Framework-Substituted Lanthanide MCM-22 Zeolite: Synthesis and Characterization

Incorporation of Ce and La into the framework of MCM-22 zeolite has been achieved by cohydrolysis and condensation of tetraethylorthosilicate and lanthanide salts in moderate/weak acidic media followed by a switch of synthesis gels to basic conditions for hydrothermal crystallization. The promotion effect of the framework Ce (La) when Ce(La)-MCM-22 serves as the catalyst support for hydroisomerization of n-heptane is demonstrated. Framework substitutions of lanthanides are evidenced by a set of mutually complementary characterizations, catalytic tests, and item-by-item comparisons with the impregnated and ion-exchanged counterparts. The novel synthesis strategy may give further outlines for the production of other types of heteroatomic zeolites.