Studying catalysts and the catalytic process

Heterogeneous catalysts are typically multiphase systems where the structural and chemical states of the active species depend intimately on the process conditions. When characterizing a catalyst, it is therefore necessary to carry out the study under conditions, which are close to those encountered in an industrial reactor, i.e., to study the catalyst in place, or in Latin: in situ. With such studies it is possible to obtain detailed atomic-scale descriptions of the nanostructures and the sites where the catalysis takes place – the “active sites” – under reaction conditions.

Developing new techniques

The information gained from in situ studies is important for our understanding of a working catalyst, and Topsoe has over the years been world leading in the development of several novel in situ techniques.

Since most techniques have difficulties in dealing with both the structural complexity of the catalyst, and the demanding conditions of an industrial reactor, extensive developments in both techniques and in situ reaction cells have been carried out.

In situ methods

The most successful methods introduced are within the areas of X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Fourier Transformed Infrared Spectroscopy (FTIR), and Transmission Electron Microscopy (TEM).

XRD and XAS have the unique advantage that they can be applied while the catalyst is at high pressure and temperature allowing more realistic studies and thus more detailed insight into the catalyst structure.

Fourier Transformed Infrared (FTIR) spectroscopy has been very valuable in providing information on the surface properties of the catalysts.

The Transmission Electron Microscope

Recently, we have been involved in the development of a novel high resolution Transmission Electron Microscope (TEM) with in situ capabilities.

The in situ techniques are also ideally suited for time-resolved studies making investigations of dynamic phenomena of the catalyst structure and chemical properties feasible. 

Watch the ETEM film clips recorded in our laboratory