Direct Amination of Dodecanol over Noble and Transition Metal Supported Silica Catalysts

Abstract

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.

Organonitrogen Chemicals from Oxygen-Containing Feedstock over Heterogeneous Catalysts

“…The use of the Ru/C catalyst was further extended to more biogenic sugar-based alcohols . Ru, Ir, Pt, and Rh supported on SiO 2 were also used to study the amination of dodecanol, and the authors suggested the active species on Ir/SiO 2 are the in situ reduced metallic Ir …”

“…98 Ru, Ir, Pt, and Rh supported on SiO 2 were also used to study the amination of dodecanol, and the authors suggested the active species on Ir/SiO 2 are the in situ reduced metallic Ir. 99 Pera-Titus et al introduced a Pd/CeO 2 catalyst for the reaction of benzyl alcohol with ammonia under N 2 atmosphere at 160 °C. 100 The catalyst afforded full benzyl alcohol conversion after 24 h, while its selectivity toward benzylamine was limited to 12%, with a higher selectivity to dibenzylamine of 36%.…”

Amination Reaction of Cyclohexanol over a Commercial Ni-Based Catalyst, Part I: Influence of Operating Conditions

“…For homogeneous systems, the xantphos ligand with a transition metal, acridinyl-based pincer complexes, quinolinyl-based pincer ligands, and Ru- and Ir-based complexes are the most used. ,− Nevertheless, when using this type of catalyst, acceptable selectivity toward the primary amines is hard to achieve; moreover, the majority of these catalysts or ligands are not stable to air or moisture, so they do not allow an inexpensive, risk-free process to produce amines. ,− Heterogeneous systems, on the other hand, have presented better results, and several metal catalysts have been used, namely, Ni, Pt, Cr, Fe, Ru, Rh, Pd, Ir, V, Mo, Cu, Co, Ba, and Mn on several types of supports. The use of silica and alumina has prevailed as metal supports, but other materials such as HZSM-5, Hβ, and HY zeolites were also used. ,,,− Depending on the used operating conditions, Ni, Pt, and noble metal catalysts presented the best results in terms of selectivity toward primary amines and/or yield. ,,− Among these, Ni-based catalysts seem to be the most interesting because of their large availability and low acquisition cost …”

“…The optimum performance for the amination of alcohols, namely CHOL, also depends on the adequate choice of the operating conditions. Moreover, the presence of an external source of H 2 (besides the alcohol hydride) has shown to have a significant effect on the reaction performance. ,, The NH 3 -rich reaction environment is susceptible to induce the formation of inactive metal nitrides, in parallel to catalyst de-activation because of the deposition of carbonaceous species, reducing the life-time span of the catalytic bed. ,, The presence of H 2 can reduce the formation of the metal nitrides and help maintaining catalyst activity. − This catalytic behavior has been explained by the de-activation–re-activation mechanism induced by the presence of H 2 in the reaction medium through reduction of the formed metal nitrides and the decoking role. ,− ,, On what concerns the effect of the operating conditions, the total pressure enhances the disproportionation of the formed primary amines, therefore promoting side reactions, adversely affecting the process performance. ,− The molar ratio of reactants also plays a key role. Depending on the desired product, the amination of alcohols can be conducted either with excess of alcohol or excess of the aminating agent.…”

“…31−37 This catalytic behavior has been explained by the de-activation−re-activation mechanism induced by the presence of H 2 in the reaction medium through reduction of the formed metal nitrides and the decoking role. 14,[31][32][33][34][35]38,39 On what concerns the effect of the operating conditions, the total pressure enhances the disproportionation of the formed primary amines, therefore promoting side reactions, adversely affecting the process performance. 29,32−35 The molar ratio of reactants also plays a key role.…”