Pulse Chemisorption: Overview
Previous issues of AMI Notes have discussed different selective chemisorption techniques and how they may be used to determine the specific metal surface area of supported metal catalysts. One additional technique commonly used for the same purpose is pulse chemisorption. This method is one of the simplest, most straightforward ways to measure adsorbate uptake by a metal surface; however, as with most other measurements in catalysis, interpretation of the results can be problematic if the nature of the catalyst system and the experiment itself are not well-understood.
Pulse chemisorption is often used to calculate the particle dispersion and surface area of reduced metal catalysts supported on metal oxides. Both CO and H2 are commonly used adsorbates; CO equilibrates quickly and adsorbs more strongly to most metals, while H2 is effective and non-toxic.
A 2025 study by Kanuri et al. used an AMI 300 Chemisorption Analyzer with H2 adsorbate to calculate the dispersion and metallic surface area of Cu0 in CuO-ZnO-CeO2 catalysts.(1) Combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM), H2 pulse chemisorption was used to determine which synthesis method yielded the highest Cu dispersion. However, adsorbate gas is not limited to CO and H2. Warmuth et al. also used an AMI 300 with N2O gas to calculate the surface area of Cu0 catalyst supported on ZnO/ZrO2 and ZnO/ZrO2/SiO2.(2) They were able to quantify the decrease in Cu0 surface area as a function of reaction time on stream.
