Gas-phase Hydrogen Research Articles

Solar hydrogen production from ethanol-water vapours over metal/TiO2 photocatalysts supported on β-SiC alveolar foams

In this work, we have explored the feasibility of alveolar open-cell β-SiC foams as catalyst support for solar hydrogen production. For that purpose, Pt and Ru nanoparticles have been obtained, by means of photoassisted synthesis, on TiO2-coated foams and tested in gas-phase hydrogen production from water-ethanol mixtures in a tubular reactor coupled to a compound parabolic solar collector (CPC). Subnanometre-sized metal or metal/oxide nanoparticles are obtained for Pt/TiO2/SiC and Ru/TiO2/SiC foams, respectively, where co-catalyst nanoparticles decorate the TiO2 coating which in turn is attached to the SiC foam through an amorphous SiO2 washcoat formed by SiC pre-calcination. In solar photocatalytic reactions, all of the assayed foam-supported photocatalysts are active for the production of hydrogen, with Pt/TiO2 ones being the most active and foam pore size exerting little influence on hydrogen outcome. In the best conditions, 14 % UV-to-hydrogen (equivalent to 0.49 % solar-to-hydrogen) conversion efficiency, with photonic efficiency higher than 30 %, is attained.

Hydrogen-Induced Intergranular Fracture Behavior Accelerated by Needle-like MC Carbide in IN740H Superalloy

Hydrogen embrittlement of a Ni-based superalloy, IN740H, was evaluated after gas-phase hydrogen pre-charging. Specimens with different grain sizes were prepared to induce different precipitation behavior under annealing treatment; the formation of needle-like MC carbide was found only in a specimen with a larger grain size and incoherent twin boundaries after annealing treatment at 1173 K. While other parameters including the grain size and annealing treatment turned out not to undermine the resistance to hydrogen embrittlement, the needle-like MC carbide was found to induce premature failure after hydrogen absorption.

Detection of Hydrogen Peroxide in Liquid and Vapors Using Titanium(IV)-Based Test Strips and Low-Cost Hardware.

Titanium(IV) solutions are known to detect hydrogen peroxide in solutions by a colorimetric method. Xplosafe’s XploSens PS commercial titanium(IV)-based peroxide detection test strips are used to detect hydrogen peroxide in liquids. The use of these test strips as gas-phase detectors for peroxides was tested using low-cost hardware. The exposure of these strips to hydrogen peroxide liquid or gas leads to the development of an intense yellow color. For liquids, a digital single-lens reflex camera was used to quantify the color change using standardized solutions containing between 50 and 500 ppm peroxide by mass. Analysis of the images with color separation can provide a more quantitative determination than visual comparison to a color chart. For hydrogen peroxide gas, an inexpensive web camera and a tungsten lamp were used to measure the reflected light intensity as a function of exposure from a test strip held in a custom cell. First-order behavior in the color change with time was observed during the exposure to peroxide vapor over a range of peroxide concentrations from 2 and 30 ppm by volume. For a 1-min measurement, the gas-phase detection limit is estimated to be 1 ppm. A 0.01 ppm detection limit can be obtained with a 1-h exposure time. Titanium(IV)-based peroxide detection test strips are sensitive enough to work as a gas-phase hydrogen peroxide detector.

