74-98-6Relevant articles and documents
Novel Rate Constants for a Catalytic Hydrogenation Reaction of Propylene Obtained by a Frequency Response Method
Yasuda, Yusuke,Iwai, Kayo,Takakura, Kazumi
, p. 17852 - 17861 (1995)
"Reaction rate (or FR) spectra" of a catalytic hydrogenation of propylene over Pt or Rh at 314 K were observed in a cell reactor composed of a proton-conducting membrane.It is shown that a variety of the spectra can be reproduced well by "characteristic functions", K*H(ω) and K*C(ω), which may be derived from a three-stage model composed of five elementary steps: X(g) -->/X(a) -->/X(a) --> propane (X: hydrogen or propylene), where X denotes the gaseous molecule; AX and BX are the first and second intermediate adsorbed species.Seven rate constants concerning these five steps were evaluated by matching K*H(ω) or K*C(ω) to the spectrum; five of them, kPX, k-AX, kAX, k-BX, and kBX, are ordinary rate constants, while the other two, l-BX and lBX, are novel ones.Since all these constants except kPX are independent of the amounts of catalyst, they are characteristic of active sites and can be compared with each other.On the basis of these constants, kinetic details have been discussed; for instance, mean residence times of AX and BX, τAX and τBX, respectively, were determined by (k-AX + kAX)-1 and (k-BX + kBX)-1, resulting in (in second units) τAH ca. 0.3 and τBH ca. 3 for hydrogen and τAC ca. 3 for propylene over Pt, while over Rh they were τAH ca. 1 and τBH ca. 3; τAC ca. 102 and τBC ca. 102.The nondimensional rate constants, l-BX and lBX, were indispensable to reproduce the various FR spectra; l-BH and lBH were positive, whereas l-BC and lBC were negative over both catalysts, which suggests heat effects.
Chemisorption and Surface Reactions in Cooperative Adsorption Systems.
Hesse
, p. 156 - 165 (1985)
The kinetics of propylene hydrogenation catalyzed by thermally treated supported platinum catalysts can be described by a Langmuir-Hinshelwood mechanism. The parameter values of the resulting rate equation, however, clearly depend on the coverage of the catalyst surface. Because of the instabilities observed with this reaction, it has to be assumed that lateral interaction of chemisorbed hydrogen and chemisorbed propylene is the main reason for this parameter variation. Using the lattice-gas model and the methods of statistical thermodynamics, straight-forward equations are derived which take into account the influence of this interaction on chemisorption and surface reaction in binary adsystems. The usefulness of these equations for the evaluation of kinetic measurements is demonstrated.
Frequency Response Method for the Study of Kinetics of a Heterogeneous Catalytic Reaction of Gases
Yasuda, Yusuke
, p. 7185 - 7190 (1989)
A new frequency response method is proposed on the basis of actual data on C3H6 + H2 -> C3H8 over Pt/Al2O3 at 273 K observed under each partial pressure of ca. 10 Pa: the gas space of a continuous-flow reactor was varied sinusoidally, and every partial pressure variation induced was followed by a mass spectrometer.Both amplitude and phase difference of ΔR observed in the angular frequency region from 40 to 60 rad/min were described well by , where Rs and PH(s) denote the overall reaction rate and the partial pressure of H2 at the steady state before the oscillation and is the time derivative of the pressure variation, dΔPH/dt.The "rate constant" n and κ were 0.15 and 7 * 1E-2 min, respectively.The unordinary rate equation involving PH was interpreted by R = ?dμd in terms of the driving force or the free energy drop, μd, and the frequency factor, ?d, at the rate-limiting step; Δ?d/?d = nΔPH/PH(s) and .The newly derived rate constant κ seemed to decrease with increasing temperature.The turnover frequency could be given by n/κ.
Organometallic complexes in supported ionic-liquid phase (SILP) catalysts: A PHIP NMR spectroscopy study
Gong, Qingxia,Klankermayer, Juergen,Bluemich, Bernhard
, p. 13795 - 13799 (2011)
para-Hydrogen induced polarization (PHIP) NMR spectroscopy emerges as an efficient and robust method for on-line monitoring of gas-phase hydrogenation reactions. Here we report detailed investigations of supported ionic liquid phase (SILP) catalysts in a continuous gas-phase hydrogenation of propene with PHIP NMR spectroscopy. A relocation of the rhodium complex in the thin layer of ionic liquid in the SILP catalyst at the initial stage of the propene hydrogenation is demonstrated. PHIP NMR spectroscopy can provide profound insight into the evolution of SILP catalysts during hydrogenation reactions.
Reductive dehalogenation of 1,3-dichloropropane by a [Ni(tetramethylcyclam)]Br2-Nafion modified electrode
Fontmorin,He,Floner,Fourcade,Amrane,Geneste
, p. 511 - 517 (2014)
Dechlorination reaction of 1,3-dichloropropane, a contaminant solvent, was investigated by electrochemical reduction in aqueous medium using a Ni(tmc)Br2complex, known as effective catalyst in dehalogenation reactions. The catalytic activity of the complex was first investigated by cyclic voltammetry and flow homogeneous redox catalysis using a graphite felt as working electrode. A total degradation of 1,3-dichloropropane was obtained after 5 h of electrolysis with a substrate/catalyst ratio of 2.3. The concentration of chloride ions determined by ion chromatography analysis showed a dechlorination yield of 98%. The complex was then immobilized on the graphite felt electrode in a Nafion film. Flow heterogeneous catalytic reduction of 1,3-dichloropropane was then carried out with the [Ni(tmc)]Br2-modified Nafion electrode. GC analyses underlined the total degradation of the substrate in only 3.5 h with a substrate/catalyst ratio of 100. A dechlorination yield of 80% was obtained, as seen with ion chromatography analyses of chloride ion. Comparison of both homogeneous and heterogeneous reactions highlighted the interest of the [Ni(tmc)]Br2-modified Nafion electrode that led to a higher stability of the catalyst with a turnover number of 180 and a higher current efficiency.
