Preparation and characterization of microporous 18 Å Al-pillared structures from natural phlogopite micas

✍ Scribed by F del Rey-Perez-Caballero; G Poncelet

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 267 KB
• Volume: 41
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/s1387-1811(00)00284-5

✦ Synopsis

A new method to prepare Al-pillared phlogopite micas with thermally resistant 18 # A spacings is reported. They are obtained in a two-step process, one consisting of a preliminary treatment of mica in controlled conditions, which allows a permanent reduction of the layer charge density, and brings the charge-reduced mica to a homoionic Na, or Ca form. Pillaring is achieved in a second step by bringing the Na-exchanged phlogopite in contact with a base-hydrolyzed Al solution or commercial Al-chlorhydrol. Al-pillared phlogopites exhibit textural and structural features similar to those of pillared smectites (temperature resistant spacings, high surface areas and micropore volumes). As to the dierence with Al-pillared smectites, Al-pillared micas withstand temperature treatments up to 800°C, owing to the higher intrinsic thermal stability of the host structure. They also have a higher content of Brùnsted acid sites.