683-73-8Relevant articles and documents
A Comparative Analysis of the CO-Reducing Activities of MoFe Proteins Containing Mo- and V-Nitrogenase Cofactors
Lee, Chi Chung,Tanifuji, Kazuki,Newcomb, Megan,Liedtke, Jasper,Hu, Yilin,Ribbe, Markus W.
, p. 649 - 653 (2018/04/16)
The Mo and V nitrogenases are structurally homologous yet catalytically distinct in their abilities to reduce CO to hydrocarbons. Here we report a comparative analysis of the CO-reducing activities of the Mo- and V-nitrogenase cofactors (i.e., the M and V clusters) upon insertion of the respective cofactor into the same, cofactor-deficient MoFe protein scaffold. Our data reveal a combined contribution from the protein environment and cofactor properties to the reactivity of nitrogenase toward CO, thus laying a foundation for further mechanistic investigation of the enzymatic CO reduction, while suggesting the potential of targeting both the protein scaffold and the cofactor species for nitrogenase-based applications in the future.
Reaction Mechanism and Kinetics of Olefin Metathesis by Supported ReOx/Al2O3 Catalysts
Lwin, Soe,Wachs, Israel E.
, p. 272 - 278 (2016/01/12)
The self-metathesis of propylene by heterogeneous supported ReOx/Al2O3 catalysts was investigated with in situ Raman spectroscopy, isotopic switch (D-C3= → H-C3=), temperature-programmed surface reaction (TPSR) spectroscopy, and steady-state kinetic studies. The in situ Raman studies showed that two distinct surface ReO4 sites are present on alumina and that the olefins preferentially interact with surface ReO4 sites anchored at acidic surface sites of alumina (olefin adsorption: C4= > C3= > C2=). The isotopic switch experiments demonstrate that surface Re?CH3 and Re?CHCH3 are present during propylene metathesis, with Re? representing activated surface rhenia sites. At low temperatures (3=][Re?]2. At high temperatures (>100 °C), the rate-determining step is the recombination of two surface propylene molecules (rate ≈ [C3=]2[Re?]). To a lesser extent, the recombination of surface Re?CH3 and Re?CHCH3 intermediates also contributes to self-metathesis of propylene at elevated reaction temperatures.
On ethane ODH mechanism and nature of active sites over NiO-based catalysts via isotopic labeling and methanol sorption studies
Skoufa,Heracleous,Lemonidou
, p. 118 - 129 (2015/09/28)
In this paper, the ethane oxidative dehydrogenation (ODH) mechanism is thoroughly investigated via isotopic labeling and methanol sorption studies over NiO and highly selective Ni0.85Nb0.15Ox catalysts. ODH experiments with unlabeled and deuterium labeled ethane demonstrated the existence of strong kinetic isotope effect (KIE) over both NiO and Ni0.85Nb0.15Ox, indicating that C-H bond scission is the rate determining step in ethane ODH. Similar KIE values obtained for NiO and Ni0.85Nb0.15Ox mixed oxide indicate that both catalysts share similar active sites for ethane activation. Methanol adsorption/desorption followed by TGA, MS, and in situ DRIFTS showed that pure and Nb-doped nickel oxide surfaces primarily host the same redox active sites that differ in terms of abundance (i.e. surface concentration) and activity. O2-TPD studies of used catalysts verified the participation of non-stoichiometric oxygen species in the reaction, which proceeds via a redox mechanism. Based on the above, a detailed reaction mechanism is proposed.
