The present invention relates to 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 oxyhydroxides, solidified with oxides and/or (oxy)hydroxides of the elements Al, Mg and Ti, the pellets or granules based on iron oxides and/or iron oxyhydroxides and iron(III) hydroxide for the absorbent/catalyst, and processes for their production and their use.