Quartz Wool Research Articles

TiO2 Supported on Quartz Wool for Photocatalytic Oxidation of Hydrogen Sulphide

A spacial system consisting of TiO2 on a fibrous support was prepared by hydrolysis of titanium isopropoxide in the presence of quartz wool, followed by calcination. The material was characterized by X-ray diffraction, nitrogen adsorption–desorption at 77 K, X-ray photoelectron spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The TiO2/support system was examined as a photocatalyst for UV-assisted oxidation of H2S in air. The results obtained confirmed a superior performance of the TiO2/support system over TiO2 powder. H2S underwent oxidation to elemental sulphur and/or S6+. The relative amounts of these species were influenced by humidity.

Effect of dielectric packing materials on the decomposition of carbon dioxide using DBD microplasma reactor

Carbon dioxide (CO2) decomposition was performed at a normal atmosphere and room temperature in dielectric barrier discharge microplasma reactors to reduce CO2 emissions and convert CO2 into valuable chemical materials. The outlet gases, including CO2, CO, and O2, were analyzed with gas chromatography. The results indicated that the conversions of CO2 in dielectric material‐packed reactors were all higher than that in nonpacked reactors. Particle size, dielectric constant, particle morphology, and acid‐base properties of the dielectric materials (including quartz wool, quartz sand, γ‐Al2O3, MgO, and CaO) all affected the CO2 decomposition process. The conversion of CO2 and energy efficiency achieved the highest values of 41.9 and 7.1% in a CaO‐packed reactor for the higher dielectric constant and basicity of CaO. Quartz wool was also an excellent dielectric packing material because its fiber structure provided rigid sharp edges. © 2014 American Institute of Chemical Engineers AIChE J, 61: 898–903, 2015

Comparison of different types of outlet frits in slurry-packed capillary columns.

Fused-silica capillary columns for high-performance liquid chromatography with 320 and 250 μm inner diameter were prepared by slurry packing with 5 and 3 μm Nucleosil C18 stationary phase. Different types of mechanical and monolithic outlet frits were used and their influence on the resulting column performance was evaluated. Columns with quartz wool exhibited symmetrical peaks and low theoretical plate height, and the preparation time was short. The performance of monolithic frits varied based on type of monolith, length of the frit, and silanization procedure. The best frit performed similarly to the quartz wool ones, but the preparation took several hours. Their main advantage lies in the possibility of on-column detection, because the detection window can be burnt immediately behind the frit.

Testicular Perfusion Apparatus

A reproductive biology laboratory requires to provide reliable instruments for regular use of research workers. To understand an organ and perform scientific study and reach on a conclusion good instruments and techniques are essential. Such a suitable one is not available in case of testicular study. The present study is aimed to clear this lacuna. A new testicular perfusion apparatus for rabbit and rat is designed and fabricated with glass. The glass blowing instrument available is used. The perfusion fluid preferred is Krebs Ringer bicarbonate buffer (pH 7.4). Quartz wool provided in stem tube filters emboli present in it. Perfusate temperature is maintained to that of testis. A 26-gauge needle is introduced into the spermatic artery to allow entry of perfusate into testis. Method for the collection of perfusate leaving testis is available. This permits to measure the level of an injected substance before its entry through perfusion fluid into the testis, which shall be compared in the fluid after completion of perfusion. Initially few animal testes were used and found the instrument to be functioning well. A new simple perfusion apparatus for testes of rabbit and rat is designed. The apparatus made out of glass could be prepared with the help of glass blowing facility and used regularly in any laboratory.

Measuring Cr Volatility from Ferritic Stainless Steels: Novel and Conventional Methods Compared

Reactive evaporation of Cr-species from ferritic stainless steels is a technical challenge for solid oxide fuel cell (SOFC) systems and other devices operating in high-temperature (>500°C) oxidizing environments. A traditional method for quantitatively measuring Cr volatility is by using a transpiration system, in which oxidizing gases are flown by Cr-containing materials and the exhaust is condensed and subsequently analyzed using ICP-MS. While this method is well established and accurate, it also has limited sensitivity and challenges associated with sample collection. Novel methods have recently been developed to quickly and accurately evaluate and quantify low levels of Cr volatility. These include the denuder technique, which employs a water-soluble reactive collection and optical analysis; a cold quartz wool collection method with ICP-MS; a cold Si-wafer collection with ion-beam analysis; an ionic conductivity measurement of condensed exhaust solution; and, a simple staining method. Each method has advantages and disadvantages in terms of cost, operation, sensitivity and accuracy. In this poster, Cr volatility measurement techniques will be presented and compared in the context of facilitating new and ongoing research efforts.