The Source Permeator System and Tritium Transport in the TEX PbLi Loop

Permeation is investigated for the introduction of hydrogen isotopes into lead lithium (PbLi) for the Tritium Extraction eXperiment (TEX). TEX is a forced-convection PbLi loop under construction at Idaho National Laboratory that will test the vacuum permeator (VP) method of tritium extraction from PbLi. The source permeator (SP) delivers atomic hydrogen (H, D, and T) from a gas-phase reservoir into the PbLi via a permeable dense metal membrane. A modular system and a fixed SP system are presented. In the modular design, PbLi flows through the inside of a tubular membrane, and gas-phase hydrogen is introduced on the outside of the membrane. Atomic hydrogen permeates radially inward through the membrane into the PbLi. In the fixed design, PbLi flows into an expansion chamber with closed-ended tubular membranes inserted. Gas-phase hydrogen is introduced on the inside of the closed-ended membranes, and atomic hydrogen permeates radially outward into the flowing PbLi. Hydrogen transport models based on steady-state mass transport through PbLi and permeation through the metal membrane were developed to assess the operation of the SP relative to experimental variables and to allow understanding of uncertain parameter effects, such as PbLi hydrogen transport properties and the effective hydrogen permeability of the VP. This modeling effort considers iron as the SP material and vanadium as the VP material.

Fully anhydrous HCl electrolysis using polybenzimidazole membranes

We demonstrate for the first time a fully anhydrous gas-phase hydrogen chloride electrolyzer. By taking advantage of polybenzimidazole's (PBI) low membrane resistivity in anhydrous conditions (0.87 ± 0.57 Ω-cm2 at 160 °C) and its temperature and acid environment stability, we are able to directly convert pure hydrogen chloride gas to dry hydrogen and dry chlorine at efficiencies nearing 100% at an electrolyzer temperature of 160 °C and electrolyzer potential of 1.8 V. Finally, we discuss steps to further improve this electrolysis process in terms of both electrolyzer performance and cost reduction.

Strong impacts of biomass burning, nitrogen fertilization, and fine particles on gas-phase hydrogen peroxide (H2O2)

Gas-phase hydrogen peroxide (H2O2) plays an important role in atmospheric chemistry as an indicator of the atmospheric oxidizing capacity. It is also a vital oxidant of sulfur dioxide (SO2) in the aqueous phase, resulting in the formation of acid precipitation and sulfate aerosol. However, sources of H2O2 are not fully understood especially in polluted areas affected by human activities. In this study, we reported some high H2O2 cases observed during one summer and two winter campaigns conducted at a polluted rural site in the North China Plain. Our results showed that agricultural fires led to high H2O2 concentrations up to 9 ppb, indicating biomass burning events contributed substantially to primary H2O2 emission. In addition, elevated H2O2 and O3 concentrations were measured after fertilization as a consequence of the enhanced atmospheric oxidizing capacity by soil HONO emission. Furthermore, H2O2 exhibited unexpectedly high concentration under high NOx conditions in winter, which are closely related to multiphase reactions in particles involving organic chromophores. Our findings suggest that these special factors (biomass burning, fertilization, and ambient particles), which are not well considered in current models, are significant contributors to H2O2 production, thereby affecting the regional atmospheric oxidizing capacity and the global sulfate aerosol formation.

Multiplexed Conformationally Selective, Localized Gas-Phase Hydrogen Deuterium Exchange of Protein Ions Enabled by Transmission-Mode Electron Capture Dissociation.

In this article, we present an approach for conformationally multiplexed, localized hydrogen deuterium exchange (HDX) of gas-phase protein ions facilitated by ion mobility (IM) followed by electron capture dissociation (ECD). A quadrupole-IM-time of flight instrument previously modified to enable ECD in transmission mode (without ion trapping) immediately following a mobility separation was further modified to allow for deuterated ammonia (ND3) to be leaked in after m/z selection. Collisional activation was minimized to prevent deuterium scrambling from giving structurally irrelevant results. Gas-phase HDX with ECD fragmentation for exchange site localization was demonstrated with the extensively studied protein folding models ubiquitin and cytochrome c. Ubiquitin was ionized from conditions that stabilize the native state and conditions that stabilize the partially folded A-state. IM of deuterated ubiquitin 6+ ions allowed the separation of more compact conformers from more extended conformers. ECD of the separated subpopulations revealed that the more extended (later arriving) conformers had significant, localized differences in the amount of HDX observed. The 5+ charge state showed many regions with protection from HDX, and the 11+ charge state, ionized from conditions that stabilize the A-state, showed high levels of deuterium incorporation throughout most of the protein sequence. The 7+ ions of cytochrome c ionized from aqueous conditions showed greater HDX with unstructured regions of the protein relative to interior, structured regions, especially those involved in heme binding. With careful tuning and attention to deuterium scrambling, our approach holds promise for determining region-specific information on a conformer-selected basis for gas-phase protein structures, including localized characterizations of ligand, epitope, and protein-protein binding.

