Methanol Vapor Research Articles

Carbon-Based Solid Acid Catalyzed Esterification of Soybean Saponin-Acidified Oil with Methanol Vapor for Biodiesel Synthesis

In this study, carbon-based solid acids were used to catalyze the esterification of soybean saponin-acidified oil (SSAO) with methanol vapor for the synthesis of biodiesel. The esterification conversion under different conditions was determined, and the catalyst components were determined using acid-base titration, elemental analysis, and inductively coupled plasma spectroscopy. The results showed that the conversion of SSAO under the optimal esterification conditions (i.e., catalyst loading of 6 wt%, methanol/oil molar ratio of 50:1, reaction temperature of 76 °C, and reaction time of 4 h) was 98.9%. The conversion was still higher than 80% after the catalyst was reused for four batches. The methanol vapor esterification (MVE) effectively mitigated the leaching of sulfonic acid groups and the production of sulfonate esters, while the activated white clay adsorption can significantly reduce the metal ion content in SSAO, which weakens its ion exchange with sulfonic acid groups. MVE for biodiesel synthesis is less costly compared to liquid methanol esterification because of the high recovery of methanol and the improved catalyst stability. Therefore, the addition of methanol in the form of vapor in the carbon-based solid acid-catalyzed esterification system is an effective way to maintain the catalyst activity and reduce the production cost of biodiesel.

Molecularly Imprinted Polymer Based Antenna Sensor for Methanol Vapor Sensing

Molecularly Imprinted Polymer Based Antenna Sensor for Methanol Vapor Sensing

Modeling and Calculation of an Adsorber for Methanol Vapor Capture Using Active Carbon with a Diffusion Flow Structure in the Gas Phase

Modeling and Calculation of an Adsorber for Methanol Vapor Capture Using Active Carbon with a Diffusion Flow Structure in the Gas Phase

Sorption of vapors in methanol soaked and in thermally annealed Matrimid® films

AbstractMatrimid® shows well separated sub‐glass transitions and substantial entrapment of dichloromethane (DCM) in the solution‐cast films. The entrapped DCM was removed by soaking the polymer in the excess of liquid methanol followed either by thermal annealing (vacuum at 200°C) or by the desorption at mild conditions. These physical treatments influenced the sorption kinetics and even the sorption isotherms for vapors of DCM, methanol (MeOH) and acetonitrile (MeCN) at 35.0°C. The sorption isotherms for the thermally annealed Matrimid® were shifted to those for the methanol‐soaked Matrimid® upon its exposure to sufficiently saturated vapors. The physical treatments changed the β sub‐glass transition of the polymer, and did not cause changes in the chemical composition and microstructure as sensed using ATR‐FTIR and SEM, respectively. Relaxation of the annealed Matrimid® was achieved by its soaking in liquid MeOH and by the exposure to vapors, their threshold saturation followed the same order as diffusivity: MeOH > MeCN > DCM. Although methanol appears the least effective agent to induce the relaxation of Matrimid®, it diffuses in and desorbs from the polymer readily. Liquid MeOH and its vapor thus appear the media of choice for causing the relaxation and removal of entrapped solvents from Matrimid®.

An in-situ FTIR-LCR meter technique to study the sensing mechanism of MnO2@ZIF-8/CNPs and a direct relationship between the sensitivity of the sensors and the rate of surface reaction

Diethylamine vapor is harmful to people if inhaled or swallowed, as it results in the oxidation of hemoglobin in the body into unwanted methemoglobin, which is unable to transport oxygen in the blood, resulting in reduced blood oxygenation. Lack of blood oxygenation leads to hypoxemia. MnO2 nanorods, carbon soot, and MnO2@ZIF-8 are sensing materials used to prepare solid-state gas sensors that operate at room temperature. The prepared sensing materials were characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The performance of the MnO2@ZIF-8 based sensor improved significantly when the carbon soot was introduced into the composite. The effect of the amount of CNPs in the composite on the performance of the sensors was studied. The MnO2@ZIF-8/CNPs-based sensor with a 3:1 mass ratio was highly selective towards diethylamine vapor over acetone, methanol, ethanol, and 3-pentanone vapors. An in situ FTIR coupled with LCR meter was used to understand the sensing mechanism of diethylamine vapor and it was found that the sensing mechanism was by deep oxidation of diethylamine to CO2, H2O, and other molecules. The sensing mechanism was studied by monitored by CO2 band intensity which was produced from the reaction between the sensing materials and the analyte vapor. As the sensor's exposure time increased the intensity of the CO2 IR band increased. We observed the direct relationship between the surface reaction rate and the sensor's sensitivity.

