One must understand the mechanism of bottoms cracking in asphaltene conversion in order to design a catalyst to affect this change. Asphaltene molecules are big, multiple stacked, porphyrin structures containing high concentrations of heteroatoms. They readily deactivate catalysts. Until now, the first stage of asphaltene conversion has not been given much attention. This first stage, that of demetallization, has been regarded as a simple metal take-up zone which guards the subsequent hydrotreating portion of the catalyst from undue fouling by metal sulfides. Large pore size and good strength are more important for a demetallization catalyst than are hydrotreating activity. Supported sepiolite catalysts and modifications thereof are good candidates to meet these targets.