SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis
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(NO_3)_2 and tetrabutylammonium fluoride. Powder X-ray diffraction data are consistent with a loss of long-range order along the z-direction, while ^(29)Si 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.
Additional Information
© 2018 The Royal Society of Chemistry. The article was received on 25 Jul 2018, accepted on 03 Oct 2018 and first published on 03 Oct 2018. The authors are grateful to the National Science Foundation (PFI: AIR-TT 1542974), which provided funding for enabling reported materials synthesis activities, and the Office of Basic Energy Sciences of U.S. Department of Energy (DE-FG02-05ER15696), which provided funding for undertaking all reported catalysis experiments. The authors are also grateful for the Management and Transfer of Hydrogen via Catalysis Program funded by Chevron Corporation, which provided funding for a postdoctoral fellowship to X. O. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. C. S. acknowledges Deutsche Forschungsgemeinschaft (DFG) for a research fellowship. Conflicts of interest: The authors declare the following competing financial interests: (1) The funding for the research partially came from Chevron Energy Technology Co. and (2) X. O. and S. I. Z. are employees and stockholders in Chevron Corp. (3) A.K. and A.O. have ownership in Berkeley Materials Solutions, a company that is commercializing zeolitic materials for applications in catalysis, including olefin epoxidation.Attached Files
Supplemental Material - c8dt03044h1_si.pdf
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Additional details
- Eprint ID
- 90263
- Resolver ID
- CaltechAUTHORS:20181012-101821745
- IIP-1542974
- NSF
- DE-FG02-05ER15696
- Department of Energy (DOE)
- Chevron Corporation
- DE-AC02-05CH11231
- Department of Energy (DOE)
- Deutsche Forschungsgemeinschaft (DFG)
- Created
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2018-10-12Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field