Hydrogen production from the electrooxidation of methanol and potassium formate in alkaline media on carbon supported Rh and Pd nanoparticles
摘要:
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 degrees 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(Rh)(1) Rh. The energy cost and conversion efficiency for hydrogen production was determined in complete electrochemical reforming cells at 80 degrees C using both anode catalysts. The energy costs are low for both substrates (< 14 KWh kg(H2)(1)) with Pd/C producing hydrogen from potassium formate at an energy cost of 5 KWh kg(H2)(1). 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. (C) 2017 Elsevier B.V. All rights reserved.
Solvent influence on the thermodynamics for hydride transfer from bis(diphosphine) complexes of nickel
作者:Samantha J. Connelly Robinson、Christopher M. Zall、Deanna L. Miller、John C. Linehan、Aaron M. Appel
DOI:10.1039/c6dt00309e
日期:——
metal hydride and CO2 to produce formate. Because the hydricities of these species do not vary consistently between solvents, reactions that are thermodynamically unfavourable in one solvent can be favourable in others. The hydricity of a water-soluble, bis-phosphine nickel hydride complex was compared to the hydricity of formate in water and in acetonitrile. Formate is a better hydride donor than [HNi(dmpe)2]+
Carbon dioxide reduction on platinum and carbon felt electrodes coated with polymeric films obtained by oxidative electropolymerization of pyrrole-containing Re(L)(CO)3Cl complexes, where L is a 2,2'-bipyridine, has been investigated. Catalytic activities of modified electrodes prepared by polymerization of differently substituted complexes have been compared, on the basis of cyclic voltammetry and
Ionisation constants of ˙OH and HO˙2 in aqueous solution up to 200 °C. A pulse radiolysis study
作者:George V. Buxton、Nicholas D. Wood、Sally Dyster
DOI:10.1039/f19888401113
日期:——
The ionisationconstant of ˙OH has been determined up to 200 °C from measurements of its rate of reaction with CO2–3 in alkaline solution, where O˙– is unreactive. The Van't Hoff plot shows the same curvature as that for Kw, so that ˙OH and H2O have the same heats of ionisation. ΔH for the equilibrium ˙OH + OH–⇌ O˙–+ H2O is independent of temperature and equal to –15.4 ± 0.5 kJ mol–1. ΔH for the ionisation
CCSO nano catalyzed solid phase synthesis of 3-oxo-5,6-disubstituted-2,3-dihydropyridazine-4-carbonitrile
作者:Praveen Singh、Ranjeet Kumar、Brijesh Kumar Yadav、Ranjana S. Khanna、Ashish Kumar Tewari
DOI:10.1039/c4ra06640e
日期:——
CCSO nano particles successfully catalyzed the synthesis of substituted pyridazines from substituted benzil and cyanoacetylhydrazide.
CCSO纳米颗粒成功地催化了从取代苯二酮和氰乙酰肼合成取代吡啶并的反应。
Reduction of CO<sub>2</sub>Directed toward Carbon–Carbon Bond Formation
作者:Koji Tanaka
DOI:10.1246/bcsj.71.17
日期:1998.1
electrochemical reduction of CO2 directed toward carbon–carbonbondformation via metal–CO2 adducts. An electrophilic attack of CO2 to penta-coordinated low valent polypyridyl Ru complexes affords a Ru–η1-CO2 adduct, which is easily converted to Ru–CO species either by an acid-base equilibrium in protic media and oxide transfer to CO2 under aprotic conditions. Two-electron reduction of resultant Ru–CO
本文描述了通过金属-CO2 加合物直接形成碳-碳键的 CO2 电化学还原。CO2对五配位低价多吡啶Ru配合物的亲电攻击提供了Ru-η1-CO2加合物,通过质子介质中的酸碱平衡和在非质子条件下氧化物转移到CO2,它很容易转化为Ru-CO物种. 质子溶液中所得 Ru-CO 的双电子还原竞争性地导致 Ru-CO 键断裂(CO 析出)并形成热不稳定的 Ru-CHO 键。除了将后者进一步还原为 Ru-CH2OH 作为 CH3OH 和 HOOCCH2OH 的前体之外,Ru-CHO 与 CO2 反应生成 HCOOH,并再生 Ru-CO 作为 CO 的前体。因此,在质子溶液中多电子还原 CO2 的困难归因于 Ru-CHO 的热不稳定性和强氢化物供体特性。另一方面,在 (CH3)4N+ 或 CH3I 的非质子条件下,Ru-CO 的双电子还原会产生...