abstracts - Институт катализа им. Г.К. Борескова

TAP-APPROACH IN CATALYTIC MECHANISM REVEALING:“STATE-BY-STATE TRANSIENT SCREENING”KS-I-5Yablonsky G.S., Gleaves J.Department of Chemical Engineering, Washington University,Box1198, 1 Brookings Dr., St. Louis, MO 63130, USAE-mail: gy@che.wustl.eduA new approach, “state-by-state transient screening”, is presented. According to theapproach, the detailed kinetic mechanism is extracted from primary non-steady-state kineticdata. The key idea is to kinetically test a catalyst with a particular composition (e.g. amount ofsurface oxygen) that changes insignificantly during the test. A complete screening experimentincludes the sequence of such tests performed over a catalyst with different compositionprepared separately and scaled (e.g. oxidation degree). The approach is based on threeexperimental principles: a) insignificant catalyst change during a single-pulse experiment; b)control of reactant amount stored/released by catalyst in a multi-pulse experiment; c) uniformchemical composition within the catalyst zone.An efficient theory of integral analysis of single-pulse tests (small perturbations) isdeveloped. Integrals (moments) of the experimentally measured exit flow are used to calculatethe basic kinetic coefficients (including apparent kinetic constant, time delay etc.) given bythe theoretical expressions derived with no assumption regarding kinetic model. Then, thethorough understanding of the non-steady-state catalyst activity is constructed in two steps: 1)description with no preliminary assumption about the kinetic model (“model-free”description) in terms of basic kinetic coefficients; 2) analysis of the basic kinetic coefficientsfor different reactants/products as functions of catalyst composition (e.g. catalystoxidation/reduction degree) and development of the detailed kinetic model.The approach is illustrated using selective butane, butadiene and furane oxidation over aVPO catalyst and water-gas-shift reaction.33