Spatially resolving infrared spectroscopy for parallelized characterization of acid sites of catalysts via pyridine sorption: Possibilities and limitations

A new high-throughput analysis setup has been developed to investigate the acidity of up to eight solid materials in a parallel way. This method applies an IR focal plane array detector and an especially designed measurement cell adapted to this system. The whole system was validated by using zeolite Y, H-ZSM-5, and H-Mordenite as acidic materials and amorphous silica as nonacidic material. It was found that with zeolite Y and H-ZSM-5 it is possible to get IR spectra of the adsorbed pyridine with comparable quality as that in a conventional setup. By heating the samples in the measurement cell it is possible to follow the desorption of the adsorbed pyridine to distinguish different adsorbed pyridine species on the surface. For amorphous silica only physisorbed pyridine has been found and after heating of the sample there was no pyridine left. In contrast to this it was not possible to analyze the acid sites of H-Mordenite with this setup. This could be due to scattering effects caused by the particle size of the material which has a severe influence on the feasibility of measurements in this setup. Also other adsorptives could be used in this cell to analyze different surface properties.