Redox

About: Redox is a research topic. Over the lifetime, 26853 publications have been published within this topic receiving 862368 citations. The topic is also known as: reduction-oxidation & reduction-oxidation reaction.

Redox Reactions of Copper Complexes Formed with Different β-Amyloid Peptides and Their Neuropathalogical Relevance†

Abstract: The binding stoichiometry between Cu(II) and the full-length β-amyloid Aβ(1−42) and the oxidation state of copper in the resultant complex were determined by electrospray ionization−Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) and cyclic voltammetry The same approach was extended to the copper complexes of Aβ(1−16) and Aβ(1−28) A stoichiometric ratio of 1:1 was directly observed, and the oxidation state of copper was deduced to be 2+ for all of the complexes, and residues tyrosine-10 and methionine-35 are not oxidized in the Aβ(1−42)−Cu(II) complex The stoichiometric ratio remains the same in the presence of more than a 10-fold excess of Cu(II) Redox potentials of the sole tyrosine residue and the Cu(II) center were determined to be ca 075 and 008 V vs Ag/AgCl [or 095 and 028 V vs normal hydrogen electrode (NHE)], respectively More importantly, for the first time, the Aβ−Cu(I) complex has been generated electrochemically and was found to catalyze the reduction of ox

Selective catalytic reduction of nitric oxide with ethane and methane on some metal exchanged ZSM-5 zeolites

Abstract: The selective reduction of nitric oxide by methane or ethane, in the presence and in the absence of a large excess of oxygen, has been investigated on Cu/ZSM-5, Co/ZSM-5, Rh/ZSM-5 and Pt/ZSM-5 catalysts over a wide range of temperatures. It has been found that the maximum nitric oxide conversion is higher with ethane than with methane and the temperature of this maximum is lower with ethane. In the absence of oxygen the order of activity is Rh/ZSM-5>Pt/ZSM-5>Co/ZSM-5 > Cu/ZSM-5 with the Cu/ZSM-5 being essentially inactive, while in the presence of oxygen the order is: Rh/ZSM-5>Co/ZSM-5>Cu/ZSM-5 > Pt/ZSM-5 when ethane is used as reductant and: Rh/ZSM-5>Co/ZSM-5 > Cu/ZSM-5>Pt/ZSM-5 when methane is used. The effect of the oxygen content has been investigated for the Co/ZSM-5 catalyst. It has been found that with a small quantity of oxygen the catalytic activity decreases markedly; with higher oxygen content the activity of the catalyst rises again. It appears that two different reaction schemes may be operative, one in the absence of oxygen the other in the presence of oxygen. It is concluded that neither carbonaceous deposits, nor nitrogen dioxide formation in the gas phase are important in the reaction mechanism on metal-containing zeolites. It is proposed that the reaction is essentially a redox process in which decomposition of nitric oxide occurs on reduced metallic or metal ion sites (the relative activity of each of these depending on the choice of metal), leading to the formation of gaseous nitrogen and adsorbed oxygen, followed by the removal of the adsorbed oxygen by the hydrocarbon, thus recreating the active centres.

SCR of NO by NH3 over TiO2-supported V2O5-MoO3 catalysts: reactivity and redox behavior

Abstract: The reactivity in the selective catalytic reduction (SCR) reaction and the redox behavior of V2O5–MoO3/TiO2 catalysts was investigated by means of the temperature programmed reduction (TPR)/reaction technique, and compared with that of binary V2O5/TiO2 and MoO3/TiO2 catalysts having the same metal oxide loading. It was found that the ternary catalysts are more active in the SCR reaction at low temperatures compared to the corresponding binary samples: hence the ‘temperature window’ of the reaction is widened and shifted towards lower temperatures. Transient reactivity data provide clear evidence in favor of the hypothesis of a redox mechanism for the SCR reaction and point out that the ternary catalysts are more easily reduced and reoxidized than the corresponding binary samples: this indicates that the simultaneous presence of V and Mo enhances the catalyst redox properties, and thus its reactivity. Such conclusions are also in line with the results of the characterization studies pointing out the existence of electronic interactions involving the V and Mo surface oxide species. The overall picture closely resembles the one obtained in the case of the analogous V2O5–WO3/TiO2 system and indicates that the effects of the addition of WO3 and MoO3 to V2O5/TiO2 are similar, both oxides acting as ‘chemical’ promoters besides playing a ‘structural’ function as well.