The original catalyst was HCo(CO)4, discovered by Otto Roelen.[2][3] Subsequent work demonstrated that the ligand tributylphosphine (PBu3) improved the selectivity of the cobalt-catalysed process.
In the 1960s, highly active rhodium catalysts were discovered.[4] Since the 1970s, most hydroformylation relies on catalysts based on rhodium.[5] Subsequent research led to the development of water-soluble catalysts that facilitate the separation of the products from the catalyst.[6]