74-84-0Relevant articles and documents
Catalytic hydrosilylation of oxalic acid: Chemoselective formation of functionalized C2-products
Feghali, Elias,Jacquet, Olivier,Thuery, Pierre,Cantat, Thibault
, p. 2230 - 2234 (2014)
Oxalic acid is an attractive entry to functionalized C2-products because it can be formed by C-C coupling of two CO2 molecules under electrocatalytic reduction. Herein, we describe the first attempts to reduce oxalic acid by catalytic hydrosilylation. Using B(C6F 5)3 as a Lewis acidic catalyst, oxalic acid can be converted to reduced C2-molecules, with high chemoselectivity, under mild reaction conditions.
New mechanism of photodissociation of gaseous acetone
Skorobogatov,Meilakhs,Pogosyan,Khripun
, p. 1271 - 1275 (2002)
It is found for the first time that photolysis of gaseous acetone under UV irradiation produces ethane not only via recombination of methyl radicals, but also by the mechanism of induced predissociation.
Gold-doping of carbon-supported palladium improves reduction catalysis
Fang, Yu-Lun,Heck, Kimberly N.,Zhao, Zhun,Pretzer, Lori A.,Guo, Neng,Wu, Tianpin,Miller, Jeffrey T.,Wong, Michael S.
, p. 1776 - 1786 (2016)
Bimetallic palladium-gold (PdAu) catalysts have better catalytic performance than monometallic catalysts for many applications. PdAu catalysts with controlled nanostructures and enhanced activities have been extensively studied but their syntheses require multiple and occasionally complicated steps. In this work, we demonstrated that supported PdAu catalysts could be simply prepared by doping a supported Pd catalyst with gold through wet impregnation and calcination. Resulting PdAu-on-carbon (PdAu/C) catalysts were tested for the room-temperature, aqueous-phase hydrodechlorination of trichloroethene. The most active PdAu/C catalyst (Pd 1.0 wt%, Au 1.1 wt%, dried/air/H2 process) had an initial turnover frequency (TOF) of 34.0 × 10?2 molTCE molPd?1 s?1, which was >15 times higher than monometallic Pd/C (Pd 1.0 wt%, initial TOF of 2.2 × 10?2 molTCE molPd?1 s?1). Through X-ray absorption spectroscopy, the gold kept Pd from oxidizing under calcination at 400 °C. Probable nanostructure evolution pathways are proposed to explain the observed catalysis.
Kinetic limit of the ethane and ethylene yield in the gas phase condensation of methane
Vedeneev, V. I.,Arutyunov, V. S.,Basevich, V. Ya.
, p. 372 - 373 (1995)
A kinetic simulation of the initiated condensation of methane in the gas phase showed that the additional generation of methyl radicals via the reaction CH4 + I2 -> CH3 + HO2 causes a nearly tenfold increase in the C2 hydrocarbon yield.However, a kinetic limit of the yield exist that is close to that determined in experiments on the catalytic oxidative condensation of methane. - Key words: kinetic simulation; oxidative condensation of methane.
Back,Winkler
, p. 718,719 (1954)
Novel catalysts for carbon dioxide-induced selective conversion of methane to C2 hydrocarbons
Cai, Yingchun,Chou, Lingjun,Li, Shuben,Zhang, Bing,Zhao, Jun
, p. 828 - 829 (2002)
The combination of Mn with BaCO3 leads to active catalysts for carbon dioxide-induced selective conversion of methane to ethane and ethylene in the absence of oxygen.
The Role of Coke in Acetylene Hydrogenation on Pd/α-Al2O3
Larsson, Mikael,Jansson, Jonas,Asplund, Staffan
, p. 49 - 57 (1998)
The formation of coke and the influence of the coke on selectivity were investigated during hydrogenation of acetylene on supported palladium catalysts. It was found that the total amount of coke was not directly related to the increase in formation of undesired ethane. Instead, the surface coverage of hydrogen during the deactivation was found to be a crucial parameter. A catalyst deactivated at low hydrogen surface coverage showed a higher ethane selectivity than a sample deactivated at higher surface coverage of hydrogen when compared under the same reaction conditions. In contrast, the coke formation rate was found to increase with increased hydrogen surface coverage. The role of carbon monoxide was also investigated, and the impact on selectivity and coke formation was explained by the reduced surface coverage of hydrogen in the presence of carbon monoxide. The coke was characterized by temperature-programmed oxidation, and deconvolution of the obtained peaks was carried out using a power-law model.
