Characterization of isomorphously substituted ZSM-23 and catalytic properties in n-buteneisomerization
Pure and well crystallized Al- and Fe-ZSM-23 were synthesized by a hydrothermal method. The products were characterized by XRD, SEM, n-hexane adsorption, chemical analysis, TPD of NH3 and IR thermodesorption of pyridine. The characterization results reveal that the substitution of Al with Fe leads to a considerable decrease in the strength of the Brönsted acid sites. n-Butene isomerization over Al- and Fe-ZSM-23 has been tested. It is shown that the lower Brönsted acidity of Fe-ZSM-23 compared with Al-ZSM-23 is reflected in a lower activity and higher selectivity in n-butene isomerization.