Dehydrogenation of ethane

Athene formation requires that X and Y be substituents on adjacent carbon atoms By mak mg X the reference atom and identifying the carbon attached to it as the a carbon we see that atom Y is a substituent on the p carbon Carbons succeedmgly more remote from the reference atom are designated 7 8 and so on Only p elimination reactions will be dis cussed m this chapter [Beta (p) elimination reactions are also known as i 2 eliminations ] You are already familiar with one type of p elimination having seen m Section 5 1 that ethylene and propene are prepared on an industrial scale by the high temperature dehydrogenation of ethane and propane Both reactions involve (3 elimination of H2... 

Before dehydrogenation of ethane became the dominant method ethylene was pre pared by heating ethyl alcohol with sulfunc acid... 

Although ethylene is produced by various methods as follows, only a few are commercially proven thermal cracking of hydrocarbons, catalytic pyrolysis, membrane dehydrogenation of ethane, oxydehydrogenation of ethane, oxidative coupling of methane, methanol to ethylene, dehydration of ethanol, ethylene from coal, disproportionation of propylene, and ethylene as a by-product. 

Wang SB, Murata K, Hayakawa T, Hamakawa S, Suzuki K (1999) Excellent performance of lithium doped sulphated zirconia in oxidative dehydrogenation of ethane. Chem Commun 103-104. 

Selective transformations Selective styrene ring opening [103] One-pot domino process for regioselective synthesis of a-carbonyl furans [104] Tandem process for synthesis of quinoxalines [105] Atmospheric oxidation of toluene [106] Cyclohexane oxidation [107] Synthesis of imines from alcohols [108] Synthesis of 2-aminodiphenylamine [109] 9H-Fluorene oxidation [110] Dehydrogenation of ethane in the presence of C02 [111] Decomposition of methane [112] Carbon monoxide oxidation [113]... 

A new process for the manufacture of acetylene has been proposed. The process will involve the dehydrogenation of ethane over a suitable catalyst (yet to be found). Pure ethane will be fed to a reactor and a mixture of acetylene, hydrogen, and unreacted ethane will be withdrawn. The reactor will operate at 101.3 kPa total pressure and at some as yet unspecified temperature T. 

For consistency, an initial well associated with the formation of an adduct of the metal ion with the alkane should be included in Figure 11. The chemical activation associated with the formation of such an adduct is likely to be essential in overcoming intrinsic barriers associated with insertion into C-H bonds. In comparison to larger hydrocarbons, the weaker interaction of ethane with first row group 8-10 metal ions may be insufficient to overcome intrinsic barriers for insertion. This would explain the failure to observe dehydrogenation of ethane by these metal ions, even though the process is known to be exothermic. The well depths could be determined from high pressure equilibria. Studies in our laboratory and elsewhere have indicated the ease with which many of... 

Dehydrogenation of ethane over vanadium, cobalt and nickel based catalysts... 

This problem is an extension of problems 7-10 and 7-11 on the dehydrogenation of ethane to produce ethylene. It can be treated as an open-ended, more realistic exercise in reaction mechanism investigation. The choice of reaction steps to include, and many aspects of elementary gas-phase reactions discussed in Chapter 6 (including energy transfer) are significant to this important industrial reaction. Solution of the problem requires access to a computer software package which can handle a moderately stiff set of simultaneous differential equations. E-Z Solve may be used for this purpose. 

The dehydrogenation of ethane (A) to ethene (B) is conducted in a 0.5-m3 PFR. The reaction is first-order with respect to A, with a rate constant of 15.2 min-1 at 725°C. The feed contains pure ethane at 725°C, 400 kPa, and a flow rate of 1. 0 kmol min-1. Compare the conversion predicted if isothermal, isobaric conditions are assumed with that if the pressure drop is accounted for with isothermal flow. The diameter of the reactor tube is 0.076 m, and the viscosity of the gas is 2.5 X 10-5 Pa s. 

Oxidative Dehydrogenation of Ethane. The dehydrogenation of alkanes also occurs, but in a catalytic manner, over molybdenum supported on silica (22,23). In addition to the stoichiometric reactions, the role of the 0 ion in this catalytic reaction is further suggested by the observation that N2O is an effective oxidant at temperatures as low as 280°C, but no reaction is observed at these temperatures with O2 as the oxidant (22). It should be noted that at moderate temperatues N2O gives rise to 0 , whereas O2 yields O2 over Mo/Si02. Under steady-state conditions the rates of formation of C2Hi were in the ratio of 7 1 at 375°C and 3.7 1 at 450°C when N2O and O2 were used as the oxidants, respectively (23). ... 

Dehydrogenation of Ethane to Ethylene Porous AI2O3 membranes Nonporous Pd/Ag membranes Fumeaux, Davidson and Ball (1987) Pfefferie (1966)... 

Another route to ethylbenzene is available for those remote places where olefin plants or refinery crackers are not nearby but a supply of ethane is— catalytic dehydrogenation of ethane to ethylene followed by its reaction with benzene to produce EB. The first of two steps in Figure 8-4 use a gallium zinc zeolyte catalyst that promotes ethane dehydrogenation to ethylerie at 86% selectivity and up to 50% conversion per pass. 

A. Christodoulakis, E. Heracleous, A.A. Lemonidou and S. Boghosian, An operando Raman study of structure and reactivity of alumina-supported molybdenum oxide catalysts for the oxidative dehydrogenation of ethane, J. 

Our ancestors made alcohol by anaerobic fermentation of sugar, while industrial ethanol is made by hydration of ethylene, which is obtained by dehydrogenation of ethane. 

We wish to produce ethylene by the oxidative dehydrogenation of ethane. Over a suitable catalyst the reactions and rates are found to be... 

We have a catalyst that causes the oxidative dehydrogenation of ethane to ethylene... 

For example, the oxidative dehydrogenation of ethane and propane was examined via UV-visible and Raman spectra. The study investigated the catalytic properties vanadia formulations that possessed a range of VO surface species density (1.4—34.2 V/nm ) on an AI2O3 support. The observations showed increased surface densities, greater than 2.3 V/nm , favored two-dimensional polyvanadates. At lower surface densities, ca. 2.3 V/nm , predominately isolated monovanadate species were observed. Further increasing surface densities to more than 7.0 V/nm yielded V2O5 crystallites. ... 

A technology called the Ethoxene process was developed by Union Carbide for the oxidative dehydrogenation of ethane.165 Under the relatively mild conditions applied (300-400°C, 1-40 atm) cracking is minimal and the only byproduct is acetic acid. The combined efficiency to ethylene and acetic acid is about 90% with an ethylene acetic acid ratio of 10. 

Similar improvements of activity and selectivity were reported in the oxidative dehydrogenation by C02 of ethane over Ga2C>3 (18.6% ethylene yield and 94.5% selectivity)391 and that of propane over rare earth vanadates.392 Cr203 shows medium activity in the oxidative dehydrogenation of ethane, but support on Si02 enhances the catalytic performance (55.5% ethylene yield at 61% conversion at 650°C).393... 

Combinatorial methods were also applied in the discovery of new catalysts for the low-temperature oxidation213 and oxidative dehydrogenation of propane.214 A 144-member catalyst library was screened by photothermal deflection spectroscopy and mass spectrometry to find the most active compositions of V-Al-Nb and Cr-Al-Nb oxides for the oxidative dehydrogenation of ethane.215 The ternary combination V(45)-Sn(45)-Mo(10)-O selected by laser-induced fluorescence imaging gave much higher yield than did V205 in the selective oxidation of naphthalene to naphthoquinone.216... 

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