Tailoring the physical and catalytic properties of lanthanum oxycarbonate nanoparticles
Estruch Bosch,Copley,Eralp,Bilbé,Thybaut,Marin,Collier
, p. 104 - 112 (2017)
The synthesis of lanthanum oxide and its carbonate analogues has been performed by flame spray pyrolysis (FSP). Two different feeds have been studied: an organic solution and an aqueous/organic microemulsion. A key experimental parameter of FSP, the O2 dispersion, i.e., the flow rate of the dispersing gas in the FSP nozzle, exhibits an effect on the properties of the materials prepared. Increasing the level of O2 dispersion led to an increase in surface area and a decrease in mean particle size and basicity when a lanthanum containing organic solution was used as FSP feed. Lanthanum can form different phases, such as oxides, hydroxides, oxycarbonates and carbonates. The increase of O2 dispersion also produced a phase change, going from a mixture of type Ia and type II La2O2CO3 and La2O3 to pure La2O3. The use of an aqueous/organic microemulsion feed, which had a higher viscosity than the organic feed, resulted in materials with a lower surface area and a higher mean particle size than those prepared using the organic solution at the same O2 dispersion. In this case a mixture of type II La2O2CO3 and La2O3 was obtained. The materials were tested for oxidative coupling of methane (OCM). We were able to demonstrate that the OCM performance of the materials could be modified by changing the synthesis parameters. For example, lower O2 dispersion produced the highest CH4 and O2 conversions. We also demonstrated that on ageing the mean particle size remain stable; however, the phases do not, showing a new phase, La(OH)3, formation and resulting in an increase in OCM activity. While the OCM performances are modest they do demonstrate the power of this approach for controlled synthesis of lanthanum materials.
Oxidative Coupling of Methane over SrCO3 and SrO
Aika, Ken-ichi,Aono, Kenji
, p. 1273 - 1277 (1991)
The oxidative coupling of methane has been studied with an SrCO3-SrO mixed catalyst.Two surface states (an SrO-rich surface and an SrCO3-rich surface) were prepared and examined by various methods including XPS.SrO-rich surfaces, prepared by H2 treatment of SrCO3, had a high C2 yield, and evolved CO2 was absorbed by the catalyst at 1023 K.The bulk diffusion of CO2 was considered to be rapid enough to absorb most of the evolved CO2 and to keep SrO partly on the surface (SrCO3-rich surface) at 1023 K.SrCO3-rich surfaces gave low C2 yields, and the surface was composed of both oxides and carbonates.The active sites were considered to be oxides.The SrO surface was more active than MgO in this reaction.However, it was less active under the steady state because of carbonate formation.
Electrocatalytic Dehalogenation of 1,2-DihaIoethanes by the C60, C70, C76, C78, and C84 Fullerene Anions: Structure-Reactivity Aspects
D'Souza, Francis,Choi, Jai-Pil,Kutner, Wlodzimierz
, p. 2892 - 2896 (1999)
The homogeneous electrocatalytic reduction of 1,2-dihaloethanes by anions of larger fullerenes, C76, C78, and C84, is presented, and structure-reactivity correlations are derived by including our data reported earlier for the C60 and C70 electrocatalytic process. Cyclic voltammetry measurements indicate that dianions of C76 and C78, as well as trianions of C76, C78, and C84, electrochemically generated in 0.1 M (TBA)PF6, in benzonitrile, catalyze dehalogenation of 1,2-dihaloethanes. Values of the second-order rate constant, k, for the electrocatalytic dehalogenation of 1,2-dihaloethanes by the fullerene anions were determined by using the rotating-disk electrode voltammetry under pseudo-first-order conditions with respect to the 1,2-dihaloethanes. For each fullerene anion, k increases in the order: Cl 84 78 76 70 60, as a function of respective redox potentials of the fullerene, for each 1,2-dihaloethane. Unlike the C60n- electrocatalysis, reported by us earlier to be accompanied by chemical reaction between C60n- and certain ?±,??-diiodoalkanes yielding alkyl adducts of C60, no reaction between the anions of larger fullerenes and 1,2-dihaloethanes was observed within the voltammetric time scale. Because of the high stability with respect to adduct formation and more positive potentials of the electrocatalyses, the larger fullerenes may be more useful than C60 as catalysts, even though the corresponding catalytic rate constants are smaller.
