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Abstract

Montmorillonite and synthetic beidellite were pillared with hydroxy-Al-polymers, and the physicochemical properties and catalytic activities of the pillared products were characterized by several techniques. The basal 001 reflection of the pillared clays was found to be about 18 Å and to decrease slightly after calcination. Infrared spectra of pillared beidellite exhibited an OH-stretching band at 3440 cm−1, similar to that observed for H+-exchanged beidellite or for the calcined form of NH4-beidellite. These OH groups, which interact with pyridine to give pyridinium ions (Brönsted acidity), were formed by the proton attack of Si—O—Al linkages of the tetrahedral layer to form Si—OH … Al entities. Such a band was not evident in the pillared montomorillonite. In both pillared clays, Lewis acidity was also detected by pyridine adsorption and was generated by the aluminum pillars.

Hydroisomerization-hydrocracking of n-decane was performed in a continuous flow reactor at at-omospheric pressure. The catalytic activity and the distribution of the products were determined for the pillared beidellite and montmorillonite and compared with the same data obtained for noncrystalline silica-alumina, ultrastable zeolite Y, and zeolite H-ZSM-5. Pillared montmorillonites and beidellites showed substantially different catalytic activities. Pillared beidellites had an overall activity only slightly less than that of the zeolites. The clays behaved similarly to zeolite-based bifunctional catalysts; i.e., they displayed high selectivity for isomerization at high conversion and symmetrical distribution of the individual products. They appear to be promising dewaxing catalysts. The pillared montmorillonites were much less active than the pillared beidellites. The high activities and selectivities of the pillared beidellites are likely due to the presence of Si—OH acid sites exposed in the interlamellar space.

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