Hydrogen Peroxide In Methanol Research Articles

Effect of Hydrogen Bonding Network on Raman Modes of Methanol–Hydrogen Peroxide Binary Solutions

Effect of Hydrogen Bonding Network on Raman Modes of Methanol–Hydrogen Peroxide Binary Solutions

Reactant Transport Engineering Approach at Cathode to High Power Direct Methanol Hydrogen Peroxide Fuel Cell

The development of high-power fuel cells could advance the electrification of the transportation sector, including marine and air transport. Liquid-fueled fuel cells are particularly attractive for such applications as they obviate the issue of fuel transportation and storage. Herein, we report a direct methanol hydrogen peroxide fuel cell (DMHPFC) for high-power propulsion applications that delivers 0.8 W cm2 peak power density by using a pH gradient-enabled microscale bipolar interface (PMBI) to effectively meet the incongruent pH requirements for methanol oxidation/peroxide reduction reactions.DMHPFCs are an important alternative to hydrogen-fed polymer electrode membrane fuel cell (PEMFCs) and anion exchange membrane fuel cells (AEMFCs) due to methanol’s high energy density compared to that of hydrogen and superior kinetics of hydrogen peroxide reduction reaction as compared to Oxygen. A unit volume of Hydrogen gas stored at a pressure of approximately 69 MPa corresponds to volume-specific energy density of roughly 2.1 kWh/l while 39% volume of aqueous methanol and 41% volume of aqueous hydrogen peroxide corresponds to volume-specific energy density of 9.2 kWh/l. So, DMHPFC’s energy density is approximately four times higher than hydrogen fuel cell’s energy density and is comparable to gasoline which contains roughly 9.2 kWh/l of available bond energy. The theoretical potential for Methanol oxidation reaction (MOR) in basic medium is lower than that in an acidic medium (-0.78 V vs. -0.02 V) and the theoretical potential for the Hydrogen peroxide reduction reaction (HPRR) is higher than that for oxygen reduction (1.77 V vs. 1.23 V in acidic medium). This results in the highest theoretically possible cell voltage for cells with alkaline anodes and acidic cathodes. We achieved sustained operation of the DMHPFC with an alkaline anode and an acidic cathode by incorporating our pH-gradient-enabled microscale bipolar interface (PMBI).However, the system exhibits a relatively low Faradaic efficiency of 50% due to the parasitic evolution of O2 by the decomposition of H2O2. The O2 evolution results in a mixed potential at the cathode due to the occurrence of both the HPRR (E0 = 1.77 V versus standard hydrogen electrode [SHE]) and the oxygen reduction reaction (ORR); (E0 = 1.23 V versus SHE), lowering the overall cell potential. The O2 surface coverage reduces the available sites for the HPRR, effectively deactivating the catalyst. Electrocatalysts exhibiting a combination of high HPRR activity and selectivity (by inhibiting H2O2 decomposition, and hence inhibiting ORR) would result in higher faradic efficiency and have been the subject of sustained interest. Here, we examine an alternate reactant-transport engineering approach to improve the overall cell potential and cell performance of the DMHPFC. Our reactant-transport engineering approach has examined the impact of reactant flowrate, flow velocity, residence time, and flow regime (via the Reynolds number ([Re]) on DMHPFC performance. Balancing the competing demands of high residence time to improve Hydrogen peroxide reduction reaction (HPRR) rates with high flowrates to detach adsorbed O2, we identify a critical Re and Damkholer number (Da) to efficiently exclude O2 gas bubbles while maintaining large current densities during the operation of a DMHPFC. Reactant-transport engineering of the cathode flow field architecture and fuel flowrates mitigates parasitic hydrogen peroxide decomposition and oxygen reduction reactions and lessens cathode passivation by oxygen bubbles. DMHPCs fulfilling these criteria provide a power density of >500 mW cm-2 at 1.0 V compared to state-of-the-art polymer electrolyte membrane fuel cells (PEMFCs) that typically operate at 0.75 V. The high peak power density of 800 mW cm-2 at 1.1 V may offer a pathway to reduce fuel cell stack size for propulsion applications. Our work paves the way for such other liquid fuel cells with hydrogen peroxide as the oxidant and enabled with PMBI resulting in significantly improvement in the performance. Figure 1

Synthesis, Identification and Study of the Anti-microbial Activity of Novel Chalcone and Epoxy Chalcone Compounds

Abstract In this study, new chalcone and epoxy chalcone synthesized by condensation of 4-acetylbiphenyl with the appropriate aldehydes. The epoxy chalcone prepared via the reaction chalcone with alkaline hydrogen peroxide in methanol. We characterized their mass spectra and 1H, 13C-NMR, and 2D-HSQC spectra to confirm their structure and absolute configuration. The target compounds were then screened for their potential antibacterial and antifungal activities. Most of the tested chalcone compounds had better activity against the fungal strains Fusarium and Aspergillus niger.

