We will use operando X-ray diffraction computed tomography (XRDCT) to study the progress of deactivation in hollow catalyst spheres specially designed to allow their entire volume to be accessible to reactants. Using a sub-micron beam we will track the progress of coke-based deactivation through the sphere walls using crystallographic descriptors established in our earlier work. The experiment challenges the limits of the XRDCT technique and will help us to understand the benefits of using more complex catalyst shapes.