Rochow,Dennis
, p. 486 (1935)
MANGANESE CATALYSTS FOR THE OXIDATIVE CONDENSATION OF METHANE WITH ALKALI AND ALKALINE-EARTH METAL SALT ADDITIVES
Minachev, Kh. M.,Usachev, N. Ya.,Khodakov, Yu. S.,Udut, V. N.,Makarov, P. A.
, p. 1975 - 1977 (1987)
-
-
Ackermann
, (1937)
-
Peroxide Anions as Possible Active Species in Oxidative Coupling of Methane
Otsuka, Kiyoshi,Jinno, Kiyotaka,Komatsu, Takayuki
, p. 77 - 80 (1987)
Oxidative coupling of CH4 forming C2H6 and C2H4 proceeded smoothly upon contact with Na2O2, BaO2, and SrO2 at low temperature below 673 K.This indicates that O22- ions are very reactive for activation of CH4.O2- ions contained in the peroxides did not activate CH4.
A kinetics study for the oxidative coupling of methane on a Mn/Na 2WO4/SiO2 catalyst
Tiemersma,Tuinier,Gallucci,Kuipers,Annaland, M. Van Sint
, p. 96 - 108 (2012)
This paper presents an experimental kinetic study for the oxidative coupling of methane (OCM) over a Mn/Na2WO4/SiO2 catalyst prepared by incipient wetness impregnation. Because the catalyst is a reducible metal oxide, the stability of the catalyst has been assessed by Thermo Gravimetric Analysis (TGA). These experiments show that the catalyst has to be pre-treated with oxygen in order to obtain high C2 selectivity (around 85%) and that a low oxygen partial pressure during the OCM reactions is already sufficient to maintain the catalyst stable in the oxidized state. The catalyst has subsequently been tested in a micro-catalytic fixed bed reactor. The overall reaction orders and rate constants of the primary reactions were determined by measuring the intrinsic reaction rates at different methane and oxygen inlet concentrations. It was found that the reaction order in oxygen for the coupling reaction is 0.38, while the reaction order in oxygen for ethylene oxidation approaches unity, indicating that low oxygen concentration levels are beneficial for obtaining a high C2 selectivity (up to 80-90%). Such a low oxygen concentration can be obtained with distributive feeding in a membrane reactor. Based on the experiments and least-squares minimization, a simplified reaction mechanism is proposed, where the dependency of the ethane (coupling) and carbon dioxide (oxidation) production rates and the secondary ethylene production and C2 oxidation rates can be described with power-law type reaction rate expressions.
Group 5A Metal Oxides as Promoters for Oxidative Coupling of Methane
Yamamura, Masami,Okado, Hideo,Tsuzuki, Naohide
, p. 203 - 206 (1992)
Group 5A metal oxides were tested as promoters for oxidative coupling of methane.They were effective promoters for the coupling reaction, when mixed with 1A, 1A/2A, and 1A/3A oxide catalysts, respectively.Addition of Group 5A metal increased the activity
Reactions of C2H5 radicals with HBr and Br at 298 K and millitorr pressures
Dobis, Otto,Benson, Sidney W.
, p. 8171 - 8179 (1995)
The rates of the reactions of ethyl radicals with HBr (k7) and with Br atoms (k8) have been measured at 298 K and millitorr pressures using the Very Low Pressure Reactor (VLPR) technique. The rate constants at 298 K are the following: k7 = (6.67 ± 0.14) × 10-13 cm3/(molecule's) and k8 = (1.19 ± 0.04) × 10-11 cm3/(molecule's). Reaction 7 is a factor of about 14 times slower than had been reported in the only other two direct measurements made (Nicovich, J. M. et al. J. Phys.Chem. 1991, 95, 9890. Seakins, P. W. et al. J. Phys Chem. 1992, 98, 9847) which also reported a negative activation energy for k7 of from -0.8 to -1.1 kcal/mol. Using broadly accepted thermochemistry for reaction 7 and reported values for the reverse reaction, it is shown that all reported data give a positive activation energy for k7.
