25549-98-8Relevant articles and documents
Blades,Gilderson
, p. 1407 (1960)
Oxidative dehydrogenation of ethane on dynamically rearranging supported chloride catalysts
G?rtner, Christian A.,Van Veen, Andr C.,Lercher, Johannes A.
, p. 12691 - 12701 (2014)
Ethane is oxidatively dehydrogenated with a selectivity up to 95% on catalysts comprising a mixed molten alkali chloride supported on a mildly redox-active Dy2O3-doped MgO. The reactive oxyanionic OCl- species acting as active sites are catalytically formed by oxidation of Cl- at the MgO surface. Under reaction conditions this site is regenerated by O2, dissolving first in the alkali chloride melt, and in the second step dissociating and replenishing the oxygen vacancies on MgO. The oxyanion reactively dehydrogenates ethane at the melt-gas phase interface with nearly ideal selectivity. Thus, the reaction is concluded to proceed via two coupled steps following a Mars-van-Krevelen-mechanism at the solid-liquid and gas-liquid interface. The dissociation of O2 and/or the oxidation of Cl- at the melt-solid interface is concluded to have the lowest forward rate constants. The compositions of the oxide core and the molten chloride shell control the catalytic activity via the redox potential of the metal oxide and of the OCl-. Traces of water may be present in the molten chloride under reaction conditions, but the specific impact of this water is not obvious at present. The spatial separation of oxygen and ethane activation sites and the dynamic rearrangement of the surface anions and cations, preventing the exposure of coordinatively unsaturated cations, are concluded to be the origin of the surprisingly high olefin selectivity.
Photolysis of Thietane and Thietane-d6 in Argon Matrix: Infrared Spectra of Matrix-Isolated Thioformaldehyde and Thioformaldehyde-d2
Watanabe, Osamu,Suzuki, Eiichi,Watari, Fumio
, p. 1389 - 1391 (1991)
Argon-matrix isolated thietane at 10 K decomposed by irradiation (λ > 290 nm) to form ethylene and thioformaldehyde.The photolysis of thietane under these conditions has been shown to be a clean source of thioformaldehyde.The CH2S and CD2S molecules generated this way are indefinitely stable and their infrared spectra could be recorded.
Kinetics and mechanism of ethanol dehydration on γ-Al 2O3: The critical role of dimer inhibition
DeWilde, Joseph F.,Chiang, Hsu,Hickman, Daniel A.,Ho, Christopher R.,Bhan, Aditya
, p. 798 - 807 (2013)
Steady state, isotopic, and chemical transient studies of ethanol dehydration on γ-alumina show unimolecular and bimolecular dehydration reactions of ethanol are reversibly inhibited by the formation of ethanol-water dimers at 488 K. Measured rates of ethylene synthesis are independent of ethanol pressure (1.9-7.0 kPa) but decrease with increasing water pressure (0.4-2.2 kPa), reflecting the competitive adsorption of ethanol-water dimers with ethanol monomers; while diethyl ether formation rates have a positive, less than first order dependence on ethanol pressure (0.9-4.7 kPa) and also decrease with water pressure (0.6-2.2 kPa), signifying a competition for active sites between ethanol-water dimers and ethanol dimers. Pyridine inhibits the rate of ethylene and diethyl ether formation to different extents verifying the existence of acidic and nonequivalent active sites for the dehydration reactions. A primary kinetic isotope effect does not occur for diethyl ether synthesis from deuterated ethanol and only occurs for ethylene synthesis when the β-proton is deuterated; demonstrating olefin synthesis is kinetically limited by either the cleavage of a Cβ-H bond or the desorption of water on the γ-alumina surface and ether synthesis is limited by the cleavage of either the C-O bond of the alcohol molecule or the Al-O bond of a surface bound ethoxide species. These observations are consistent with a mechanism inhibited by the formation of dimer species. The proposed model rigorously describes the observed kinetics at this temperature and highlights the fundamental differences between the Lewis acidic γ-alumina and Bronsted acidic zeolite catalysts.
Shigehara,Ozaki
, p. 309 (1973)
deuterium generation ethylene preparation method
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Paragraph 0027; 0038; 0040; 0041-0049; 0056-0067, (2018/02/04)
The invention discloses a preparation method of deuteroethylene. According to the preparation method, calcium carbide is reacted with D2O to generate deuteroacetylene; a deuteration reaction is performed on the prepared deuteroacetylene and deuterium gas in the presence of a composite catalyst Cu-Ni/SiO2 to obtain the deuteroethylene; the volume ratio of the deuteroacetylene to the deuterium gas is 1: (10-60). The preparation method of the deuteroethylene is applicable to industrial production and has been verified and utilized in an industrial pilot plant already; experimental results prove that the preparation method has the advantages of simple reaction steps, mild reaction conditions, high deuteroethylene yield, recyclability of superfluous deuterium gas in the reaction as the raw material, and great reduction of the production cost.
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.
