1111-72-4Relevant academic research and scientific papers
Promotion of photocatalytic steam reforming of methane over Ag0/Ag+-SrTiO3
Tan, Bingqing,Ye, Yinghao,Huang, Zeai,Ye, Liqun,Ma, Minzhi,Zhou, Ying
, p. 1530 - 1534 (2020)
Methane (CH4) is not only used as a fuel but also as a promising clean energy source for hydrogen generation. The steam reforming of CH4 (SRM) using photocatalysts can realize the production of syngas (CO + H2) with low energy consumption. In this work, Ag0/Ag+-loaded SrTiO3 nanocomposites were successfully prepared through a photodeposition method. When the loading amount of Ag is 0.5 mol%, the atom ratio of Ag+ to Ag0 was found to be 51:49. In this case, a synergistic effect of Ag0 and Ag+ was observed, in which Ag0 was proposed to improve the adsorption of H2O to produce hydroxyl radicals and enhance the utilization of light energy as well as the separation of charge carriers. Meanwhile, Ag0 was regarded as the reduction reaction site with the function of an electron trapping agent. In addition, Ag+ adsorbed the CH4 molecules and acted as the oxidation reaction sites in the process of photocatalytic SRM to further promote electron-hole separation. As a result, 0.5 mol% Ag-SrTiO3 exhibited enhancement of photocatalytic activity for SRM with the highest CO production rate of 4.3 μmol g?1 h?1, which is ca. 5 times higher than that of pure SrTiO3. This work provides a facile route to fabricate nanocomposite with cocatalyst featuring different functions in promoting photocatalytic activity for SRM.
13C and 14C kinetic isotope effects in the catalytic oxidation of CO over ZnO
Kobal, I.,Senegacnik, M.,Kobal, H.
, p. 1815 - 1824 (1983)
13C and 14C kinetic effects in the reaction CO+1/2 O2->CO2 over ZnO catalyst were experimentally determined.The k12/k13 and k12/k14 ratios were found to be temperature independent in the temperature range studied (200-500 deg C) and amounted to 1.0101+/-0.0010 and 1.0204+/-0.0019, respectively.Interpretation of the experimental values, following Bigeleisen's formalism, reveals that (CO2)(excit) with an interband angles of (90+/-10) deg and planar (CO3) (excit) with two interband angles in the range of (120+/-10) deg may be considered as activated complexes of the rate determining and isotope effect fractionation governing step of the reaction mechanism.
Isotope Exchange and the Sodium-catalysed CO2 Gasification of Carbon
Saber, John M.,Falconer, John L.,Brown, Lee F.
, p. 445 - 447 (1987)
Distinct oxidation (reversible) and reduction steps, and the stoicheiometries of the catalytic species have been identified for sodium-catalysed CO2 gasification of 13C.
Oxidation of H2 and CO over ion-exchanged X and Y zeolites
Lahr, Daniel G.,Li, Junhui,Davis, Robert J.
, p. 3420 - 3425 (2007)
Zeolites X and Y exchanged with Group IA cations were synthesized by aqueous ion exchange of NaX and NaY and used as catalysts in the oxidation of H2 and CO at temperatures ranging from 473 to 573 K. The CsX zeolite was the most active material of the series for both reactions whereas HX was the least active. Moreover, the oxidation of CO in H2 was very selective (～80%) over the alkali-metal exchanged materials. Isotopic transient analysis of CO oxidation during steady-state reaction at 573 K was used to evaluate the coverage of reactive carbon-containing intermediates that lead to product as well as the pseudo-first-order rate constant of the reaction. A factor of 4 enhancement in activity achieved by exchanging Cs for Na was attributed to a higher coverage of reactive intermediates in CsX because the pseudo-first-order rate constant was nearly same for the two materials (～0.7 s-1). The number of reactive intermediates on both materials was orders of magnitude below the number of alkali metal cations in the zeolites but was similar to the number of impurity Fe atoms in the samples. Because the trend in Fe impurity loading was the same as that for oxidation activity, a role of transition metal impurities in zeolite oxidation catalysis is suggested.
Nickel-catalyzed release of H2 from formic acid and a new method for the synthesis of zerovalent Ni(PMe3)4
Neary, Michelle C.,Parkin, Gerard
, p. 14645 - 14650 (2016)
Ni(PMe3)4 serves as a catalyst for the release of H2 and CO2 from formic acid. The capacity of Ni(PMe3)4 to achieve this transformation is linked to the ability of the PMe3 ligand to induce decarboxylation, as illustrated by the observation that both Ni(py)4(O2CH)2 and Ni(O2CH)2·2H2O react with PMe3 to afford Ni(PMe3)4; the latter transformation also provides a convenient method for the synthesis of a zerovalent nickel compound.
Hybrid enzymatic and organic electrocatalytic cascade for the complete oxidation of glycerol
Hickey, David P.,McCammant, Matthew S.,Giroud, Fabien,Sigman, Matthew S.,Minteer, Shelley D.