Selective Synthesis of Ethylene by Dehydrogenative Coupling of Methane by Use of Thermal Diffusion Column
Yamaguchi, Tatsuaki,Saito, Chiaki
, p. 2649 - 2650 (1988)
Ethylene was found to be obtained dehydrogenatively from methane in extremely high selectivities (91.5percent at 9.4percent conversion of methane) with the downward introduction to the modified thermal diffusion column with electrically heated tungsten wire at 1200 deg C.
The study of supported manganese catalysts in the course of the oxidative coupling of methane
Kulichkov,Semikin,Kuzichkin,Lisitsyn
, p. 458 - 461 (2013)
The effect of the process parameters on the yield of the main products, ethane and ethylene, was studied for the methane oxidative dimerization over manganese catalysts deposited on solid carrying agents. The effect of various factors defining activity of manganese systems on their properties was analyzed. The best carrying agent for the catalytic system under study was chosen, and the optimal contents of an active component and a promoting additive providing a high yield of C2 hydrocarbons were determined.
Surface processes in the catalytic oxidative coupling of methane to ethane
Buyevskaya, Olga,Wolf, Dorit,Baerns, Manfred
, p. 459 - 464 (1994)
Recent results on surface reaction steps in the oxidative coupling of methane (OCM) obtained from (1) transient experiments and (2) a microkinetic analysis are summarized.The interaction of methane and oxygen with MgO and Sm2O3 surfaces was investigated by applying H/D- and oxygen-isotope-exchange reactions.The role of short-lived adsorbed oxygen species in methane activation and product formation over MgO and Sm2O3 catalysts is discussed.Furthermore, elementary reaction steps and their rate constants are derived for the oxidative conversion of methane to COx and ethane from kinetic data for different (CaO)x(CeO2)1-x catalysts; the rate constants are related to the solid's properties, i.e., electron and O(2-) conductivity.
Norman,Pitt
, p. 6104 (1955)
CATALYSTS FOR THE OXIDATIVE CONDENSATION OF METHANE TO FORM C2 HYDROCARBONS
Minachev, Kh. M.,Usachev, N. Ya.,Khodakov, Yu. S.,Kozlov, L. L.,Udut, V. N.,Fomin, O. A.
, p. 1544 (1985)
-
Kinetics and mechanism of ethylene hydrogenation poisoned by CO on silica-supported monodisperse Pt nanoparticles
Rioux, Robert M.,Komor, Russell,Song, Hyunjoon,Hoefelmeyer, James D.,Grass, Michael,Niesz, Krisztian,Yang, Peidong,Somorjai, Gabor A.
, p. 1 - 11 (2008)
The influence of particle size on the poisoning of ethylene hydrogenation by CO was studied over a series of catalysts composed of nearly monodisperse Pt nanoparticles (1.7-7.1 nm) encapsulated in mesoporous silica (SBA-15). The turnover frequency at 403 K in the presence of 0.5 Torr CO was ～2 × 10-2 s-1 (compared with ～102 s-1 in the absence of CO). The apparent activation energy in the absence and presence of 0.2 Torr CO was ～10 and 20 kcal mol-1, respectively. The pressure dependency changes significantly in the presence of CO; reaction orders in hydrogen were 1/2 in the presence of CO at 403 K and noncompetitive with regard to co-adsorption with C2H4. In the absence of CO at similar temperatures, H2 adsorption was primarily irreversible (first-order dependence), and H2 and C2H4 compete for the same sites. Ethylene orders at 403 K were first order in the presence of 0.2 Torr CO and remained unity with increasing CO pressure. At similar reaction conditions in the absence of CO, ethylene had an inhibitory effect (negative reaction order) on the overall hydrogenation reaction. The change in C2H4 and H2 kinetics suggests strong competitive adsorption between C2H4 and CO for the same type of site, whereas H2 apparently adsorbs on distinct surface sites due either to steric hindrance or H2-induced CO desorption. Incorporation of a quasi-equilibrated CO adsorption step into a noncompetitive Langmuir-Hinshelwood mechanism predicts the experimentally observed pressure dependencies and a doubling of the apparent activation energy. Hydrogenation of ethylene in the presence of 1 Torr CO was examined under reaction conditions at 403 K by infrared spectroscopy; the only surface species identified under reaction conditions was linear-bound CO. The hydrogenation of ethylene on clean Pt catalysts was structure-insensitive and remains insensitive in the presence of CO; rates decreased only by a factor of two with increasing particle size.
