Interaction with methane

There are some arguments for the involvement of O radicals in the selective oxidations of methane. The 0 is registered by ESR upon adsorption of N20 on partially reduced surfaces of supported Mo and V oxides [28, 35]. The radical exhibits a very high reactivity. At room temperature, it readily interacts with methane to yield methanol as the main product, which can be registered by the IR in situ [36] or desorbed from the catalyst surface by heating [29, 30]. 

According to the multisite mechanism shown, H202 heterolytically reacts with Fe3+OH and, with synchronous participation of acidic-basic sites of the carrier, forms a PPFe3+OOH/ AlSiMg intermediate. As interacted with methane, this intermediate forms a stable product of the catalytic cycle, methanol. 

A mutual interaction of solubilities exists in all multicomponent systems. The interaction with methane is pronounced. This interdependence is treated in detail in [56], [59], [70] and [71]. 

Pure and NaP-modified MnOx-catalysts were used in our study. Due to easy visualization by AFM, the MnOx layer was placed on a Si-wafer substrate (1 cm x 1 cm plate), by a reactive deposition technique. The sample preparation was carried out in a vacuum installation equipped with an resistance evaporator. Metallic manganese (99.8%) as a source and a Si wafer with a surface orientation (111) and resistivity of 7.5 ohm/cm as support, were used. During MnOx deposition, an oxygen partial pressure of ca 10 torr, in dynamic mode, was maintained. Before used for the catalytic purpose, MnOx samples were calcined in air at 700°C for 60min. In order to prepare the NaP-modified catalyst, the MnOx samples were impregnated in a diluted Na4P20 solution (5 wt %), dried and finally calcined at 500° C, in air during 30 min. The interaction with methane was performed in a quartz reactor in a methane atmosphere at 700° 5° C. 

At high temperature metals react with alkanes. For example, at temperatures > 1600 °C, tungsten interacts with methane [23] according to the equation ... 

In contrast to the above described behavior of the basic component of an amphoteric metal oxide catalyst, the electrophilic function interacts with methane in a different manner. Here, the relatively electron rich C-H hydrogen bonds serve as electron donors to the metal center, resulting in a weakening of these bonds and methane activation, leading to formation of ethane or even direct formation of ethylene. 

Methane dissociation requires a reduced metal surface, but at elevated temperatures oxides of the active species may be reduced by direct interaction with methane or from the reaction with H, Hg, C or CO. The comparison of elementary reaction steps on Pt and Rh illustrates that a key factor to produce hydrogen as a primary product is a high activation energy barrier to the formation of OH. A catalytic material and support which does not easily form or stabilise OH species is therefore desirable. Another essential property for the formation of Hg and CO as primary products is a low surface coverage of intermediates, such that the probability of O-H, OH-H and CO-O interactions is reduced. ... 

The study of the dynamics of N isotope transfer under adsorption-desorption equilibrium (NO -1- O2 + He) revealed two types of NOx complexes, and their concentrations and formation rates (depending on NO and O2 concentrations) were estimated. According to in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) data, these complexes are assigned to nitrite-nitrate (1520 cm" ) and N02 species (2130 cm" ). Note that nitrite-nitrates and N02 differ clearly in the rates of their formation. Under the reaction conditions, the concentrations of both active species drop considerably. Therefore, two parallel reaction pathways were proposed that involve both active complexes. The rates of NOx complexes interaction with methane were also calculated, and the reaction with participation of N02 species was shown to proceed about 2.5 times faster than that of nitrite-nitrate. The N02 species was determined to form at the interface between CoO clusters and acid OH groups in zeolite (or at the paired Co -OH sites). This finding agrees well with in situ DRIFTS data that indicates that the N02 formation correlates with a drop in the acid OH group band intensity. 

The key initiation step in cationic polymerization of alkenes is the formation of a carbocationic intermediate, which can then interact with excess monomer to start propagation. We studied in some detail the initiation of cationic polymerization under superacidic, stable ion conditions. Carbocations also play a key role, as I found not only in the acid-catalyzed polymerization of alkenes but also in the polycondensation of arenes as well as in the ring opening polymerization of cyclic ethers, sulfides, and nitrogen compounds. Superacidic oxidative condensation of alkanes can even be achieved, including that of methane, as can the co-condensation of alkanes and alkenes. 

