- Kinetics and mechanism study of oxidation of 2,3-diaminopropionic acid by diperiodatocuprate(III) in alkaline medium
-
The oxidation of 2,3-diaminopropionic acid (APA) by diperiodatocuprate(III) was studied spectrophotometrically between 298.2 K and 313.2 K in alkaline medium. The oxidation rate law was obtained : kobs = 2kK1[OH-][APA]/(K1[OH-] + [H2IO6 2-]). A reaction mechanism including a pre-equilibrium step was proposed. Activation parameters and the rate constants of the rate-determining step are calculated.
- Song, Changying,Zhang, Lei,Qi, Ziyu,Shen, Shigang
-
-
Read Online
- Cost effective and energy efficient catalytic support of Co and Ni in Pd matrix toward ethanol oxidation reaction: Product analysis and mechanistic interpretation
-
The present investigation deals with the comparative analysis of electro-catalytic behaviour of Pt, Pd and ternary combinations of Co and Ni with Pd NPs, supported on vulcan XC72 as the anode component in direct ethanol fuel cell (DEFC) operating in alkaline environment. Catalyst NPs were synthesized by ethylene glycol reduction method and their structure, composition and surface morphology were determined through XRD, EDAX and TEM techniques. The superb catalytic efficiency of PdCoNi/C toward ethanol oxidation reaction (EOR) is ascribed to the catalytic intervention of transition metal ad atoms and their surface oxides, culminating to enhanced electrochemical surface area, preferred OH? adsorption on the surface and remarkable yield of oxidation products (CH3CO2? and CO32 ?) estimated by ion chromatography. The performance output parameters collectively substantiate not only to the catalytic superiority of the PdCoNi/C catalyst but also affordability to a considerable extent over both the Pt/C and Pd/C catalysts.
- Mondal, Achintya,De, Abhishek,Datta, Jayati
-
-
Read Online
- The X-ray structure of a sodium peroxide hydrate, Na2O2·8H2O, and its reactions with carbon dioxide: Relevance to the brightening of mechanical pulps
-
The main component of the solid originally believed to be a peroxosilicate with pulp-brightening properties has been shown to be Na2O2·8H2O. The solid crystallizes in the monoclinic space group C2/c, with an empirical formula H8O5Na, and with a = 14.335(3), b = 6.461(1), c= 11.432(2) A, β = 118.28(3)°, and Z = 8. The centrosymmetric structure consists of a peroxide anion with an O-O distance of 1.499(2) A. Each of these oxygen atoms is at the apex of an approximate square-based pyramid, the base of which consists of four oxygen atoms of water molecules. The bases of the two pyramids are staggered when viewed down the peroxide bond. Each sodium is at the centre of an approximate octahedron of water molecules, four of which bridge other sodium atoms and two bridge to the peroxide anions. One hydrogen atom of each of these two water molecules is terminal and the other two are hydrogen bonded to peroxide oxygen atoms. The compound reacts very rapidly with CO2 in moist air to form Na2CO3, but in drier conditions, formation of the carbonate can take many days and proceeds via a percarbonate, believed to be Na2CO4. This has been identified by infrared spectroscopy and X-ray powder diffraction and can persist for long periods in dry air.
- Hill, Geoffrey S.,Holah, David G.,Kinrade, Stephen D.,Magnuson, Vincent R.,Polyakov, Valery,Sloan, Todd A.
-
-
Read Online
- Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst
-
The development of low-cost and sustainable hydrogen production is of primary importance for a future transition to sustainable energy. In this work, the selective and simultaneous production of pure hydrogen and chemicals from renewable alcohols is achieved using an anion exchange membrane electrolysis cell (electrochemical reforming) employing a nanostructured Pd-CeO2/C anode. The catalyst exhibits high activity for alcohol electrooxidation (e.g. 474 mA cm?2 with EtOH at 60 °C) and the electrolysis cell produces high volumes of hydrogen (1.73 l min?1 m?2) at low electrical energy input (Ecost = 6 kWh kgH2?1 with formate as substrate). A complete analysis of the alcohol oxidation products from several alcohols (methanol, ethanol, 1,2-propandiol, ethylene glycol, glycerol and 1,4-butanediol) shows high selectivity in the formation of valuable chemicals such as acetate from ethanol (100%) and lactate from 1,2-propandiol (84%). Importantly for industrial application, in batch experiments the Pd-CeO2/C catalyst achieves conversion efficiencies above 80% for both formate and methanol, and 95% for ethanol.
