CuO/ZnO/SiO2 catalysts for cyclization of propyleneglycol with ethylenediamine to 2-methylpyrazine Original Research Article

The cyclization of ethylenediamine with propyleneglycol to 2-methylpyrazine was carried out over CuO/SiO2, ZnO/SiO2 and CuO/ZnO/SiO2 catalysts at 360 °C. CuO/ZnO/SiO2 catalyst, which possesses a proper combination of cyclization (dehydration) and dehydrogenation activity, shows almost quantitative reactant conversions and excellent 2-methylpyrazine selectivity of 87% for 350 h.The improvement in 2-methylpyrazine selectivity and stability of CuO/ZnO/SiO2 catalyst may be attributed to the cooperative combinational effect of CuO/SiO2 catalyst and ZnO/SiO2 catalyst in which the thermally stable Zn2SiO4 phase is developed by the synergic action of CuO component to result in the preservation of Cu(0) species and the dual function activities for the catalytic reaction are properly adjusted.