Tailoring the Acidity of Ru Supported on Sepiolite for Enhanced Catalytic Reductive Amination of Furfural to Furfurylamine

Abstract

Abstract The catalytic reductive amination of bio‐based carbonyls has emerged as a promising route for producing N‐containing compounds, having a wide range of applications in pharmaceuticals and agrochemicals. In this work, Ru supported on acid‐treated sepiolite (Ru/ASep) is designed for the reductive amination of furfural (FUR) to furfurylamine (FUA) using H 2 and NH 3 as reductant and nitrogen source, respectively. Ru/ASep exhibited two times higher catalytic activity compared to its counterpart, that is, Ru supported on parent sepiolite (Ru/Sep), yielding 98.4% FUA. The NH 3 ‐temperature‐programmed desorption (TPD) and NH 3 ‐diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy studies show that Ru/ASep exhibited an increase in total acidic sites with relatively more Lewis acidic sites than Ru/Sep, contributing to C═N bond activation and leading to the formation of FUA in high yield. The CO 2 ‐TPD results indicate that ASep possesses a large amount of basic sites, which contribute to a facile reduction of RuO x to Ru 0 in Ru/ASep, as confirmed by H 2 ‐temperature programmed reduction (TPR) studies. H 2 ‐TPD studies indicate a higher amount of H 2 activated over Ru/ASep, favoring the intermediate hydrogenation step to form FUA. Furthermore, the poisoning studies with KSCN indicated that Lewis acidic sites on the surface of Ru/ASep played a crucial role in the formation of FUA.