Abstract: The present invention relates to pellets or granules based on iron oxides and/or iron oxyhydroxides and iron(III) hydroxide, a unit suitable for the through-flow of a fluid medium at least partially filled with an adsorbent/catalyst in pellet form consisting essentially of iron oxide and/or iron oxyhydroxide embedded in an iron hydroxide matrix, processes for their production comprising filtering, drying and shaping steps and their processes of their use.