In situ x-ray absorption spectroscopy and nonclassical catalytic hydrogenation with an iron(II) catecholate immobilized on a porous organic polymer
Kraft, Steven J.,Hu, Bo,Zhang, Guanghui,Miller, Jeffrey T.,Hock, Adam S.
, p. 3972 - 3977 (2013)
The oxidation state and coordination number of immobilized iron catecholate EtO2Fe(CAT-POP) were determined by X-ray absorption spectroscopy (XAS) under a variety of conditions. We find the as-prepared material to be three-coordinate Fe2+ that readily oxidizes to Fe3+ upon exposure to air but remains three-coordinate. Both the reduced and oxidized Fe(CAT-POP) catalyze olefin hydrogenation in batch and flow reactors. We determined the catalytic rates for both species and also observed by means of XAS that the oxidation state of the iron centers does not change in hydrogen at the reaction temperature. Therefore, we postulate that the mechanism of hydrogenation by Fe(CAT-POP) proceeds through one of several possible nonclassical mechanisms, which are discussed.
Selective Catalytic Chemistry at Rhodium(II) Nodes in Bimetallic Metal–Organic Frameworks
Shakya, Deependra M.,Ejegbavwo, Otega A.,Rajeshkumar, Thayalan,Senanayake, Sanjaya D.,Brandt, Amy J.,Farzandh, Sharfa,Acharya, Narayan,Ebrahim, Amani M.,Frenkel, Anatoly I.,Rui, Ning,Tate, Gregory L.,Monnier, John R.,Vogiatzis, Konstantinos D.,Shustova, Natalia B.,Chen, Donna A.
, p. 16533 - 16537 (2019)
We report the first study of a gas-phase reaction catalyzed by highly dispersed sites at the metal nodes of a crystalline metal–organic framework (MOF). Specifically, CuRhBTC (BTC3?=benzenetricarboxylate) exhibited hydrogenation activity, while other isostructural monometallic and bimetallic MOFs did not. Our multi-technique characterization identifies the oxidation state of Rh in CuRhBTC as +2, which is a Rh oxidation state that has not previously been observed for crystalline MOF metal nodes. These Rh2+ sites are active for the catalytic hydrogenation of propylene to propane at room temperature, and the MOF structure stabilizes the Rh2+ oxidation state under reaction conditions. Density functional theory calculations suggest a mechanism in which hydrogen dissociation and propylene adsorption occur at the Rh2+ sites. The ability to tailor the geometry and ensemble size of the metal nodes in MOFs allows for unprecedented control of the active sites and could lead to significant advances in rational catalyst design.
REDISPERSION OF COBALT METAL PARTICLES IN Co/TiO2 CATALYST AND ITS EFFECT ON PROPENE HYDROGENATION
Takasaki, Seiji,Takahashi, Kaoru,Suzuki, Hideo,Sato, Yuzuru,Ueno, Akifumi,Kotera, Toyohashi
, p. 265 - 268 (1983)
The rate of propene hydrogenation on Co/TiO2 catalyst, prepared by an alkoxide technique, was significantly enhanced when the catalyst was reduced by hydrogen at 700 deg C.However, over the catalyst prepared by an usual impregnation method, the enhancement of the rate was not observed at any reduction temperatures.The effects of reduction temperatures on the rate of propene hydrogenation were elucidated by redispersion of metallic cobalt particles.
Kinetic Determination of the Gas-Phase Decarbonylation of Butyraldehyde in the Presence of HCl Catalyst
Julio, Libia L.,Cartaya, Loriett,Maldonado, Alexis,Monascal, Yeljair,Mora, José R.,Cordova, Tania,Chuchani, Gabriel
, p. 333 - 338 (2017)
The gas-phase kinetics and mechanism of the homogeneous elimination of CO from butyraldehyde in the presence of HCl has been experimentally studied. The reaction is homogeneous and follows the second-order kinetics with the following rate expression: log k1 (s?1 L mol?1) = (13.27 ± 0.36) – (173.2 ± 4.4) kJ mol?1(2.303RT)?1. Experimental data suggested a concerted four-membered cyclic transition state type of mechanism. The first and rate-determining step occurs through a four-membered cyclic transition state to produce propane and formyl chloride. The formyl chloride intermediate rapidly decomposes to CO and HCl gases.
A stable 16-electron iridium(iii) hydride complex grafted on SBA-15: A single-site catalyst for alkene hydrogenation
Rimoldi, Martino,Fodor, Daniel,Van Bokhoven, Jeroen A.,Mezzetti, Antonio
, p. 11314 - 11316 (2013)
The dihydride pincer complex [IrH2(POCOP)] reacts with surface silanols of mesoporous silica (SBA-15) to give the coordinatively unsaturated, yet stable hydridesiloxo Ir(iii) species [IrH(O-SBA-15)(POCOP)]. The silica-grafted complex catalyses the hydrogenation of ethene and propene at low temperature and pressure without prior activation.