Hydrogen chloride (HCl) at ground sites during CalNex 2010 and insight into its thermodynamic properties.

Gas phase hydrogen chloride (HCl) was measured at Pasadena and San Joaquin Valley (SJV) ground sites in California during May and June 2010 as part of the CalNex study. Observed mixing ratios were on average 0.83 ppbv at Pasadena, ranging from below detection limit (0.055 ppbv) to 5.95 ppbv, and were on average 0.084 ppbv at SJV with a maximum value of 0.776 ppbv. At both sites, HCl levels were highest during midday and shared similar diurnal variations with HNO3. Coupled phase partitioning behavior was found between HCl/Cl- and HNO3/NO3 - using thermodynamic modelling and observations. Regional modeling of Cl- and HCl using CMAQ captures some of the observed relationships but underestimates measurements by a factor of 5 or more. Chloride in the 2.5-10 μm size range in Pasadena was sometimes higher than sea salt abundances, based on co-measured Na+, implying that sources other than sea salt are important. The acid-displacement of HCl/Cl- by HNO3/NO3 - (phase partitioning of semi-volatile acids) observed at the SJV site can only be explained by aqueous phase reaction despite low RH conditions and suggests the temperature dependence of HCl phase partitioning behavior was strongly impacted by the activity coefficient changes under relevant aerosol conditions (e.g., high ionic strength). Despite the influence from activity coefficients, the gas-particle system was found to be well constrained by other stronger buffers and charge balance so that HCl and Cl- concentrations were reproduced well by thermodynamic models.

Effect of gravity conditions on heat transfer and flow fluctuations of liquid hydrogen in a non-isothermal horizontal circular tube

Liquid hydrogen phase transition is a common phenomenon in space missions for space vehicles using low temperature liquid hydrogen as propellant. In this study, a numerical model with coupled RANS solver and VOF/Level-set method was used to simulate the liquid hydrogen phase transition in a non-isothermal horizontal circular tube under different gravity conditions (1g-10−4 g). The gas phase hydrogen produced by evaporation of liquid hydrogen was calculated by Lee model. The statistics of the overall volume, heat flux, mass flow rate, mean velocity of gas phase hydrogen was carried out. The data results shown that the flow fluctuations were strongest under the gravity acceleration of 10−1 g relative to other gravity conditions. The average bubble volume at 10−1 g was the smallest, which was 11.58% smaller than that at 10−3 g condition. The intermittent contact with the tube wall, which leaded to intermittent long bubble and flow resistance, was the main reason.

Global potential energy surface and product pair-correlated distributions for the F(2P) + SiH4 reaction - comparison with experiments.

