Oxidation of methane to methanol

The lower than expected yields can be explained by the nature of methane oxidation to methanol in these bacteria. This reaction, catalysed by methane mono-oxygenase, is a net consumer of reducing equivalents (NADH), which would otherwise be directed to ATP generation and biosynthesis. In simple terms the oxidation of methane to methanol consumes energy, lowering the yield. [Pg.89]

Direct oxidation of methane to methanol is an obvious dream reaction ... [Pg.310]

The Active Oxygen for Direct Oxidation of Methane to Methanol in the Presence of Hydrogen... [Pg.397]

Oremland et al. [136] subsequently demonstrated that methane-oxidizing bacteria also had the capacity to co-oxidize methyl bromide by methane monooxygenase produced during the oxidation of methane to methanol. They also showed that methanotrophic soils that had a high capacity to oxidize methane degraded14C-labeled methyl bromide to 14C02. [Pg.390]

The direct catalytic conversion of methane has been actively pursued for many years. Much of the emphasis has been on the direct production of methanol via selective partial oxidation (8), coupling of methane to ethylene (9), or methane aromatization (10). At this time none of these technologies has been demonstrated commercially due to low yields of desired products due to combustion by-products or low equilibrium conversion at reasonable process temperatures and pressures. The potential benefits of a hypothetical process for the direct partial oxidation of methane to methanol (11) are presented as an example. [Pg.442]

Q. Zhang, D. He, Q. Zhu, Recent Progress in Direct Partial Oxidation of Methane to Methanol, 12, Journal of Natural Gas Chemistry, 81-89, (2003). [Pg.445]

J.M. Maher, Development of Novel Catalysts for the Oxidation of Methane to Methanol with High Selectivity and Throughput, Proposal for the Chemicals and Forest Products Industries of the Future, Solicitation DE-PS36-03GO93015, (2004). [Pg.445]

The current two-step industrial route for the synthesis of methanol, from coal or methane to synthesis gas and then from synthesis gas to methanol, has certain drawbacks. The economic viability of the whole process depends on the first step, which is highly endothermic. Thus a substantial amount of the carbon source is burned to provide the heat for the reaction. It would be highly desirable, therefore, to replace this technology with a technically simpler, single-step process. This could be the direct partial oxidation of methane to methanol, allowing an excellent way to utilize the vast natural-gas resources. Although various catalysts, some with reasonable selectivity, have been found to catalyze this reaction (see Sections 9.1.1 and 9.6.1), the very low methane conversion does not make this process economically feasible at present. [Pg.117]

Oxidation of Methane. A variety of new catalyst systems have been disclosed, and new reagents were developed with the aim to perform selective transformation of methane to methanol, methyl esters, and formaldehyde. Much work was carried out in strongly acidic solutions, which enhances the electrofilicity of the metal ion catalyst, and the ester formed is prevented from further oxidation. An important advance in the selective oxidation of methane to methanol is Periana s 70% one-pass yield with high selectivity in sulfuric acid solution under moderate conditions.1073 The most effective catalyst is a Pt-bipyrimidine complex. Pt(II) was shown to be the most active oxidation state generating a Pt-methyl intermediate that is oxidized to yield the product methyl ester. A density functional study... [Pg.519]

A systematic study to identify solid oxide catalysts for the oxidation of methane to methanol resulted in the development of a Ga203—M0O3 mixed metal oxide catalyst showing an increased methanol yield compared with the homogeneous gas-phase reaction.1080,1081 Fe-ZSM-5 after proper activation (pretreatment under vacuum at 800-900°C and activation with N20 at 250°C) shows high activity in the formation of methanol at 20°C.1082 Density functional theory studies were conducted for the reaction pathway of the methane to methanol conversion by first-row transition-metal monoxide cations (MO+).1083 These are key to the mechanistic aspects in methane hydroxylation, and CuO+ was found to be a likely excellent mediator for the reaction. A mixture of vanadate ions and pyrazine-2-carboxylic acid efficiently catalyzes the oxidation of methane with 02 and H202 to give methyl hydroperoxide and, as consecutive products, methanol and formaldehyde.1084 1085... [Pg.520]

