Decarboxylation of Amino Acids to Bioamines over BaHPO₄-Buffered Ru-RuO₂ Catalysts

Waste protein-derived l-lysine was decarboxylated and hydrogenated to 1,5-pentanediamine (1,5-PDA) with great potential, which is an important feedstock for the production of the nylon PA56 monomer. In this study, a partially coated Ru-RuO₂/BaHPO₄ catalyst, with a controlled 26.5% surface Ru⁰ species, was developed from the RuO₂/BaCO₃ precursor using an encapsulation strategy with in situ generated 1,5-PDA as a gelling agent. As a result, l-lysine was decarboxylated and hydrogenated to 1,5-PDA via an intermediate of lysinal, affording a selectivity of 94.1%, space-time yield of 0.97 g·g_cat^-1·h^-1, and TON of 374.6 at 170 °C. The Ru/RuO₂-based catalyst demonstrated strong acid and over-reduction resistance, thereby providing a way to prepare robust catalysts for the synthesis of a wide range of amines from waste protein-derived amino acids.