676-55-1Relevant academic research and scientific papers
Platinum catalyzed c-h activation and the effect of metal-support interactions
Sattler, Aaron,Paccagnini, Michele,Lanci, Michael P.,Miseo, Sabato,Kliewer, Chris E.
, p. 710 - 720 (2020/01/02)
Catalytic C-H bond activation of methane and ethane on a series of silica supported platinum catalysts (Pt/SiO2) was studied by using hydrogen/deuterium (H/D) exchange. Kinetic experiments demonstrate that under the reaction conditions studied, the rate of C-H bond activation shows approximate first order dependence in alkane and inverse first order dependence in D2. The rate of C-H activation is affected by the presence of sodium on the silica support, where sodium-free supports have the fastest rates of C-H activation, as assessed by H/D exchange. CO adsorption and FTIR studies indicate that the Pt particles on the sodium-free support are more electron-deficient, having the most blue-shifted linear CO stretch, while sodium-containing supports are more electron-donating, having the most red-shifted linear CO stretch. It is proposed, based on the results described in this article and previous work in the literature, that more electron-donating supports cause the Pt particles to be more electron-rich and to adsorb D? (or H*) more strongly, thereby stabilizing the ground state and resting state of the catalyst, resulting in a decreased rate of C-H activation.
Photocatalytic halohydrocarbon dehalogenation conversion method
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Paragraph 0107; 0108, (2019/04/02)
The invention provides a photocatalytic halohydrocarbon dehalogenation conversion method which comprises the following steps: adding a photocatalyst quantum dot/rod into a solvent to obtain a solutionA; adding halohydrocarbon and an electronic sacrificial body into the solution A to obtain a solution B; utilizing a light source to irradiate the solution B and catalyzing the solution B to performhalohydrocarbon dehalogenation conversion. According to the photocatalytic halohydrocarbon dehalogenation conversion method disclosed by the invention, a nano quantum dot and a nano quantum rod are applied to dehalogenation conversion reaction of alkyl halide, alkenyl halide and alkyne halide for the first time; the reaction conditions are moderate, visible light is utilized as driving energy, a product is hydrocarbon compound, and the whole process has the advantages of environmental protection, conciseness and high efficiency. In addition, higher hydrocarbon of carbon chain growth can be generated after dehalogenation reaction, so that the method has potential application in preparation of higher hydrocarbon. According to the method disclosed by the invention, halohydrocarbon dehalogenation conversion and deuteration marking processes are jointly performed; hydrocarbon deuteration marking can be finished when a halohydrocarbon dehalogenation process is finished. The invention furtherprovides a method for performing deuteration marking on hydrocarbon.
Catalytic Activation of Unstrained, Nonactivated Ketones Mediated by Platinum(II): Multiple C-C Bond Cleavage and CO Extrusion
Sarju, Julia P.,Dey, Debashish,Torroba, Javier,Whitwood, Adrian C.,Redeker, Kelly,Bruce, Duncan W.
supporting information, p. 4539 - 4542 (2019/11/29)
The complexes [Pt(tolpy)Cl(L)] (tolpy = 2-(4-tolyl)pyridyl; L = dmso, dms, py, PPh3, CO) are precursors for the catalytic cleavage of C-C bonds and extrusion of CO from a series of unactivated ketones such as cyclohexanone; deuterium labeling experiments demonstrate the involvement of a transfer hydrogen step in the mechanism.
High-temperature Shilov-type methane conversion reaction: Mechanistic and kinetic studies
Kang, Shujuan,Ma, Qisheng,Chen, Weiqun,Chen, Guanyi,Tang, Yongchun
, p. 1777 - 1784 (2015/10/20)
Traditional Shilov reactions (performed in aqueous solution with a PtCl2 catalyst) for methane conversion suffer from catalyst deactivation at high temperatures (> 100 °C), therefore only very low conversion rates have been achieved. In this paper, we show that Shilov-type C-H activations are achievable at much higher temperatures (～200 °C) by addition of concentrated aqueous solutions of Cl- to inhibit Pt catalyst precipitation. Various chloride-based ionic liquids also stabilized the Pt catalyst at mild reaction temperatures (～140 °C). Under high-pressure conditions (> 25.5 MPa), achieved using a specially designed sealed gold-tube reactor, very high methane conversion rates (> 90%) were obtained; this is attributed to the improved methane solubility in aqueous solution. Deuterium isotope (H/D) exchange between methane and water was used to examine the reaction reactivity and selectivity. Multiply D-substituted products were observed, indicating that multiple C-H activations occurred. A comprehensive network reaction that included all the chain reactions was set up to clarify the reactivities and product selectivities of the methane activation reactions. The reaction network consisted of a series of parallel first-order reactions, which can be described by the Arrhenius equation. The kinetic parameters such as the frequency factor, activation energies, and stoichiometric coefficients were obtained by fitting the experimental data. Because all four C-H bonds in a methane molecule are equivalent, multiple substitutions during methane conversion cannot be avoided. Our studies indicate that mono-substituted and di-substituted methane isotopologue generations have similar activation energies, suggesting that the highest mono-substitution selectivity cannot be greater than 50%.
Highly efficient and stable photocatalytic reduction of CO2 to CH4 over Ru loaded NaTaO3
Li, Mu,Li, Peng,Chang, Kun,Wang, Tao,Liu, Lequan,Kang, Qing,Ouyang, Shuxin,Ye, Jinhua
supporting information, p. 7645 - 7648 (2015/06/16)
An efficient and stable photocatalytic activity was obtained over NaTaO3 by introducing an electron donor (H2) into the CO2 reduction process with water. Ru/NaTaO3 demonstrated the best activity (CH4 51.8 μmol h-1 g-1) and product selectivity in converting CO2 to CH4.
Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr2O3(0001)
Dong, Yujung,Brooks, John D.,Chen, Tsung-Liang,Mullins, David R.,Cox, David F.
, p. 28 - 38 (2015/02/02)
The reaction of CH2Cl2 over the nearly-stoichiometric α-Cr2O3(0001) surface produces gas phase ethylene, methane and surface chlorine adatoms. The reaction is initiated by the decomposition of CH2Cl2 into surface methylene and chlorine. Photoemission indicates that surface cations are the preferred binding sites for both methylene and chlorine adatoms. Two reaction channels are observed for methylene coupling to ethylene in temperature-programmed desorption (TPD). A desorption-limited, low-temperature route is attributed to two methylenes bound at a single site. The majority of ethylene is produced by a reaction-limited process involving surface migration (diffusion) of methylene as the rate-limiting step. DFT calculations indicate the surface diffusion mechanism is mediated by surface oxygen anions. The source of hydrogen for methane formation is adsorbed background water. Chlorine adatoms produced by the dissociation of CH2Cl2 deactivate the surface by simple site-blocking of surface Cr3 + sites. A comparison of experiment and theory shows that DFT provides a better description of the surface chemistry of the carbene intermediate than DFT+U using reported parameters for a best representation of the bulk electronic properties of α-Cr2O3.
Iridium(iii) catalyzed trifluoroacetoxylation of aromatic hydrocarbons
Bischof, Steven M.,Hashiguchi, Brian G.,Lokare, Kapil S.,Gunsalus, Niles,Yousufuddin, Mohammed,Periana, Roy A.
, p. 35639 - 35648 (2014/12/10)
A tridentate, NNC-tb (where NNC-tb = 2-(pyridin-2-yl)benzo[h]quinoline) ligated IrIII complex (NNC-tb)Ir(Ph)(4-MePy)(TFA), 11 along with analogues are very active for CH activation as evidenced by rapid catalytic H/D exchange between benzene and trifluoroacetic acid-d1 (DTFA). The complexes were examined with a variety of oxidants for the catalytic conversion of benzene to phenyltrifluoroacetate. Herein, the synthesis and characterization of (NNC-tb)Ir complexes is described along with the reactivity of these complexes towards arenes and alkanes.
On-stream regeneration of a sulfur-poisoned ruthenium-carbon catalyst under hydrothermal gasification conditions
Dreher, Marian,Steib, Matthias,Nachtegaal, Maarten,Wambach, Joerg,Vogel, Frederic
, p. 626 - 633 (2014/03/21)
Catalytic processes that employ Ru catalysts in supercritical water are capable of converting organics, such as wood waste or biosolids, into synthetic natural gas (CH4) with high efficiencies at relatively moderate temperatures of around 400 °C. However, Ru catalysts are prone to S poisoning and are quickly deactivated. As S is ubiquitous in raw biomass and technologies to remove S from hydrothermal biomass feeds are lacking, regeneration protocols that efficiently reactivate S-poisoned catalysts are required to realize efficient conversion processes and long catalyst lifetimes. In this work, we developed a method to remove S from a S-poisoned Ru catalyst under hydrothermal conditions through an oxidative treatment in the aqueous phase. By using in situ X-ray absorption spectroscopy under the reaction conditions, we show that Ru is oxidized by dilute H2O2 at low temperatures, which leads to the removal of adsorbed S species from the catalyst surface. By optimizing the regeneration conditions, it was possible to prevent oxidation of the catalyst carbon support, as revealed by ex situ TEM. This treatment led to a reactivation of the Ru catalyst with a significant increase in carbon-to-gas conversion and methane selectivity. Don't preach, bleach! Dilute hydrogen peroxide effects the reactivation of a sulfur-poisoned ruthenium catalyst under hydrothermal conditions. This mild oxidative treatment efficiently removes adsorbed sulfur from the ruthenium surface and restores the catalytic activity without corroding the catalyst support. Copyright
Catalytic activity of systems based on supported potassium salts of transition metal carbonyl hydrides in hydrogen-deuterium exchange of hydrocarbons
Yunusov,Rummel,Herrmann,Kalyuzhnaya,Shur
, p. 1191 - 1194 (2014/03/21)
The deposition of K2[Ru4(CO)13], K 2[Os3(CO)11], K2[Fe 2(CO)8], and K[Re(CO)5] onto graphite-like carbon Sibunit followed by the thermal decomposition of the supported carbonylmetallate in a flow of dihydrogen or argon affords systems capable of activating C-H bonds of methane, ethylene, and acetylene and of introducing them into hydrogen-deuterium exchange reactions. In the case of ethylene and acetylene, the isotope exchange proceeds at room temperature, while in the case of methane reaction temperatures not lower than 150 C are needed.
Hydrogen-deuterium exchange of methane on nickel and potassium promoted nickel prepared by the reduction of nickel oxide
Osawa, Tsutomu,Futakuchi, Takashi,Imahori, Tomoharu,Lee, I-Yin Sandy
experimental part, p. 68 - 71 (2010/06/20)
The hydrogen-deuterium exchange reactions of methane in a deuterium stream were studied by a pulse experiment over a reduced nickel (Ni1373 prepared from nickel oxide calcined at 1373 K, and Ni773 prepared from nickel oxide calcined at 773 K) and K2O promoted reduced nickel (K-Ni1373 and K-Ni773). Ni1373 had a higher exchange activity than Ni773. The effects of the addition of K2O resulted in the decrease in the exchange activity due to the inhibition of step defect sites and/or the promotion of the change of nickel crystal structure. High activity of Ni1373 could be due to that the Ni1373 had the surface of a higher Ni(1 0 0)/Ni(1 1 1) ratio.
