Showing papers on "Dehydrogenation published in 1978"
TL;DR: In this paper, a single-crystal Ag(110) surface was preoxidized with oxygen-18, and deuterated methanol, CH3OD, was used to distinguish the hydroxyl hydrogen from the methyl hydrogens.
372 citations
TL;DR: Mixed oxide catalysts, containing molybdenum and vanadium (MoV) together with another transition metal oxide (Ti, Cr, Mn, Fe, Co, Ni, Nb, Ta, or Ce), are active as low as 200 °C for the oxydehydrogenation of ethane to ethylene.
365 citations
274 citations
259 citations
TL;DR: In this paper, high-resolution electron energy-loss measurements of ethylene on Ni(111) and cyclohexane on Ni (111 and Pt(111), showed an extra CH stretching vibration which is strongly broadened and shifted to lower frequencies relative to another, more typical CH vibration.
Abstract: High-resolution electron energy-loss measurements of ethylene on Ni(111) and cyclohexane on Ni(111) and Pt(111) show an extra CH stretching vibration---not found in free molecules or organometallic compounds---which is strongly broadened and shifted to lower frequencies relative to another, more typical CH stretching vibration. This softened and broadened CH frequency is attributed to a new electronic interaction with the surface which we relate to the mechanism of hydrocarbon dehydrogenation.
218 citations
TL;DR: In this article, the I (V) characteristics of a p-n junction were used to monitor the hydrogenation of dangling bonds in amorphous silicon, which can be rehydrogenated by exposure to atomic H, but not to undissociated H2.
Abstract: The dehydrogenation of amorphous silicon leaves dangling bonds which can be rehydrogenated by exposure to atomic H, but not to undissociated H2. The hydrogenation of dangling bonds in crystalline Si was monitored via the I (V) characteristics of a p‐n junction.
158 citations
TL;DR: In this paper, temperature-programmed reaction spectroscopy was used to study the ability of both surfaces to dissociatively chemisorb ethanol and showed that the Ag surface was more active than the Cu(110) surface for the dehydrogenation of ethoxide to acetaldehyde and hydrogen.
128 citations
80 citations
TL;DR: In this paper, the alkenes reacted initially via hydrogen abstraction to form radicals; the 1-butene radical is oxidized to the alkoxide ion and forms mainly butadiene by a mechanism similar to that previously reported for alkane dehydrogenation; ethylene and propylene radicals form carboxylate ions which yield methane and carbonate ions as the main products.
Abstract: Ethylene, propylene, 1-butene, and cis-2-butene were adsorbed on magnesium oxide containing O/sup -/ and the product distributions of their temperature-programed desorption compared with those of the desorption of possible intermediates (e.g., acetaldehyde) from untreated magnesium oxide. The results and ESR and IR spectroscopic studies suggested the alkenes reacted initially via hydrogen abstraction to form radicals; the 1-butene radical is oxidized to the alkoxide ion and forms mainly butadiene by a mechanism similar to that previously reported for alkane dehydrogenation; ethylene and propylene radicals form carboxylate ions which yield methane and carbonate ions as the main products.
68 citations
TL;DR: The commercial production of styrene was started in the 1930s and is made worldwide by the catalytic dehydrogenation of ethylbenzene or by a process in which styrene is produced as a coproduct with propylene oxide.
Abstract: The commercial production of styrene was started in the 1930s. Currently 7 million tons of styrene a year is made worldwide by the catalytic dehydrogenation of ethylbenzene or by a process in which styrene is produced as a coproduct with propylene oxide. An estimated 62% of the styrene monomer is consumed in the manufacture of polystyrene, 12% in acrylonitrile-butadiene-styrene resins, 17% in styrene-butadiene rubber and latex, 7% in unsaturated polyester resins, and 2% in other applications. Occupational exposure to styrene occurs in monomer production and polymerization plants, during the fabrication of plastic products from monomeric or partly prepolymerized styrene, and during the transportation and handling of liquid styrene. Due to unreacted residual monomer or thermal degradation of the polymer, low concentrations of styrene can be detected during the use of plastic products. The most extensive and intensive exposure occurs in the reinforced plastics industry, in which over 200,000 workers are exposed to a styrene concentration typically ranging from 20 to 300 ppm.
