Engineered Catalytic Metal—Metal-Oxide Nano-heterostructures for CO Oxidation

Abstract

Owing to its interesting chemistry and toxic nature, catalytic oxidation of CO is of both fundamental and practical interest. Two applications, viz. CO conversion in the catalytic converters and pre-treatment of CO-rich reformate feed for the polymer electrolyte membrane fuel cells (PEMFCs) stand out because of their focus on the current and future energy scenario, respectively. Both demand catalytic oxidation of CO to CO2 at low temperatures. To facilitate this, in this thesis, we address various aspects of the catalyst playing a role during CO oxidation. The heterogeneous catalysts generally employed for CO oxidation rely on the use of noble metals supported on reducible metal oxides, as this combination leads to exceptionally good synergistic properties for CO oxidation. Here, we have investigated different heterostructure systems for CO oxidation and preferential CO oxidation (PrOx) reactions The thesis addresses preferential CO oxidation (PrOx) to purify H2 for the fuel cell feed, at operating temperatures of PEMFCs. To develop such catalysts, along with introducing the oxygen vacancies in the support, engineering the supported-metal for their better selectivity is another feasible option. A facile nucleation of PtCu alloy nanoparticles is done over the reduced SrTiO3 support in four different compositions. These PtCu decorated supports are tested for their activity in preferential oxidation of CO under excess hydrogen. The effect of Cu dilution in the Pt catalyst is discussed with respect to the activity, selectivity and stability of the catalysts for preferential CO oxidation. In conclusion, various prospects of the catalytic nano-heterostructures presented in this thesis are presented. The insights obtained from this thesis work can be utilized in understanding fundamental aspects of the catalysts required to prepare commercially viable catalysts for CO oxidation as well as preferential CO oxidation