Delamination of Layered Zeolite Precursors under Mild Conditions: Synthesis of UCB-1 via Fluoride/Chloride Anion-Promoted Exfoliation
journal contributionposted on 2011-03-16, 00:00 authored by Isao Ogino, Michael M. Nigra, Son-Jong Hwang, Jeong-Myeong Ha, Thomas Rea, Stacey I. Zones, Alexander Katz
New material UCB-1 is synthesized via the delamination of zeolite precursor MCM-22 (P) at pH 9 using an aqueous solution of cetyltrimethylammonium bromide, tetrabutylammonium fluoride, and tetrabutylammonium chloride at 353 K. Characterization by powder X-ray diffraction, transmission electron microscopy, and nitrogen physisorption at 77 K indicates the same degree of delamination in UCB-1 as previously reported for delaminated zeolite precursors, which require a pH of greater than 13.5 and sonication in order to achieve exfoliation. UCB-1 consists of a high degree of structural integrity via 29Si MAS NMR and Fourier transform infrared spectroscopies, and no detectable formation of amorphous silica phase via transmission electron microscopy. Porosimetry measurements demonstrate a lack of hysteresis in the N2 adsorption/desorption isotherms and macroporosity in UCB-1. The new method is generalizable to a variety of Si:Al ratios and leads to delaminated zeolite precursor materials lacking amorphization.
pH 9silica phasePorosimetry measurementsdelaminated zeolite precursor materialsLayered Zeolite Precursors77 Ktransmission electron microscopydelaminated zeolite precursors353 Kcetyltrimethylammonium bromide29 Si MAS NMRdelaminationMild ConditionsUCBtetrabutylammonium chloridetetrabutylammonium fluorideMCMnitrogen physisorption