A study carried out by the “Laboratory of Catalysis and Catalytic Processes (LCCP)” group of the Department of Energy at Politecnico di Milano has been selected for the cover of the journal ChemCatChem. The article highlights the importance of describing from a molecular point of view the complex catalytic phenomena involved in reactions for the abatement of pollutants (NOx).

The study shows that the presence of water in the reduction hemicycle of the NH3-SCR redox mechanism changes the reaction environment at the molecular level. On the one hand, the addition of water to the system leads to a lower activation energy of the reaction due to kinetically relevant enthalpic stabilisation effects of the transition state. On the other hand, the reduced mobility of the transition state leads to entropic penalties that reduce the reaction rate.

Enrico Tronconi, co-author of the study, explains:

This study provides the first theoretical understanding of the role of water in the NH3-SCR process: this is technologically relevant in the field of pollution abatement because H2O is abundant as a reaction product.

Matteo Maestri, co-author of the study, adds:

Our research deepens the engineering importance of an atomistic study of catalytic mechanisms, providing a detailed description of the elementary steps and molecular identities involved in the reactions. These tools, in synergy with experimental work, play an important role in the optimisation and development of catalytic processes.