Comprehensive Optimization of Western Blotting.

Western blotting is one of the most extensively used techniques in the biomedical field. However, it is criticized by many researchers due to its considerable time consumption, multiple steps, and low method results. Therefore, we modified the steps of gel preparation, electrophoresis, electrotransfer, blocking, and gel cutting. First, we simplified the gel preparation step by premixing various reagents and varying the amounts of catalysts or radical generators, which shortened the entire process to 10 min. Second, we shortened the electrophoresis process to 35 min by modifying the formula of the electrophoresis running buffer. Then, we removed the hazard of methanol vapor by replacing methanol with ethanol in the electrotransfer buffer. Finally, the use of polyvinylpyrrolidone-40 shortened the blocking procedure to 10 min. Our modifications shortened the time, improved the experimental productivity, and minimized the experimental cost without hindering compatibility with most existing equipment. The entire experiment up to primary antibody incubation can be completed within 80 min.

Zn(II)-Siloxane Clusters as Versatile Building Blocks for Carboxylate-Based Metal-Organic Frameworks.

Siloxanes have long been known for their highly desirable properties suited for a wide range of practical applications; however, their utilization as modular building blocks for crystalline open frameworks has been limited. In this study, a simple solvothermal pathway has been found to synthesize unprecedented Zn(II)-siloxane clusters supported by acetate ligands, [(RSiO2)8Zn8(CH3CO2)8] (R = Me or Ph). The same reaction using a dicarboxylate ligand such as 1,4-benzenedicarboxylate or 2,6-naphthalenedicarboxylate produces a new type of metal-organic framework, named SiMOF here, based on the [Si8Zn8] units. With the maximum connectivity of 8, the building block is shown to form topologically interesting structures such as octahedral supercages or uninodal 8-connected frameworks. All SiMOFs synthesized possess permanent porosity and high thermal stability and are naturally hydrophobic, as demonstrated by adsorptions of toluene, ethanol, methanol, and water vapor as well as water contact angle measurements. These promising characteristics for well-defined porous solids are attributed to metal-bound siloxane groups in the structural building units.

UV activated single aligned TiO2 nanofiber embedded silver nanoparticles as room temperature ammonia gas sensor

In this work, by using an electro-spinning process and a secondary electrostatic field on rectangular electrodes, a single-aligned nanofiber of silver nanoparticle (SNP)-TiO2 fabricated for NH3 gas sensing with UV irradiation at room temperature. XRD, FE-SEM and UV spectroscopy adopted for characterization of the single nanofiber. The response of SNP-TiO2 single nanofiber sensor evaluated for 70 ppb to 12 ppm ammonia gas at room temperature up to the optimum temperature of 150 °C. The response of this sensor for 5 ppm ammonia gas is 46.1 at the optimum temperature of 150 °C. However, the response is also evaluated at room temperature under 365 nm UV illumination. The response improved up to 4 times from 11 at dark condition to 45.1 under UV illumination for the ammonia gas concentration of 5 ppm. In addition, UV light exposure led to a considerable reduction in both the response and recovery times. Moreover, the results for detecting other gases such as methanol, ethanol, propanol and water vapor compare to ammonia shows that for SNP-TiO2 sensor the best response is for ammonia gas, whereas its sensitivity to humidity is considerably low (about 9%). This shows the sensor can be used in related applications like breath analysis.

Volatile organic compound sensing in breath using conducting polymer coated chemi-resistive filter paper sensors.

