Binderless nano-HZSM-5 zeolite coatings prepared through combining washcoating and dry-gel conversion (DGC) methods

作者：You Zhiqiang; Liu Guozhu^*; Wang Li; Zhang Xiangwen

来源：Microporous and Mesoporous Materials, 2013, 170: 235-242.

DOI：10.1016/j.micromeso.2012.12.012

• Washcoating
• Dry-gel conversion
• HZSM-5
• Nanocrystals
• Adhesion

Binderless nano-HZSM-5 zeolite coatings were successfully prepared through a two-step process: washcoating zeolites on the surface of the substrates with controllable thickness, and then converting SiO2 binders into the crystal structure by dry-gel conversion (DGC) method to remarkably improve the adhesion strength. Ethylene diamine, tetrapropylammonium hydroxide and triethylamine were used as organic amines in DGC. The conversion of SiO2 binders into MFI structure around the nano-HZSM-5 zeolite crystals was confirmed by characterizations of X-ray diffraction, Si-29 and Al-27 nuclear magnetic resonance and transmission electron microscopy. As a result, the adhesion strength of the prepared coatings was significantly improved by ca. one order, which is ascribed to the higher interlocking between the crystals and the aggregates after DGC treatment. NH3-Temperature programmed desorption characterization showed that the total amount of acid sites of the coatings were improved by ca. 30% due to the incorporation of extra-framework Al species of nano-HZSM-5 crystals into the framework of ZSM-5 through DGC treatment. Slight differences in DGC mechanism and thus the acidities as well as adherences of the obtained coatings were also observed depending on the amines used in DGC.

• 出版日期2013-4
• 单位天津大学