A superior methanol-to-propylene catalyst:Construction via synergistic regulation of pore structure and acidic property of high-silica ZSM-5 zeolite
Combined strategy of alkali treatment and chromium modification was used to synergistically regulate the pore structure and acidic property of the high-silica ZSM-5 zeolite.During the alkaline treatment,the abundant intergrowth boundaries constructed by adjusting the composition of the synthesis gel induced the formation of meso-pores.Thereby,the limitation of the conventional alkali treatment method coming from the framework Si/Al ratio of parent zeolite was circumvented.In the process of chromium modification,the unique hierarchical pore structure promoted the dispersion of chromium species in the catalyst.Thus,a deep modification of the acidic property was realized.As a result,a high-silica hierarchical zeolite catalyst with suitable acidities was obtained.During the cata-lytic conversion of methanol to propylene,the variation of the pore structure and acidic property caused obvious changes in the coke deposition behavior of the catalyst and the mass transfer of products.Consequently,the pre-pared catalyst exhibited excellent catalytic stability and a high selectivity towards propylene and total light olefins.
methanol to propylenehierarchical poreacidity regulationzeolitecatalytic performance