Reaction of methane

The direct reaction of methane and hydrogen sulfide to yield hydrogen and carbon disulfide is being studied (189). 

Commercial-scale processes have been developed for the production of hydrogen sulfide from heavy fuel oils and sulfur as well as from methane, water vapor, and sulfur. The latter process can be carried out in two steps reaction of methane with sulfur to form carbon disulfide and hydrogen sulfide followed by hydrolysis of carbon disulfide (116). 

For equation 26, starting with methane and soHd sulfur at 25°C, and ending with gaseous products at 600°C, the reaction is endothermic and requires 2.95 MJ /kg (705 kcal/kg) of CS2. The reaction of methane and sulfur vapor in the diatomic form is actually exothermic (23,78). Superheating of the sulfur is claimed to be preferable (79), and series operation of reactors offers a means of reducing process temperatures at which the sulfur dissociates (80). 

The oxidation of the hydrogen is not complete so that the converter off-gas contains hydrogen. The overall reaction is carried out adiabaticaHy. This is accomphshed by the addition of air (O2). The air oxidizes a portion of the methane, making the overall reaction exothermic, even though the reaction of methane with ammonia to form hydrogen cyanide is quite endothermic. 

The chemical reactions that occnr in flames transform an initial reactant mixtnre into final reaction prodncts. In the case of fnel-oxygen combns-tion, the final prodncts are principally water vapor and carbon dioxide, althongh nnmerons other prodncts snch as carbon monoxide may be formed, depending on the reactant composition and other factors. If the ratio of fnel-to-oxygen is stoichiometric, the final reaction prodncts, by definition, contain no excess fnel or oxygen. Theoretically, this means that partial oxidation prodncts snch as CO (itself a fnel) are not formed. In reality, partial oxidation prodncts snch as CO or OH are formed by high tem-peratnre reactions. For example, the molar stoichiometric reaction of methane is written ... 

The reaction of methane tricarboxylate with indoline 342 gave the tricyclic derivative 361 which can be transformed to the amide derivatives 362 (97JHC969). Alkylation of the iV-benzyl indoline 360 with pentafluor-oacetone gave 363 which upon debenzylation and subsequent acylation with diketene followed by cyclization gave 364. Other haloacetones were used to prepare different halogenated derivatives (79BEP872311) (Scheme 63). 

A few chemicals are based on the direct reaction of methane with other reagents. These are carbon disulfide, hydrogen cyanide chloromethanes, and synthesis gas mixture. Currently, a redox fuel cell based on methane is being developed. ... 

Based on these definitions, the chlorination reaction of methane to yield chloromethane is an oxidation because a C-H bond is broken and a C—Cl bond... 

Use Appendix 2A to determine (a) the standard reaction enthalpy (b) the standard entropy (c) the standard Gibbs energy at 25°C for the re-forming reaction of methane. 

The kinetics of H-O recombination is very important in the reforming reaction of methane to produce CO and H2. When more weakly bonded O js recombines with Hads (preferred on Pt), the main product next to CO will be H2. On planar Rh with a stronger M-O bond interaction, this reaction is suppressed and therefore H2 is the main product [23]. Clearly this selectivity will be dramatically affected by the presence of surface steps. 

Molecular picture ofthe reaction of methane (CH4) with oxygen (O2) to produce carbon dioxide (CO2)... 

Example describes the synthesis of acetylene (C2 H2) from calcium carbide (CaC2). Modem industrial production of acetylene is based on a reaction of methane (CH4) under carefully controlled conditions. At temperatures greater than 1600 K, two methane molecules rearrange to give three molecules of hydrogen and... 

Regardiess of the conditions, the reaction of methane with molecular oxygen to form water and carbon dioxide invoives breakage of two ODO bonds and four C—H bonds and subsequent formation of four O— H bonds and two C O bonds for every molecule of methane that reacts. 

A block diagram of two different paths for the reaction of methane and oxygen. Occurring inside an engine (Path 1), the process transfers heat and work. Occurring in a furnace (Path 2), the process does no work and transfers only heat. 