In this paper we study the gas-phase hydrogen abstraction reaction between fluorine atoms and silane in a three-step process: potential energy surface, kinetics and dynamics. Firstly, we developed for the first time an analytical full-dimensional surface, named PES-2021, using high-level explicitly-correlated ab initio data as the input. PES-2021 represents a continuous and smooth potential with analytical gradients and includes intuitive concepts (stretching and bending nuclear motions). Based on the PES-2021 quasi-classical trajectory (QCT) calculations were performed to analyse the kinetics and dynamics. Secondly, in the kinetics study at room temperature we observed a very fast reaction with a rate constant of 3.90 × 10-10 cm3 molecule-1 s-1, reproducing the scarce experimental evidence. Finally, the third step is the dynamics study, which was performed under two different conditions, a temperature of 77 K and a collision energy of 2.5 kcal mol-1, for direct comparison with experiments. In the first case, we found the largest fraction, 44%, deposited as HF(v) vibration, where the most populated states were HF(v = 2, 3), both results reproducing the experimental evidence. The largest discrepancy with the experiment was found in the HF(j) rotational distribution, where hotter distributions were found, this discrepancy being associated with limitations of the QCT method. The second case, E = 2.5 kcal mol-1, was a state-to-state correlated study and, therefore, more difficult. The theory overestimates (again) and consequently underestimates, respectively, the rotational and vibrational fractions of the HF(v,j) product as compared with experiments. While experimentally the SiH3 product appears excited only in the umbrella mode, ν2 = 0-5, correlated with the HF(v) co-product vibrational excited in v = 3 and 4, theoretically a wider vibrational distribution is found in both products, and these distributions have, obviously, an influence on the product correlated speed distributions. However, the product correlated angular distribution is well reproduced. In general, these results allowed us to test the capacity of PES-2021 + QCT tools to simulate the experimental evidence, revealing that agreement is better when average properties are compared, making the comparison worse when state-to-state properties are compared. Different causes of the theory/experiment discrepancies were analysed, and it was found that they are due, mainly, to limitations of the QCT method.

Photochemical Aging of Atmospheric Fine Particles as a Potential Source for Gas-Phase Hydrogen Peroxide.

Atmospheric hydrogen peroxide (H2O2), as an important oxidant, plays a key role in atmospheric sulfate formation, affecting the global radiation budget and causing acid rain deposition. The disproportionation reactions of hydroperoxyl radicals (HO2) in both gas and aqueous phases have long been considered as dominant sources for atmospheric H2O2. However, these known sources cannot explain the significant formation of H2O2 in polluted areas under the conditions of high NO levels and low ambient relative humidity (RH). Here, we show that under relatively dry conditions during daytime, atmospheric fine particles directly produce abundant gas-phase H2O2. The formation of H2O2 is verified to be by a reaction between the particle surface -OH group and HO2 radicals formed by photooxidation of chromophoric dissolved organic matters (CDOMs), which is slightly influenced by the presence of high NO levels but remarkably accelerated by water vapor and O2. In contrast to aqueous-phase chemistry, transition metal ions (TMIs) are found to significantly suppress H2O2 formation from the atmospheric fine particles. The H2O2 formed from relatively dry particles can be directly involved in in situ SO2 oxidation, leading to sulfate formation. As CDOMs are ubiquitous in atmospheric fine particles, their daytime photochemistry is expected to play important roles in formation of H2O2 and sulfate worldwide.

Regularities of hydrogen accumulation and distribution in titanium coatings formed on a steel substrate by the cathode-arc method

The main direction in the field of the use of hydrocarbon resources is the creation of a metal hydride hydrogen battery. Hydrides are solid non-volatile substances that are formed when certain metals are combined with hydrogen. The principle of using hydrides as a medium for storing hydrogen is simple: under pressure, the metal captures hydrogen, which dissolves in the metal, forming a new chemical, and when the hydride is heated, the gas is given back. The metal hydride method of hydrogen storage is based on the ability of a number of intermetallic compounds, metals, alloys and composite materials to reversibly and selectively absorb hydrogen. The object of the study is titanium coatings formed on samples of 12X18H10T stainless steel by the cathode-arc method. In the course of the study, ion-plasma deposition of coatings was carried out. Scanning electron microscopy was also performed. The phase composition and structure of the titanium coating in the initial and submerged state were evaluated. Gas-phase hydrogenation was carried out, followed by an assessment of the effect of hydrogen on the alloy structure. Titanium was deposited by the cathode-arc method. Deposition of titanium coatings was carried out on the Raduga-Spektr installation, microstructure analysis was carried out on SEM using a Hitachi TM–2800 gas-phase hydrogen saturation microscope using an automated Gas Reaction Controller complex, a Shimadzu XRD-7000S diffractometer, and an inert gas melting method using a LECO RHEN 602 hydrogen analyzer.

