In the field of catalysis our main interest is in the design of structural reactors applied in environmental protection. Structural reactors is an idea which allow to increase the mass and heat transfer of the reactants as well as enables for an easy scale-up of the process, which is a fundamental problem in the design of large-scale processes.
Practical use of such structures is dependent on the invention of active nanocomposite catalysts, to cope with the enhanced transport properties and precise methods for the preparation of catalysts with the desired structure and properties of the metal surfaces (structured reactors), which would not result in any change in their geometry. These are two main tasks that our Group deals with. The catalysts based on metal oxides are tested for their use in the process of combustion of volatile organic compounds and the reduction of nitrogen oxides. For the application of catalytic material on solid surfaces, apart of standard methods of deposition, Langmuir films and low-temperature plasma are used.
Currently, studies are carried out in collaboration with dr hab. Andrzej Kolodziej (Institute of Chemical Engineering, Polish Academy of Sciences, Gliwice and Department of Chemical Engineering, Technical University of Silesia), prof. Jacek Tyczkowski (Institute of Process Engineering and Environmental Protection, Technical University of Lodz) and prof. Stan Kołaczkowski (Department of Chemical Engineering, University of Bath, UK).
The development of heterogeneous catalysis has reached a level where many processes, to improve the efficiency of their course, depends only on the already insurmountable barrier transport of heat, momentum and mass. In the traditional heterogeneous catalysis carried out in fixed deposits in tubular reactors, transport processes are considered in the scale imposed by the grain size (> 10-3 m). Reducing the conventional tubular reactor by decreasing its diameter (10-2 m) and grain size.
Microstructured reactors are usually made from a specially shaped mesh, wire or sheet metal with specific surface areas (geometric) from 500 to more than 10 000 m2/m3. On specially prepared surfaces of such structured reactors a catalyst layer is deposited according to the requirements of the chemical process for which the reactor is being designed. In comparison with ceramic monoliths, structured reactors can provide a much better performance. In particular, they can get a lower diffusion resistance and flow resistance, lower thermal inertia and a greater resistance to thermal inactivation. Their advantage is that, the geometry can be optimized to meet the specific catalytic process.
The microstructure virtually eliminates the possibility of deposition of coke agglomerates, which is important for the processes associated with the conversion of hydrocarbons. Very small size channels in microstructures pose specific requirements for the preparation of the catalyst on the surface. From the point of view of designing microstructures, the catalyst should satisfy several conditions:
- have small, uniform, tightly controlled and repeatable thickness,
- exhibit very good adhesion to the substrate,
- has very good thermal and mechanical stability,
- have high activity, adapted to the increased transport parameters of the reactor.
These requirements eliminate many commonly used methods of preparation.
Several experiments and tests have shown that a promising method for the deposition of catalytic metal surfaces is a technique of nonequilibrium plasma. Such tests were performed in the laboratory of Prof. Jacek Tyczkowski. The choice of preparation conditions allowed the deposition on the surfaces of the structural carrier of the cobalt catalyst in the form of Co3O4 spinel with a high dispersion.