49 citations
TL;DR: In this article, a mechanism was proposed which accounts for dehydration under low pressure conditions and dehydrogenation under high pressure conditions, in which ethanol chemisorbed on magnesium oxide doped with various transition metals revealed that such impurities have the effect of lowering the temperature at which ethylene is desorbed.
TL;DR: In this paper, a single center mechanism implying a series of II-σ shifts is proposed for cyclohexane dehydrogenation by highly dispersed Pt-bimetallic catalysts.
TL;DR: In this paper, the physicochemical properties of two series of catalysts comprising magnesia and sodium were determined, and the specific surface areas of the catalysts determined, including the concentration and strengths of basic and acid sites, as well as the amounts of oneelectron donor and one-electron acceptor sites.
Abstract: Physico-chemical and catalytic properties of two series of catalysts comprising magnesia and sodium were determined. The first (I) series of catalysts was prepared by doping magnesia with varying amounts of NaOH. The second (II) series of catalysts was obtained by evaporating metallic sodium onto MgO preparations precalcined at different temperatures.The concentration and strengths of basic and acid sites, as well as the amounts of one-electron donor and one-electron acceptor sites, were measured, and the specific surface areas of the catalysts determined. Catalytic activity in isomerization of pent-1-ene, trans-pent-2-ene and the conversion of cumene was studied. It was concluded that the (II) series of catalysts displayed remarkably strong basic and one-electron donor properties. Also, it was proved that basic sites coexist on the surfaces of catalysts with the one-electron donor sites. Catalytic activity in alkene isomerization and cumene dehydrogenation was unambiguously associated with the presence of well-defined surface active sites.
TL;DR: The dehydrogenation of substituted 3,5-cyclohexadiene-1,2-diol-1-carboxylic acids by dihydrodihydroxybenzoic acid dehydrogenases from benzoate grown cells of Alcaligenes eutrophus and Pseudomonas sp.
TL;DR: Pyrazoline (I) and Chalkonphenylhydrazone (IV) reagieren with Co-Ionen in Form katalytischer Mengen Cobaltseifen von C6- bis C 1 o-Fettsauren in Gegenwart von Sauerstoff uber radikalische und ionogene Zwischenstufen zu den Pyrazolen (VI) as discussed by the authors.
Abstract: Pyrazoline (I) und Chalkonphenylhydrazone (IV) reagieren mit Co-Ionen in Form katalytischer Mengen Cobaltseifen von C6- bis C 1 o-Fettsauren in Gegenwart von Sauerstoff uber radikalische und ionogene Zwischenstufen zu den Pyrazolen (VI).
TL;DR: In this article, the role of surface acidic properties on isomerization and extensive oxidation reactions was investigated in the presence and absence of steam in the feed, and strong analogies within the series of the investigated catalysts were observed.
TL;DR: A number of steroidal ketones have been dehydrogenated in excellent yield and under mild conditions using benzeneseleninic anhydride; in some cases A-nor ketones were also formed as mentioned in this paper.
Abstract: A number of steroidal ketones have been dehydrogenated in excellent yield and under mild conditions using benzeneseleninic anhydride; in some cases A-nor ketones were also formed.
Patent•
27 Sep 1978TL;DR: In this article, a catalyst composite consisting of one or more metals selected from the group consisting of Ni, Pd, Pt, Ir and Os in association with tin and a metal selected from cesium, rubidium, thalium and cerium deposited on a support such as alumina, silica or a Group II aluminate spinel is presented.
Abstract: Dehydrogenatable organic compounds, diluted with steam, are dehydrogenated in the absence of free oxygen at high conversion and selectivity to less saturated compounds with a catalyst composite consisting essentially of one or more metals selected from the group consisting of Ni, Pd, Pt, Ir and Os in association with tin and a metal selected from the group consisting of cesium, rubidium, thalium and cerium deposited on a support such as alumina, silica or a Group II aluminate spinel.
