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.
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.
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.
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.
NATURE OF ACTIVITY AND SELECTIVITY OF CATALYSTS BASED ON DEALUMINIZED ZEOLITES. COMMUNICATION 2. ACTIVITY OF DEALUMINIZED Y ZEOLITES AND MORDENITE IN CRACKING STRAIGHT-CHAIN HYDROCARBONS
Tsybulevskii, A. M.,Klyachko, A. L.,Pluzhnikova, M. F.,Stepanova, I. N.,Brueva, T. R.,et al.
, p. 2395 - 2399 (1983)
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RHODIUM-CATALYSED HYDROGENATION OF ALLENE AS REVEALED BY 14C>PROPYLENE AND 14C>CARBON MONOXIDE TRACER STUDIES
Kuhnen, Nivaldo C.,Thomson, Samuel J.,Webb, Geoffrey
, p. 2195 - 2210 (1983)
The low-pressure hydrogenation of allene has been studied over alumina-supported rhodium catalysts.During a series of hydrogenation reactions the activity of the catalyst progressively decreases to a steady-state value and thereafter remains constant.The reaction proceeds in two distinct stages.During the first stage the selectivity for the formation of propylene is ca. 95percent.Hydrogenation of allene+14C>propylene mixtures shows that, in the first stage allene hydrogenation, the yield of propane from the hydrogenation of propylene is relatively small.Direct hydrogenation of adsorbed allene to propane is the major route to formation of the latter, the selectivity being a measure of the relative rates of hydrogenation of allene directly to propylene and propane.Adsorption of 14C>propylene on freshly reduced catalysts occurs in two distinct stages: a non-linear primary region followed by a linear secondary region.No primary region is observed for propylene adsorption on steady-state catalysts or on freshly reduced catalysts in the presence of allene.However, 14C>propylene adsorption and hydrogenation occurs in the presence of allene on the secondary region with both freshly reduced and steady-state catalysts.Adsorption of 14C>carbon monoxide shows that, whilst the decrease in activity of the catalyst to a steady-state constant value corresponds to the progressive build-up of a surface hydrocarbonaceous layer, the combined effects of allene and hydrogen on a carbon monoxide-precovered surface leads to an increase in the capacity of that surface for carbon monoxide adsorption.Treatment of the carbon-monoxide-precovered surface with hydrogen alone does not lead to such an increase.It is suggested that, under the influence of the allene hydrogenation reaction, the surface undergoes some reconstruction.Evidence is presented to show the presence of separate surface site for the hydrogenation of allene to propane and for the hydrogenation of propylene to propane.
Kinetics of Propene Hydrogenation over Platinum and Platinum-Tin Catalysts Supported on Polyamide
Galvagno, Signorino,Staiti, Pietro,Antonucci, Pierluigi,Donato, Andrea,Pietropaolo, Rosario
, p. 2605 - 2612 (1983)
The rate of propene hydrogenation has been measured, in a flow system, over platinum supported on inorganic materials (Al2O3, MgO) and polyamides(Nylon 66 and Nylon 610).The effect of adding tin to Pt/Nylon 66 has also been investigated.The orders of reaction with respect to the reactants have been found to be strongly influenced by the nature of the support used.In particular, higher values of the reaction order with respect to propene have been found on Pt/Nylon samples.The presence of electron-deficient sites is suggested.Addition of Sn causes a drastic decrease in catalytic activity, suggesting Sn enrichment on the surface and/or an electronic interaction between the two metal components.
Heterogeneous Parahydrogen Pairwise Addition to Cyclopropane
Salnikov, Oleg G.,Kovtunov, Kirill V.,Nikolaou, Panayiotis,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Koptyug, Igor V.,Chekmenev, Eduard Y.
