TY - JOUR

T1 - Probing the Nature of Active Centers in Pt-Cu/TiO2 Catalysts for Selective Ammonia Oxidation

AU - Kibis, Lidiya s.

AU - Ovsyuk, Ivan yu

AU - Popov, Anton a.

AU - Svintsitskiy, Dmitry a.

AU - Slavinskaya, Elena m.

AU - Stonkus, Olga a.

AU - Korenev, Sergey v.

AU - Boronin, Andrei i.

N1 - This work was funded by the Russian Science Foundation (project no. 23-23-00322, 12.01.2023). The TEM experiments were carried out using the facilities of the shared research center “National Center of Investigation of Catalysts” at the Boreskov Institute of Catalysis.

PY - 2024/11/7

Y1 - 2024/11/7

N2 - The activity and selectivity of catalytic systems are influenced by many important factors, such as the composition of the surface, the size and structure of the active sites, as well as the oxidation state of the active components. In this study, we investigated the nature of the active components in Pt/TiO2 catalysts for selective ammonia oxidation upon their modification with copper. Analysis using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) revealed that an increase in copper content led to a significant dispersion of platinum particles due to the formation of subnanoscale Pt(Cu)Ox species. Application of temperature-programmed reduction (TPR-H2) and X-ray photoelectron spectroscopy (XPS) techniques provided valuable data on the redox properties of the catalysts. The introduction of copper resulted in a notable increase in the fraction of oxidized platinum. Once reduced, platinum in the composition of the Pt-Cu/TiO2 catalysts was easily reoxidized upon subsequent exposure to oxygen already at room temperature. The Pt-Cu/TiO2 catalysts comprised oxidized copper species, which demonstrated more labile redox behavior at lower temperatures compared to the Cu/TiO2 catalyst. The facilitated redox transitions of the active components contributed to the enhanced selectivity of the Pt-Cu/TiO2 samples toward N2 by affecting the reaction mechanism. The obtained results provide new insights into key aspects governing the effective oxidation of slip ammonia at low temperatures.

AB - The activity and selectivity of catalytic systems are influenced by many important factors, such as the composition of the surface, the size and structure of the active sites, as well as the oxidation state of the active components. In this study, we investigated the nature of the active components in Pt/TiO2 catalysts for selective ammonia oxidation upon their modification with copper. Analysis using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) revealed that an increase in copper content led to a significant dispersion of platinum particles due to the formation of subnanoscale Pt(Cu)Ox species. Application of temperature-programmed reduction (TPR-H2) and X-ray photoelectron spectroscopy (XPS) techniques provided valuable data on the redox properties of the catalysts. The introduction of copper resulted in a notable increase in the fraction of oxidized platinum. Once reduced, platinum in the composition of the Pt-Cu/TiO2 catalysts was easily reoxidized upon subsequent exposure to oxygen already at room temperature. The Pt-Cu/TiO2 catalysts comprised oxidized copper species, which demonstrated more labile redox behavior at lower temperatures compared to the Cu/TiO2 catalyst. The facilitated redox transitions of the active components contributed to the enhanced selectivity of the Pt-Cu/TiO2 samples toward N2 by affecting the reaction mechanism. The obtained results provide new insights into key aspects governing the effective oxidation of slip ammonia at low temperatures.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85208278042&origin=inward&txGid=108c900c09e0b8c846c233e5cb984aa3

U2 - 10.1021/acs.jpcc.4c06021

DO - 10.1021/acs.jpcc.4c06021

M3 - Article

VL - 128

SP - 18793

EP - 18806

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 44

ER -