Ru and Ruδ+ Synergistic Catalysis Efficiently Promotes 2,2,6,6-Tetramethyl-4-Piperidone Hydrogenation for 2,2,6,6-Tetramethyl-4-Piperidinol Preparation

Abstract

The catalytic hydrogenation of nitrogen-containing heterocyclic compounds is a crucial process; however, nitrogen removal severely restricts product selectivity. Consequently, this study utilized a simple heat treatment method to synthesize ruthenium (Ru)-based catalysts supported on N-doped activated carbon for application in the selective catalytic hydrogenation of 2,2,6,6-Tetramethyl-4-piperidone (TTA). The results show that the selectivity of 2,2,6,6-Tetramethyl-4-piperidinol (TMP) is as high as 99.87% under the premise of almost complete TAA reaction. The catalyst was characterized using N2-physisorption-desorption, XRD, TEM, Raman, XPS, ICP-OES, and H2-TPR techniques. N-doped activated carbon introduced numerous defect sites to the catalyst, improved the surface wettability of the activated carbon support, provided abundant active metal anchoring sites, resulting in highly uniform dispersion of Ru nanoparticles (NPs) on the carrier surface, forming relatively smaller nanoparticles, and enhancing the catalyst's activity. Additionally, a strong interaction exists between the active metal Ru and N-doped activated carbon support, facilitating the transfer of free electrons from Ru to N species, increasing the relative content of Ruδ+ in the catalyst, and the synergistic effect between Ru and Ruδ+ contributes to improving the catalyst's performance. This work holds significant potential for controlling the selectivity of nitrogen-containing heterocyclic compounds in the catalytic hydrogenation process.

Keywords: TAA, Catalytic hydrogenation, N-doping, Synergistic effect