Increased Hydrophilicity of Silicon Surface through Plasma Treatment with Hydrogen Peroxide Gas

Increased Hydrophilicity of Silicon Surface through Plasma Treatment with Hydrogen Peroxide GasSpiegelman, D. Alvarez, C. Ramos (RASIRC), K. Andachi, G. Tsuchibuchi, and K. Suzuki (Taiyo Nippon Sanso Corporation)Wafer bonding is a critical step in the development of advanced semiconductor and MEMS devices.1 Wafer bonding enables the bonding of dissimilar materials as well as the union of separate manufacturing pathways where the pathway steps are dissimilar and frequently incompatible to a single wafer process. Oxide wafer bonding is a common bonding method that requires the wafer surface to have a uniformly flat surface with sufficiently dense hydroxyl (-OH) groups. The hydroxyl groups provide a pathway for chemical covalent bonding between two wafer surfaces (EG Si-O-Si). Ultimately, the wafer bonding strength is a function of the density of the hydroxyl groups populated on the wafer surface before bonding.Several challenges are associated with functionalizing wafer surfaces. Wet Thermal oxidation is a common method for incorporating surface hydroxyl groups on silicon, however this process typically takes place at very high temperatures (>600C °) where surface hydroxyl groups may reversibly desorb, thus limiting surface functionalization. Surface oxidation by Oxygen plasma is another common method for the creation of hydrophilic surfaces,2 however, this property may be attributed to bridging oxides on the surface, where hydroxyl groups may not be present. In the latter case, residual charge or surface radical species may lead to the observed improvement in wafer bonding properties. Plasma oxidation allows for lower temperature activation.2 Oxygen or clean dry air are frequently used in the plasma process with argon.Our investigation involves the use of hydrogen peroxide gas. In recent years this material has become available in the gas phase where:Gas-phase H2O2/H2O mixture is delivered from an ampoule-based formulation. (RASIRC® BRUTE® Peroxide)High concentration H2O2/H2O is vaporized by in situ concentration methods and use of a membrane vaporizer as a gas generator. (RASIRC Peroxidizer®)Early studies by Kummel3 demonstrated that Hydrogen peroxide gas provides a denser hydroxyl surface on SiGe and Ge vs water. Here, all thermal methods were utilized at reduced temperatures.Before our current work, the creation and use of gas-phase hydrogen peroxide plasma has not been addressed. The objective of this work is to demonstrate the generation of hydrogen peroxide plasma and compare its surface functionalization characteristics to those of water and oxygen plasma methods.A constant gas stream of H2O2/H2O mixture in a carrier gas was introduced to a remote plasma source (MKS). (Figure 1). The use of an argon carrier gas led to stable ignition of the plasma mixture. The subsequent addition of oxygen gas gives rise to plasma instability.In the comparative study, the H2O2 gas stream was mixed with water vapor, molecular oxygen, and argon in different ratios, subjected to a remoted plasma. Functionalization was then carried out on a Si-H terminated surface (HF last silicon wafer surface). Thermal effects without plasma were also compared. Surface hydrophilicity (relative Hydroxyl density) was determined by contact angle measurements with the use of a goniometer.The initial wafer surface after HF clean had a water contact angle of 84.9 °. The smallest wetting angle was found for H2O2/H2O/Ar plasma at 4 °. Water alone led to a wetting angle that was 62.5% larger than the hydrogen peroxide mixture. The angle increased with increasing oxygen concentration in the H2O2 gas stream. The wetting angle with dry oxygen at 200C ° was 27.3°. Thermal only H2O2 gas at 150C° was 47.3 ° and further reduced to 11.4 ° when the temperature was increased to 300C °. (Figure 2). These results along with mechanism and ramifications for wafer bonding will be discussed.

