Catalysts methane

Labeling studies indicated that the obtained formic acid was originated from both substrate and solvent. When the catalyst was supported onto silica to provide a heterogeneous catalyst, methane is oxidized at 80 °C and 32 bars CH4 to CH2O (up to 1.1 TON) and HCOOH (up to 27.3 TON). 

Hoffmann, C., Schmidt, H.W. and Schuth, F. (2001) A multipurpose parallelized 49-channel reactor for the screening of catalysts methane oxidation as the example reaction. J. Catal., 198, 348. 

Carhon monoxide and hydrogen react to form CH in the presence of a nickel catalyst. Methane also is formed by reaction of magnesium methyl iodide in anhydrous ether (Grignard s rcagentl with substances containing the hydroxyl group. See also Grignard Reactions. Methyl iodide (bromide, chloride) is preferably made by reaction of methyl alcohol and phosphorus iodide (bromide, chloride)... 

Hydrogen sulfide causes a permanent poisoning of iron catalysts. Methane does not poison ammonia catalysts under normal synthesis conditions. Equilibrium data (Browning, De Witt, and Emmett, 77 Browning and Emmett, 78) should be mentioned in this connection. 

Catalyst Methanation turnover numbers (sec Activation energy (kJ/mol)... 

After this bulk removal of the carbon oxides, the typical synthesis gas still contains 0.2-0.5vol% CO and 0.005 0.2 vol% CO2. All oxygen-containing compounds have to be reduced to a very low ppm level, as they are poisonous toward the ammonia synthesis catalysts. Methanation is the simplest method to reduce the concentrations of the carbon oxides well below 10 ppm, and is widely used in steam-reforming plants. 

This paper is an attempt to summarize the situation with respect to the selective catalytic oxidation of light alkanes using heterogeneous catalysts. Methane oxidation reactions and the oxidation of butane to maleic anhydride will only be alluded to occasionally, because they have been reviewed in detail in a large number of papers. 

Figure 5.10 shows that C5+ yields are equivalent for the platinum-rhenium catalyst and the combined catalyst system and about 1.0 to 1.5 vol% higher than for the platinum-iridium catalyst. Methane and ethane yields for the combined catalyst system are higher than those for the platinum-rhenium catalyst but lower than those for the platinum-iridium catalyst. Yields of H2 are about equivalent for the combined catalyst system and the platinum-iridium catalyst and are lower than those for the platinum-rhenium catalyst. Similarly, the yields of C3 and C4 hydrocarbons are about equivalent for the platinum-iridium catalyst and the combined catalyst system but are lower than the yields for the platinum-rhenium catalyst. 

Table 7.8. NiMo04 Catalyst Methanation Reaction Temperatures (291)...

Key-words Gold catalysts Methane combustion Deposition-precipitation Gold acetate Urea Ti02 Sn02... 

If the predominant reaction mechanism involves CO dissociation (as appears to be the case over nickel and most other transition-metal catalysts), methane formation may be expressed by writing the following elementary surface reaction steps ... 

Figure 2 gives the CO2 and CH4 selectivity over the potassium promoted catalyst. Methane selectivity decreased from 3.5% at 24 hours of reaction time to a stable level of 1.6% in 300 hours of time on stream. While methane selectivity decreased monotonously, carbon dioxide went through a conditioning period similar to that of CO conversion. The CO2 selectivity started from 23% at 24 hours of time on stream, and then increased to its... 

Table 7. Oxidative coupling of methane with Co substituted aluminophosphate catalysts. Methane activation experiments at 500 C ...

The produced hydrogen from SR is separated through a dense proton-conducting membrane to react with oxygen contained in an air stream. The exothermic reaction between H2 and O2 is used as heat source for ATR of methane. A 10% Ni supported on Y-AI2O3 catalyst is placed on top of the perovskitic membrane. Without the presence of catalysts, methane conversion is quite poor at 850 °C, less than 20%. As nickel supported catalysts is introduced into the system, the methane conversion increases to 88% (thermodynamic equilibrium conversion is around 96%). This phenomenon is related to the low contact time between gas and catalysts, because the gas flow rate used is high. 

During ammonia synthesis, the major reactions of production and purification of synthesis gas and the synthesis of ammonia, all are carried out over different catalysts. At least eight kinds of catalysts are used in the whole process, where natural gas or naphtha is used as feedstock and steam reforming is used to produce synthesis gas. These catalysts are Co-Mo hydrogenation catalyst, zinc oxide desulfurizer, primary- and secondary-steam reforming catalysts, high- and low-temperature shift catalysts, methanation catalyst and ammonia synthesis catalyst etc (Table 1.1). 

The cyclic dimerization of HIBA proceeded smoothly in the presence of the dehydration catalyst methane sulfonic acid to isolate the cyclic dimer TMG in a 67% 5deld. Another simple and convenient route for the s5mthesis of TMG from lactic acid has been reported [102]. This method involves three steps (1) one-step protection of lactic acid hy cyclic acetalization employing acetone (2) cc-methylation of the obtained 2,2,5-trimethyl-l,3-dioxolan-4-one and [3] one-pot s5mthesis of TMG including the hydrolysis of 2,2,5,5-tetramethyl-l,3-dioxolan-4-one, resulting in moderate 5deld [49-51%] of TMG. 

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