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

Abstract The cyclization of ethylenediamine with propyleneglycol to 2-methylpyrazine was carried out over CuO/SiO 2 , ZnO/SiO 2 and CuO/ZnO/SiO 2 catalysts at 360 °C. CuO/ZnO/SiO 2 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/SiO 2 catalyst may be attributed to the cooperative combinational effect of CuO/SiO 2 catalyst and ZnO/SiO 2 catalyst in which the thermally stable Zn 2 SiO 4 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.