Catalytic hydrodenitrogenation, hydrodeoxygenation and hydrogenation reactions of amides, amines, and nitriles over NiMoSX/Al2O3 catalysts: Mechanisms, kinetics and transport

Abstract

The presence and possibility of removal of nitrogen from the bio-based feedstock is a major challenge for efficient use of these sources. Herein, we propose a unique micro-kinetics model which enables the fundamental competing selective mechanism elucidation using sulfided NiMo/Al₂O₃, a conventional hydrotreating catalyst. The model was built based on varying temperature and hydrogen pressure. Both, homogeneous and heterogeneous reactions are described in presence and absence of hydrogen with hexadecanamide and hexadecanamine as model compounds. We show that the process can undergo hydrodeoxygenation or hydrodenitrogenation reaction path based on the water/ammonia presence in the reaction mixture. This finding shows that the presence of nitrogen in feedstocks can be manipulated by influencing equilibria. Detailed catalyst characterization and mass transfer analysis support the study. The results represent the foundation for the understanding of catalytic and non-catalytic relationships between the reactants. It was elucidated that the influence of process parameters, including the small molecules presence, can direct of the process selectivity towards amines, dimers, and alkanes.