Search results for "Isobutane"
showing 8 items of 8 documents
Reaction products and pathways in the selective oxidation of C-2-C-4 alkanes on MoVTeNb mixed oxide catalysts
2010
[EN] The catalytic properties of MoVTeNbO catalysts during the selective oxidation of short chain alkanes and olefins (C-2-C-4) have been comparatively studied The main reaction products have been ethylene from ethane acrylic acid from propane maim anhydride from n-butane and methacrolein from isobutane FTIR studies of the adsorption of the main reaction products i e olefins and aldehydes over MoVTeNbO catalyst has been carried out Accordingly the reaction pathway is explained on the basis of the characteristics of the alkane fed the stability and reactivity of both the intermediates and the reaction products and the nature of the catalytic sites involved in each reaction (C) 2010 Elsevier …
Oxidative dehydrogenation of isobutane over Co-MCM-41 catalysts
2004
Abstract Cobalt-containing mesoporous silicates with MCM-41-like structure, with Si/Co≥49, are active and selective catalysts for the oxidative dehydrogenation (ODH) of isobutane. The formation of dehydrogenation products is analysed in terms of the nature of the cobalt species, tetrahedral Co(II), and heterogeneously initiated gas-phase reactions inside the mesopores.
Studies in organic mass spectrometry. Part 25. Benzyl ion formation in chemical ionisation (methane or isobutane) of someortho-alkylhetero-substitute…
2000
The behaviour of some ortho-alkylhetero-substituted diphenylcarbinols, including deuterium labelled derivatives, under chemical ionisation (methane or isobutane) conditions has been investigated. It has been determined that ortho-alkylhetero diphenylmethyl cations formed by water elimination from the protonated molecule undergo consecutive rearrangements which afford benzyl (or tropylium) ions previously observed for ortho-substituted diphenylcarbenium ions generated by electron ionisation. This reaction also occurs under low-energy collision conditions. Copyright © 2000 John Wiley & Sons, Ltd.
13C NMR study of some polychloro-isobutane and -isobutene compounds
1984
The 13C chemical shifts and the carbon–proton coupling constants have been determined for some chlorinated isobutane and isobutene compounds. The one-bond coupling constants in isobutane derivatives showed a regular increase with an increasing number of γ-chlorine substituents. The three-bond coupling constant of the methyl carbon decreased from 4.2 to 2.0 Hz as the number of chlorine substituents in the γ-position increased. In the isobutene compounds, the vicinal coupling of C-1 was larger to protons in a group that is trans with respect to a chlorine substituent on C-1 than to those in the corresponding group cis to the chlorine. The vicinal coupling constants between atoms in geminal gr…
Cracking behavior of zeolites with connected 12- and 10-member ring channels: The influence of pore structure on product distribution
1997
n-Heptane has been cracked on a CIT-1 zeolite which has connected 12- and 10-member ring (MR) channels, and its behavior was compared with that of MCM-22 with nonconnected 12- and 10-MR channels, and SSZ-24 and BETA with unidirectional and tridirectional 12-MR channels, respectively. The kinetic rate constant is highest for CIT-1, and the decay constant is lowest. From the selectivity point of view, its behavior can be better represented by a system with large cavities (the intersections between the 12- and 10-MR) connected by windows. This gives a behavior typical of that of large pore zeolites. CIT-1 produces a remarkably high selectivity toi-C4, and specially to isobutane. This zeolite s…
Selective oxidative activation of isobutane on a novel vanadium-substituted bimodal mesoporous oxide V-UVM-7
2006
Abstract New vanado-silicates with a bimodal mesoporous system (V-UVM-7) and high vanadium contents (Si/V ≥ 7) have been prepared by a modification of the so-called atrane method. Its morphology consists of aggregation of nano-particles with V-MCM-41 structure, creating a second broader porous system in their interparticle space. Its structure allows to incorporate a high V contents into tetrahedral sites of the framework while keeping vanadium dispersion. V-UVM-7 catalysts are very active and selective for the direct transformation of isobutane to isobutene and methacrolein. Total conversion and methacrolein-to-isobutene ratio in the products increased with increasing vanadium contents. Th…
Direct oxidation of isobutane to methacrolein over V-MCM-41 catalysts
2004
High vanadium content mesoporous vanado-silicates with MCM-41-like structure, obtained by the atrane route, catalyse the direct oxidation of isobutane to methacrolein with 30% selectivity, and a total dehydrogenation (olefin plus methacrolein) selectivity up to 74%.
Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide
2014
International audience; The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10−3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, prop…