Issue 27, 2014

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

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

Supplementary files

Article information

Article type
Paper
Submitted
14 janv. 2014
Accepted
20 févr. 2014
First published
21 févr. 2014

Dalton Trans., 2014,43, 10501-10511

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

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements