A general process for the cyclization of aminoalcohols to the corresponding amines over Cu-Cr-La/γ-Al2O3

A general process for the cyclization of aminoalcohols to the corresponding amines over Cu-Cr-La/gamma-Al2O3 is established in a continuous fixed-bed reactor. The catalyst was characterized by XRD, XPS and NH3-TPD. The doped Cr is found to improve the copper particle dispersion. The addition of La neutralized the strong acid sites and decreased the amount of the acid sites, which facilitated the desorption of amino compounds on the surface of catalysts and inhibited the carbon deposition. Under the optimum conditions, the yields of pyrrolidine, piperidine and piperazine were 99.5, 99.5 and 98.6 %, in order, while the yields of hexahydro-1H-azepine and homopiperazine were 46.5 and 32.7 % due to the unstable seven-membered ring by the cyclization of the corresponding aminoalcohols over Cu-Cr-La/gamma-Al2O3.