TiO2-reduced graphene oxide-Pt nanocomposites for the photogeneration of hydrogen from ethanol liquid and gas phases

The production of hydrogen by photocatalysis presents attractive features but also stringent requirements of materials properties. A series of TiO2-based photocatalysts containing reduced graphene oxide (rGO) and platinum, TiO2-rGO(x)-Pt(y) (x=0−5 wt%; y=1.5, 2.5, 3.8 wt%), were synthesized by a simple two-step procedure. The ternary composites exhibited promising performance for hydrogen generation, in both liquid and gas phase photocatalysis, using ethanol as hole scavenger, under UV light. The effect of the concentration of ethanol, graphene oxide, and Pt, as well as photocatalyst loading and solution pH were assessed. The photocatalyst TiO2-rGO3%-Pt3.8%, in the liquid phase, produced gases containing over 95% hydrogen at very high initial production rates, ∼560 mmolh−1gcat−1. The gas production vs irradiation time (6 h) showed linear dependence in a two-slope graph, with a drastic decrease of the rate due to Pt poisoning. Solution pH reached values of 3.5, regardless of the initial value. In the liquid phase, partial oxidation of ethanol took place with the dehydrogenation of ethanol to acetaldehyde. In the gas phase photocatalysis, TiO2-rGO3%-Pt3.8% showed capability for photo-reforming as indicated by produced gases with a molar ratio H2/CO2 of 3. rGO reinforces the effect of Pt as a suppressor of charge recombination.

Effect of hydrogen- and oxygen-containing heterogeneities on the tensile strength of solid and molten aluminum

Low tensile strength of aluminum melt is a problem for traditional casting and additive manufacturing, while the tensile strength of solid aluminum is relevant for its application. Heterogeneities are considered as the main reason of decrease in the tensile strength, and investigation of their influence is a topical problem. We perform MD study of the effect of alumina inclusions, hydrogen bubbles and dissolved hydrogen on the tensile strength of aluminum in both solid and molten states. It is shown that uniformly dissolved hydrogen itself does not alter the tensile strength in most cases. An admixture of alumina can halve the tensile strength of solid aluminum, but in the case of a melt, the decrease in strength is only about 10% and even less at high temperatures. The most reducing the melt strength is the presence of non-collapsing bubbles stabilized by gas phase of hydrogen inside them. The tensile strength of the melt with hydrogen bubbles drops down in more than 10 times and even down to zero at high temperatures in comparison with the homogeneous melt for the total hydrogen concentration of about 1.4 at. %. Decrease in the hydrogen content leads to squeeze of the initial bubbles and increases the tensile strength. In the case of solid aluminum, the effect of hydrogen-filled bubbles does not depend on the hydrogen content and is equal to the effect of empty pores or alumina inclusions of the same size. Almost zero tensile strength of aluminum melt at casting and other technological processes can be explained by the combination of the admixture of hydrogen in the metal and spatial heterogeneities of the melt flow, which results in the hydrogen-stabilized bubbles tearing the melt at tension.

Chemical Characteristics of Cloud Water and Sulfate Production Under Excess Hydrogen Peroxide in a High Mountainous Region of Central Japan

Over the last two decades, atmospheric sulfur dioxide (SO2) concentrations have decreased in air-polluted regions. However, this decrease was accompanied by a rise in cloud water acidity (pH), which remains below 5. With this change, gas-phase hydrogen peroxide (H2O2) exceeded SO2 in most of these regions. These conditions where SO2 10) in our observation site, which was due to power plant restrictions in Japan since the 1970s. The ion species concentrations in cloud water indicated that cloud acidification resulted from dissolution of gaseous HNO3 and SO2, whereas gaseous hydrochloric acid and organic acid had a minor contribution to the acidification. Significant losses of Cl− and Mg2+ were observed in some of the cloud water. The excess value of non-sea-salt sulfate (nss-SO42−) over NH4+ in cloud water implies the in-cloud oxidation of gaseous SO2 to aqueous SO42−. A Se tracer technique was used to conduct in-situ measurements of in-cloud SO42− production. The results showed that the in-cloud production varied in a range between 7 ± 2 and 41 ± 14%. This temporal variation might be due to ambient SO2 concentrations based on Henry’s law.

