OP-II-3

KN-1OXIDATIVE COUPLING OF METHANE. THIRTY YEARS OF STUDIES:FROM PHENOMENOLOGICAL TO NON-CONTRADICTORY KINETICDESCRIPTIONSinev M.Yu. 1 , Tulenin Yu.P. 1 , Fattakhova Z.T. 1 ,Lomonosov V.I. 2 , Gordienko Yu.A. 21 Semenov Institute of Chemical Physics, R.A.S., Moscow, Russia,E-mail: sinev@chph.ras.ru2 ZAO "SCHAG" Company, Moscow, RussiaOxidative coupling of methane (OCM) to higher hydrocarbons, that wasdiscovered in early 1980's [1-3], is one of attractive methods of natural gastransformation to value-added products. During the passed three decades the mainfeatures of OCM mechanism have been elucidated and for a number of systems(mainly - oxides, simple and complex) a high efficiency as OCM catalysts wasdemonstrated. It was shown that because of the mechanistic and kinetic reasons, theprocess under discussion can efficiently proceed only at high temperatures (above1000 K), and only a limited per-pass yield (20-25%) of target products (C 2 -hydrocarbons, first of all, ethylene) can be achieved due to their higher reactivity ascompared to methane. These two factors are among those hampering the practicalimplementation of the OCM process.Also, the development of adequate kinetic model is an indispensable condition forthe transfer from a phenomenological description to the process engineering andscaling-up. However, the compilation of really-working kinetic OCM model meetsserious obstacles due to a complex free-radical heterogeneous-homogeneous natureof the process under consideration. On the one hand, multi-step kinetic schemessimilar to those used to describe homogeneous gas reactions reflex the intrinsicfeatures of the process and can be used for mechanistic studies. Unfortunately, theuncertainty in kinetic parameters does not allow one to utilize such schemes for aquantitative description of the process that is required for its practical implementation.An alternative approach that describes the formation of the final products (mainlyC 2 -hydrocarbons and carbon oxides) by the limited number of stoichiometricreactions and corresponding kinetic equations (based on the mass-action andArrhenius laws) is able to assure any prescribed accuracy, but only within relativelynarrow limits of parameters achieved during the model experiments. Such kinetic22