Selective propylene epoxidation by low cost microporous/mesoporous hierarchical Titanium silicalite-1

TS-1 (Titanium silicalite-1) with micro/mesoporous hierarchical framework with regular pores diameter of 3–5 nm has been produced efficiency in a low molar ratio of tetrapropyl ammonium hydroxide/silica (TPAOH/SiO2) by utilizing tetraethyl silicate-40 (TES) as silica source under hydrothermal conditions. For reducing the cost of TS-1 production, TPAOH/SiO2 molar ratio decreased to 0.08 in the presence of non-ionic surfactant. Furthermore, cheaper TES is used instead of tetraethyl orthosilicate (TEOS), which is normally used for industrial synthesis of TS-1. The resulting samples are characterized by XRD, SEM, TEM, FT-IR, UV–Vis spectroscopy and N2 adsorption–desorption. The preparation condition is greatly influenced on TS-1 textural features, particle size, morphology and coordination of titanium species in the structure. Hierarchical TS-1 samples were utilized as catalysts in the propylene epoxidation with hydrogen peroxide in methanol. The catalytic activity was compared with the conventional TS-1.

Passive Direct Methanol–Hydrogen Peroxide Fuel Cell with Reduced Graphene Oxide–Supported Prussian Blue as Catalyst

Herein, a reduced graphene oxide–supported Prussian Blue (rGO‐PB) composite as the cathode catalyst for a passive direct methanol–hydrogen peroxide fuel cell (DMHPFC) is used. Unlike the conventional passive direct methanol fuel cell (DMFC) with a cathodic catalyst of noble metal platinum (Pt), the new fuel cell uses hydrogen peroxide as the oxidant. This nonnoble metal catalyst has a low cost, high catalytic activity, and high conductivity due to its 3D conductive network. The fuel cell has a theoretical voltage of 1.76 V (higher than 1.21 V related to the traditional DMFC) and can be used in an oxygen‐free environment. Results show that the cell shows good performance with a peak power density of 20.5 mW cm−2 at a higher temperature of 85 °C. The polarization and impedance curves indicate that as the temperature increases, the cell performance improves continuously with the decrease in mass transfer resistance. The discharging tests show a stable cell performance under continuous operation. The cell voltage has an instant response to the change in the current output.

A direct methanol–hydrogen peroxide fuel cell with a Prussian Blue cathode

In this work, a direct methanol–hydrogen peroxide fuel cell is developed and tested. Theoretically, it is shown that the use of hydrogen peroxide in a direct methanol fuel cell (DMFC) not only increases the cell's voltage from 1.21 V to 1.76 V, but also reduces the activation loss of the reduction reaction as a result of two-electron transfer. Experimentally, it is demonstrated that the fuel cell with the use of an inexpensive carbon nanotube supported Prussian Blue catalyst, exhibits a peak power density of 125 mW cm−2 at 60 °C, which is comparable to that of conventional DMFCs with platinum-based catalysts.

Kinetics of allyl chloride epoxidation with hydrogen peroxide catalyzed by extruded titanium silicalite

A mechanism is suggested for the heterogeneous catalytic epoxidation of allyl chloride with hydrogen peroxide in methanol. The kinetics of allyl chloride oxidation into epichlorohydrin in the presence of extruded titanium silicalite has been investigated. A kinetic model of the process has been derived from experimental data, and the activation energies of the target and side reactions, the rate constants of the reactions, and the adsorption equilibrium constant have been determined. The allyl chloride epoxidation process has been tested using a bench-scale continuous apparatus, and the adequacy of the kinetic model has been estimated.

ChemInform Abstract: Nucleophilic Dimerization of Indoline under Oxidative Conditions.

