Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

CATALYTIC TECHNOLOGIES APPLYING ARTIFICIALLYCREATED CATALYST NONSTATIONARITYAND SORPTION-CATALYTIC PROCESSESA.N. ZagoruikoBoreskov Institute of Catalysis, pr. Akad. Lavrentieva, 5, Novosibirsk, 630090, Russia;fax: -7-383-3307678; e-mail: zagor@catalysis.ruKN-6The review is dedicated to catalytic processes performed under artificially created catalystnonstationarity. It is shown that the highest technological effect can be achieved for acontrolled combination of the thermal nonstationarity with the composition nonstationarity ofthe catalyst surface. In the elaboration of a new technology, when choosing the main activefactor (e.g., periodic concentration changes), it is necessary to take into account the otherfactors (the dynamic changes in the temperature and the pressure). Otherwise, in place of theexpected improvement in the characteristics as compared with stationary processes, one mayobtain a zero and even negative effect.The development of non-stationary and adsorption-catalytic processes is very tedioustask, which requires consideration of a large number of different factors and their combinedaction on different-scale levels of the process. The diversity of methods for the developmentof unsteady state conditions and their combinations is even reflected in the yet uncertainterminology used in the literature – the terms «non-stationary catalysis», «sorption-enhancedcatalytic processes», «multifunctional reaction/separation processes», «chemical looping»,«reaction chromatography processes» are often used.It should be noted that many fundamental regularities typical for stationary processes arenot in principle present in the processes with catalysts in the unsteady state. Particularly, innon-stationary processes, even in formally adiabatic catalyst beds, the temperature in the bedmay substantially deviate from the adiabatic value. This difference is determined, in additionto the dynamic effects associated with the regeneration heat exchange and the travel ofthermal fronts in the catalyst layer (a property typical of conventional reverse processes withthe thermal nonstationarity of the catalyst), by the possible dynamic redistribution of releasedheat, which occurs in different reaction stages and phases in both space and time (this is aunique property of systems with the sorption nonstationarity). Depending on the chosenstrategy of the realization of a non-stationary mode, the maximum temperature in the processcan be either substantially lower or higher than the adiabatic temperature in an equivalentstationary process. The use of the sorption capacity of the catalyst allows one to carry out25