The aerobic oxidation of methane in water catalyzed by [Pt(Mebipym)Cl2] [PV2Mo1004o]5 (Mebipym = N-methy-2,2 -bipyrimidine) complex supported on Si02 was reported [149]. The conjugation of [PV2Mo1004o]5 to a known Pt2 + -bipyrimidine complex by electrostatic interaction could fadlitate the oxidation of the Pt2 + intermediate to a Pt4 + intermediate by 02, resulting in the catalytic aerobic oxidation of methane to methanol in water and then surprisingly further to acetaldehyde via a carbon-carbon coupling reaction. [Pg.206]

Numerous works on the oxidation of methane to methanol and/or formaldehyde as well as on the oxidative dimerization of methane were reviewed by many authors [22-27]. First, high selectivity of methane oxidation by N20 was reported by Lunsford et al. [28-30], Over a supported Mo oxide [30], the total selectivity to methanol and formaldehyde at low methane conversions attained 100%, although this rapidly dropped as the conversion increased (Table 7.4). High selectivity for this reaction was obtained also with supported vanadium oxide [31]. [Pg.220]

The economic estimation based on the pilot unit results showed that ammonia contributes 70% to the prime cost of the N20. Using this result and the ammonia price 0.37 kg-1 [191], one can evaluate the N20 price to be 0.53 kg-1. Certainly, this cost far exceeds that of dioxygen. Therefore, for reactions producing inexpensive products, like the oxidation of methane to methanol, the application of N20 cannot be economically sound. However, this modest cost opens great N20 prospects for the preparation of more expensive chemical products. For instance, the theoretical expenditure for N20 in the oxidation of benzene to phenol is 17%, and in the oxidation of phenol to hydroquinone is 4%, of the cost of the target product. The commercial viability of such processes will depend primarily on their technological advantages rather than the cost of nitrous oxide. [Pg.245]

Gold has emerged as an effective catalyst for the selective oxidation of methane to methanol. Various possible pathways for the oxidation are discussed.29 Suitably substituted furans are transformed into phenols by the use of gold catalyst (1). It has been suggested, on the basis of kinetic isotope effect and trapping studies, that the key intermediate is an arene oxide. The postulation is also supported by DFT calculations.30... [Pg.87]

Direct pressurized oxidation of methane to methanol with hydrogen peroxide... [Pg.123]

Direct one-stage oxidation of methane to methanol is performed by two methods catalytic and thermal. Modernization of the process of methane conversion to methanol using various catalysts is ineffective, because in this case methane conversion is usually below 13%. At the present time, methane conversion to methanol has been raised to 24% [122] however, this is still insufficient for an economic assessment of the process. Hence, thermal... [Pg.123]

The most widespread efforts made towards the achievement of selective oxidation of alkanes are targeted on methane, a principal constituent of natural gas f 6-8]. Activation of the very stable C-H bond of methane is a particularly demanding problem. One example in which this has been achieved on industrial scales is the Degussa process [9], Methane is coupled to ammonia by heterogeneous catalysis in order to produce HCN, an important fundamental material for industrial chemistry. An unsolved problem is the selective oxidation of methane to methanol a reaction that would convert the methane gas into a transportable liquid. In nature, monooxygenases have evolved. These are able to activate molecular oxygen and to... [Pg.37]

V.I. Sobolev, K.A. Dubkov, O.V. Panna, G.I. Panov, Catalysis Today (1995), 24, 251-252, Selective oxidation of methane to methanol on a FeZSM-5 surface... [Pg.30]

Oxygen-deficient cool flame partial oxidation of methane to methanol and/or formaldehyde has long been known,30 but methane-based selectivities of 71 percent methanol and 14 percent formaldehyde at 2 percent... [Pg.928]

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