Figure 6-13 shows three different paths for the combustion reaction of methane. One path, indicated with the blue arrow, is the path that might occur when natural gas bums on a stove burner. As CH4 and O2 combine in a flame, all sorts of chemical species can form, including OH, CH3 O, and so on. This is not a convenient path for calculating the energy change for the net reaction, because the process involves many steps and several unstable chemical species. 

A process may be spontaneous, and yet the process may not occur. Extending our water example, water can be stored behind a dam for a very long time unless a spillway is opened. A chemical example is the reaction of methane and oxygen to form carbon dioxide and water ... 

Steady state and non steady state kinetic measurements suggest that methane carbon dioxide reforming proceeds in sequential steps combining dissociation and surface reaction of methane and CO2 During admission of pulses of methane on the supported Pt catalysts and on the oxide supports, methane decomposes into hydrogen and surface carbon The amount of CH, converted per pulse decreases drastically after the third pulse (this corresponds to about 2-3 molecules of CH< converted per Pt atom) indicating that the reaction stops when Pt is covered with (reactive) carbon CO2 is also concluded to dissociate under reaction conditions generating CO and adsorbed... 

Methane reforming with carbon dioxide proceeds in a complex sequence of reaction steps involving the dissociative adsorption/reaction of methane and COj at metal sites. Hydrogen is generated during methane dissociation In the second set of reactions CO2 dissociates into CO and adsorbed oxygen. The reaction between the surface bound carbon (from methane dissociation) and the adsorbed oxygen (from CO2 dissociation ) yields carbon monoxide. A stable catalyst can only be achieved if the two sets of reactions are balanced. 

Figures. Temperature-programmed reaction of methane with FeZSM-5 surface before a-oxygen loading (a) and after ot-oxygen loading (b). A - time moment of opening the microreactor B - time moment of switching on the programmed heating (6 K/s).

In situ infrared observations show that the primary species present during the reduction of NO by CH4 over Co-ZSM-5 are adsorbed NO 2 and CN. When O2 is present in the feed NO2 is formed by the homogeneous and catalyzed oxidation of NO. In the absence of O2, NO2 is presumed to be formed via the reaction 3 NO = NO2 + N2O. The CN species observed are produced via the reaction of methane with adsorbed NO2, and transient response studies suggest that CN species are precursors to N2 and CO2. A mechanism for the SCR of NO is proposed (see Figure 10). This mechanism explains the means by which NO2 is formed from adsorbed NO and the subsequent reaction sequence by which adsorbed NO2 reacts with CH4 and O2 to form CN species. N2 and CO or CO2 are believed to form via the reaction of CN with NO or NO2. CH3NO is presumed to be formed as a product of the reaction of CH4 with adsorbed NO2. The proposed mechanism explains the role of O2 in facilitating the reduction of NO by CH4 and the role of NO in facilitating the oxidation of CH4 by O2. 

Cerium oxides are outstanding oxide materials for catalytic purposes, and they are used in many catalytic applications, for example, for the oxidation of CO, the removal of SOx from fluid catalytic cracking flue gases, the water gas shift reaction, or in the oxidative coupling reaction of methane [155, 156]. Ceria is also widely used as an active component in the three-way catalyst for automotive exhaust pollution control,... 

Microwave Catalysis in Organic Synthesis 10.3.2.1 Reactions of Methane... 

Microwave-induced, catalytic gas-phase reactions have primary been pursued by Wan [63, 64], Wan et al. [65] have used pulsed-microwave radiation (millisecond high-energy pulses) to study the reaction of methane in the absence of oxygen. The reaction was performed by use of a series of nickel catalysts. The structure of the products seemed to be function of both the catalyst and the power and frequency of microwave pulses. A Ni/Si02 catalyst has been reported to produce 93% ethyne, whereas under the same irradiation conditions a Ni powder catalyst produced 83% ethene and 8.5 % ethane, but no ethyne. 

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