Oxidation of indoline with 30% hydrogen peroxide in methanol in the presence of sodium tungstate affords the dimeric 3-oxo-1 ’H ,3 H - 2,3 ’ -biindole-1-oxide.

Nucleophilic dimerization of indoline under oxidative conditions

Oxidation of indoline with 30% hydrogen peroxide in methanol in the presence of sodium tungstate affords the dimeric 3-oxo-1 ’H ,3 H - 2,3 ’ -biindole-1-oxide.

Studies on the deactivation of Ti-MCM-41 catalyst in the process of allyl alcohol epoxidation

Abstract The synthesis of Ti-MCM-41 catalyst was performed. The obtained catalyst was characterized by the following instrumental methods: UV-vis, IR spectroscopy, XRD, and X-ray microanalysis. The activity of the obtained catalyst was tested in the process of allyl alcohol epoxidation with 30 wt.% hydrogen peroxide in methanol as a solvent and under atmospheric pressure. In the next stage, recovery of Ti-MCM-41 catalyst from the post-reaction mixture and its regeneration by washing with appropriate solvents and drying were conducted. In the case of total loss of the activity of the catalyst, calcination of the catalyst was also carried out. The loss of titanium from the structure of Ti-MCM-41 catalyst and a partial collapsing of the structure of this catalyst can be the main reason of the decrease the activity of the catalyst what was manly visible in the decrease of the values of two functions of this process: the allyl alcohol conversion and conversion of hydrogen peroxide to organic compounds.

Brucella abortus Induces Collagen Deposition and MMP-9 Down-Modulation in Hepatic Stellate Cells via TGF-β1 Production

In patients with active brucellosis, the liver is frequently affected by histopathologic lesions, such as granulomas, inflammatory infiltrations, and parenchymal necrosis. Herein, we examine some potential mechanisms of liver damage in brucellosis. We demonstrate that Brucella abortus infection inhibits matrix metalloproteinase-9 (MMP-9) secretion and induces collagen deposition and tissue inhibitor of matrix metalloproteinase-1 secretion induced by hepatic stellate cells (LX-2). These phenomena depend on transforming growth factor-β1 induction. In contrast, supernatants from B. abortus-infected hepatocytes and monocytes induce MMP-9 secretion and inhibit collagen deposition in hepatic stellate cells. Yet, if LX-2 cells are infected with B. abortus, the capacity of supernatants from B. abortus-infected hepatocytes and monocytes to induce MMP-9 secretion and inhibit collagen deposition is abrogated. These results indicate that depending on the balance between interacting cells and cytokines of the surrounding milieu, the response of LX-2 cells could be turned into an inflammatory or fibrogenic phenotype. Livers from mice infected with B. abortus displayed a fibrogenic phenotype with patches of collagen deposition and transforming growth factor-β1 induction. This study provides potential mechanisms of liver immune response induced by B. abortus-infected hepatic stellate cells. In addition, these results demonstrate that the cross talk of these cells with hepatocytes and macrophages implements a series of interactions that may contribute to explaining some of mechanisms of liver damage observed in human brucellosis.

Novel effect of palladium catalysts on chemoselective oxidation of β-pinene by hydrogen peroxide

Application of PdX2 catalysts (X=Cl−, −OAc, −OCOCF3, acac) for the oxidation of β-pinene by hydrogen peroxide in methanol is presented. The reactions performed in CH3OH were much faster and more selective than those described in the literature. Moreover, the peculiar tunability of Pd(II) selectivity dependent on the nature of the anionic ligand is highlighted. Although they present different chemoselectivity, PdCl2 and Pd(OAc)2 were the most active catalysts; high conversions of β-pinene into allylic oxidation products were obtained (ca. 80 %) when catalyzed by Pd(OAc)2 and up to ca. 99 % when catalyzed by PdCl2, both in short reaction times (ca. 2 h).