- Bellini, Marco,Pagliaro, Maria V.,Marchionni, Andrea,Filippi, Jonathan,Miller, Hamish A.,Bevilacqua, Manuela,Lavacchi, Alessandro,Oberhauser, Werner,Mahmoudian, Jafar,Innocenti, Massimo,Fornasiero, Paolo,Vizza, Francesco
-
-
- CO2 and CO/H2 Conversion to Methoxide by a Uranium(IV) Hydride
-
Here we show that a scaffold combining siloxide ligands and a bridging oxide allows the synthesis and characterization of the stable dinuclear uranium(IV) hydride complex [K2{[U(OSi(OtBu)3)3]2(μ-O)(μ-H)2}], 2, which displays high reductive reactivity. The dinuclear bis-hydride 2 effects the reductive coupling of acetonitrile by hydride transfer to yield [K2{[U(OSi(OtBu)3)3]2(μ-O)(μ-κ2-NC(CH3)NCH2CH3)}], 3. Under ambient conditions, the reaction of 2 with CO affords the oxomethylene2- reduction product [K2{[U(OSi(OtBu)3)3]2(μ-CH2O)(μ-O)}], 4, that can further add H2 to afford the methoxide hydride complex [K2{[U(OSi(OtBu)3)3]2(μ-OCH3)(μ-O)(μ-H)}], 5, from which methanol is released in water. Complex 2 also effects the direct reduction of CO2 to the methoxide complex 5, which is unprecedented in f element chemistry. From the reaction of 2 with excess CO2, crystals of the bis-formate carbonate complex [K2{[U(OSi(OtBu)3)3]2(μ-CO3)(μ-HCOO)2}], 6, could also be isolated. All the reaction products were characterized by X-ray crystallography and NMR spectroscopy.
- Falcone, Marta,Scopelliti, Rosario,Mazzanti, Marinella
-
p. 9570 - 9577
(2019/05/17)
-
- Hydrogen production from the electrooxidation of methanol and potassium formate in alkaline media on carbon supported Rh and Pd nanoparticles
-
Small organic molecules such as alcohols and formate salts can be readily transformed into hydrogen and carbon dioxide through electrochemical reforming at low energy cost. In this article methanol and potassium formate are studied for hydrogen production in alkaline anion exchange membrane electroreformers using two anode electrocatalysts, nanoparticle Pd and Rh supported on carbon (5 wt%). Firstly, we report a study of the electrochemical activity of both catalysts in electrochemical test cells at 80 °C. Formate oxidation kinetics are found to be fast on both catalysts. Rh/C shows the best performance for methanol electrooxidation with an onset potential 200 mV lower than Pd/C and a specific activity almost double reaching the value of 2600 A g?1Rh. The energy cost and conversion efficiency for hydrogen production was determined in complete electrochemical reforming cells at 80 °C using both anode catalysts. The energy costs are low for both substrates (?1H2) with Pd/C producing hydrogen from potassium formate at an energy cost of 5 KWh kg?1H2. Considering both the energy consumption and conversion efficiency (substrate to hydrogen), it is shown that the Rh/C catalyst performs best with methanol as substrate.
- Pagliaro,Bellini,Filippi,Folliero,Marchionni,Miller,Oberhauser,Vizza
-
p. 263 - 269
(2017/10/05)
-
- Destructive oxidation of mirex
-
The perchlorinated aliphatic substance Mirex (perchloropentacyclo[5.3.0.02,6.03,9.0 4,8]decane) once had widespread use as an insecticide and still has limited application as a termiticide. Mirex resists direct oxidation by ruthenium tetraoxide. It undergoes a six-electron reduction in acetonitrile at -1·2 V from the Ag/AgCl reference potential. One or more chlorines are readily substituted by methoxide at 90°C. Both the reduced and the methoxylated derivatives are oxidized at room temperature by alkaline hypochlorite or persulfate in the presence of a homogeneous ruthenium catalyst. Only a trace amount of cyclohexane-extractable residue remains, but not all of the chlorine is released as ionic chloride. This implies that the oxidation products include some unidentified water-soluble organochlorine substances.
- Beattie, James K.,Fleming, Douglas S.
-
p. 973 - 976
(2007/10/03)
-
- The reaction of fluorosulfuryl isocyanate with alkali metal fluorides
-
Fluorosulfuryl isocyanate reacts with cesium, potassium, and sodium fluorides in acetonitrile solvent at 25° to form stable, solid adducts having a molar ratio FSO2NCO: MF close to 1:1. Chemical and physical evidence indicates that these compounds may be formulated as the salts of fluoroformylfluorosulfurylimide, M+[N(SO2F)C(O)F]-.
- Roderiguez, Joseph A.,Noftle, Ronald E.
-
p. 1874 - 1877
(2008/10/08)
-
- Some perfluoroalkyliminosulfur derivatives
-
Trifluoromethyliminosulfur dichloride and pentafluoroethyliminosulfur dichloride are prepared by reaction of aluminum trichloride with trifluoromethyliminosulfur difluoride and pentafluoroethyliminosulfur difluoride, respectively. These imino dichlorides
- Lustig, Max
-
p. 1317 - 1319
(2007/10/12)
-
- The preparation and properties of N-fluoroformyliminosulfur difluoride, SF2=NCOF
-
The inorganic isocyanates derived from silicon, phosphorus, and sulfur have been found to react readily with sulfur tetrafluoride to give, in common, the novel compound, N-fluoroformyliminosulfur difluoride, SF2=NCOF, the preparation and proper
- Clifford, Alan F.,Kobayashi, Calvin S.
-
p. 571 - 574
(2007/10/05)
-