PS/Al coplanar type structure has been achieved. The current flowing throughout the structure enhances as MeOH concentration increases. The experimental values of the effective electrical conductivity are estimated from the serial resistance ( R s) of the structure. The values of R s are deduced from the dark I– V characteristics. We found that the conductivity increases as MeOH concentration increases. The sensor exhibits quasi-reproducible I– V characteristics subsequent to several MeOH adsorption/desorption cycles. The MeOH molecules are desorbed by a simple nitrogen flushing. Additionally, Fourier transform infrared (FTIR) spectroscopy revealed that the surface of meso-PS turns back to its initial structure surface once removing MeOH molecules, indicating a reversible behavior of the sensor. Effective medium theory (EMT) was used to model optical and structural features of the PSL. From FTIR spectra, we deduced the experimental refractive index values of the meso-PSL as a function of MeOH, which agree with theoretical values obtained using the Bruggeman effective medium theory (EMT).

Enhancement of Methanol Gas Sensitivity of Cu Intermediate ITO Film Gas Sensors

Sn doped (ITO) and ITO/Cu/ITO (ICI) multilayer films were prepared on glass substrates with a reactive radio frequency (RF) magnetron sputter without intentional substrate heating, and then the influence of the Cu interlayer on the methanol gas sensitivity of the ICI films were considered. Although both ITO and ICI film sensors had the same thickness of 100 nm, the ICI sensors had a sandwich structure of ITO 50 nm/Cu 5 nm/ITO 45 nm. The ICI films showed a ten times higher carrier density than that of the pure ITO films. However, the Cu interlayer may also have caused the decrement of carrier mobility because the interfaces between the ITO and Cu interlayer acted as a barrier to carrier movement. Although the ICI films had two times a lower mobility than that of the pure ITO films, the ICI films had a higher conductivity of due to a higher carrier density. The changes in the sensitivity of the film sensors caused by methanol gas ranging from 50 to 500 ppm were measured at room temperature. The ICI sensors showed a higher gas sensitivity than that of the ITO single layer sensors. Finally, it can be concluded that the ICI film sensors have the potential to be used as improved methanol gas sensors.

A dual-fuel compression ignition engine – distinctive features

For many years in the Department of Automobiles and Internal Combustion Engines in Technical University of Radom there are carried out investigations on dual-fuel compression ignition engine in which the ignition is initiated by a pilot diesel oil dose and the applied main fuels have properties similar to those applied in spark ignition engines. The tested fuels were methanol, ethanol, LPG and natural gas. Analysis of the obtained results allowed to make some generalizations and to determine advantages as well as problems which should be solved for higher efficiency, power and durability. The paper will present information on efficiency, power, toxic exhaust emission and chosen parameters of combustion process of a dual-fuel compression ignition engine as well as on a difficult to control – knock combustion which may result in lower engine durability and piston crank mechanism failure.

Submegahertz frequency stabilization of a terahertz quantum cascade laser to a molecular absorption line

The frequency of a terahertz quantum-cascade laser is stabilized to the absorption line of methanol gas at a frequency of 2.55 THz. The method is based on frequency modulation of the laser emission across the absorption line. The resulting derivativelike signal is used as an error signal for a control loop that keeps the laser frequency at maximum absorption. The unstabilized laser that is operated in a pulse tube cooler has frequency fluctuations of 15 MHz, which are reduced to 300 kHz with the control loop in action. The line shape of the locked signal is Gaussian.

Alcohol sensors based on SWNT as chemical sensors: Monte Carlo and Langevin dynamics simulation

In this research the decomposition products of the alcohol gases and their decomposition stages at the surface of the elements of single walled carbon nanotube (SWNT)-based powder are analyzed. The SWNT-based powders catalytically oxidized ethanol and methanol. The nano-crystalline and nanotubes have low band gaps and high mobility, thus offer applied potential as gas adsorption. Interaction between alcohol molecules and SWNT is investigated using Monte Carlo (MC) and Langevin dynamics (LD) simulation methods. We study the structural, total energy, thermodynamic properties and the acceptance ratio of methanol gas passing through an: armchair SWNT (4, 4) at different temperatures. Passing gas in SWNT changed the properties of it, in this research we have calculated the electrical and structural charges, in addition, transfer of charges from atoms to SWNT was investigated and it was found that there is a direct relation between the total energy and temperature.We study the structure, total energy and energy band gaps of absorption of CH3OH and C2H5OH in SWNT. When exposed to methanol and ethanol, the SWNT-based sensors showed oxidation of products consisting of CH3O and C2H5O. They are calculated with MC and LD simulation methods at different temperatures. All calculations are carried out using Hyperchem7.0 program package.

