Continuous Synthesis of 2,2-Dimorpholinodiethyl Ether over Cu ₁₆ Ni ₄ /HAP Catalysts

The catalytic amination of diethylene glycol (DEG) and morpholine to synthesize 2,2-dimorpholinodiethyl ether (DMDEE) is a green and sustainable approach. However, the catalytic amination reaction of alcohols is largely limited by the dehydrogenation step of alcohols, and developing catalysts with both high selectivity and stability remains a challenge. In this study, a Cu16Ni4/HAP catalyst was prepared by using a bimetallic synergy strategy. Under the reaction temperature of 230 °C and hydrogen pressure of 2.8 MPa, the conversion of DEG reached 99.9% and the selectivity of DMDEE was 83.2%, with stable activity maintained during 50 h continuous reaction. Combined with a series of characterizations, the excellent catalytic performance of Cu16Ni4/HAP is mainly attributed to the strong Cu–Ni synergy and unique properties of the HAP support. The bimetallic synergy improves the metal dispersion and regulates the electronic structure and surface acidity of the catalyst. Concurrently, the HAP support stabilizes key amine intermediates. These combined effects synergistically improve dehydrogenation activity and prevent the rapid deactivation of the catalyst.