abstracts - Институт катализа им. Г.К. Борескова

OP-III-32ORGANISED CATALYTIC LAYERS: MICRO-KINETIC AND MASS-TRANSFERBASED APPROACH TO EFFICIENT CONVERSION OF LIGHT ALKANESSinev M.Yu.N.N. Semenov Institute of Chemical Physics RAS, Moscow, RussiaE-mail: sinev@center.chph.ras.ruThe increasing efficiency of chemical transformations is an ultimate goal of appliedcatalytic investigations. Developments in heterogeneous catalysis present numerous exampleson the interplay between the practical industrial needs and the advances in studies ofmechanisms of catalytic reactions. For instance, nowadays an interest to light alkanes asinitial compounds for many industrial processes is increasing along with petroleum price.Unfortunately, up to now the developments in both basic understanding of catalytic chemistryof light alkanes and their utilization in chemical industry are not satisfying. As a result,peculiar features of alkane chemistry and reactivity became the focus. In particular, a revivalof a considerable interest in the so-called heterogeneous-homogeneous processes andheterogeneous reactions of free radical has appeared.Although the idea of heterogeneous-homogeneous processes implied that such processesinclude steps localized both in a gas phase and on any surface (reactor walls, “inert” reactorpacking materials, and active catalysts), their contribution was considered marginal in mostcatalytic transformations of hydrocarbons. However, in the early 1980s, the oxidativecoupling of methane (OCM) was discovered, and it was shown that the first OCM product,ethane, forms via the recombination of free methyl radicals, which escape into the gas uponmethane molecule interaction with surface active sites. In other words, the formation of freeradicals and their further transformations is the major and essential reaction pathway, whichdetermines the main features of the overall process and product distributions. In particular, itwas demonstrated that reactions of free radicals cause certain limitations in product selectivityand yield. In this paper some regularities of elementary reactions and transfer of free radicalsin the catalyst layer are re-examined. This analysis demonstrates that the efficiency of theoverall process can be substantially increased by a proper organization of the catalyst layer.The main problem in transformation of light alkanes into more valuable products consistsin a much lower reactivity of initial molecules as compared with desired products. Theapproach that that is suggested implies the creation of the spatially distributed catalyticsystem (SDCS), in which several zones of different reactivity are combined. In the simplestcase, such system can consist of two zones:391