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AEI-type aluminosilicate zeolites with sheet-like morphology were successfully synthesized by the crystal growth inhibitor (CGI)-assisted method, where cetyltrimethylammonium bromide (CTAB) worked as a CGI. The obtained sheet-like AEI-type aluminosilicates showed a higher yield of butenes and longer catalytic lifetime in the direct conversion of propene to butenes than the conventional sample. The improvement of catalytic performance originated from tuning the molecular diffusion in the zeolite particles. The sheet-like morphology gave a higher molecular diffusivity, and consecutive reactions were suppressed. Moreover, there was a significant difference in the product distribution of butene isomers; linear butenes and iso-butene were the dominant product over the typical AEI-type aluminosilicate with cubic particles induced by the shape selectivity into zeolitic micropores, while the sheet-like one yielded a higher selectivity for iso-butene. It was revealed that the distribution of Bronsted acid sites between internal and external surfaces could be controlled by increasing the external surface area coming from the sheet-like particles.

Incorporation of B atoms into the AEI-type framework was successfully achieved by addition of boric acid into the starting gel. The gel compositions, the Si/Al and Si/B ratio, and the calcination conditions were extensively investigated to tune acidic properties of the AEI-type zeolite. The incorporation of B into the framework was confirmed by solid state NMR and FT-IR techniques. In-situ FT-IR spectroscopy using CO as a probe molecule was applied to the evaluation of the acidic property. As the result of in-situ FT-IR measurement, thus obtained AEI-type boroaluminosilicate zeolites showed weak acidic properties derived from framework B species compared to the aluminosilicate one. Finally, the catalytic properties of the synthesized AEI-type zeolites in the ethene conversion reaction were investigated. We found that the AEI-type boroaluminosilicate catalyst showed a long catalytic life and a high selectivity to butenes.

A series of MCM-68 zeolites with different Si/Al ratios were prepared by treatment with nitric acid and compared with beta zeolites. Speciation of aluminum and location of acid sites changed depending on the Si/Al ratio. The location of Bronsted acid sites in MCM-68 samples was able to be classified by FT-IR measurements with pyridine and 2,6-di-tert-butylpyridine as probe molecules, and the number of Bronsted acid sites was quantified according to the locations. For high-aluminum MCM-68, Bronsted acid sites were broadly distributed in both the 12-ring channel and 10-ring windows as well as inside the supercage. The Bronsted acid sites in the 12-ring channel were easily removed by the acid treatment, and consequently, high-silica MCM-68 had Bronsted acid sites predominantly in the 10-ring windows and inside the supercage. 27Al MQMAS NMR spectra of high-silica MCM-68 showed two specific peaks assignable to T6 and T7 sites, which did not face the 12-ring channel, forming the Bronsted acid sites highly toler...