The ion source, across which an electron beam passes, is filled with methane, the reagent gas. There is a high vacuum around the ion source, so, to maintain a high pressure in the source itself, as many holes as possible must be blocked off or made small. Interaction of methane (CH4) with electrons (e ) gives methane molecular ions (CH4 "), as shown in Figure 1.2a. 

Biological—Biochemical Processes. Fermentation is a biological process in which a water slurry or solution of raw material interacts with microorganisms and is enzymatically converted to other products. Biomass can be subjected to fermentation conditions to form a variety of products. Two of the most common fermentation processes yield methane and ethanol. Biochemical processes include those that occur naturally within the biomass. 

The influence of Zn-deposition on Cu(lll) surfaces on methanol synthesis by hydrogenation of CO2 shows that Zn creates sites stabilizing the formate intermediate and thus promotes the hydrogenation process [2.44]. Further publications deal with methane oxidation by various layered rock-salt-type oxides [2.45], poisoning of vana-dia in VOx/Ti02 by K2O, leading to lower reduction capability of the vanadia, because of the formation of [2.46], and interaction of SO2 with Cu, CU2O, and CuO to show the temperature-dependence of SO2 absorption or sulfide formation [2.47]. 

Nitric acid treatment lowered the methane uptake by about ten percent. This could be due to oxygen occupying sites within pores, but may be the result of weaker interaction between methane and an oxide surface as is observed for silica. Reduction of these treated carbons with hydrogen restored their original methane uptake. Clearly for methane storage, there is no advantage in modifying the carbon surface by nitric acid treatment. 

Century organic vapour analysers are factory calibrated to measure total organic vapours according to a standard (methane). Since different organic vapours interact with the flame ionization detector (FID) to varying extents, it is vital that the instrument user be aware of the magnitude of the variation in order to obtain the most accurate data. Each user must determine relative responses for the individual instrument. 

For clarity it is emphasized that the effect occurs because the transition state develops an electric dipole. Neither nitrogen nor methane has a dipole in the gas phase, but when interacting with the metal electrons they develop one. With nitrogen the dipole is opposite that of the alkali adsorbate, while for methane it is in the same direction, leading to promotion and inhibition respectively. 

Fig. 4. Proposed catalytic cycle for the hydroxylation of methane by MMO. The reductase and B components may interact with the hydroxylase in one or more steps of the cycle. Protons are shown in the step in which intermediate Q is generated, but other possibilities exist (see Fig. 3 and the text). The curved line represents a bridging glutamate carboxylate ligand.

If a substance is to be dissolved, its ions or molecules must first move apart and then force their way between the solvent molecules which interact with the solute particles. If an ionic crystal is dissolved, electrostatic interaction forces must be overcome between the ions. The higher the dielectric constant of the solvent, the more effective this process is. The solvent-solute interaction is termed ion solvation (ion hydration in aqueous solutions). The importance of this phenomenon follows from comparison of the energy changes accompanying solvation of ions and uncharged molecules for monovalent ions, the enthalpy of hydration is about 400 kJ mol-1, and equals about 12 kJ mol-1 for simple non-polar species such as argon or methane. 

The explosive interaction of chlorine trifluoride with methane and its homologues... 

Interaction of chlorine with methane is explosive at ambient temperature over yellow mercury oxide [1], and mixtures containing above 20 vol% of chlorine are explosive [2], Mixtures of acetylene and chlorine may explode on initiation by sunlight, other UV source, or high temperatures, sometimes very violently [3], Mixtures with ethylene explode on initiation by sunlight, etc., or over mercury, mercury oxide or silver oxide at ambient temperature, or over lead oxide at 100°C [1,4], Interaction with ethane over activated carbon at 350°C has caused explosions, but added carbon dioxide reduces the risk [5], Accidental introduction of gasoline into a cylinder of liquid chlorine caused a slow exothermic reaction which accelerated to detonation. This effect was verified [6], Injection of liquid chlorine into a naphtha-sodium hydroxide mixture (to generate hypochlorite in situ) caused a violent explosion. Several other incidents involving violent reactions of saturated hydrocarbons with chlorine were noted [7],... 

The spontaneously explosive interaction of dichlorine oxide with methane, ethane, propane, ethylene or butadiene was investigated at 50-150°C. Self-heating occurs with ethylene, ethane and propane mixtures. 

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