In this work, a disposable sensor array was designed based on the chemi-resistive behavior of the conducting polymers to detect three volatile organic compounds (VOCs), i.e., acetone, ethanol, and methanol in air and breath. Four disposable resistive sensors were designed by coating polypyrrole and polyaniline (in their doped and de-doped forms) on filter paper substrates and tested against VOCs in air. Change in conductivity of the polymer resulting from exposure to various VOC concentration was measured as percentage resistance change using a standard multimeter. The lowest concentration detected for acetone, ethanol, and methanol vapors was 400ppb, 150ppb, and 300ppb, respectively within 2min. These VOC-responsive sensors, housed in an indigenous inert chamber, showed good stability, repeatability, and reversibility while sensing, thus making it suitable for environmental pollutant detection at room temperature. Furthermore, the non-specific nature of these easy to fabricate sensors towards all VOCs is considered favorable and upon classifying with principal component analysis (PCA), the gases were qualitatively distinguished in separate clusters. These developed sensors were also tested and analyzed using VOC spiked real breath samples as proof of concept.

Laser-assisted Synthesis of Pd/Metal-Organic Framework and Its Application in the Sensing of Ethanol and Methanol Vapors

Laser-assisted Synthesis of Pd/Metal-Organic Framework and Its Application in the Sensing of Ethanol and Methanol Vapors

The Use of Methanol Vapour for Effective Drying of Cellulose Insulation

The paper deals with a new method of drying cellulose insulation, which uses methanol vapour present in nitrogen as a drying medium. Compared to the insulation drying methods currently used in the industry, the method presented in the article has the following advantages: there is no cellulose depolymerization because there is no need to heat the insulation, there is no need to use large-size and energy-intensive dryers because the whole process takes place in the tank of the transformer. Important parameters of the drying process, such as methanol concentration in the nitrogen, flow rate, and process duration, were determined in four separate experiments. For the purposes of these experiments, a special system was constructed to control and measure the flow of drying medium. Controlling the flow rate of the carrier gas (nitrogen) made it possible to obtain different concentrations of methanol in nitrogen. Such values of concentration and flow rate were determined that allow drying of pressboard and paper in less than 144 h to a level lower than 1%.

Ultrasensitive gas sensor developed from SnS/TiO2-based memristor for dilute methanol detection at room temperature

Metal oxide-based gas sensors are widely studied and applied due to simple operation principle, small size and high stability. However, numerous gas sensors based on metals oxides usually exhibit high optimal operating temperatures and show poor response/recovery performance at room temperature (RT). To overcome the above problems, innovative device forms should be explored. Herein, we developed a memristor-based gas sensor (gasistor) for the detection of dilute methanol vapor at RT, and the resistive layer material was SnS-modified TiO2. Compared with the general film-based gas sensors, the gasistor exhibits unique resistive switching function, and the baseline resistance in the high resistance state is reduced by about 3 × 104 times, demonstrating the construction of gasistor is an effective way to solve the high resistance of metal oxides at RT. Meanwhile, the SnS/TiO2-based gasistor showed a high response of 85.2 for 1 ppm methanol, a fast response/recovery within 1.2 s for rarefied methanol (< 5 ppm), and remarkable selectivity towards methanol at RT. This indicates that the SnS/TiO2-based gasistor is a competitive candidate for methanol detection. Besides, the mechanisms of resistive switching and gas sensing were further discussed. The present work brings new inspiration to the future research of gas sensors.

Conducting 2D Nanosheets: Photo Driven Crystallinity in Self-Assembled Cu (II) Metalated Porphyrin-Bispyridylquinoxaline

Tuning the crystallinity in self-assembled nanostructures has a significant impact on the electronic properties. Although several approaches have been adopted for organic π-conjugated systems to generate the amorphous to crystalline structures, the bulky structure of extended macrocyclics is hitherto unknown. Herein, we have developed three symmetric freebase and metallo substituted porphyrin appended bispyridylquinoxalines (PFb-DPQ, PCu-DPQ and PZn-DPQ) in which copper metalated P-DPQ exhibits crystalline phase transitions under light stimuli. Notably, light irradiated P-DPQ derivatives undergo a protonation, demetalation, and anion binding mechanism, resulting in the formation of self-assembled open, closed 0D nanospheres together with 2D nanosheets via methanol vapor diffusion approach. Interestingly, light stimulation regulates the morphology from 0D nanosphere to 2D nanosheets in PCu-DPQ and H+[PCu-DPQ(Cl)]−, which promotes the amorphous to crystalline nature. Consequently, the bulk conductivity of 2D nanosheets exhibits ∼32 mS cm–1, and it is remarkably 102 times higher than 0D nanospheres. Thus, these results promote that the stimuli responsive metallo substituted macrocyclic systems is a significant initiative to manipulate the electronic properties in organic electronics.

