On the role of hydrogen-deficient species during alkylamine hydrotreating on platinum catalysts
Year: 2025
Type: article
Abstract: In this work, the mechanism of hydrodenitrogenation (HDN) of aliphatic primary amines was studied both computationally and experimentally. Such amines are intermediates during HDN of renewable feedstocks, and studying amine HDN is thus important for both catalyst and process design. The computational work studied the reactions of methylamine, ethylamine and dimethylamine on Pt(111). Experimental HDN studies of amines with a more industrially relevant carbon chain length were performed to support the conclusions of the computational work. To this end, dodecylamine HDN was studied with a Pt/ZrO2 catalyst using both hydrogen and deuterium gas, and the effect of hydrogen pressure on hexadecylamine HDN was investigated. The results show that the C-H bonds of the amines are labile at HDN conditions: the amines are adsorbed on Pt through the NH2-group, after which C-H bond dissociation can occur, even for C-H bonds far from the initially adsorbed NH2-group. Thus, a variety of hydrogen deficient species are formed. The computational results imply that nitrogen removal preferentially occurs through these hydrogen-deficient species since removal of hydrogen from the α-carbon favors C-N bond dissociation. The hydrogen deficient species can also react with each other, forming heavier condensation products such as the secondary amines or imines. We found experimentally that the nitrogen removal rate of hexadecylamine on Pt/ZrO2 increases with decreasing hydrogen partial pressure, which agrees with hydrogen-deficient species being an important part of the reaction mechanism.
Source: Journal of Catalysis
Institution: Aalto University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,250
OpenAlex ID: W4416580052