The magnetism and surface behaviour of Pt-Dy/γ-Al_2O_3 catalysts were studied respectively by means of a Faraday magnetic balance and the method of carbon disulfide.The ferromagnetic impurity in the support,γ-Al_2O_...The magnetism and surface behaviour of Pt-Dy/γ-Al_2O_3 catalysts were studied respectively by means of a Faraday magnetic balance and the method of carbon disulfide.The ferromagnetic impurity in the support,γ-Al_2O_3,at low temperature was corrected for the first time.The magnetic susceptibilities of the cat- alysts follow the sequence in different stage of preparation:χ_(uncalcined)<χ_(calcined)<χ_(reduced). The magnetic susceptibilities of the catalysts decrease as they adsorb hydrogen,cyclohexane or benzene. There is a correlation between the aromatization yield of cyclohexane or heptane on these catalysts and the magnetic susceptibility of the catalysts.Since addition of Dy increases the number of adsorption sites and the relevant proportions of weak adsorption sites,the abilities of sulfur-resistance and cyclohexane dehydrogenation are improved.In Pt-Dy/γ-A:_2O_3 catalysts,Dy improves the aromatization activity and stability of the catalyst and plays the role of the electron promoter.展开更多
文摘The magnetism and surface behaviour of Pt-Dy/γ-Al_2O_3 catalysts were studied respectively by means of a Faraday magnetic balance and the method of carbon disulfide.The ferromagnetic impurity in the support,γ-Al_2O_3,at low temperature was corrected for the first time.The magnetic susceptibilities of the cat- alysts follow the sequence in different stage of preparation:χ_(uncalcined)<χ_(calcined)<χ_(reduced). The magnetic susceptibilities of the catalysts decrease as they adsorb hydrogen,cyclohexane or benzene. There is a correlation between the aromatization yield of cyclohexane or heptane on these catalysts and the magnetic susceptibility of the catalysts.Since addition of Dy increases the number of adsorption sites and the relevant proportions of weak adsorption sites,the abilities of sulfur-resistance and cyclohexane dehydrogenation are improved.In Pt-Dy/γ-A:_2O_3 catalysts,Dy improves the aromatization activity and stability of the catalyst and plays the role of the electron promoter.
