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Issue 27, 2014
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High acidity unilamellar zeolite MCM-56 and its pillared and delaminated derivatives

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Abstract

The unilamellar form of zeolite MWW, MCM-56, which is obtained by direct hydrothermal synthesis has been studied with regard to acidity and porosity in its original and post-synthesis modified pillared and delaminated forms. The acidity measured by FTIR was found to be only slightly lower than the highly active 3-D MWW forms, MCM-22 and MCM-49. Pivalonitrile adsorption, which is a measure of spatial openness, showed 50% accessibility vs. <30% for MCM-22/49. It highlights the potential of MCM-56 as a layered material with increased access to acid sites because it does not entail laborious post-synthesis modification. Swelling, pillaring and delamination of MCM-56 are facile but result in a reduction in the number of Brønsted acid sites (BAS) while increasing accessibility to pivalonitrile. The delamination procedure involving sonication and acidification of the highly basic mother liquor produces the most visible increase in surface area and access to all BAS. The accompanying doubling of the solid yield and the decrease in absolute number of BAS suggest significant precipitation of dissolved silica generated during swelling and sonication in high pH medium. The viability of separating surfactant covered layers upon sonication with the consequence of exposing hydrophobic hydrocarbon tails to aqueous environment is addressed.

Graphical abstract: High acidity unilamellar zeolite MCM-56 and its pillared and delaminated derivatives

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Publication details

The article was received on 14 Jan 2014, accepted on 20 Feb 2014 and first published on 21 Feb 2014


Article type: Paper
DOI: 10.1039/C4DT00130C
Citation: Dalton Trans., 2014,43, 10501-10511

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    High acidity unilamellar zeolite MCM-56 and its pillared and delaminated derivatives

    B. Gil, W. Makowski, B. Marszalek, W. J. Roth, M. Kubu, J. Čejka and Z. Olejniczak, Dalton Trans., 2014, 43, 10501
    DOI: 10.1039/C4DT00130C

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