Analytical electron microscopy of a sulfur-poisoned palladium catalyst with a dedicated stem

Greater beam current into a smaller electron probe permits better detectability of elements with a dedicated field-emission STEM than with the more conventional analytical electron microscope based on the TEM/STEM configuration. This advantage is important for catalyst research since active species, promoters, and poisons may be present in extremely small amounts. Digital X-ray images with resolution < 5 nm show distributions of elements that are difficult to locate with other analysis methods. A Pd/Ce/Al2O3 catalyst was found to exhibit a nonuniform distribution of sulfur on the Pd crystal when poisoned by SO2