Thermal analysis of a micro tubular reactor for methanol steam reforming by optimizing the multilayer arrangement of catalyst bed for the catalytic combustion of methanolr

Packed bed tube reactors are commonly used for hydrogen production in proton exchange membrane fuel cells. However, the hydrogen production capacity of methanol steam reforming (MSR) is greatly limited by the poor heat transfer of packed catalyst bed. The hydrogen production capacity of catalyst bed can be effectively improved by optimizing the temperature distribution of reactor. In this study, four types of reactors including concentric circle methanol steam reforming reactor (MSRC), continuous catalytic combustion methanol steam reforming reactor (MSRR), hierarchical catalytic combustion methanol steam reforming reactor (MSRP) and segmented catalytic combustion reactor with fins (MSRF) are designed, modeled, compared and validated by experimental data. It was found that the maximum temperature difference of MSRC, MSRR, MSRP and MSRF reached 72.4 K, 58.6 K, 19.8 K and 11.3 K, respectively. In addition, the surface temperature inhomogeneity Uf and CO concentration of the MSRF decreased by 69.8% and 30.7%, compared with MSRC. At the same reactor volume, MSRF can achieve higher methanol conversion rate, and its effective energy absorption rate is 4.6%, 3.9% and 2.6% higher than that of MSRC, MSRR and MSRP, respectively. The MSRF could effectively avoid the influence of uneven temperature distribution on MSR compared with the other designs. In order to further improve the performance of MSRF, the influences of methanol vapor molar ratio, inlet temperature, flow rate, catalyst particle size and catalyst bed porosity on MSR were also discussed in the optimal reactor structure (MSRF).

Room temperature sensing of alcohol vapours using novel radially aligned nanorutile titania

1D nanostructures of TiO2 have been extensively researched in chemical sensing. The need for deployment of 3D nanostructures such as flower-like and urchin-like morphology for chemical sensing is very essential. This morphology provides distinctive attributes because of the properties afforded by the micrometre and nanometre building blocks within the crystal of the nanomaterial. 3D nanostructure nanorutile titania was fabricated using a facile hydrothermal method. The gas sensing performance showed that the hierarchical morphology, high surface area, high porosity and humidity played a vital role in the sensing of ethanol vapour at room temperature. The radially aligned nanorutile (RANR) TiO2 sensor showed high sensitivity with responses of 86.75% and 38.27% towards ethanol and methanol vapours, respectively. The sensor displayed good sensitivity, reproducibility, rapid response, and recovery times towards alcohol vapours.

One-Dimensional Heterobimetallic Au/Ag Coordination Polymer Showing a Selective, Reversible, and Visible Vapor-Chromic Photoluminescent Response toward Methanol.

A heterobimetallic coordination polymer [Au4(dppmt)4(AgCl)2]n (1) incorporating an in situ generated P-S ligand (dppmtH) was synthesized from the solvothermal reaction of Au(tht)Cl, AgCl, and dpppyatc in CH3CN/CH2Cl2 (dppmtH = (diphenylphosphino)methanethiol, tht = tetrahydrothiophene, dpppyatc = N,N-bis((diphenylphosphaneyl)methyl)-N-(pyridin-2-yl)-amino-thiocarbamide). The structure of 1 contains a one-dimensional helical Au-Au chain in which the unique [Au4Ag2S2] cluster units are connected by [Au2(dppmt)2] dimers. Upon excitation at 343 nm, 1 exhibited cyan (495 nm) phosphorescent emission at quantum yield (QY) = 22.3% and τ = 0.78 μs (λex = 375 nm). Coordination polymer 1 exhibited a rapid, selective, reversible, and visible vapor-chromic response on exposure to methanol (MeOH) vapor with its emission shifting to a more intense green (530 nm, λex = 388 nm) with QY = 46.8% and τ = 1.24 μs (λex = 375 nm). A polymethylmethacrylate film containing 1 served as a reversible chemical sensor for the sensitive detection of MeOH in air.

In Situ Solution-Processed Submicron Thick SiOx Cy /a-SiNx (O):H Composite Barrier Film for Polymer:Non-Fullerene Photovoltaics.