Dynamic layer-by-layer self-assembly of multi-walled carbon nanotubes on quartz wool for on-line separation of lysozyme in egg white

The multi-walled carbon nanotubes (MWNTs) coated quartz wool (MWNTs/QW) prepared by dynamic layer-by-layer self-assembly was used as solid-phase extraction (SPE) absorbent for on-line separation and preconcentration of lysozyme in egg white. The coating procedures were performed continuously in a flow system operated by a set of sequential injection devices. The quartz wool was placed in a microcolumn forming a loose packing to guarantee the minimized flow impedance and the intimate contact between proteins and absorbent surface. Various parameters affecting SPE efficiency including the volume, pH, ionic strength and flow rate of sample and eluent were systematically studied. The feasibility of the proposed method was validated by successfully applied to the separation of lysozyme in egg white.

High and rapid hydrogen release from thermolysis of ammonia borane near PEM fuel cell operating temperatures: Effect of quartz wool

Ammonia borane (NH3BH3, AB), containing 19.6 wt% hydrogen, is a promising hydrogen storage material for use in proton exchange membrane fuel cell (PEM FC) powered vehicles. We recently demonstrated that using quartz wool, the highest H2 yield (2.1–2.3H2 equivalent) values were obtained by neat AB thermolysis near PEM FC operating temperatures, along with rapid kinetics, without the use of either catalyst or chemical additives. It was found that quartz wool minimizes sample expansion and facilitates the production of diamoniate of diborane (DADB), which is a key intermediate for the release of hydrogen from AB. It was also found that only trace amount of ammonia (<10 ppm) is produced during dehydrogenation reaction and spent AB products are found to be polyborazylene-like species, which can be efficiently regenerated using currently demonstrated methods. The results indicate that our proposed method is the most promising one available in the literature to-date for hydrogen storage, and could be used in PEM FC based vehicle applications.

A novel method for the preparation of non-agglomerated nanometre sized particles of lanthanum phosphate phosphors utilising a high surface area support in the firing process

A convenient method is described that uses a quartz wool substrate to immobilise nanometre sized phosphor precursor particles enabling them to be fired at high temperature without sintering/agglomeration. The nanometre sized phosphor particles are easily removed from the substrate by re-dispersion into liquid for subsequent use.

Effects of Reactor Packing Materials on H2 Production by CO2 Reforming of CH4 in a Dielectric Barrier Discharge

AbstractNon‐thermal plasma has been investigated for CO2 reforming of CH4 in a coaxial DBD reactor with different reactor packing materials placed into the discharge gap. Both the chemical and physical effects on reaction performance have been examined for the addition of quartz wool, γ‐Al2O3 and zeolite 3A, in order to gain a better understanding of plasma interactions with materials during CH4 reforming reactions. Quartz wool was found to enhance the conversion of CH4 and improve H2 yields as a result of changes in the physical properties of the discharge; electrical measurements showed an increase in the intensity of microdischarge filaments over quartz wool. In the presence of Al2O3 and zeolite 3A, the discharge intensity was reduced and consequently CH4 and CO2 conversions were lower for these materials. However, in the presence of zeolite 3A improved selectivities towards H2 and light hydrocarbons acetylene/ethylene were obtained and formation of liquid hydrocarbons was inhibited due to shape‐selectivity determined by the zeolite pore size.magnified image

Microscope–ICCD Imaging of an Atmospheric Pressure $\hbox{CH}_{4}$ and $\hbox{CO}_{2}$ Dielectric Barrier Discharge

Images of plasma generation during dry reforming of methane with carbon dioxide in a dielectric barrier discharge reactor using a microscope-intensified charge-coupled device camera have been taken. Comparisons have been made between plasma generations in the absence of a packing material and with different packing materials, including quartz wool, alumina, and barium titanate inside the discharge gap. It has been found that quartz wool can enhance the intensity of plasma generation, leading to improved reaction performance.