, p. 2621 - 2626 (2018)
Hyperpolarized gases revolutionize functional pulmonary imaging. Hyperpolarized propane is a promising emerging contrast agent for pulmonary MRI. Unlike hyperpolarized noble gases, proton-hyperpolarized propane gas can be imaged using conventional MRI scanners with proton imaging capability. Moreover, it is non-toxic odorless anesthetic. Furthermore, propane hyperpolarization can be accomplished by pairwise addition of parahydrogen to propylene. Here, we demonstrate the feasibility of propane hyperpolarization via hydrogenation of cyclopropane with parahydrogen. 1H propane polarization up to 2.4 % is demonstrated here using 82 % parahydrogen enrichment and heterogeneous Rh/TiO2 hydrogenation catalyst. This level of polarization is several times greater than that obtained with propylene as a precursor under the same conditions despite the fact that direct pairwise addition of parahydrogen to cyclopropane may also lead to formation of propane with NMR-invisible hyperpolarization due to magnetic equivalence of nascent parahydrogen protons in two CH3 groups. NMR-visible hyperpolarized propane demonstrated here can be formed only via a reaction pathway involving cleavage of at least one C–H bond in the reactant molecule. The resulting NMR signal enhancement of hyperpolarized propane was sufficient for 2D gradient echo MRI of ～5.5 mL phantom with 1×1 mm2 spatial resolution and 64×64 imaging matrix despite relatively low chemical conversion of cyclopropane substrate.
Robust In Situ Magnetic Resonance Imaging of Heterogeneous Catalytic Hydrogenation with and without Hyperpolarization
Kovtunov, Kirill V.,Lebedev, Dmitry,Svyatova, Alexandra,Pokochueva, Ekaterina V.,Prosvirin, Igor P.,Gerasimov, Evgeniy Y.,Bukhtiyarov, Valerii I.,Müller, Christoph R.,Fedorov, Alexey,Koptyug, Igor V.
, p. 969 - 973 (2019)
Magnetic resonance imaging (MRI) is a powerful technique to characterize reactors during operating catalytic processes. However, MRI studies of heterogeneous catalytic reactions are particularly challenging because the low spin density of reacting and product fluids (for gas phase reactions) as well as magnetic field inhomogeneity, caused by the presence of a solid catalyst inside a reactor, exacerbate already low intrinsic sensitivity of this method. While hyperpolarization techniques such as parahydrogen induced polarization (PHIP) can substantially increase the NMR signal intensity, this general strategy to enable MR imaging of working heterogeneous catalysts to date remains underexplored. Here, we present a new type of model catalytic reactors for MRI that allow the characterization of a heterogeneous hydrogenation reaction aided by the PHIP signal enhancement, but also suitable for the imaging of regular non-polarized gases. These catalytic systems permit exploring the complex interplay between chemistry and fluid-dynamics that are typically encountered in practical systems, but mostly absent in simple batch reactors. High stability of the model reactors at catalytic conditions and their fabrication simplicity make this approach compelling for in situ studies of heterogeneous catalytic processes by MRI.
Hoey,Le Roy
, p. 580 (1955)
Tetrahedral Nickel(II) Phosphosilicate Single-Site Selective Propane Dehydrogenation Catalyst
Zhang, Guanghui,Yang, Ce,Miller, Jeffrey T.
, p. 961 - 964 (2018)
Silica-supported Ni catalysts usually show poor stability, low selectivity, and short lifetime in high-temperature alkane dehydrogenation reactions owing to the reduction to Ni0 nanoparticles under the reaction conditions. The introduction of a phosphate ligand to silica-supported NiII provided single-site tetrahedral NiII phosphosilicate as a stable and selective propane dehydrogenation catalyst. The NiII?OSi bonds activate the C?H bonds of propane and make the NiII sites catalytically active, whereas the Ni?OP bonds prevent the reduction of NiII to Ni0 under the dehydrogenation conditions and help to achieve high stability and selectivity.
Silica-Encapsulated Pt-Sn Intermetallic Nanoparticles: A Robust Catalytic Platform for Parahydrogen-Induced Polarization of Gases and Liquids
Zhao, Evan W.,Maligal-Ganesh, Raghu,Xiao, Chaoxian,Goh, Tian-Wei,Qi, Zhiyuan,Pei, Yuchen,Hagelin-Weaver, Helena E.,Huang, Wenyu,Bowers, Clifford R.
