MICROANALYSIS AND MICRODIFFRACTION OF MULTICOMPONENT CATALYSTS IN STEM.

The precursor of a highly active Cu/ZnO methanol synthesis catalyst has been shown to be synthetic aurichalcite, (Cu//0//. //3Zn//0//. //7)//5 (CO//3)//2 (OH)//6, in the form of platelets. In the reported investigation, the mineral aurichalcite, (Cu//0//. //5Zn//0//. //5)//5 (CO//3)//2 (OH)//6, which consisted of large, thin platelets having dimensions on the order of mu m, was used as a model compound. The chemical structure and morphological changes of aurichalcite that occurred during catalyst preparation procedures were followed to help determine the microstructural properties of the activated catalyst. After the various stages of preparation, comparison was made between the synthetic sample and the mineral sample. The larger platelet dimensions of the mineral, as compared to the synthetic sample, provided an ideal morphology for studying these transformations by transmission electron microscopy (TEM). Techniques in X-ray diffraction (XRD) and selected area diffraction (SAD), micro diffraction ( mu D), dark field and bright field imaging in the TEM, were used to characterize the mineral during and after calcination and after reduction.