"

Synthesis of structured porous materials with a controlled pore structure at various scales supervisor: prof.dr.ir. M.-O. Coppens Background,  relevance, problem definition Goal Approach Publications

Background, relevance, problem definition
In recent years, great progress has been made in designing porous materials with a controlled nano-structure. It has been realized that a lot can be learnt from nature in designing the materials of the future. In this regard, it is important to observe that not only the nano-scale matters. Biophysical chemical processes are controlled at the molecular (nano-) scale, yet the accessibility of cells and small capillaries is equally important, because many of these processes are transport limited. This is a motivation to design new materials that do not only have a controlled structure at the micro-scale (molecular or nano-scale, such as microporous and mesoporous molecular sieves), but at scales ranging from the micro- to the meso- and the macro-scale.


Goal
The ultimate goal is to make multi-structured materials that have a specified pore size distribution on all scales. Manmade multi-structured, hierarchical materials can be of great use in catalysis, separations, optical, electrochemical and electronic applications.


Approach
Using a fully chemical route, we synthesize new types of bimodal structured silicas in which the small meso- and large meso- or macropore sizes and volumes can be controlled independently, while maintaining or improving the stability and the long-range structural order. The preparation consists of a sequential or combined use of various structure-directing agents, in an  appropriately tuned environment of acidity and temperature. Combinations of very narrow and broad pore size distributions can be imposed at different scales, as is often the case for natural materials. More specifically, nano-structured materials are cross-linked in a way which preserves the nano-structure, but creates a regular uni-sized, broad or continuous pore size distribution on larger scales. The basic material can be, e.g., MCM-41 or other mesoporous sieves; primary particles are chemically cross-linked to form a new porous material with a bimodal mesopore distribution, consisting of well-defined small mesopores of 3.3 nm as well as a broad distribution of tubular mesopores with a controlled pore size between 10 and more than 100 nm. The latter are intra- and not inter-particle pores. These materials can have very high N2 BET surface areas (1000 m²/g) and high porosity (up to 3.5 cm³/g), and at the same time have a very good molecular accessibility of their area through a well defined network of pores. Initial catalytic experiments demonstrate the potential of such materials.

The described method paves the way to the production of tailor-made silicas and other materials with any imposed spatial ordering. The materials are bio-mimetic in the sense that control is exerted at the regular uni-sized micro-scale, necessary for regulating the physico-chemical phenomena occurring at that scale, high surface areas can be obtained, and easy access toward that surface is  possible through a controlled pore structure at the larger meso- and macro-scale.

Publications
J. H. Sun, J .A. Moulijn, J .C. Jansen, Th. Maschmeyer and M.-O. Coppens, 2001, Alcotherma1 synthesis under basic conditions of an SBA-15 with increased long-range order and stability. Adv. Mat. 2001,13(5),327-331.

M.-O. Coppens, J. H, Sun and Th. Maschmeyer, 2001, Synthesis of hierarchical porous silicas with a controlled pore size distribution at various length scales. Catal. Today 2001,69, 331-335.

J. H. Sun, z. Shan, Th. Maschmeyer, J.A. Moulijn and M.-O. Coppens, 2001, Synthesis of tailored bimodal mesoporous materials with independent control of the dual pore size distribution. Chem. Commun. 2001,24,2670-2671.

J. H. Sun and M.-O. Coppens, 2002, Alcothermal synthesis of large pore, high quality MCM-48 silica. Stud. Surf. Sci. and Catal. In press.

J.H. Sun, Y. Q. Lei, J.H. Cao, W.Y. Xu, Study of cyanide-containing wastewater treatment by zinc-iron-cyanide complex, Journal of Taiyuan university of Technology, 1993, 24(3), 78-82.

J.H. Sun, Y. Q. Lei, J.H. Cao, W.Y. Xu, Kinetic studies of polyesterication of ethylene glycol and dibasic acid over resin, Journal of Taiyuan university of Technology, 1993, 24(4), 7-11.

J.Q. Li, G.H. Liu, J.X. Dong, J.H. Sun, J.H. Cao, W.Y. Xu, Synthesis of ZSM-35 zeolite in the extremely dense system and its characterization, Journal of Chinese Catalysis, 1994, 15(4), 304-308.

J.H. Sun, Y. Q. Lei, J.H. Cao, W.Y. Xu, Study of preparation and properties of layered metal oxide, Journal of Chinese Inorganic Chemicals industry, 1995, 5, 13-18.

J.H. Sun, Y.Q. Lei, New technology for the production of active zinc oxide from smithsonite, together with the production of potassium nitrate and ammonium chloride, Journal of Chinese Inorganic Chemicals industry, 1996, 2, 5-10.

J.H. Sun, Y. Q. Lei, J.H. Cao, W.Y. Xu, Ion-exchange properties of layered metal oxides, Journal of Taiyuan university of  Technology, 1996, 27(1), 50-55.