TL;DR: In this article, X-ray photoelectron spectroscopy and catalytic, desorption and basicity measurements of MgO samples were investigated by means of Xray photo-electron, spectrometric and computational methods.
Abstract: Different MgO samples were investigated by means of X-ray photoelectron spectroscopy and catalytic, desorption and basicity measurements. The O 1s peak of MgO showed a shoulder (or was split into two peaks) as a function of storage time. This shoulder and the second peak were identified as oxygen atoms of Mg(OH)2 with a binding energy of 531.5 ± 0.3 eV, compared with 529.9 ± 0.3 eV for pure MgO.In desorption measurements, only one H2O peak at ≈ 373 K was found with a freshly prepared MgO sample, whereas the other samples showed two peaks, one at ≈ 373, the other at 573 K. These experiments demonstrated the formation of a hydroxide layer on MgO with increasing storage time. With the growth of the hydroxide layer the basicity of the MgO samples decreased.The dehydrogenation and dehydration of butan-2-ol was used as test reaction. With increasing hydroxide layer and decreasing basicity the selectivity changed from dehydrogenation to dehydration.
TL;DR: In this article, the reaction mechanism of propylene oxidation to acetone over SnO 2 MoO 3 catalyst has been investigated in terms of the kinetics at 130 °C.
Patent•
04 Dec 1978TL;DR: Spinels promoted with an alkali metal oxide and vanadium, oxide are useful catalysts for the dehydrogenation of hydrocarbons to the corresponding more unsaturated polymers and result in an improved catalyst as discussed by the authors.
Abstract: Spinels promoted with an alkali metal oxide and vanadium, oxide are useful catalysts for the dehydrogenation of hydrocarbons to the corresponding more unsaturated hydrocarbons and result in an improved catalyst.
TL;DR: The reaction of Os3 (CO)10(NCCH3)2 and triethylamine provides H2 Os3(CO) 10 and HOs3( CO) 10(CHCHNEt2) in equimolar amounts.
TL;DR: In this paper, butanal and butanol and hydrogenation of cyclopentanone have been studied in a flow apparatus in mixtures with hydrogen and at a total pressure of 1 atm.
TL;DR: In this paper, the catalytic decomposition of 2-propanol has been studied in a flow system from 200 to 280 °C on vanadium pentoxide and modified vanadium Pentoxide catalysts.
Abstract: The catalytic decomposition of 2-propanol has been studied in a flow System from 200 to 280 °C on vanadium pentoxide and modified vanadium pentoxide catalysts. Results were obtained with separate melts of the oxide containing 9.09 mol% of each of the alkali metal sulfates and with individual preparations of the pentoxide containing 1.01, 2.00, and 4.98 mol% potassium sulfate, respectively. In addition to expected dehydration and dehydrogenation reactions, propane was formed over the entire temperature range and became a dominant product at higher temperatures.Kinetic experiments showed that the dehydration and dehydrogenation reactions were zero order with respect to ail components while the propane-forming reaction gave a rate order of 0.3 with respect to 2-propanol concentration. Elimination-type mechanisms have been proposed to explain the results and some evidence of a relationship between catalyst activities and surface acidity is presented. The observed kinetic compensation effect bas been shown to ...
Patent•
10 Aug 1978
TL;DR: In alkalischem Medium unter Edelmetallkatalyse erhalt man aus dem Glucose-Anion (I) das Spaltprodukt (II) as discussed by the authors.
TL;DR: In this article, the activity variation of catalysts with pretreatment temperature and the reaction of 4-isopropyl-1-methyl-1,3-cyclohexadiene suggest that selectivity is determined by relative activity for hydrogenation to that for double bond isomerization.
Abstract: 4-Isopropenyl-1-methylcyclohexene undergoes hydrogenation over ZrO2 and ThO2 to 4-isopropyl-1-methylcyclohexene, while it undergoes mainly dehydrogenation over MgO, CaO, and La2O3 to 1-isopropyl-4-methylbenzene. The activity variation of catalysts with pretreatment temperature and the reaction of 4-isopropyl-1-methyl-1,3-cyclohexadiene suggest that selectivity is determined by relative activity for hydrogenation to that for double bond isomerization.