EXPANDED VERY LARGE ARRAY DETECTION OF 36.2 GHz CLASS I METHANOL MASERS IN SAGITTARIUS A

We report on the interferometric detection of 36.2 GHz Class I methanol emission with the new 27-40 GHz Ka band receivers available on the Expanded Very Large Array (EVLA). The brightness temperatures of the interferometric 36 GHz detections unambiguously indicate for the first time that the emission is maser emission. The 36 GHz methanol masers are not co-spatial with 1720 MHz OH masers, indicating that the two species trace different shocks. The 36 GHz and 44 GHz methanol masers, which both are collisionally pumped, do not necessarily co-exist and may trace different methanol gas. The methanol masers seem correlated with NH_3(3,3) density peaks. We favor an explanation in which the 36 GHz Class I methanol masers outline regions of cloud-cloud collisions, perhaps just before the onset of the formation of individual massive stars. The transition of the Very Large Array (VLA) to the EVLA is well under way, and these detections demonstrate the bright future of this completely renewed instrument.

Total electron scattering cross sections for methanol and ethanol at intermediate energies

Absolute total cross section (TCS) measurements of electron scattering from gaseous methanol and ethanol molecules are reported for impact energies from 60 to 500 eV, using the linear transmission method. The attenuation of intensity of a collimated electron beam through the target volume is used to determine the absolute TCS for a given impact energy, using the Beer–Lambert law to first approximation. Besides these experimental measurements, we have also determined TCS using the additivity rule.

Preparation, testing and performance of a TiO2/polyester photocatalyst for the degradation of gaseous methanol

TiO2 modified polyester photocatalysts were prepared by immersion, drying and curing of the polyester in TiO2 containing suspensions under different experimental conditions. The structure of TiO2 layers on the polyester varied according to the time of immersion and type of polyester used. The optical microscopy (OM) and scanning electron microscopy (SEM) show a more uniform distribution of TiO2 on the polyester prepared by sol–gel as compared to the silicone as a binder. Energy diffuse spectroscopy (EDS) and infrared (ATR-FTIR) spectroscopy confirmed that TiO2 bonded to the polyester textile. BET analysis showed that TiO2–SiO2 applied by sol–gel on polyester led to a higher surface area compared to silicon. Photodegradation of gaseous methanol mediated by the TiO2–polyester was followed by gas chromatography (GC) and ATR-FTIR spectroscopy. The TiO2–polyester sample prepared by sol–gel with an immersion time of 11h exhibited the most favorable photocatalytic performance during methanol degradation in the gas phase. The best performance during methanol photodegradation was observed for the smallest agglomerate TiO2 size. The structure–reactivity relationship for different photocatalysts was systematically explored. Quantitative evaluation of the cluster size, immersion time and catalyst loading provided the evidence for the best performance for methanol degradation by the catalyst prepared at 11h immersion time. The photocatalytic activity of the TiO2–polyester catalyst was observed to remain stable during methanol over several degradation cycles.

Adsorption properties of various forms of aluminium trifluoride investigated by PulseTA®

The current study employs the Pulse Thermal Analysis (PTA) method to investigate the adsorption of gaseous methanol onto various forms of aluminium trifluoride drawing special attention to the strongly adsorbing β-AlF 3 and the recently described high-surface (HS) AlF 3. Simultaneously or subsequently occurring physisorption and chemisorption can be clearly distinguished and partly quantified. BET surface and NH 3-TPD data will be discussed together with the surface coverage by methanol determined by TA. The extraordinary sorptive properties of HS-AlF 3 are due to acidic sites at the remarkably large surface. The crystalline modifications η-AlF 3, θ-AlF 3, and κ-AlF 3 are less-important as they poorly adsorb exhibiting thermogravimetric curves without clearly expressed mass changes. Their surface loading is comparably poor as found for the stable modification α-AlF 3.

