Mechanisms of hydrodenitrogenation of alkylamines and hydrodesulfurization of alkanethiols on NiMo/Al2O3, CoMo/Al2O3, and Mo/Al2O3 |
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| Affiliation: | 1. Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China;2. School of Architecture, Huaqiao University, Xiamen 361021, China;3. State Key Laboratory of Subtropical Architecture Science, South China University of Technology, Guangzhou 510640, China;1. Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA;2. Department of Chemical Engineering, University of Idaho, Idaho Falls, ID 83402, USA;3. Department of Chemical Systems Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;4. Department of Chemical Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, Berlin 14195, Germany;5. Institut für Chemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany;6. Otto-Schott-Institut für Materialforschung, Friedrich-Schiller-Universität Jena, Löbdergraben 32, D-07743 Jena, Germany |
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| Abstract: | The simultaneous hydrodenitrogenation (HDN) of alkylamines and hydrodesulfurization (HDS) of alkanethiols, with the NH2 and SH groups attached to primary, secondary, and tertiary carbon atoms, were studied at 270–320 °C and 3 MPa over sulfided NiMo/Al2O3, CoMo/Al2O3, and Mo/Al2O3 catalysts. Pentylamine and 2-hexylamine reacted by substitution with H2S to form alkanethiols and with another amine molecule to form dialkylamines. Alkenes and alkanes were not formed directly from pentylamine and 2-hexylamine, but indirectly by elimination and hydrogenolysis of the alkanethiol intermediates, as confirmed by their secondary behavior and the similar alkene/alkane ratios in the simultaneous reactions of amines and thiols. Only 2-methyl-2-butylamine, with the NH2 group attached to a tertiary carbon atom, produced alkenes as primary products by E1 elimination. NiMo/Al2O3 and CoMo/Al2O3 have a higher activity for the HDS of alkanethiols than does Mo/Al2O3; H2S has a negative influence. This shows that the thiols react on vacancies on the catalyst surface (Lewis acid sites). Mo/Al2O3 is the best HDN catalyst; H2S has a positive influence on the HDN of amines with the NH2 group attached to a secondary and a tertiary carbon atom. This indicates that the HDN of alkylamines occurs on Brønsted acid sites. |
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