Catalyst and reactor requirements for the oxidative coupling of methane

Reaction engineering studies in a polytropic fixed‐bed reactor over a highly active and selective catalyst for oxidative methane coupling

“…For an undiluted feed, application of high partial pressures of oxygen is restricted in order to avoid reactor runaway (see e.g. [4]). As a consequence also conversion of methane is limited.…”

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“…144 The same considerations have been reported for methane oxidative coupling. 145 By assuming a selectivity of 84% for C2 products (including 46% for ethene), the remaining product being CO 2 , the overall reaction heat per mole of C2 produced is around 123 kcal·mor l , which is at the limit for the use of multitubular reactors. However, in this reactor type, excessively long tubes would be required to control the heat transfer and avoid runaway.…”

Oxidative Coupling of Methane Using Inorganic Membrane Reactors

“…The fact that metering the oxygen flow into flowing methane in the catalyst bed enhances the C2 selectivity can fi.u-therbe substantiated if only the products from die tube Many different reactor configurations have been tried [47], with some of the more recent being the use of membrane reactors to provide a distributed oxygen feed [79,116] to lower the oxygen partial pressure in the reactor, thus fal-oring Cz formation over COX formatio~and the removal of the Cz products following the reactor, as in t~e gas-recycle . electrocatalytic reactor-separator [46] and in the countercurrent moving-@l "chromatographic reactor [45].…”

“…It was shown by runaway analysis that the required tube diameter in a fixed-bed tubular reactor is too small to be practical [47]. Proposed , methods to cope with the heat removal problem include the use of single-or multi-stage fluidized-bed reactors [70] and reactors in Heterogeneous reactions in OCM series with inter-stage cooling.…”

“…Dautzenberg et al [47] report that while the coupling reaction itself is exothermic (-66 Kcal/mole of Czs produced), the overall contribution of deep oxidation reactions makes the process even more exothermic (-123 Kcal/mole of Czs produced). Their study concludes that multi-tubular reactors of impractical dimensions would be required to control the heat transfer and avoid temperature runaways and that newer reactor designs are necessary for commercialization.…”