Abstract
As a new class of porous materials, pillared clays have been more and more investigated as a potential substituent or complement to zeolite materials. Despite of intensive research, real industrial applications are still lacking. Somehow, the porosity of these materials is lower than what was expected. To evaluate the potential of the pillared clays as adsorbent, theoretical calculations were carried out to obtain a better insight of the influence of the PILC's macrostructure on the micro- and mesoporosity.
Assuming the layers to stack in a 3-dimensional brick-like fashion, the micro- and mesoporosity and interpillar free distance were calculated taking into account: the clay layer dimensions, interlayer free spacing, lateral distance between adjacent layers, partial pillaring/collapse and pillar symmetry. The calculations were performed for Al-pillared montmorillonite and hectorite and validated with experimental results.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Abbreviations
- a :
-
height of the mesopore
- Al-pilM:
-
aluminium pillared montmorillonite
- Al-pilH:
-
aluminium pillared hectorite
- b :
-
lateral distance between two stacks
- CEC:
-
cation exchange capacity meq/g
- d pp :
-
interpillar free distance
- H :
-
height of a clay layer Å
- IFS:
-
interlayer free spacing Å
- L :
-
length and width of a clay layer Å
- P :
-
pillar height Å
- pil/g:
-
number of pillars in 1 g clay
- (pil/g)in :
-
number of pillars, in 1 g clay, intercalated between the layers
- (pil/g)out :
-
number of pillars, in 1 g clay, not intercalated
- (pil/g)tot :
-
total number of pillars in 1 g clay
- pl/g:
-
number of clay layers in 1 g clay
- s :
-
number of layers in a stack
- SAav :
-
layer surface area available for pillaring m2/g
- SABET :
-
BET surface area m2/g
- SAmax :
-
maximum surface area of the clay layers m2/g
- SA avmeso :
-
available surface area in the mesopores m2/g
- Ustr:
-
unit structure
- Ustr/g:
-
number of unit structures in 1 g clay
- Vfree :
-
free volume in the unit structure
- V avmeso :
-
calculated available mesopore volume cc/g
- V ultmeso :
-
calculated ultimate mesopore volume cc/g
- V avmicro :
-
calculated available micropore volume cc/g
- V ultmicro :
-
calculated ultimate micropore volume cc/g
- V1pil :
-
volume of one pillar cc/g
- Vpil(in):
-
total volume of the pillars between the layers cc/g
- Vpil(out):
-
total volume of the pillars outside the layers cc/g
- Vtot :
-
total pore volume atp/p 0 = 0.98 cc/g
- Wpil :
-
width of a pillar Å
- Wt%pil :
-
weight percentage Al2O3 present as pillars
References
R. Burch,Catalysis Today (Elsevier Science Publishers, Amsterdam, 1988).
I.V. Mitchel,Pillared Layered Structures: Current Trends and Applications (Elsevier Applied Science, London, 1990).
M.L. Occelli and H.E. Robson,Expanded Clays and Other Microporous Solids (Van Nostrand Reinhold, New York, NY, 1992).
T.J. Pinnavaia, Science220, 365 (1983).
R.A. Schoonheydt, J. Van den Eynde, H. Tubbax, H. Leeman, M. Stuyckens, I. Lenotte, and W.E.E. Stone, Clays Clay Miner.41(5), 598 (1993).
R.A. Schoonheydt, H. Leeman, A. Scorpion, I. Lenotte, and P. Grobet, Clays Clay Miner.42(5), 518 (1994).
L. Mercier and C. Detellier, Clays Clay Miner.42(1), 71 (1993).
J.H. De Boer, B.G. Linsen, and T.H.J. Osinga, J. Catalysis4, 643 (1965).
H.Y. Zhu, N. Maes, A. Molinard, and E.F. Vansant, Microporous Materals3, 235 (1994).
N. Maes, H.Y. Zhu, and E.F. Vansant, J. Porous Materials2, 97 (1995).
L. Bargaoui, J.-F. Lambert, R. Franck, H. Suquet, and J.-L. Robert, J. Chem. Soc. Faraday Trans.91(14), 2229 (1995).
N. Maes, I. Heylen, P. Cool, M. De Bock, C. Vanhoof, and E.F. Vansant, J. Porous Materials (1996), (submitted).
P. Cool, N. Maes, I. Heylen, M. De Bock, and E.F. Vansant, J. Porous Materials (1995), (submitted).
M.L. Occelli, J.M. Dominguez, and H. Eckert, J. Catalysis141, 510 (1993).
A. Clearfield and B.D. Roberts, Inorg. Chem.27, 3237 (1988).
A. Molinard,Physicochemical and Gas Adsorption Properties of Ion Exchanged Alumina Pillared Clays (Ph.D. Thesis, University of Antwerp (UIA), Belgium, 1994), p. 71.
S.J. Gregg and K.S.W. Sing, Adsorption, Surface Area and Porosity (Academic Press Inc., London, 1982).
R.A. Schoonheydt,Clays, from two to three Dimensions in Studies in Surface Science and Catalysis (Elsevier Science, B.V., Amsterdam, 1991).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
De Bock, M., Maes, N., Cool, P. et al. Theoretical evaluation of pillared clay adsorbents: Part III: The total porosity and the macrostructure of Al-pillared montmorillonite and hectorite. J Porous Mater 3, 207–216 (1996). https://doi.org/10.1007/BF01137909
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01137909