Aiming to improve the environmental stability of organic photovoltaics, a multilayered SiOx Cy /a-SiNx (O):H composite barrier film coated with a hydrophobic perfluoro copolymer stop layer for polymer:non-fullerene solar cells is developed. The composite film is prepared by spin-coating of polysilicone and perhydropolysilazane (PHPS) following a densification process by vacuum ultraviolet irradiation in an inert atmosphere. The transformation of polysilicone and PHPS to SiOx Cy and a-SiNx (O):H is confirmed by Fourier transform infrared and energy-dispersive X-ray spectroscopy measurement. However, the as-prepared PHPS-derived silicon nitride (PDSN) can react with moisture in the ambient atmosphere, yielding microscale defects and a consequent poor barrier performance. Treating the incomplete PDSN with methanol vapor significantly densifies the film yielding low water vapor transmission rates (WVTRs)of 5.0 × 10-1 and 2.0 × 10-1 gm-2 d-1 for the one- and three-couple of SiOx Cy /a-SiNx (O):H (CON) composite films, respectively. By incorporating a thin hydrophobic perfluoro copolymer layer, the three-coupled methanol-treated CON film with a total thickness of 600nm shows an extremely low WVTR of 8.7 × 10-4 gm-2 d-1 . No performance decay is measured for the PM6:Y6 and PM6:L8-BO cells after such an encapsulation process. These encapsulated polymer cells show good stability storaged at 25°C/50% relative humidity, or under simulated extreme rainstorm tests.

The sensitivity enhancement of TiO2-based VOCs sensor decorated by gold at room temperature

Detection of hazardous toxic gases for air pollution monitoring and medical diagnosis has attracted the attention of researchers in order to realize sufficiently sensitive gas sensors. In this paper, we fabricated and characterized a Titanium dioxide (TiO2)-based gas sensor enhanced using the gold nanoparticles. Thermal oxidation and sputter deposition methods were used to synthesize fabricated gas sensor. X-ray diffraction analysis was used to determine the anatase structure of TiO2 samples. It was found that the presence of gold nanoparticles on the surface of TiO2 enhances the sensitivity response of gas sensors by up to about 40%. The fabricated gas sensor showed a sensitivity of 1.1, 1.07 and 1.03 to 50 ppm of acetone, methanol and ethanol vapors at room temperature, respectively. Additionally, the gold nanoparticles reduce 50 s of response time (about 50% reduction) in the presence of 50 ppm ethanol vapor; and we demonstrated that the recovery time of the gold decorated TiO2 sensor is less than 40 s. Moreover, we explain that the improved performance depends on the adsorption-desorption mechanism, and the chemical sensitization and electronic sensitization of gold nanoparticles.

Efficient and stable subzero operation of a PEM fuel cell with a composite anode using hydrogen-methanol composition during freeze/thaw cycles

The present research deals with the adaptation of hydrogen-air fuel cells with proton exchange membrane (PEMFC) to autonomous periodic operation at subzero ambient temperatures. The main goal of the research is to limit the influence of subzero temperatures on component integrity and electrochemical performance stability of PEMFC in the cause of the freeze-thaw (F/T) cycling test. The MEAs stability in cycling from subzero (−35 °C) to operating temperature (+35 °C) was ensured without any specific preparatory operations modeling the PEMFC stop and “cold start” procedure. This is provided through the use of hydrogen-methanol compositions (no more than 4 vol % of methanol vapor) as fuel and a composite anode. Advanced membrane-electrode assembly (MEA) based on the composite anode layer (Pt 40 /C + Pt 20 /10 wt%–SnO 2 /C) for efficient and stable subzero operation during F/T cycling. High stability of electrochemical performance of the MEA with the composite anode at subzero ambient temperatures is shown. Advantages of use a two-component fuel PEMFC for autonomous periodic operation at subzero ambient temperatures are highlighted. • The hydrogen-methanol composition is applied as a fuel for cold start procedure. • Efficiency of two-component anode in methanol vapor oxidation has been proven. • Stability of fuel cell electrochemical performance at subzero temperatures is ensured.

A novel gas sensor based on activated charcoal and polyaniline composites for selective sensing of methanol vapors

A novel gas sensor based on activated charcoal and polyaniline composites for selective sensing of methanol vapors