Simple method for preparing monoclinic single crystals of zeolite ZSM-5 and analysis of their structure

Abstract

A simple method for preparing monoclinic single crystals of ZSM-5 is developed. The ZSM-5 crystals are pressed with a weight of 50 g at an angle of 45° relative to the b and c crystallographic axes of twin ZSM-5 crystals while the temperature is simultaneously increased to 573 K. The temperature is then slowly reduced to 313 K, and these steps are repeated three times. The monoclinic structure of the single crystals of ZSM-5 produced using this method is then determined.

Determining the structure of a benzene7.2-silicalite-1 zeolite using a single-crystal X-ray method

“…The authors assumed that these single crystals were orthorhombic by analogy with the preparation of simple monoclinic silicalite-1 (Kamiya et al, 2010). The authors confirmed that they were orthorhombic according to the results of the structure analysis of orthorhombic benzenesilicalite-1.…”

“…Normally calcination of the crystals to remove TPA ions results in cracking over 80% of the crystals (Geus & van Bekkum, 1995). A sodium perchlorate treatment was developed by the authors to avoid crystal cracking (Kamiya et al, 2010). After this treatment, the crystals were calcined at 763 K in flowing air for 1 h to obtain monoclinic twin silicalite-1 crystals.…”

“…The preparation of monoclinic single crystals of silicalite-1 was described in detail in Kamiya et al (2010).…”

“…In the case of benzene, however, no work using single crystals had yet been reported. Recently, a simple monoclinic single-crystal preparation of silicalite-1 was developed by the authors (Kamiya et al, 2010). After this preparation, these monoclinic silicalite-1 crystals adsorbed benzene, but were twinned.…”

“…They also analyzed the single-crystal structure of monoclinic ZSM-5 (van Koningsveld, Jansen & van Bekkum, 1990). The authors recently developed a simple method for preparing monoclinic single crystals of ZSM-5 and determining the monoclinic structure of ZSM-5 (Kamiya et al, 2010). Generally, monoclinic twin MFI crystals transform into orthorhombic sorbate-MFI single crystals after adsorbing aromatic compounds other than benzene.…”