Formation and Reactivity of a Biomimetic Hydroperoxocopper(II) Cryptate

AbstractCopper(II)‐hydroperoxo species are proposed as key intermediates in the catalytic cycles of copper‐monooxygenase enzymes that perform C–H bond hydroxylation. Herein we report on the oxidation chemistry of a copper(II) complex with a coordinating cryptand based on a peralkylated tetradentate tris(2‐aminoethyl)amine (tren) moiety. X‐ray crystallography of the copper(II) acetate complex of this cryptand revealed that the copper(II) ion is in a square‐pyramidal environment, with the cryptand acting only as a tridentate ligand. This geometry is conserved in solution and likely results from restraints imposed by the semi‐rigid cryptand. Reaction of this complex with basic hydrogen peroxide in methanol led to the decomposition of the complex with an oxygen‐atom transfer to the ligand, as evidenced by mass spectrometry analysis after reaction and demetallation. Low‐temperature stopped‐flow experiments (down to –90 °C) support the formation of a copper(II)‐hydroperoxo intermediate, CuOOH, before ligand oxygenation occurs. It is proposed that this intermediate performs the oxygen‐atom transfer to a weak benzylic C–H bond of the cryptand, thereby mimicking the behavior of dopamine‐β‐hydroxylase.

Role of hydrogen peroxide in the synthesis of nitrogen heterocycle containing cobalt complexes

The reactions of Co(O 2CCH 3) 2·4H 2O with the sodium salt of p-toluene sulfonic acid (NapTS) and pyridine (py) or 4-methylpyridine (4mepy) in the presence of hydrogen peroxide in methanol led to the formation of [Co(py) 3(H 2O) 3](pTS) 2 or [Co(4mepy) 2(H 2O) 4](pTS) 2·MeOH, respectively. The coordination polymer [{Co(44′bpy)(H 2O) 4}(pTS) 2] n (4,4′-bipyridine = 44′bpy) was obtained from the reaction of Co(O 2CCH 3) 2·4H 2O with 44′bpy in the presence of NapTS. The reaction of Co(O 2CCH 3) 2·4H 2O, 2,2′-bipyridine (22′bpy) and NapTS with hydrogen peroxide resulted in the formation of the dinuclear complex [Co 2(μ-OH) 2(μ-O 2CCH 3)(O 2CCH 3) 2(22′bpy) 2](pTS). Characterization of these complexes and the role of hydrogen peroxide in these reactions are discussed. Similar reactions with sodium sulfamate gave the mononuclear [Co(22′bpy) 2(O 2CCH 3)]NH 2SO 3·2H 2O complex and [Co 2(μ-OH) 2(μ-O 2CCH 3)(O 2CCH 3) 2(22′bpy) 2](NH 2SO 3).

Selection of Brain Metastasis-Initiating Breast Cancer Cells Determined by Growth on Hard Agar

An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44(+) and CD133(+) and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice.

Implantable hybrid chrome silicide temperature sensor for power MEMS devices

In this Letter, an implantable hybrid temperature sensor for use in a micro-scale space in power MEMS devices is proposed. The developed sensor use chrome silicide (CrSi2), which has a very high electromotive force, and nickel as a base metal. Since a thermocouple is an appropriate device to measure temperature at a specific spot, the correlations between the junction sizes and electromotive forces should be verified to reduce the junction size of the thermocouple. Furthermore, it is necessary to verify the performance of the thermocouple implanted in a microdevice by patterning a resistance temperature detector (RTD) on the side of the cold junctions to evaluate the reference temperature of the nickel. The Seebeck coefficients of the CrSi2 thin film thermocouples occur at approximately 70 µV/°C, and the values have been shown to be 1.8 times higher than those of commercial thermocouples. The value of the slope, αNi, which is the temperature coefficient of resistance (TCR) of the nickel RTD is 0.0063/°C at 20°C, whereas the reference value of the TCR of nickel, αNi-ref is 0.0067/°C at 20°C. The third-order polynomial compensation is 99.989% of the regression square value. Based on the verification, a prototype of the hybrid temperature sensor is implanted in a micro methanol–hydrogen peroxide auto-thermal reforming module by stacking six different layers that consist of temperature sensors for the base and different channel figures for the reforming reaction.

