PROMOTIONAL EFFECT OF RU ON THE DEHYDROGENATION AND AROMATIZATION OF METHANE IN THE ABSENCE OF OXYGEN OVER MO HZSM-5 CATALYSTS/

A reaction rate of methane conversion of 14.54 nmol(-1) m(-2) and the formation rate of aromatics of 2.22 nmol(-1) m(-2) at 973 K for the de hydrogenation and aromatization of methane in the absence of oxygen wa s attained over Mo-Ru/HZSM-5 catalysts. Ey comparison, over unpromoted Mo/HZSM-5 catalysts, the reaction rate of methane conversion was 10.1 7 nmol(-1) m(-2) and the formation rate of aromatics was 1.52 nmol(-1) m(-2). The Ru-promoted Mo/HZSM-5 catalysts also show better stability . The catalyst with 2% Mo loading and with Mo/Ru atomic ratio ranging from 3 to 7 shows much better catalytic performance. NH3-TPD shows tha t the addition of Ru onto 2Mo/HZSM-5 causes a further decrease in the amount of strong acid sites and at the same time, creates new acid sit es with moderate acid strengths. TPR and DTA studies illustrate that t he existence of Ru with a proper dispersion promotes the reduction of Mo species and the splitting of the C-H bond of methane. (C) 1997 Acad emic Press.