The Laboratory of Adsorption and Catalysis at the University of Antwerpen is an internationally recognized and specialized research laboratory for:
(a) the synthesis and characterization of micro-, meso- and combined micro/mesoporous siliceous and non-siliceous materials,
(b) pore size engineering in porous structures by impregnation techniques, ion-exchange processes and chemical modification reactions and
(c) the development of chemical activation/deactivation processes in porous materials.
Recently, the synthesis and properties tuning of various silica based mesoporous organic hybrid materials are under investigation. The skills of this research group are focused on the development of new synthesis routes, new chemical modification processes to tune the material properties towards applications in the area of adsorption, separation and catalysis. An extensive experience is present for detailed characterization and evaluation of the performance of porous solids.
In the area of synthesis and catalysis, the research group focuses on the following topics:
By controlling the synthesis methods and the modification techniques of a broad range of porous materials, designed materials are formed for specific applications in the field of adsorption and catalysis. The focus is on microporous, mesoporous and combined micro/mesoporous materials as well as on organic-inorganic hybrid materials. Both siliceous and non-siliceous materials are developed.
Following topics are currently under investigation:
i) Mesoporous siliceous materials with internal nanoparticles: nanoparticles (zeolite precursors, transition metal oxides) are introduced into mesoporous materials (MCM, SBA, MCF,…) by post-synthesis impregnation or in-situ synthesis methods. The obtained materials having both open and narrowed sections in their mesopores, exhibit unique properties (diffusion, stability,…) that can be adjusted to the application (sorption, catalysis, encapsulation, separation,…)
ii) Combined micro- and mesoporous materials: These materials are known to have advantages towards diffusion, stability, multifunctionality to process a wide variety of feeds, capabilities to encapsulation, controlled release,…They are prepared by a templated method using zeolite precursor particles.
iii) Hybrid organic-inorganic materials: The selectivity and stability of mesoporous materials are changed by modifying the inorganic materials with organic functional groups. This can be done by grafting (post-modification) or by co-condensation (in-situ) or by synthesizing PMO’s (periodic mesoporous organosilica’s). Also microporous hybrid materials can be made by grafting or in a direct way (metal organic framework-MOF). Moreover, the modification methods also apply on metal oxides or silica films and membranes.
iv) Mesoporous photocatalytically active transition metal oxides: Mesoporous transition metal oxides (TiO2, SnO2, ZnO, …) are prepared via different synthesis approaches such as sol-gel route, EISA method, carbon replicas or other templated routes. Also template free, fast synthesis routes of e.g. nanotubes is one of the main topics.
Among the research activities related to catalysis is the activation, combined with a stabilization, of ordered mesoporous materials with transition metals.
Active catalysts can be made from ordered mesoporous materials by:
i) Molecular designed dispersion of the heteroatoms on the surface of the catalyst. To make active catalysts, the metals V, Cr, Ti, Mo, Fe and Al are used.
ii) Plugged hexagonal templated silicas (PHTS materials) containing catalytically active plugs in the mesoporous channels: The obtained materials have a combined micro- and mesoporosity and a high mechanical and hydrothermal stability.
iii) Use of multifunctional chloro- or alkoxysilanes: The obtained materials have an improved mechanical and hydrothermal stability. Furthermore, leaching of the active centers can be drastically reduced in liquid-phase catalytic reactions.
iv) Direct hydrothermal incorporation of active metals during the synthesis of the mesoporous materials or use of starting materials with intrinsically incorporated heteroelements.
v) Hybrid organic-inorganic materials for heterogenization of homogeneous catalytic reactions.
Furthermore, the Antwerp group focuses on liquid-phase reactions and photocatalytic degradation reactions under UV radiation. In a first step, the characteristics of the catalyst, such as leaching, hydrothermal stability, regeneration and mechanical strength are evaluated. The activity and product selectivity will be compared – initially by using a simple test reaction – with commercial and/or conventional catalysts. In a second step, industrially more relevant synthetic reactions from the fields of fine chemicals, pharmacy and petrochemistry can be investigated.