A comparative study of direct versus post-synthesis alumination of mesoporous FSM-16 silica. (November 2016)

• Record Type: Journal Article
• Authors: Zimowska, M.; Michalik-Zym, A.; Kryściak-Czerwenka, J.; Dula, R.; Socha, R.P.; Pamin, K.; Bazarnik, M.; Bahranowski, K.; Olejniczak, Z.; Lityńska-Dobrzyńska, L.; Serwicka, E.M.
• Is Part Of: Materials research bulletin. Volume 83(2016)
• Page Start: 623
• Page End: 631
• Publication Date: 2016-11
• Subjects: FSM-16 -- Mesoporous silica -- Alumination -- Al distribution -- Acidity; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2016.07.016
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: Long, medium and short range order depends on the manner of Al insertion. Distribution of Al can be controlled by the method of alumination. Direct alumination affects skeleton vibrations more than the post-synthesis one. Post-synthesis alumination is a more efficient means of introducing acid sites. Abstract: Al-FSM-16 mesoporous silicas were synthesized either by direct method, from Al-kanemite (Al-FSM-16/D), or by post-synthesis impregnation of purely siliceous FSM-16 with Al(NO3 )3 (Al-FSM-16/P) and characterized with XRD, XRF, SEM, TEM, nitrogen sorption isotherms, 27 Al and 29 Si MAS NMR, FTIR, XPS, NH3 -TPD, FTIR of pyridine adsorption and catalytic decomposition of ethanol. Only substitutional Al sites exist in Al-FSM-16/D, while in Al-FSM-16/P some Al remains in extra-lattice positions. Upon transformation of Al-FSM-16/D into hydrogen form a certain amount of extra-framework Al is formed. Direct alumination introduces a higher degree of structural disorder. In Al-FSM-16/D, Al is preferentially accumulated at inner pore walls, while in Al-FSM-16/P external surface is Al-rich. Post-synthesis alumination is more efficient in introducing acid sites into FSM-16. The generated acidity is of Brønsted and Lewis nature, the latter being stronger than the former.