Facilitated Synthesis of Mg2Ni Based Composites with Attractive Hydrogen Sorption Properties.

Composites based on Mg2Ni with 5% activated carbon from apricot stones (ACAP) have been prepared by ball milling and subsequent annealing in hydrogen atmosphere. The purpose of the primary metal (Mg, Ni, and V) milling was to reduce the particle size and achieve a good contact between them, without forming intermetallic compounds. During hydriding/dehydriding at 300 °C the amount of the Mg2Ni phase progressively increased, and after 10 cycles about 50% Mg2(Ni,V) was achieved. The hydrogenation produced mainly Mg2NiH4, but small amounts of MgH2 and VHx were also detected in the powder mixture. Relatively high hydrogen storage capacity and fast hydriding/dehydriding kinetics of the Mg2.1Ni0.7V0.3—5 wt.% ACAP composite were determined both from hydrogen gas phase and electrochemically.

Investigation on surface smoothing of silicon-on-insulator with gas phase hydrogen chloride etching

Silicon-on-insulator (SOI) substrates are widely used in integrated circuit manufacture because of the advantages of SOI devices. To obtain smooth and uniform top silicon layer, the process of smoothing and thinning becomes more and more critical. Surface smoothing and thinning of top silicon layer of SOI are achieved by applying gas phase hydrogen chloride etching. In this work, gas mixture with HCl proportion below 1% is used to etch the top silicon layer at various conditions. Etch rate is influenced by HCl proportion and gas flow, however, the etch rate almost keeps constant at the temperature range between 1000 °C and 1100 °C. Root mean square roughness value of etched sample can be lower than 0.2 nm, which is close to the value of bare silicon substrate, and could satisfy the requirements of CMOS applications.

Metal hydride mediated water splitting: Electrical energy saving and decoupled H2/O2 generation

Reversible hydrogen absorption/desorption, the very fundamental property of metal hydrides (MHs), can be utilized to innovate the water splitting process. Spontaneous hydrogen absorption by a MH electrode shifts the water reduction potential to 0.3 V above the reversible hydrogen electrode. Then, the absorbed hydrogen can be released to give H2 by thermal dehydrogenation at mild temperature below 70 °C by utilizing low grade heat. The MH mediated water splitting combines the electrochemical hydrogen absorption in Ni-MH batteries and the thermal dehydrogenation in gas phase hydrogen storage, which significantly reduces the electrical energy consumption for water splitting up to 25 kJ (mol H2)−1 compared to an ideal hydrogen evolution catalyst and also automatically leads to decoupled H2/O2 generation. The advantages and mechanisms of the MH mediated water splitting are demonstrated by MH electrodes with surface Pd coating.

A novel study on CHEMCAD simulation of isopropyl alcohol dehydrogenation process development

Acetone is a product which is obtained via several processes. It is produced mainly by cumene hydroperoxide process. As an alternative process, acetone is obtained by isopropyl alcohol (IPA) dehydrogenation. The conversion of IPA to acetone is an endothermic gas-phase reaction which produces hydrogen as a byproduct. The process consists of an equilibrium reactor or kinetic reactor (EREA), a distillation column (SCDS), and a flash tank. As the fresh feed, liquid-phase IPA, combined with a recycle stream which contains slight amount of unseparated acetone, is vaporized and given into the equilibrium reactor. Reactor effluent is then cooled by two heat exchangers and pressurized by a compressor until unreacted IPA and formed acetone are liquidised. This stream is fed to a flash tank in order to separate the gas-phase hydrogen, which contains slight amount of acetone. The distillation column distinguishes the acetone from unreacted IPA. The distillate stream has an acetone purity over 99%. The bottoms stream, which consists of residual IPA and slight amount of acetone, is recycled back into the mixer. The purpose of this study is to improve the simulation of isopropyl alcohol (IPA) dehydrogenation process by using the ChemCad program in terms of industrial applications.