Reports: ND555575-ND5: Supported Single-Atom and Subnanometer Pt Clusters for the Selective Oxidative Dehydrogenation of Ethane to Ethylene
Ayman M. Karim, PhD, Virginia Polytechnic Institute and State University
The goal of the project is to tune the selectivity of Pt for oxidative dehydrogenation (ODH) of ethane to ethylene by controlling the metal nuclearity in the subnanometer regime. This is achieved by controlling the synthesis of Pt/MgAl2O4 using strong electrostatic adsorption (varying the pH, metal loading as well as the pretreatment conditions) to achieve Pt ensemble size ranging from single atoms to subnanometer clusters to nanoparticles.
In the second year the focus was on testing the activity and selectivity of Pt/MgAl2O4 for ethane ODH. Catalysts with 100% single atoms were not very active due to the low weight loading. Therefore, while we are working on increasing the loading while maintaining Pt as atomically dispersed, we tested catalyst with higher weight loading where a mixture of single atoms and nanoparticles. The selectivity for C2H4 was low higher than on 100% Pt nanoparticles. The results suggest that the presence of small number of nanoparticles has a detrimental effect on selectivity. The focus in the final year is on increasing the loading of Pt single atoms and quantifying the activity and selectivity for ethane ODH and ethane hydrogenolysis to compare against Pt nanoparticles. Additionally, X-ray absorption spectroscopy studies is planned for beamtime acquired in December to determine the structure of Pt single atoms.