A Nafion®-based co-planar electrode amperometric sensor for methanol determination in the gas phase

A co-planar electrode device, fabricated with all electrodes (working, counter and reference) on the same face of a Nafion® polymer electrolyte membrane, is proposed for the amperometric detection of gaseous methanol using Pt as the working electrode. Clear voltammetry is obtained for methanol oxidation from its vapours in equilibrium with methanol aqueous solutions, both in the absence and presence of oxygen in the gas stream. Using an appropriate pulse sequence to keep the indicator electrode active, methanol vapours in the 1–13 Torr partial pressure range (in equilibrium with methanol aqueous solutions in the 1–10% w/w concentration range) could be determined, in a constant potential, amperometric mode. The methanol detector could be operated both in a nitrogen stream and (in what is essential for practical applications) in an air atmosphere too, with estimated detection limits of 1·2 and 1·4 Torr respectively.

The Potential for Alcohol-containing Gas Sensors Based on DBRPorous Silicon

In order to use porous silicon as an alcohol gas sensor, we made DBR (distributed Bragg reflector) porous silicon and monitored the change in two parameters during exposure of the DBR porous silicon to an alcohol-containing gas. The sensing parameters were the shift of the reflectance peak and the electrical conductance. When DBR porous silicon is exposed to ethanol and methanol gas, the reflectance spectrum peak is red shifted by 11 nm and 25 nm, respectively. The direct current increases rapidly during exposure to alcohol gas due to the fact that alcohol has a higher dielectric constant than air. After removing the alcohol-containing gas, all sensing parameters returned to exactly their initial values.

Production of hydrogen by partial oxidation of methanol over bimetallic Au–Cu/TiO 2–Fe 2O 3 catalysts

Partial oxidation of methanol (POM) to produce H 2 was investigated over Au–Cu/TiO 2 and Au–Cu/TiO 2–Fe 2O 3 catalysts. The catalysts were prepared by deposition-precipitation method and characterized by XRD, TEM, HRTEM, ICP-AES, TPR, NH 3-TPD and XPS analyses. Detail study on the Au–Cu/TiO 2–Fe 2O 3 catalysts was performed to optimize Ti/Fe ratio, pH during preparation of the catalyst, calcination temperature and reaction temperature. The Au–Cu/TiO 2–Fe 2O 3 catalyst with Ti/Fe = 9/1 atomic ratio is more active and exhibits higher methanol conversion compared to the Au–Cu/TiO 2 catalyst. The higher activity of Fe-containing catalyst was attributed to the ability to supply reactive oxygen, thereby stabilize active gold species (Au δ+ ) in the catalyst. Studies on the optimization of pH during preparation of the Au–Cu/TiO 2–Fe 2O 3 catalyst and calcination temperature showed that the catalyst prepared at pH 7 and dried at 373 K (uncalcined) exhibited higher activity. The catalytic performance at various reaction temperatures shows that both methanol conversion and hydrogen selectivity are increased with increasing the temperature. A small increase in CO selectivity was observed beyond 523 K, which is due to the decomposition of methanol and reverse water gas shift at high temperatures.

Investigation of photocatalytic activity of TiO2∕WO3 bilayered thin films with various amounts of WO3 exposed surface

Transparent WO3∕TiO2 bilayered thin films were deposited on glass substrates by facing target sputtering technique with different amounts of WO3 exposed surface (0%, 30%, 50%, 80%, and 100%) to study the separate role of WO3 and TiO2 in the photocatalytic activity of the composite system. The crystallographic and optical properties of WO3 and the TiO2 layers were investigated in detail. The photocatalytic activity was evaluated by the measurement of decomposition of methanol in gas phase under visible light irradiation with very little ultraviolet content. The rate of decomposition of gaseous methanol largely depends on the ratio of WO3∕TiO2 exposed surface. The decomposition efficiency of WO3∕TiO2 films increased with an increase in TiO2 exposed surface and the sample with 70% TiO2 exposed area showed the highest efficiency. The surface morphology of all the layers was investigated by the measurement of field emission scanning electron microscope and atomic force microscope. The variation in photocatalytic activity has been tried to be explained on the basis of methanol-photodecomposition mechanism and the intrinsic properties of WO3 and TiO2 semiconductor.