Novel and Effective Copper–Aluminum Propane Dehydrogenation Catalysts

Novel and Effective Copper–Aluminum Propane Dehydrogenation Catalysts

Chromium as reactant for solar thermochemical synthesis of ammonia from steam, nitrogen, and biomass at atmospheric pressure

Abstract Ammonia for fertilization plays a crucial role in agriculture. It is an important commodity chemical, and it can serve as a fuel for combustion engines or as a carrier molecule for hydrogen. Global NH3 production of over 100 million metric tons per year relies almost entirely on natural gas for energy and hydrogen. About 2% of the world’s energy budget is spent to produce NH3. Experiments towards a solar thermochemical cycle for NH3 synthesis at near atmospheric pressure using a transition metal reactant and a Fresnel-lens solar furnace are reported here: reacting Cr metal powder with gaseous N2 to Cr nitride, hydrolyzing Cr nitride powder with steam to NH3 and Cr2O3, and finally reducing Cr2O3 powder back to Cr with mixtures of H2, CO, and N2. At about 1000 °C it was found that Cr readily fixes N2 from the gas phase as Cr nitride (4.13 × 10−2 mol N2/mol Cr/min, 85 ± 4 mol% of hexagonal Cr2N after 5.6 min). Cr2N converts over time to a cubic CrN phase. Corrosion of Cr nitride with steam at 1000 °C and about 1 bar forms Cr2O3 and CrO while liberating 53 ± 11 mol% of the nitrogen contained in the solid Cr nitride in 60 min. Of the N liberated, 0.28 ± 0.07 mol% forms the desired NH3. This results in a yield of 0.15 ± 0.02 mol% NH3 relative to the N in the nitride (1.07 × 10−4 mol NH3/mol Cr/min). Addition of CaO/Ca(OH)2 powder or quartz wool to provide more reactive sites and promote protonation of N increased the yield of NH3 only slightly (0.24 ± 0.01 or 0.39 ± 0.03 mol% NH3 relative to the N in the nitride respectively). The thermochemical cycle is closed by heating Cr2O3 to 1200–1600 °C with a reduction yield near the surface of the particles of approximately 82.85 mol% (40 min at 1600 °C) in a gas stream of H2 and CO (2.7 × 10−3 mol Cr/mol Cr2O3/min). An unreacted core model was applied to estimate the activation energy of Cr2O3 reduction with 128 ± 4 kJ/mol. Cr appears promising to promote nitridation and oxide reduction as a basis for a future custom-designed reactant with high specific surface area enabling sustainable and more scalable NH3 production from N2 and H2O at ambient pressure without natural gas consumption.

Design of selective emitting media within a cylindrical tube for conversion of wasted heat energy to electrical energy

Thermophotovoltaic (TPV) energy conversion is the conversion of heat energy to electrical energy via light. This manuscript focuses on the geometric design of emitting material within an exhaust tube to convert wasted heat energy to light, and achieve an optimal amount of irradiance at the PV diode cells. Due to the large value of the absorption coefficient for the selectively emitting erbia-doped nanofibers under discussion, the diffusion approximation to the equation of radiation transfer is used. This approximate equation is solved for emission from hot-spot sources within the emitting material. Several geometric distributions of the emitting material are considered. Within an axisymmetric geometry all erbia-doped nanofibers, all quartz wool, and mixtures of disk-shaped or cylindrical shell shaped distributions of nanofibers and wool are investigated. Within a polar geometry all erbia-doped nanofibers, all quartz wool, and mixtures of spoke-shaped or cylindrical shell shaped distributions are investigated. In both geometries the mixture distributions consist of alternating thin layers of emitting and non-emitting material. Homogenization techniques are applied to these distributions to define expressions for the effective absorption and scattering coefficients for these spatially distributed emitting structures. The effective expressions are input into the diffusion approximation that is solved for the spectral irradiance. The net radiation obtained from these emitting structures is examined to optimize the geometry of the TPV material to maximize emission with use of minimal TPV material. Results show that disk-shaped bands or spokes allow for maximum irradiation in the radial direction toward the diode collectors. A large volume fraction of erbia-doped nanofibers is optimal when hot spots are close to the diodes. Smaller volume fractions work better when hot spots are away from the diodes due to reabsorption of emitted light by the emitting material.

