Effect of crystal size on the skeletal isomerization of n-butene over H-FER zeolite

Three H-FER zeolites with different crystal sizes were successfully obtained via the conventional static hydrothermal method by introducing an aging step to the synthesis procedure. The samples were characterized by XRD, SEM, TEM, NH3-TPD, XRF, and BET analyses. While the number of acid sites decreased with decreasing crystal sizes, the H-FER zeolite with submicron-scale crystal sizes exhibited not only high activity but also good stability during the skeletal isomerization of n-butene. These results are attributed to the large external surface area and abundance of mesopores in the sample. The resulting isobutylene yield reached approximately 45 wt%. The concept of pore mouth catalysis over H-FER zeolites for the reaction was also supported by catalytic performance varied with crystal size.