Comparison of chemisorption close to ambient vs. under reaction conditions for Group VIII metal catalysts

A comparison of the relationship of H2 or CO chemisorption measurements at 25–100 °C to similar results obtained under CO hydrogenation conditions by steady-state isotopic transient kinetic analysis (SSITKA) is made for the first time for a wide variety of Group VIII metal catalysts. The ratio image (amount of chemisorption by SSITKA vs. by static chemisorptions) was found to be almost always ca. unity for Co catalysts. SSITKA can, thus, be used as a complementary characterization technique to TEM, XRD, and static chemisorption for better understanding of Co metal catalyst dispersion and metal surface site availability for Co catalysts with a wide variety of promoters/supports. Unfortunately, application of SSITKA chemisorption measurements under reaction conditions for characterizing metal dispersion for the other metals is limited at this time. However, the results do suggest some possibilities for Ru and Rh.