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SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis

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Abstract

We report a scalable delamination procedure for a SSZ-70-framework layered-zeolite precursor, which for the first time does not involve either sonication or long-chain surfactants. Our approach instead relies on the mild heating of layered zeolite precursor B-SSZ-70(P) in an aqueous solution containing Zn(NO3)2 and tetrabutylammonium fluoride. Powder X-ray diffraction data are consistent with a loss of long-range order along the z-direction, while 29Si MAS NMR spectroscopy demonstrates preservation of the zeolite framework crystallinity during delamination. The resulting delaminated material, DZ-2, possesses 1.4-fold higher external surface area relative to the nondelaminated three-dimensional zeolite B-SSZ-70, based on N2 physisorption data at 77 K. DZ-2 was functionalized with cationic Ti heteroatoms to synthesize Ti-DZ-2 via exchange with framework B. Ti-DZ-2 contains isolated titanium centers in its crystalline framework, as shown by UV-Vis spectroscopy. The generality of the synthetic delamination approach and catalyst synthesis is demonstrated with the synthesis of delaminated material DZ-3, which is derived from layered zeolite precursor ERB-1(P) with MWW framework topology. Upon catalytic testing for the epoxidation of 1-octene with ethylbenzene hydroperoxide as oxidant, under harsh tail-end conditions that deactivate amorphous Ti-silica-based catalysts, Ti-DZ-2 exhibits the highest per-Ti-site activity, selectivity, and stability for 1-octene epoxidation of all catalysts investigated. This testing includes the prior benchmark delaminated zeolite catalyst in this area, Ti-UCB-4, which possesses similar external surface area to Ti-DZ-2 but requires sonication and long-chain surfactants for its synthesis. The synthesis of DZ-2 is the first example of an economical delamination of layered zeolite precursor SSZ-70(P) and opens up new doors to the development of delaminated zeolites as commercial catalysts.

Graphical abstract: SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis

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Publication details

The article was received on 25 Jul 2018, accepted on 03 Oct 2018 and first published on 03 Oct 2018


Article type: Paper
DOI: 10.1039/C8DT03044H
Citation: Dalton Trans., 2018, Advance Article
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    SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis

    A. Okrut, M. Aigner, C. Schöttle, N. A. Grosso-Giordano, S. Hwang, X. Ouyang, S. Zones and A. Katz, Dalton Trans., 2018, Advance Article , DOI: 10.1039/C8DT03044H

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