Methane mechanism of reaction

Compounds derived from Aldehydes and Ketones Reaction between PCI3 and Unsaturated Ketones, Mechanism of Reaction of PClj with Benzaldehyde, 1 4 Addition of Phenyldichlorophosphme, Interaction of Phosphorus Halides with Distyryl Ketone and Phenyl Cinnamylidene Methyl Ketone, Action of PCI3 on turated Aldehydes and Ketones, Interaction of Di-phenylohlorophosphine with Benzaldehyde and Benzal etophenone, Addition of Alkoxy- and Aryloxy-chlorophosphines to Carbonyl Compounds— Phosphorus Derivatives of Dimethylaniline— Derivatives of Dibenzyl-methane and Hydroxymethylene Camphor— Heterocydio Rings containing... 

The mechanism of reaction (SBm) continues to (ercise the imagination. Recently, four sets of Arrhenius parameters have beoi obtained from studies of the shock-initiated oxidation of methane coupled with spectroscopic detection of various molecule and radical species the results are summarized in Table 10. Jachimowski and Tsuboi and Wagn offCT no guidance as to the medumism,... 

The mechanism of the Fischer-Tropsch reactions has been the object of much study (note Eqs. XVI11-55-XV111-57) and the subject of much controversy. Fischer and Tropsch proposed one whose essential feature was that of a metal carbide—patents have been issued on this basis. It is currently believed that a particular form of active adsorbed carbon atoms is involved, which is then methanated through a series of steps such as... 

This paper presents a review of the chemistry of the methanation process, the mechanisms of the key reactions, the kinetics of the reactions over various catalysts, and the application of this background to commercial processes. 

According to this scheme, the process is initiated by the activation of only the hydrogen on the catalyst surface, after which the reaction takes place in the gas volume. Mills and Steffgen (5) questioned this mechanism and concluded that the mechanism of C02 methanation is uncertain and that this would be a fruitful field for investigation. 

It was shown in laboratory studies that methanation activity increases with increasing nickel content of the catalyst but decreases with increasing catalyst particle size. Increasing the steam-to-gas ratio of the feed gas results in increased carbon monoxide shift conversion but does not affect the rate of methanation. Trace impurities in the process gas such as H2S and HCl poison the catalyst. The poisoning mechanism differs because the sulfur remains on the catalyst while the chloride does not. Hydrocarbons at low concentrations do not affect methanation activity significantly, and they reform into methane at higher levels, hydrocarbons inhibit methanation and can result in carbon deposition. A pore diffusion kinetic system was adopted which correlates the laboratory data and defines the rate of reaction. 

Maleic acid hydrogenation, 481 Metal-support interactions and electrochemical promotion, 490 and electrophobic reactions, 499 mechanism of, 490 model for, 507 Metcalfe, modeling, 316 Methanation, electrochemical promotion of, 406, 409... 

Both this and previous studies demonstrate the existence of rather long chains of consecutive ion-molecule reactions in methane, ethylene, and acetylene, and thus they provide direct evidence for ionic mechanisms of condensation or polymerization in these gases. Polymers have been found in relatively high yields among the radiolysis products of these... 

We have previously examined the mutual dependence of [HO ] upon [NO,jj and [NMHC] as calculated by a combined clean/polluted air chemical mechanism (76), and extend those calculations here to the more modem CAL mechanism of Lurmann et al. (182). To do this we have combined the NO,/NMHC chemical reactions of the CAL mechanism with the methane chemistry of Logan et al. (58). The results of these calculations are shown as contour maps or isopleths for [O3], [HO ], and [HO2 ] in Figure 7. Figure 7a, for ozone, is similar to isopleths used to determine reductions in NMHC and/or... 

Other reactions which apparently involve transfer to nucleophiles include those of [MeCo(salen)] with MeMgl to give ethane as well as methane and H2 64), and of [MeCo(DMG)2X]complexes with CN and PhNMe , apparently to give MeCN and PhNMe2 161). The mechanisms of these processes have not been studied. Nevertheless it is known that the reaction of methyl- and ethylcobalamin with cyanide (products not known) requires oxygen, and shows an induction period [see Chapter 13 of ref. 136)). 

Basch, H., Mogi, K., Musaev, D. G., Morokuma, K., 1999, Mechanism of the Methane —> Methanol Conversion Reaction Catalyzed by Methane Monooxygenase A Density Functional Study , J. Am. Chem. Soc., 121, 7249. 

Metalloenzymes with non-heme di-iron centers in which the two irons are bridged by an oxide (or a hydroxide) and carboxylate ligands (glutamate or aspartate) constitute an important class of enzymes. Two of these enzymes, methane monooxygenase (MMO) and ribonucleotide reductase (RNR) have very similar di-iron active sites, located in the subunits MMOH and R2 respectively. Despite their structural similarity, these metal centers catalyze very different chemical reactions. We have studied the enzymatic mechanisms of these enzymes to understand what determines their catalytic activity [24, 25, 39-41]. 

---