Promotional Effect of Cu for Catalytic Amination of Diethylene Glycol with Tertiarybutylamine over Ni–Cu/Al₂O₃ Catalysts

Abstract

In this work, we synthesized a series of 20% Ni-x% Cu/Al₂O₃ catalysts containing various Cu loading by the impregnation method and investigated their catalytic performance in the amination of diethylene glycol (DEG) with tertiarybutylamine (TBA) to tertiarybutylaminoethoxyethanol (TBEE). A variety of characterization techniques including XRD, TEM, BET, XPS, H₂-TPR, NH₃-TPD, CO₂-TPD were applied. The promotional influence of Cu on the catalytic performance of Ni/Al₂O₃ catalyst was studied, and the optimal addition of Cu was obtained. Indeed, we found that Ni–Cu alloy was formed after reduction of the Ni–Cu/Al₂O₃ catalysts. Due to the strong interaction between Cu and Ni, Cu could improve the reducibility of NiO and the dispersion of Ni species on the catalyst surface, which were critical factors for higher reactivity of the bimetallic Ni–Cu/Al₂O₃ catalysts. Moreover, the influence of catalyst reduction temperature and reaction temperature were examined. When operating at 230 °C, the 20% Ni-10% Cu/Al₂O₃ catalyst reduced at 500 °C for 2 h exhibited superior catalytic performance in this reaction.

Graphic Abstract

Ni-Cu/Al₂O₃ catalyst was found to be an effective catalyst for catalytic amination of diethylene glycol with tertiarybutylamine.