J.H. Sun, Y. Q. Lei, J.H. Cao, W.Y. Xu, Preparation and characteristics of K-Ni-Ti layered metal oxide, Journal of Taiyuan university of Technology, 1996, 27(2), 47-51.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Structure control of SiO2 sol-gels via addition of PEG, Studies in Surface Science and Catalysis, 1998, 118, 617-624.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Behavior of SiO2-PEG sol-gel processing in different pH medium, The Catalytic Prepared Technology, X.M. Zhou, Y.H. Sun, S.Y. Chen, Editors, Hanzhou University Press, 1998, 26-28.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Textural characterization of SiO2-PEG xerogels, The Catalytic Synthesis and Technology, X.M. Zhou, Y.H. Sun, S.Y. Chen, Editors, Hanzhou University Press, 1998, 46-48.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Sol-Gel technology and chemical tailoring of nano-sized materials, Chinese Chemical  Progress, 1999, *********

J.H. Sun, W.H. Fan, Y. Xu, D. Wu, Y.H. Sun, Nano-sized SiO2 sol-gel for structure-controlled optical coatings, Molecular  Crystals & Liquid Crystals Science and Technology (Section: A), 1999, 337, 85-88.

W.H. Fan, Y. Xu, J.H. Sun, D. Wu, Y.H. Sun, ZrO2-SiO2 coatings for wavelength-selective reflection filter, Molecular Crystals & Liquid Crystals Science and Technology (Section: A), 1999, 337, 497-500.

J.H. Sun, Z.H. Li, W.H. Fan, D. Wu, Y.H. Sun, The network structure and fractal behavior of SiO2-PEG sols, Chinese Journal of Chemical Physics, 1999, 12(5), 570-574.

J.H. Sun, Y.J. Gong, W.H. Fan, D. Wu, Y.H. Sun, Thermal physical chemical characteristics of SiO2-PEG xerogels, Acta Physico-Chimica Sinica, 1999, 15(6), 517-521.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Behavior of PEG in SiO2 sol-gel processing - Particle formation and growth, Journal of the Chinese Material Science, 1999, 19(3), 301-304.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Chinese Journal of Ceramic Social Bulletin, 1999, *****

Z.H. Li, J.H. Sun, D. Wu, Y.H. Sun, Y. Liu, W.J. Sheng, B.Z. Dong, Surface Area determination of SiO2 Xerogel by SAXS, Chinese Science Bulletin, 2000, 45(7), 706-710.

Z.H. Li, J.H. Sun, D. Wu, Y.H. Sun, Y. Liu, W.J. Sheng, B.Z. Dong, Study of sol structure by SAXS, Acta Physica Sinica,  2000, 49(4), 775-780.

Z.H. Li, J.H. Sun, D. Wu, Y.H. Sun, Y. Liu, W.J. Sheng, B.Z. Dong, Determination of average pore diameter of SiO2 xerogels  by small angle X-ray scattering, Acta Physica Sinica, 2000, 49(7), 1312-1315.

J.H. Sun, W.H. Fan, B. Zhang, D. Wu, Y.H. Sun, N.H. Yang, J.W. Zhou, Y. Yue, Preparation of mesoporous SiO2 via of triblock copolymer, Journal of Inorganic Materials, 2000, 15(1), 38-44.

J.H. Sun, Y.J. Gong, S.G. Wang, W.H. Fan, D. Wu, Y.H. Sun, N.H. Yang, J.W. Zhou, Y. Yue, Behavior of block copolymer in SiO2 sol-gel processing, Chinese Journal of Inorganic Chemistry, 2000, 16(1), 131-135.

J.H. Sun, D. Wu, Y.H. Sun, N.H. Yang, J.W. Zhou, Y. Yue, Textural characterization of SiO2-AEO xerogels, Acta Physico-Chimica Sinica, 2000, 16(2), 121-125.

J.H. Sun, Y.J. Gong, W.H. Fan, D. Wu, Y.H. Sun, Textural characterization of SiO2-PEG xerogels, Chemical Journal of Chinese  Universities, 2000, 21(1), 95-98.

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, Sol-gel chemistry and its application, Journal of the Chinese Material Science forward, 2000, *********

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, The network structure of SiO2 sols and their sol-gel derived optical coating, Journal of the Chinese Optical Technology, 2000, *******

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, The network structure of SiO2-PEG200 sols and their sol-gel derived optical coating, Journal of the Chinese Optical Technology, 2000, *******

J.H. Sun, W.H. Fan, D. Wu, Y.H. Sun, The network structure of SiO2 sols and their sol-gel derived optical coating, Journal of the Chinese Optical Technology, 2000, *******
 

Physical Chemistry and Molecular Thermodynamics
Julianalaan 136, 2628 BL Delft, The Netherlands, Phone: +31 15 2784748, Fax: +31 15 2788047,
Last update: 12 July, 2006 webmaster