Oxidative Coupling of Methane over BaO Mixed with CaO and MgO
Yamagata, Nobutsugu,Tanaka, Katsutoshi,Sasaki, Shoichi,Okazaki, Susumu
, p. 81 - 82 (1987)
Various metal oxides mixed with BaO were studied as a catalyst for coupling of methane.For example, a BaO-CaO catalyst shows a high activity (20.9 mmol/hg) for the C2 formation (C2H6+C2H4) with a high C2 selectivity (61.1percent) under the following conditions; 1073 K, P(CH4)=40 kPa, a ratio of CH4 to O2 = 5.0, and W/F = 3.39 gh/mol.
Acetylene Hydrogenation to Ethylene in a Hydrogen-Rich Gaseous Mixture on a Pd/Sibunit Catalyst
Shlyapin,Glyzdova,Afonasenko,Temerev,Tsyrul’nikov
, p. 446 - 452 (2019)
Abstract: The reaction of the gas-phase hydrogenation of acetylene on a Pd/Sibunit catalyst was studied depending on the H2 : C2H2 molar ratio, the process temperature, and the presence of carbon monoxide. It was shown that for the reaction mixture of the composition H2 : C2H2 2 : C2H2 > 20, on the contrary, the order in hydrogen becomes zero and the reaction rate is determined by the acetylene content in the reaction mixture. It was found that an increase in the reaction temperature (from 30 to 85°C) leads to an increase in the contribution of complete hydrogenation to ethane. The introduction of CO into the reaction mixture up to a molar ratio of CO : C2H2 = 0.1 is accompanied by the almost complete blocking of the C2H4 readsorption sites, which results in a sharp increase in ethylene selectivity from 4 to 73%. With a further increase in the CO : C2H2 ratio, the number of sites available for hydrogen adsorption gradually decreases, and, correspondingly, the conversion decreases.
Efficient Polyester Hydrogenolytic Deconstruction via Tandem Catalysis
Kratish, Yosi,Marks, Tobin J.
supporting information, (2021/12/22)
Using a mechanism-based solvent-free tandem catalytic approach, commodity polyester plastics such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) are rapidly and selectively deconstructed by combining the two air- and moisture-stable catalysts, Hf(OTf)4 and Pd/C, under 1 atm H2, affording terephthalic acid (or naphthalene dicarboxylic acid for PEN) and ethane (or butane for PBT) in essentially quantitative yield. This process is effective for both laboratory grade and waste plastics, and comingled polypropylene remains unchanged. Combined experimental and DFT mechanistic analyses indicate that Hf(OTf)4 catalyzes a mildly exergonic retro-hydroalkoxylation reaction in which an alkoxy C?O bond is first cleaved, yielding a carboxylic acid and alkene, and this process is closely coupled to an exergonic olefin hydrogenation step, driving the overall reaction forward.
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).
Continuous methane to ethane conversion using gaseous oxygen on ceria-based Pd catalysts at low temperatures
Kim, Gunjoo,Kwon, Gihun,Lee, Hyunjoo
, (2021/06/16)
Methane upgrading into more valuable chemicals has been a promising challenge. It was previously reported that highly oxidized Pd/CeO2 could produce ethane from methane. Here, we enhanced the ethane productivity by controlling oxygen mobility of the catalyst support and adding water adsorbents. Pd/Ce1-xPdxO2-y catalyst, in which Pd atom was doped at the ceria support, showed enhanced oxygen activation and oxygen transfer, improving the ethane productivity from 0.04 molC2H6/mmolSurfacePd/h in Pd/CeO2 to 0.57 molC2H6/mmolSurfacePd/h in Pd/Ce1-xPdxO2-y. In order to remove the water produced from methane oxidation, zeolite 13X was physically mixed with Pd/Ce1-xPdxO2-y. The water adsorbent could increase the ethane production significantly, especially at low temperatures. The ethane yield of 0.30 % could be obtained at 290 °C using gaseous O2 as an oxidant. This work can provide useful ways to enhance the yield of value-added products in oxidative methane conversion.