Direct synthesis of hydrogen peroxide in methanol and water using scCO2and N2as diluents

Direct synthesis of hydrogen peroxide is of high importance nowadays due to its improvement over the traditional anthraquinone hydrogenation-oxidation process. In this work we show how H2O2 can be obtained from H2 and O2 in water pressurised with CO2 under supercritical conditions or with N2 at similar conditions without using organic solvents. Pressures up to 16.7 MPa and mild temperatures from 10 to 45 °C using a commercial 5 wt.% Pd/C catalyst lead to yields from 10.8% to 82.6%, concentrations from 0.22 to 4.01 wt.% of H2O2 and Turn Over Frequency at 30 minutes values, TOF30, from 6.0 to 1538 mol·h−1·kgcat−1. The effect of several variables on H2O2 yield has been examined: amount of catalyst, promoters/Pd ratio, amount and nature of solvent and inert gas, reaction temperature, and O2/H2 ratio. Results for methanol and water are compared.

Nano-Scaled Particles of Titanium Dioxide Convert Benign Mouse Fibrosarcoma Cells into Aggressive Tumor Cells

Nanoparticles are prevalent in both commercial and medicinal products; however, the contribution of nanomaterials to carcinogenesis remains unclear. We therefore examined the effects of nano-sized titanium dioxide (TiO(2)) on poorly tumorigenic and nonmetastatic QR-32 fibrosarcoma cells. We found that mice that were cotransplanted subcutaneously with QR-32 cells and nano-sized TiO(2), either uncoated (TiO(2)-1, hydrophilic) or coated with stearic acid (TiO(2)-2, hydrophobic), did not form tumors. However, QR-32 cells became tumorigenic after injection into sites previously implanted with TiO(2)-1, but not TiO(2)-2, and these developing tumors acquired metastatic phenotypes. No differences were observed either histologically or in inflammatory cytokine mRNA expression between TiO(2)-1 and TiO(2)-2 treatments. However, TiO(2)-2, but not TiO(2)-1, generated high levels of reactive oxygen species (ROS) in cell-free conditions. Although both TiO(2)-1 and TiO(2)-2 resulted in intracellular ROS formation, TiO(2)-2 elicited a stronger response, resulting in cytotoxicity to the QR-32 cells. Moreover, TiO(2)-2, but not TiO(2)-1, led to the development of nuclear interstices and multinucleate cells. Cells that survived the TiO(2) toxicity acquired a tumorigenic phenotype. TiO(2)-induced ROS formation and its related cell injury were inhibited by the addition of antioxidant N-acetyl-l-cysteine. These results indicate that nano-sized TiO(2) has the potential to convert benign tumor cells into malignant ones through the generation of ROS in the target cells.

Matrix Metalloproteinase-3 Accelerates Wound Healing following Dental Pulp Injury

Matrix metalloproteinases (MMPs) are implicated in a wide range of physiological and pathological processes, including morphogenesis, wound healing, angiogenesis, inflammation, and cancer. Angiogenesis is essential for reparative dentin formation during pulp wound healing. The mechanism of angiogenesis, however, still remains unclear. We hypothesized that certain MMPs expressed during pulp wound healing may support recovery processes. To address this issue, a rat pulp injury model was established to investigate expression of MMPs during wound healing. Real-time RT-PCR analysis showed that expression MMP-3 and MMP-9 (albeit lower extent) was up-regulated at 24 and 12 hours after pulp injury, respectively, whereas expression of MMP-2 and MMP-14 was not changed. MMP-3 mRNA and protein were localized in endothelial cells and/or endothelial progenitor cells in injured pulp in vivo. In addition, MMP-3 enhanced proliferation, migration, and survival of human umbilical vein endothelial cells in vitro. Furthermore, the topical application of MMP-3 protein on the rat-injured pulp tissue in vivo induced angiogenesis and reparative dentin formation at significantly higher levels compared with controls at 24 and 72 hours after treatment, respectively. Inhibition of endogenous MMP-3 by N-Isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid resulted in untoward wound healing. These results provide suggestive evidence that MMP-3 released from endothelial cells and/or endothelial progenitor cells in injured pulp plays critical roles in angiogenesis and pulp wound healing.

Tantalum(V) or niobium(V) catalyzed oxidation of sulfides with 30% hydrogen peroxide

Tantalum(V) and niobium(V) are effective catalysts for the oxidation of sulfides with 30% hydrogen peroxide. The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride or niobium(V) chloride in acetonitrile, i-propanol or t-butanol selectively provided the corresponding sulfoxides in high yields. The corresponding sulfones are efficiently obtained from the reaction of sulfides with 30% hydrogen peroxide in methanol catalyzed by tantalum(V) or niobium(V).