Catalytic amination of diethylene glycol with tert‑butylamine to tertiarybutylaminoethoxyethanol over NiCu/Al2O3 catalysts: Facilitation of NiCu alloy

Abstract

Herein, a series of NiCu/Al2O3 catalysts were prepared by impregnation method and subsequent thermal treatment under different reduction temperatures. The catalysts exhibited excellent catalytic activity for the amination of diethylene glycol (DEG), and satisfactory yield of tertiarybutylaminoethoxyethanol (TBEE) could be obtained. XRD, N2 adsorption-desorption, SEM, TEM, XPS, and H2-TPR were employed to characterize the catalysts, the interaction between Ni and Cu on the catalytic activity was studied. It was found that NiCu alloy was formed after catalyst reduction, which strengthened the reduction ability of NiO and increased the number of Ni0 active center, contributing to the enhanced catalytic activity. Moreover, the effects of reaction parameters on catalytic activity were explored. There was no need for a solvent, only 3 molar equivalents of tert‑butylamine (TBA) and 1 wt.% catalyst was required. After 7 h of reaction at 220 °C, satisfactory conversion (89.6%) and selectivity (84.6%) were obtained over the prepared catalyst. Cycle experiment demonstrated that the prepared catalyst retained excellent stability and reusability after six runs without significant loss of catalytic activity. This work provided an efficient catalyst for the catalytic amination of diethylene glycol with tert‑butylamine to TBEE.