A New Portable Instrument for In Situ Measurement of Atmospheric Methane Mole Fraction by Applying an Improved Tin Dioxide–Based Gas Sensor

Abstract A new portable instrument based on a tin dioxide natural gas leak detector was developed to monitor the atmospheric methane mixing ratio in areas lacking sufficient infrastructure to sustain a conventional measurement system, such as a large power source, carrier gas supply, and temperature-stabilized laboratory. The effect of water vapor, the dominant factor influencing the stable measurement of methane, was examined. Reducing water vapor to less than 10 ppm in the sample air enabled stable and sensitive detection of atmospheric methane. The selectivity of the sensor to other flammable gases was also examined and improved, without additional power consumption, by applying an additional catalytic layer made of platinum-black powder suspended in quartz wool. The developed system is small (W × D × H = 300 mm × 250 mm × 200 mm) and lightweight (4 kg). The normal power consumption of the detector unit, consisting of a detector, a heater for controlling temperature, and an electronic circuit for each device, is less than 10 W. The precision of the tin dioxide–based sensor system for methane measurement in ambient air was compared with that of a conventional system, a gas chromatograph equipped with a flame ionization detector. Diurnal variations were clearly detected, and an excellent linear relationship was found between the two systems, with a standard deviation of 4 ppb (1σ).

Development and testing of an intermediate temperature glass sealant for use in mixed ionic and electronic conducting membrane reactors

High temperature ceramic membranes have interesting possibilities for application in areas of new and developing technologies such as hydrocarbon combustion with carbon dioxide capture and electrochemical promotion of catalysis (EPOC). However, membrane module sealing remains a significant technical challenge. In this work a borosilicate glass sealant (50SiO 2·25B 2O 3·25Na 2O, mol%) was developed to fit the requirements of sealing an air separation membrane system at intermediate temperatures (300–600 °C). The seal was assessed by testing the leak rates under a range of conditions. The parameters tested included the effect of flowrate on the leak rate, the heating and cooling rates of the reactor and the range of temperatures under which the system could operate. Tests for durability and reliability were also performed. It was found that the most favourable reactor configuration employed a reactor with the ceramic pellet placed underneath the inner chamber alumina tube (inverted configuration), using a quartz wool support to keep the membrane in place prior to sealing. Using this configuration the new glass-based seal was found to be a more suitable sealant than traditional alternatives; it produced lower leak rates at all desirable flowrates, with the potential for rapid heating and cooling and multiple cycling, allowing for prolonged usage.

Modeling of a TiO2-coated quartz wool packed bed photocatalytic reactor

A fixed-bed, photocatalytic laboratory reactor aimed to degrade pollutants from water streams was designed and built. Quartz wool coated with a thin film of TiO2 was employed as the reactor filling. The photocatalyst was placed in the reactor forming a loose packing to guarantee the intimate contact among reactants, photons, and the photocatalytic surface. This reactor was employed to study the photocatalytic decomposition of a model pollutant (formic acid). A reactor–radiation–reaction model was developed, which was comprised of the reactor mass balance, radiation model, and kinetic model for the degradation of formic acid. The local superficial rate of photon absorption, which was necessary to evaluate the kinetic, was obtained from the results of a radiation model. The Monte Carlo approach was employed to solve the radiation model, where the interaction between photons and the TiO2-coated fibers of the packing was considered. The kinetic model was derived from a plausible kinetic scheme. Experimental results obtained in the packed-bed reactor, operating in a differential mode and without mass transfer limitations, were used to estimate the parameters of the kinetic model. A satisfactory agreement was observed between model simulations with the derived parameters and experimental results, with a root mean square error less than 8.3%.

Radiation model of a TiO2‐coated, quartz wool, packed‐bed photocatalytic reactor

AbstractThe radiation field of a packed‐bed photocatalytic reactor filled with quartz wool coated with titanium dioxide was modeled using the Monte Carlo technique and the following information: the radiation flux emitted by the lamps, the diameter size distribution of the quartz fiber cloth, the mass of quartz fibers and of TiO2 that was immobilized on the fiber surface as well as the refractive index, and the spectral absorption coefficient of the materials of the system. Modeling predictions were validated with radiometer measurements of the transmitted radiation through the reactor, the root mean square error being &lt;9.7%. Finally, by means of a parametric study, the validated model was used to analyze the effect of the design variables, such as the radii of the quartz fibers, thickness of the TiO2 coatings, and amount of TiO2‐coated quartz wool, on the distribution and nonuniformity of the radiative energy distribution inside the reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2010

Assessment of dose rate scaling factors used in NCTPlan treatment planning code for the BNCT beam of THOR

