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Microporous PILCs : Synthesis, pillaring mechanism and selective cation exchange

Title data

Stöcker, Melanie ; Seyfarth, Lena ; Hirsemann, Dunja ; Senker, Jürgen ; Breu, Josef:
Microporous PILCs : Synthesis, pillaring mechanism and selective cation exchange.
In: Applied Clay Science. Vol. 48 (March 2010) Issue 1-2 . - pp. 146-153.
ISSN 0169-1317
DOI: https://doi.org/10.1016/j.clay.2009.11.013

Abstract in another language

Based on a 3-dimensionally ordered, synthetic Cs-hectorite (Cs0.56[Mg2.44Li0.56]<Si4> O10F2) a truly microporous pillared inter-layered clay (PILC) was obtained by intercalation of diprotonated DABCO molecules (DABCO = 1,4-diazabicyclo[2.2.2]-octane). Not only is the stacking order retained upon pillaring (C 2/m (no. 12); a = 5.247(1) Å, b = 9.083(2) Å, c = 14.581(5) Å and β = 96.799°), additionally, a 2-dimensional long range order of the pillars in the interlamellar space was observed. Indexing proved this 2-dimensional superstructure to be commensurable with the host (a⁎ ≈ 3 × a = 15.731(3) Å, b⁎ ≈ b = 9.090(2) Å). This in turn suggests that it is not the electrostatic repulsion between the positively charged pillars but instead the host–guest-fit that determines the lateral arrangement of pillars in the interlamellar space.

The large crystal sizes, which this PILC comes with, allowed to verify that intercalation of the organic pillars follows the ring mechanism in accordance with what has been proposed some years ago by Weiss et al. (1970).

Noteworthy, upon intercalation, the acidic protons undergo a fast dynamic exchange between the pillars, water molecules present in the micropores, and framework atoms of the host. Consequently, a considerable amount of the open space between the pillars is actually occupied by H3O+ and H2O, which cannot be removed completely by drying. Interestingly, a selective partial cation exchange of these acidic protons by Na+ could be achieved.

Thus, pillaring with 2H-DABCO affords a well ordered, Brønsted-acidic, microporous material with a narrow pore size distribution.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Clay; Hectorite; Intercalation mechanism; Microporous hybrid material; PILC; Porosity
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry I > Chair Anorganic Chemistry I - Univ.-Prof. Dr. Josef Breu
Research Institutions > Collaborative Research Centers, Research Unit > SFB 840 Von partikulären Nanosystemen zur Mesotechnologie
Research Institutions > Collaborative Research Centers, Research Unit > SFB 840 Von partikulären Nanosystemen zur Mesotechnologie > SFB 840 - TP A 6
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry I
Research Institutions
Research Institutions > Collaborative Research Centers, Research Unit
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 540 Chemistry
Date Deposited: 23 Mar 2018 07:56
Last Modified: 23 Mar 2018 07:56
URI: https://eref.uni-bayreuth.de/id/eprint/9953