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Results for “ALKANE”
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Contrasting Mechanisms and Reactivity of Tl(III), Hg(II), and Co(III) for Alkane C–H Functionalization
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Colloidal Synthesis of Well-Defined Bimetallic Nanoparticles for Nonoxidative Alkane Dehydrogenation
Abstract not provided
Manganese Catalyzed Partial Oxidation of Light Alkanes
The catalytic partial oxidation of methane is achieved at low temperatures (<200 °C) using manganese oxides and manganese salts in mixtures of trifluoroacetic acid and trifluoroacetic anhydride. Dioxygen is used as the in situ terminal oxidant. For Mn oxides (e.g., MnO 2 , Mn 2 O 3 , and Mn 3 O 4 ), we studied stoichiometric methane partial oxidation in HTFA (TFA = trifluoroacetate). Using a Mn trifluoroacetate salt, at 180 °C and under 25 psig of methane, product selectivity for the mono-oxidized product methyl trifluoroacetate (MeTFA) is observed to be >90% at ~35% methane conversion at approximately 6 turnovers. Under our catalytic methane oxidation reaction conditions, MeTFA is stable against overoxidation, which explains the likely high selectivity at conversions >15%. Using combined experimental studies and DFT calculations, a mechanism involving soluble and molecular Mn species in the catalytic cycle is proposed. The proposed reaction pathway involves initial activation of Mn II by dioxygen, cleavage of a methane C–H bond by a Mn III hydroxo intermediate, rebound of the methyl radical to generate MeTFA, and finally regeneration of the starting Mn II complex. Also, this process is shown to be applicable to the oxidation of ethane, favoring the mono-oxidized product ethyl trifluoroacetate (EtTFA) and reaching ~46% conversion.
Hydrodeoxygenation of m -Cresol over WO x -Pt/SBA-15 Using Alkanes as Hydrogen Carriers
Not provided.
Role of Sn in the Regeneration of Pt/γ-Al 2 O 3 Light Alkane Dehydrogenation Catalysts
Not Available
Computational Predictions and Experimental Validation of Alkane Oxidative Dehydrogenation by Fe 2 M MOF Nodes
Not provided.
Ignition Quality Tester (IQT) Investigation of the Negative Temperature Coefficient Region of Alkane Autoignition
Abstract not provided
Experiments and Computational Fluid Dynamics Modeling Analysis of Large n-Alkane Ignition Kinetics in the Ignition Quality Tester
Abstract not provided
Effects of Si/Al Ratio on the Distribution of Framework Al and on the Rates of Alkane Monomolecular Cracking and Dehydrogenation in H-MFI
For this study, the aim was to investigate the influence of Si/Al ratio on the locations of exchangeable cations in H-MFI and on the monomolecular cracking and dehydrogenation reactions of n -butane. On the basis of UV-visible spectroscopic analysis of Co(II) exchanged into MFI, it was inferred that the fraction of Co(II) (and, by extension, Brønsted protons) located at channel intersections relative to straight and sinusoidal channels increases with increasing Al content. Concurrently, turnover frequencies for all monomolecular reactions, and the selectivities to dehydrogenation versus cracking and to terminal cracking versus central cracking, generally increased. The changes in selectivity with Al content are consistent with the finding that the transition-state geometry for dehydrogenation is bulky and resembles a product state, and should therefore exhibit a stronger preference to occur at channel intersections relative to cracking. Increases in turnover frequencies are attributed partly to increases in intrinsic activation entropies that compensate for concurrent increases in intrinsic activation energies, most strongly for dehydrogenation and terminal cracking, resulting in increased selectivity to these reactions at higher Al content. This interpretation contrasts with the view that intrinsic activation barriers are constant. It is also observed that isobutene inhibits the rate of n-butane dehydrogenation. Theoretical calculations indicate that this effect originates from adsorption of isobutene at the channel intersections. Because cracking reaction rates are not affected by the presence of isobutene, this result suggests that the preference of dehydrogenation to occur at channel intersections is much stronger than the preference for cracking to occur at these locations.