Direct amination of dodecanol over noble and transition metal supported silica catalysts

Direct amination of 1-dodecanol with NH3 and H2 over Rh, Pt, Ir, Ru, Ni, Cu, and Co catalysts on SiO2 has been studied. Catalyst synthesis was performed to allow high metal dispersion. The catalysts were characterized by TPO/TPR-MS, N2 physisorption at 77 K, transmission electron microscopy, ICP analysis, and XPS. Through this characterization it was possible to relate the physical properties of the catalysts with activity and selectivity in 1-dodecanol amination. Iridium and ruthenium catalysts showed the highest conversion, about 77% after 24 h, and the selectivity of 78% and 81%, respectively, toward the desired product 1-dodecylamine. The Ru catalyst exhibited the highest yield of the desired product. In the conditions studied, the conversion increased in the order Cu < Ni < Rh < Pt < Co < Ir < Ru, and the selectivity was the highest for Ni and Co after 24 h. Both activity and selectivity of an oxidized Ir/SiO2 catalyst increased considerably as the reaction progressed showing clearly that in situ catalyst reduction occurs being beneficial for dodecanol amination. High activity of Ir was also related to high metal dispersion.