Effect of Different Acid Treatments on the Properties of NiCoOx for CO-Catalyzed Oxidation

In this study, NiCo2O4 spinel catalysts were synthesized via the coprecipitation method. These catalysts were modified using 1 mol/L HCl, H2SO4, and HNO3, and their CO oxidation performance and sulfur tolerance were systematically investigated. The physicochemical properties of the catalysts were characterized by XRD, SEM, BET, H2-TPD, CO-TPD, O2-TPD, in situ DRIFTS, and XPS. The results indicate that the sulfur resistance of NiCo2Ox catalysts was improved to varying degrees after different acid treatments. Notably, the HCl-treated NiCo2Ox catalysts exhibited significantly increased chemisorbed oxygen content, more active sites, and superior low-temperature catalytic oxidation performance and sulfur resistance, achieving a CO conversion rate of 96.67% at 90 °C. However, when exposed to 350 mg/m3 SO2 (10 times the industrial emission standard) for 260 min, the CO catalytic performance of all acid-treated catalysts decreased to varying degrees or even completely deteriorated. Only the HCl-treated NiCo2Ox catalyst demonstrated the best performance.