Tsing Hua open-pool reactor (THOR) at Tsing Hua University in Taiwan has been used to investigate the feasibility and to enhance the technology of boron neutron capture therapy (BNCT) for years. A rebuilt epithermal beam port for BNCT at THOR was finished in the summer of 2004, and then researches and experiments were performed to hasten the first clinical treatment case of BNCT in Taiwan in the near future. NCTPlan, a Monte Carlo-based clinical treatment planning code, was used to calculate the dose-rate distributions of BNCT in this work. A self-made Snyder head phantom with a servo-motor control system was irradiated in front of the THOR BNCT beam exit. The phantom was made from a 3 mm shell of quartz wool impregnated with acrylic casting resin mounted on an acrylic base, and was filled with water. Gold foils (bare and cadmium-covered) and paired ion chambers (one with graphite wall and filled with CO 2 gas, another with A-150 plastic tissue equivalent wall and filled with tissue equivalent gas) were placed inside the Snyder phantom to measure and estimate the depth-dose distributions in the central axis of the beam. Dose components include the contribution of thermal neutrons, fast neutrons, photons and emitted α particles from 10B(n,α) 7Li reaction. Comparison and analysis between computed and measured results of depth-dose distributions were made in this work. Dose rate scaling factors (DRSFs) were defined as normalization factors derived individually for each dose component in the BNCT in-phantom radiation field that provide the best agreement between measured and computed data. This paper reports the in-phantom calculated and experimental dosimetry and the determined DRSFs used in NCTPlan code for the BNCT beam of THOR.

Interactions of NiO particles with polycyclic aromatic hydrocarbons and acetylene generated from the pyrolysis of a model fuel

Experiments have been conducted to study the effects of NiO, a prevalent form of nickel in combustion-generated ash particles, on polycyclic aromatic hydrocarbons (PAH) and other hydrocarbons in a fuel product mixture. The fuel product mixture is generated from the gas-phase pyrolysis, in N 2, of the model fuel catechol in a quartz tube reactor at 1100 K and 5 s, a condition that ensures full conversion of the catechol and produces a mixture—of PAH, hydrocarbon gases, and oxygen-containing species—that is representative of the products of practical liquid and solid fuels in pyrolysis and fuel-rich combustion environments. Once formed, the product mixture is passed, at the same temperature, through a bed of ultrafine NiO particles held in place by quartz wool, in the contact zone of the reactor. The products exiting the reactor are quenched, collected, and analyzed by non-dispersive infrared analyzers, gas chromatography, and high-pressure liquid chromatography with diode-array ultraviolet–visible absorbance detection. The results from the experiments at 1100 K show that—compared to the case of no inorganics in the contact zone—when NiO is present: PAH yields are reduced 86% (from 10.8% to 1.48% fed carbon); all of the highly mutagenic 5- and 6-ring PAH are eliminated; and all of the acetylene, the highest-yield hydrocarbon product when NiO is absent, and other hydrocarbons with carbon–carbon triple bonds are eliminated from the gas phase. Most of the surface-bound carbon is released as CO. Similar experiments at 1275 K show that—except for the release of the surface-bound carbon as CO—the selective surface effects of NiO bring about similar results at higher temperature: 89% reduction in PAH yield, elimination of mutagenic 5- and 6-ring PAH, removal of acetylene and acetylenic species, as well as a decrease in the production of solid carbon (not formed at 1100 K).

Reforming of methane, ethylene, and desulfurized kerosene over Ni-8YSZ catalyst

Abstract For solid oxide fuel cell (SOFC) systems fueled by kerosene, reforming of methane, ethylene, and desulfurized kerosene was investigated over Ni-8YSZ catalyst at 750 °C and steam-to-carbon ratio (S/C) = 3 as a function of gas hourly space velocity (GHSV). At temperatures higher than 650 °C, a thick Ni-8YSZ layer exhibited a high catalytic activity for reforming of methane, ethylene, and kerosene of which gas concentration in a pre-reformate gas was less than 1%. On the other hand, thin anode layer will require some modification of the catalytic activity. Carbon was formed as particles in the inlet quartz wool via pyrolysis of ethylene at flow-stagnation points, which will cause pore closure in Ni-anode catalysts. This type of carbon formation would bring about inhomogeneous flow-and-voltage distribution in a cell. Direct feed of steam and kerosene to Ni-8YSZ was examined at GHSV = 2400 h −1 , S/C = 3 and 550–750 °C. Gas composition analysis and FTIR spectra indicate that high kerosene conversion (≥95%) could be attained at 650–750 °C over Ni-8YSZ assuming relatively thick Ni-anode layer. The catalytic activity was deteriorated at lower temperatures. Clear carbon deposition on Ni-8YSZ or inlet quartz wool was not observed on the experimental condition. The direct feeding system may be possible only at high temperatures and high S/C. As long as a temperature of anode-supported SOFCs is kept over 650 °C, small amount of methane, ethylene, and kerosene will not harm performance of the SOFCs.