Collect. Czech. Chem. Commun. 2003, 68, 1149-1162

Synthesis and Properties of the MFI Zincosilicalite

Girolamo Giordanoa, Andrea Katoviča, Ewa Szymkowiak-Janiszewskab and Stanisław Kowalakb,*

a University of Calabria, Department of Chemical Engineering and Materials, 87030 Rende, Italy
b Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland


Zincosilicalite MFI with various zinc contents (up to Zn/Si = 0.07) has been synthesized by hydrothermal crystallization. The samples with the Zn/Si ratio in the range 0.03-0.07 still show the crystalline structure of MFI, but they are less ordered and differ in properties from those with lower Zn contents. The mixtures with the Zn/Si ratios higher than 0.07 resulted in amorphous products or condensed crystalline phases (quartz). The introduction of Zn affected both the crystallization time and properties of the resulting products. Usually the higher Zn/Si ratio of the gel required a longer crystallization time. The zinc introduced affected the thermal template removal making it more difficult than for the zinc-free silicalite. The obtained zincosilicates were modified by ion-exchange with various cations. Contrary to zinc-free silicalite-1, they showed considerable catalytic activity in propan-2-ol decomposition and in cumene cracking. The activity usually increased with the Zn content up to the ratio Zn/Si = 0.03 and then decreased with rising Zn loading. It also depended on the cation introduced. The Cu-modifications resulted in dehydrogenation of propan-2-ol.

Keywords: Zincosilicates; MFI; Thermal analysis; Catalytic properties; Molecular sieves; Zeolites; Heterogeneous catalysis; Hydrothermal crystallization; Cracking.

References: 36 live references.