“…IPC class B01J21 contains catalysts comprising the elements, oxides or hydroxides of Mg, B, Al, C, Si, Ti, Zr or Hf.W hile these elements are usuallyn ot the active components in hydrogenation catalysts,t hey are often used as supports for noble metals to produce an active hydrogenation catalyst or as promoters.T he pure,c atalytically active material -e veni na highly porous form -wouldhave alot of precious material located at the inside andt hus not available as a catalytic entity.F or this reason,c atalytically active material is spread out on as uitable supporting (inactive) material that can increase the contact area of the active sites with the reactionm edium, which greatly improvesthe catalystscost efficiency.Promoters are ingredients that are not catalytically active but enhance ac atalystsp erformance,s electivity,o rl ifetime. [37] Thep atentinga ctivitiesf or elements in the IPC class B01J21 are in decreasing order:A l, C, Si, combinations of Si and Al, and Ti.T hese are typical supporting materials for heterogeneous catalysts, since they are readily available materials.…”