Heterogeneous catalysis

Up-to-date research topics and overview of the Team's research focus

Initially developed methodologies for studying the adsorption and desorption processes of probes and alkali molecules from the surface of solids, using vacuum and high-pressure systems equipped with in situ FTIR spectrometers and unique field and surface ionisation detectors, have given way to new research topics. Research can now be positioned at the interconnection of biological, chemical and engineering sciences.

The team specialises in in situ and operando spectroscopy and microscopy for the study of catalytic solids under realistic conditions. This approach provides unique insights into the mechanisms of activation and deactivation of catalytic reactions, as well as the internal structure of solid catalysts. Research is performed with a view to their application for existing technological processes (e.g. methane combustion, ammonia synthesis, ethylbenzene dehydrogenation) as well as the discovery of new materials (e.g. hybrid and functional materials), new synthesis methods (e.g. use of low-temperature plasma, electrospinning) and new reactor solutions (e.g. new structures as reactor fillers).

In situ and operando research

research on materials for industrial use

Functional materials synthesis

Development of methods of synthesis of materials for applications in chemistry, medicine, etc.

Reactor engineering

for environmental protection processes

Cooperation offer

with industry and research bodies in the field of materials chemistry

Research topics

Development and use of advanced spectroscopic methods (in situ)

The limitation of understanding the surface structure of materials can be overcome by using surface probe molecules and observing their behaviour using in situ and operando spectroscopy methods (several spectroscopic methods applied simultaneously with additional analysis of gaseous products).

Among the methods available, we use UV-Vis spectroscopy, Fourier Transformed Infrared Spectroscopy (FTIR) and Raman microscopy to track changes in the structure of the metal oxide. Complementarily, Raman and FTIR microscopy allows the structure of adsorbates and reaction transition products to be assessed. UV/VIS spectroscopy is to be used to assess the electron exit work of the oxide and therefore to classify the catalyst activity.

In the field of oxidation-reduction reactions in which we are involved, the main probe molecules are methane molecules, methanol, and carbon monoxide.

Catalytic conversion of biomass, methane and nitrogen oxides

The catalytic combustion of volatile organic compounds has been the subject of intensive research by scientists in recent years. Since catalysts commonly used in industry contain noble metals (e.g. platinum or palladium) as the main active element, current research seeks to minimise the proportion of the aforementioned metals and to build catalysts based on commonly available components (and thus reduce the final price of the catalyst). The desired catalyst characteristic is mainly high catalytic activity. Current catalysts are highly susceptible to poisoning through improperly conducted combustion and the generation of afterburning by-products. Thus, their use requires a preliminary gas analysis and elimination of factors that can reduce their activity. Despite many years of intensive research, the mechanism of hydrocarbon afterburning conducted on the catalyst bed is not fully understood. The various mechanisms discussed extensively in the literature (reaction pathways according to Langmuir-Hinshelwood, Mars van Krevelen or Eley-Rideal) must be confirmed by studies of the intermediates formed during the combustion of hydrocarbons.

Engineering of catalytic reactors

In the field of catalysis, we are looking at structured reactors in environmental processes. Structured reactors are an idea for increasing the mass and heat transport parameters of reactants, as well as for arbitrarily scaling up processes, which is a fundamental engineering problem in the design of large-scale processes.

The practical use of such structures depends on the invention of active nanocomposite catalysts to cope with the increased transport properties, as well as precise methods for the preparation of catalysts with a preset structure and properties on metal substrates (structural reactor fillers) that would not alter their geometry. These are the two main tasks addressed by the Team. Catalysts based on metal oxides are being investigated for their use in the combustion of volatile organic compounds and the reduction of nitrogen oxides. For the application of catalytic material to solid substrates, the Langmuir film method and the low-temperature plasma method have so far proved successful.

The development of heterogeneous catalysis has reached a level where, for many processes, improvements in their efficiency already depend solely on overcoming the barriers of heat, momentum and mass transport. In conventional heterogeneous catalysis running in solid beds in tubular reactors, transport processes are considered at the scale imposed by the grain size (>10-3 m). Scale down in a conventional tubular reactor by reducing its diameter (10-2 m) and grain size.

Microstructured reactor fills are usually made of specially shaped grids, wires or sheets with specific (geometric) surfaces ranging from 500 to more than 10 000 m2/m3. A catalyst layer with properties corresponding to the requirements of the chemical process in question is deposited on the suitably prepared surfaces of such fillings.

Compared to ceramic monoliths, structurally filled reactors can provide significantly better performance. In particular, they can achieve lower diffusion and flow resistance, lower thermal inertia and greater resistance to thermal deactivation. They also have the advantage that, the filling geometry can be optimised for the specific catalytic reaction. It has been shown that in mesh and short-channel microstructures, operating in the region of evolving laminar flow and designed for hydrocarbon combustion reactions, high transport coefficients can be achieved with low flow resistance, as well as essentially reducing reactor dimensions. In addition, the microstructures virtually eliminate the possibility of coke agglomerates settling and clogging the channels by them, which is important for hydrocarbon conversion processes.

The very small channel sizes in the microstructures place particular demands on the catalyst preparation on their surface. From the point of view of microstructure design, the catalyst, including all primers, should fulfil three conditions:

have a small, uniform, strictly controlled and reproducible thickness to allow it to be taken into account already at the structure design stage,
have very good adhesion to the substrate, mechanical and thermal stability,
have high activity, adapted to the increased transport parameters of the reactor.

These requirements preemptively eliminate many commonly used preparation methods.

Molecular engineering of catalytic materials

Synthesis and characterisation of porous materials with catalytic potential and using transition metal oxides. The focus is on a fundamental understanding of the formation processes of porous oxides, the development of spectroscopic tools for the evaluation of synthesis parameters and structural aspects of the materials. This provides a kind of prelude to Catalytic Materials Engineering, as the correlation of the structural properties of materials with their catalytic properties (performance, stability, etc.) allows for the rational design and creation of catalysts.

Functional nanomaterials – design and characterisation

Nanotechnology of functional materials is a new branch of our interest, but nevertheless very exciting. Research topics boil down to the development of new nanoscale engineered materials (e.g. nanoparticles, nanofibres) for biological, chemical and other applications.