, p. 15917 - 15920 (2014)
We demonstrate the complete electrochemical oxidation of the biofuel glycerol to CO2 using a hybrid enzymatic and small-molecule catalytic system. Combining an enzyme, oxalate oxidase, and an organic oxidation catalyst, 4-amino-TEMPO, we are able to electrochemically oxidize glycerol at a carbon electrode, while collecting up to as many as 16 electrons per molecule of fuel. Additionally, we investigate the anomalous electrocatalytic properties that allow 4-amino-TEMPO to be active under the acidic conditions that are required for oxalate oxidase to function.
Energy Transfer Dynamics of Formate Decomposition on Cu(110)
Quan, Jiamei,Kondo, Takahiro,Wang, Guichang,Nakamura, Junji
, p. 3496 - 3500 (2017)
Energy transfer dynamics of formate (HCOOa) decomposition on a Cu(110) surface has been studied by measuring the angle-resolved intensity and translational energy distributions of CO2 emitted from the surface in a steady-state reaction of HCOOH and O2. The angular distribution of CO2 shows a sharp collimation with the direction perpendicular to the surface, as represented by cosnθ (n=6). The mean translational energy of CO2 is measured to be as low as 100 meV and is independent of the surface temperature (Ts). These results clearly indicate that the decomposition of formate is a thermal non-equilibrium process in which a large amount of energy released by the decomposition reaction of formate is transformed into the internal energies of CO2 molecules. The thermal non-equilibrium features observed in the dynamics of formate decomposition support the proposed Eley–Rideal (ER)-type mechanism for formate synthesis on copper catalysts.
Comparative study of CO2 formation in CO oxidation by O2, NO and N2O on Pd(1 1 0) surface using infrared chemiluminescence
Nakao, Kenji,Ito, Shin-ichi,Tomishige, Keiichi,Kunimori, Kimio
, p. 4221 - 4227 (2006)
The infrared (IR) chemiluminescence spectra of CO2 were measured during steady-state CO oxidation by O2, NO and N2O over Pd(1 1 0) surface. Kinetics of these reactions were studied using a molecular-beam reaction system, a
Transient studies on the mechanism of N2O activation and reaction with CO and C3H8 over Fe-silicalite
Perez-Ramirez, Javier,Kondratenko, Evgenii V.,Debbagh, M. Naoufal
, p. 442 - 452 (2005)
The mechanism of the reaction of N2O and 13CO over Fe-silicalite was investigated with the use of the temporal analysis of products (TAP) reactor and compared with that of the reaction of N2O and C3H8 previously reported (Appl. Catal. A 267 (2004) 181). Upon direct N2O decomposition at 523-573 K, Fe-silicalite stored ca. 1018 atoms of oxygen per gram, with a ratio of 1 O atom per each 30-60 Fe atoms in the sample. Only a small fraction of the deposited oxygen was reactive for CO oxidation. Pump-probe experiments at different time delays (0-2 s) between the pulses of nitrous oxide and the reducing agent indicated the markedly different mechanisms of the N2O-13CO and N 2O-C3H8 reactions in the temperature range of 623-673 K. Fe-silicalite is active for propane oxidation in the presence of short-lived oxygen species, that are produced when N2O and C 3H8 are pulsed simultaneously. Time delays between the N2O and C3H8 pulses greater than 0.1 s are sufficient to transform these active oxygen species for hydrocarbon conversion into inactive ones. In contrast, the oxidation of CO by N2O does not depend on the lifetime of the oxygen species in the range of time delays investigated. The mechanisms of the N2O-mediated 13CO and C3H8 oxidations differ as a consequence of the different interactions of the two reducing agents with iron species in the zeolite. Pulse experiments support the occurrence of the scavenging mechanism with both propane and carbon monoxide. In this mechanism, short-lived oxygen deposited by N 2O is efficiently eliminated by the reductant. Distinctive to propane, the strikingly high affinity of carbon monoxide for isolated Fe 3+ ions in the zeolite gives rise to an additional pathway for N 2O reduction in the presence of chemisorbed CO species. These particular Fe3+-CO species were identified by in situ UV/vis and EPR spectroscopies (J. Catal. 223 (2004) 13).
Removal pathways of surface nitrogen in a steady-state NO + CO reaction on Pd(110) and Rh(110): Angular and velocity distribution studies
Rzeznicka, Izabela I.,Ma, Yunsheng,Cao, Gengyu,Matsushima, Tatsuo
, p. 14232 - 14243 (2004)
Knowledge of the relation of N2 and N2O formation is requisite for improving environmental catalysts. The angular and velocity distributions of desorbing products N2 and CO2 were investigated in a steady-state NO + CO reaction on Pd(110) and Rh(110) by cross-correlation time-of-flight methods. On Pd(110), N2 desorption was split into two inclined components collimating at ± 40° in the plane along the [001] direction. The inclined N2 formation originated from the N2O intermediate. At low temperatures, the pathway through the N2O intermediate prevailed, and, above 720 K, the associative nitrogen desorption started to dominate. N2 desorption on Rh(110) was sharply collimated along the surface normal in a wide temperature region, indicating that N(a) was mostly removed through the associative process. On both surfaces, the translational temperature of desorbing N2 was very high, reaching about 2500-3500 K. On the other hand, CO2 desorption always collimated along the surface normal on both surfaces with the translational temperature at 1600-2000 K.
