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Notes

STEADY-STATE ISOTOPIC TRANSIENT KINETIC ANALYSIS (SSITKA

In the study of reactions on heterogeneous catalysts over the past 40 years, much use has been made of transient kinetic techniques in order to provide insight into surface reaction processes and mechanisms. These techniques have typically employed at reaction conditions the use of stopping/ starting the flow of one of the reactants or of pulsing the reactants. With the exception of experiments studying the exchange reaction between molecules at steady flow (1), it is difficult to extrapolate the results from these transient, non-steady-state studies to interpret the nature of surface reaction under steady-state conditions.

INTRODUCTION TO THE DESCRIPTIVE EQUATIONS FOR CHEMICAL REACTORS

There are 3 fundamental ideal types of reactors. Laboratory reactors are almost exclusively related to these ideal forms.  Larger reactors,  pilot-plant or commercial scale,  can be mathematically described usually by deviations from these ideal reactors. Additional complications to the descriptive or "design" equations are introduced by the presence of multiple phases.

METAL CRYSTALLITE SIZE DETERMINATION: COMPARISON OF CHEMICAL AND PHYSICAL METHODS

Recent Altamira Notes have discussed the use of several different chemisorption techniques to determine crystallite sizes for supported metal catalysts.These techniques, temperature-programmed desorption, static chemisorption, and pulse chemisorption, can all be described as "chemical" methods because they rely on some way of monitoring the chemisorption or desorption of molecules on metal surfaces. A second general approach to the determination of metal crystallite sizes involves the use of techniques which may be described as "physical" methods. The objective of this Note is to compare the chemical methods described in earlier Notes to several physical methods discussed below.