On the structural, acidic and catalytic properties of zeolite SUZ-4

Highly crystalline SUZ-4 zeolite was synthesized and its acidic and catalytic properties were investigated using FTIR spectroscopy and n-hexane conversion. Based on the analysis of the published crystallographic data, it is concluded that SUZ-4 zeolite has a three-dimensional pore system that includes ten-membered ring channels parallel to unit cell c-axis which are intersected by two arrays of eight-membered ring channels running in the plane [001]. Experimental results reported here support this conclusion. About 45% of acid sites (bridging hydroxyls) are located in the large channels of SUZ-4 zeolite, while the remaining sites occupy positions in nonplanar double eight-membered rings. The bridging hydroxyls in SUZ-4 zeolite are more accessible for guest molecules (n-hexane and isobutane) than those in ferrierite. Both zeolites show similar strength of acid sites and have similar protolytic cracking activity. The hydrogen transfer activity of ferrierite is observed to be higher than that of the SUZ-4 zeolite. These results indicate that SUZ-4 zeolite has potential as a catalyst and may display unusual shape-selective properties in comparison with other zeolites.