Catalytic activity and sulfur resistance of Pt-Pd and Rh-Pd bimetallic catalysts for methane combustion

Abstract

The increasing use of natural gas in applications such as natural gas engines has led to a rise in methane emissions. Given the negative impact of methane on global climate, controlling its emissions using catalysts has become essential. Noble metal catalysts, such as Pd-based catalysts, have been extensively studied and applied due to their excellent catalytic activity for methane oxidation. However, the presence of moisture and SO₂ in real engine exhaust conditions causes severe deactivation of Pd-based catalysts. To address this issue, researchers have conducted extensive studies on introducing a second metal into Pd-based catalysts to form bimetallic catalysts.
In this study, Tetraamminepalladium(II) nitrate solution, Tetraammineplatinum(II) nitrate, and Rhodium(III) nitrate hydrate were used as precursors, and Al₂O₃-ZrO₂ was used as the support. Monometallic catalysts of Pt, Pd, and Rh, as well as bimetallic Pt-Pd and Rh-Pd catalysts with varying metal loadings, were prepared using a co-impregnation method. Various characterization techniques were employed to determine the physico-chemical properties of the catalysts. The catalytic activity for methane combustion and the resistance to moisture and sulfur poisoning were evaluated.
The main research work and findings of this thesis are summarized as follows:
The study investigated the effects of different Pt-Pd and Rh-Pd molar ratios on methane oxidation performance under dry, wet, and sulfur-containing conditions. Through structural analysis, surface property characterization, and performance testing of bimetallic catalysts prepared with three molar ratios (1:10, 1:5, and 1:2) as well as monometallic catalysts, it was found that the molar ratio significantly influenced the catalyst’s crystal structure, chemical state, and redox ability.

Bimetallic catalysts with appropriate molar ratios exhibited pronounced synergistic effects between the two noble metals, which effectively improved the sintering resistance, enhanced high-temperature thermal stability, strengthened redox capacity, and increased resistance to moisture and sulfur poisoning. These improvements ultimately enhanced the methane oxidation activity compared to monometallic catalysts.

Date of Award	13 Jul 2025
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Jun He (Supervisor) & Abubakar Yusuf (Supervisor)