Search results for "METHANE"
showing 10 items of 1763 documents
Fast orthometalation reactions at a binuclear dirhodium(II) complex. Synthesis, crystal structure and reactivity of Rh2(O2CCH3)3[(C6H4)PPh2]·(HO2CCH3…
1989
Abstract From the reaction of Rh2(O2CCH3)4(MeOH)2, in hot acetic acid with PPh3 the monometalated intermediate Rh2(O2CCH3)3[(C6H4)PPh2](HO2CCH3)2 has been isolated and characterized by an X-ray study. This compound rapidly reacts with an excess of PPh3 in dichloromethane at room temperature to give Rh2(O2CCH3)2-[(C6H4)PPh2]2(PPh3)2 with a head-to-tail structure. The same procedure at higher temperatures gives a mixture of this compound and another doubly metalated compound with a head-to-head structure.
Stable Methylene- and Oxo-Bridged Monocyclopentadienyl Titanium Compounds. Molecular Structure of {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2)
2004
Thermolysis of {Ti[μ-(η5-C5Me4SiMe2-O)]Me2}2 affords the methylene-bridged titanium compound {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2), concurrent with the evolution of methane, the first example of a fu...
Anion-controlled formation of an aminal-(bis)imine Fe(ii)-complex.
2014
In the presence of triflate as the counter anion, 1,2-diaminobenzene and 2-formylpyridine self-sort with iron(II) to a low-spin [Fe(L1)](OTf)2 complex in which both aminal and imine moieties coexist simultaneously, while under similar conditions the chloride anion leads to a high-spin [Fe(L2)Cl2] complex.
Tuning the selectivity of light hydrocarbons in natural gas in a family of isoreticular MOFs
2017
Purification of methane from other light hydrocarbons in natural gas is a topic of intense research due to its fundamental importance in the utilization of natural gas fields. Porous materials have emerged as excellent alternative platforms to conventional cryogenic methodologies to perform this task in a cost- and energy-efficient manner. Here we report a new family of isoreticular chiral MOFs, prepared from oxamidato ligands derived from natural amino acids L-alanine, L-valine and L-leucine, where, by increasing the length of the alkyl residue of the amino acid, the charge density of the MOF's channels can be tuned (1 > 2 > 3), decreasing the adsorption preference towards methane over lig…
Non-oxidative dehydroaromatization of methane:an effective reaction regeneration cyclic operation for catalyst life extension
2015
[EN] Non-oxidative methane aromatization is an attractive direct route for producing higher hydrocarbons. It is highly selective to benzene despite the low conversion due to thermodynamic limitations, and Mo/H-ZSM-5, the first catalyst proposed for this reaction, is still considered as one of the most adequate. The major problem of this process is the severe catalyst deactivation due to the rapid build-up of carbonaceous deposits on the catalysts. Here we present an effective regeneration procedure that extends the life of Mo/zeolite based catalysts by combining reaction periods of 1.5 h with 0.5 h regeneration steps in a continuous cyclic mode and methane activation after each regeneration…
Copper(I) Complexes of Bis(2-(diphenylphosphino)phenyl) Ether: Synthesis, Reactivity, and Theoretical Calculations
2007
The tricoordinated cationic Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(kappa(1)-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)(4)][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a PE bond resulting in the formation of complexes of the type [Cu(kappa(2)-P,P'-DPEphos)(kappa(2)-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(mu-4,4'-bpy)](n)[BF4](n) (5) was …
Theoretical EHT study of oxidative coupling of methane on pure MgO and MgO doped with Li and Na
1991
Abstract On the basis of Extended Huckel Theory, empirical studies on the oxidative coupling of methane with MgO pure and MgO doped with Li and Na are presented. The results obtained from the two-dimensional energy surfaces calculated for the interaction between linear clusters of these oxides and the methane molecule show a qualitative agreement with the experimental behaviour reported for these catalysts. The calculated activation energy barriers are in accord with the relative activities of these oxides (Li/MgO > Na/ MgO > MgO) and are of the same order of magnitude as the experimentally determined activation energies.
Pd/Co3O4 catalyst for CH4 emissions abatement: study of SO2 poisoning effect
2007
A catalyst with 0.7 wt% Pd load supported over Co3O4 oxide was investigated in the methane oxidation by operating under CH4/O2 stoichiometric conditions. The effect of the noble metal addition on the activity of bare Co3O4 was evaluated. Samples were characterized by BET, XRD, TPR and XPS analyses. The SO2 poisoning of Pd catalyst and Co3O4 was studied by performing CH4 oxidation tests under stoichiometric conditions in SO2 (1 ppm or 10 ppm). Experiments evidenced that in our conditions the low amount of SO2 doesn’t influence the Pd behaviour, whereas in presence of 10 ppm of SO2 some deactivation occurs that becomes more evident above 450 °C at which the catalyst doesn’t reach 100% of meth…
Tetraurea calix[4]arenes with sulfur functions: synthesis, dimerization to capsules, and self-assembly on gold.
2007
Various calix[4]arene derivatives, fixed in the cone conformation by decylether groups and functionalized at their wide rim by urea residues, were synthesized. In two compounds (4f,g) sulfur functions were attached to the urea groups via different spacers in order to allow binding to metal surfaces. While they exist as single molecules in polar solvents, tetraurea calix[4]arenes of this type (4) combine to form dimeric capsules in aprotic, apolar solvents. A solvent molecule is usually included in such a capsule, if no guest with a higher affinity is present. In the presence of an equimolar amount of the tetratosylurea 5, the exclusive formation of heterodimers, consisting of one molecule o…
Efficient Sc triflate mesoporous-based catalysts for the synthesis of 4,4′-methylenedianiline from aniline and 4-aminobenzylalcohol
2012
Abstract Sc triflate mesoporous-based catalysts have been prepared using a two-step strategy (i.e., Atrane method) based on the formation of the hierarchic bimodal porosity in the first step and the formation of Sc triflate complexes at the materials surface in the second step. All solids were analyzed by EPMA, surface area, and pore size values, XRD, TEM, FTIR, and 45Sc NMR static spectra. The catalysts have been investigated in the synthesis of 4,4′-methylenedianiline (4,4′-MDA) from aniline and 4-aminobenzylalcohol. 4,4′-MDA was obtained with selectivities over 85.0% for a conversion of aniline of 31%, at 80 °C and after 24 h. Using microwaves, selectivities of 90% in 4,4′-MDA were reach…