Catalytic Hydrodenitrogenation of Pyridine under Hydrothermal Conditions: A Comprehensive Study
Yang Guo, Xu Liu, Peigao Duan, Donghai Xu, Rafael Luque
Abstract
This article focuses on the kinetic modeling and catalytic performance of hydrodenitrogenation of pyridine under hydrothermal conditions. Piperidine derivatives are the major nitrogen-containing intermediates, including 1-piperidinecarboxaldehyde, 1-piperidineethanol, and alkyl piperidines. Catalysts overall improved the formation of N-free products including 1-pentanol and 2-methyl-1-pentanol. Commercial Pd/C provided the highest pyridine conversion rate at 350 °C, while the homemade Ni–Ru bimetallic catalyst provided a prominent denitrogenation activity at 400 °C, leading to the highest 1-pentanol yield as a major denitrogenated product. Conversion of pyridine over the Ni50Ru50/C catalyst led to formation of three major alkyl piperidines (1-ethyl piperidine, 1-methyl piperidine, and 1-pentyl piperidine). These alkyl piperidine intermediates could further be converted into amino and N-free compounds. A kinetic model was developed to mathematically describe the hydrothermal HDN reaction of pyridine over the Ni50Ru50/C catalyst, which clearly captured all data trends and fitted the temporal variation of all major products. Sensitivity analysis suggested that dehydrogenation from piperidine to pyridine has a strong impact on the whole reaction pathways.