Structural and Electronic Properties of Iron and Cobalt Molecular Sieve Catalysts: Progress Report

摘要

During the second year of this research we have focused on the characterization of highly dispersed cobalt and iron particles in zeolites with transmission electron microscopy and spin echo nuclear magnetic resonance techniques. We have continued our studies of the structure sensitivity of cyclopropane craking reaction. In-situ Moessbauer studies of iron catalysts have also been done. In addition, several ultahigh vacuum methods have been used to characterize metal-containing molecular sieves. The most significant discovery is that spin echo nuclear magnetic resonance (SENMR) methods can be used to determine the structure of small (5--40 angstrom) size particles of cobalt. Both hexagonal and cubic metal particles have been prepared and a new alloy of cobalt and iron has been characterized by SENMR. This is the first example of the use of spin echo nuclear magnetic resonance methods done in zero external magnetic field for supported catalysts. With this method the relaxation times of different cobalt species can be determined. (ERA citation 13:036932)