, p. 3925 - 3929 (2017)
Recently, a facile method for the synthesis of size-monodisperse Pt, Pt3Sn, and PtSn intermetallic nanoparticles (iNPs) that are confined within a thermally robust mesoporous silica (mSiO2) shell was introduced. These nanomaterials offer improved selectivity, activity, and stability for large-scale catalytic applications. Here we present the first study of parahydrogen-induced polarization NMR on these Pt-Sn catalysts. A 3000-fold increase in the pairwise selectivity, relative to the monometallic Pt, was observed using the PtSn@mSiO2 catalyst. The results are explained by the elimination of the three-fold Pt sites on the Pt(111) surface. Furthermore, Pt-Sn iNPs are shown to be a robust catalytic platform for parahydrogen-induced polarization for in vivo magnetic resonance imaging.
Yang
, p. 3795 (1962)
Ultra-Low Loading Pt/CeO2 Catalysts: Ceria Facet Effect Affords Improved Pairwise Selectivity for Parahydrogen Enhanced NMR Spectroscopy
Song, Bochuan,Choi, Diana,Xin, Yan,Bowers, Clifford R.,Hagelin-Weaver, Helena
, p. 4038 - 4042 (2021)
Oxide supports with well-defined shapes enable investigations on the effects of surface structure on metal–support interactions and correlations to catalytic activity and selectivity. Here, a modified atomic layer deposition technique was developed to achieve ultra-low loadings (8–16 ppm) of Pt on shaped ceria nanocrystals. Using octahedra and cubes, which expose exclusively (111) and (100) surfaces, respectively, the effect of CeO2 surface facet on Pt-CeO2 interactions under reducing conditions was revealed. Strong electronic interactions result in electron-deficient Pt species on CeO2 (111) after reduction, which increased the stability of the atomically dispersed Pt. This afforded significantly higher NMR signal enhancement in parahydrogen-induced polarization experiments compared with the electron-rich platinum on CeO2 (100), and a factor of two higher pairwise selectivity (6.1 %) in the hydrogenation of propene than any previously reported monometallic heterogeneous Pt catalyst.
Conversion of Phenol and Lignin as Components of Renewable Raw Materials on Pt and Ru-Supported Catalysts
Bobrova, Nataliia A.,Bogdan, Tatiana V.,Bogdan, Viktor I.,Koklin, Aleksey E.,Mishanin, Igor I.
, (2022/03/01)
Hydrogenation of phenol in aqueous solutions on Pt-Ni/SiO2, Pt-Ni-Cr/Al2 O3, Pt/C, and Ru/C catalysts was studied at temperatures of 150–250? C and pressures of 40–80 bar. The possibility of hydrogenation of hydrolysis lignin in an aqueous medium in the presence of a Ru/C catalyst is shown. The conversion of hydrolysis lignin and water-soluble sodium lignosulfonate occurs with the formation of a complex mixture of monomeric products: a number of phenols, products of their catalytic hydrogenation (cyclohexanol and cyclohexanone), and hydrogenolysis products (cyclic and aliphatic C2 –C7 hydrocarbons).
Heterogeneous Parahydrogen-Induced Polarization of Diethyl Ether for Magnetic Resonance Imaging Applications
Salnikov, Oleg G.,Svyatova, Alexandra,Kovtunova, Larisa M.,Chukanov, Nikita V.,Bukhtiyarov, Valerii I.,Kovtunov, Kirill V.,Chekmenev, Eduard Y.,Koptyug, Igor V.
supporting information, p. 1316 - 1322 (2020/12/14)
Magnetic resonance imaging (MRI) with the use of hyperpolarized gases as contrast agents provides valuable information on lungs structure and function. While the technology of 129Xe hyperpolarization for clinical MRI research is well developed, it requires the expensive equipment for production and detection of hyperpolarized 129Xe. Herein we present the 1H hyperpolarization of diethyl ether vapor that can be imaged on any clinical MRI scanner. 1H nuclear spin polarization of up to 1.3 % was achieved using heterogeneous hydrogenation of ethyl vinyl ether with parahydrogen over Rh/TiO2 catalyst. Liquefaction of diethyl ether vapor proceeds with partial preservation of hyperpolarization and prolongs its lifetime by ≈10 times. The proof-of-principle 2D 1H MRI of hyperpolarized diethyl ether was demonstrated with 0.1×1.1 mm2 spatial and 120 ms temporal resolution. The long history of use of diethyl ether for anesthesia is expected to facilitate the clinical translation of the presented approach.
