Improved catalytic NO oxidation over Pt supported on sulfuric acid treated TiO2

• Published in: Separation and purification technology 2025-05, Vol.357, p.130033, Article 130033
• Main Authors: Bin Bae, Wo, Park, Jiseok, Jin Go, You, Woo Byun, Sang, Shin, Hyeonwoo, Jin Kim, Young, Hee Jang, Jun, Bong Kang, Sung
• Format: Article
• Language: English
• Subjects: Dispersion and phase; NO oxidation; Pt/TiO2; Sulfuric acid treatment; Surface acidity
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.130033

[Display omitted] •Pt/SA-TiO2 exhibits enhanced NO oxidation performance compared to Pt/TiO2.•Highly dispersed Pt0 and Pt2+ on SA-TiO2 leads to improve the NO oxidation performance.•SA-treatment leads to a uniform distribution of Pt over TiO2 via increased acidic sites.•The decomposition of Pt-amine-SOx bonding prevents the formation of Pt4+. Promoting the formation of metallic Pt over the catalysts is the key to improving the NO reactivity. In general, TiO2 suppresses the oxidation of Pt by surface acidity and induces the formation of the metallic phase of Pt by Pt-Ti interaction. However, the limited number of acidic sites (–OH) contributes to the formation of large Pt particles, which may lead to the formation of Pt2+ or Pt4+, resulting in performance degradation. In this study, we further formulated the acidic sites of the TiO2 with sulfuric acid treatment (SA-TiO2) to improve catalytic NO oxidation. During the SA treatment, the TiO2 surface is positively charged by the low pH, providing an environment for well-distributed sulfate. In the subsequent introduction of Pt, the increase in acidic sites for Pt adsorption greatly enhanced the dispersion of Pt. During this process, Pt formed bonds with sulfate as [Pt(NH3)4]-SO4. The surface species combined with SO4 and NH3 were decomposed during the calcination process, thereby inhibiting the oxidation of Pt, which promotes the formation of metallic Pt. As a result, highly reactive Pt0 and Pt2+ were further formulated by increasing the acidic sites of SA-TiO2, where the low-temperature NO oxidation performance was improved, regardless of the Pt loading (0.3 to 3 wt.%).