Hydrodenitrogenation of alkylamines over supported Ru-based catalysts

• Hydrodenitrogenation (HDN) of 1-cyclohexylethylamine (1-CEA) was conducted. • Ru-Ir/α-Al 2 O 3 catalyst gave 94 % yield of ethylcyclohexane, HDN product from 1-CEA. • The dominant pathway in the HDN of 1-CEA is the direct C N bond cleavage. • Ru-Ir/α-Al 2 O 3 catalyst was effective for the HDN of various alkylamines. • The roles of Ru and Ir were proposed by propylamine-TPD. Hydrodenitrogenation (HDN) of 1-cyclohexylethylamine to ethylcyclohexane was investigated with various Ru-based catalysts. Ru-Ir/α-Al 2 O 3 (1 wt% Ru, 4 wt% Ir) catalyst was found to be superior to other supported Ru catalysts in terms of activity and selectivity to ethylcyclohexane. Characterization with XRD, TEM-EDX and XAFS showed that uniform Ru-Ir alloy particles of approximately 4 nm in size were formed on α-Al 2 O 3 . The optimal Ru-Ir/α-Al 2 O 3 catalyst gave 94 % yield of ethylcyclohexane. The time-course results and the reaction results of bis-(1-cyclohexylethyl)-amine (coupled compound of the substrate) demonstrated that the direct C N cleavage route and indirect route via the coupled compound both proceeded in the HDN of 1-cyclohexylethylamine. The propylamine-TPD results with H 2 treatment after the adsorption of propylamine on the catalyst suggested that the adsorption of H 2 and amine was favorable on the Ru and Ir species, respectively. The catalyst was reusable after washing with ethanol with a slight loss of activity. The catalyst was also effective for the HDN reaction of other amines, and the HDN of some substrates proceeded mainly in the indirect route via the coupled compound.