Simultaneous Removal of Gas-Phase Pollutants CO and NO Using Ni-Fe Bimetallic Oxides Catalyst

Abstract

Many studies have been conducted on methods to remove air pollutants. Among them, a representative commercial technology for reducing nitrogen oxides (NO<sub>X</sub>) is selective catalytic reduction (SCR) using NH<sub>3</sub> as a reductant. However, the NH<sub>3</sub>-SCR technology has problems, such as the need for additional NH<sub>3</sub> gas (Active-SCR), the fact that unreacted NH<sub>3</sub> (slipped-NH<sub>3</sub>) in the reaction process can be re-oxidized to NO<sub>X</sub>, and the facility system cost according to the added NH<sub>3</sub> gas. In order to solve these problems, CO gas that is naturally generated in industrial processes can be used, and NO and CO can be removed at the same time using passive-SCR technology that does not require a separate injection of a reductant. In this study, transition metals Ni and Fe were used as catalytic materials to replace expensive precious metals. The results confirmed that both NO<sub>X</sub> and CO removal efficiencies were about 90% or more in the catalyst with combined Ni-Fe, compared to the single catalyst. The addition of Ni to the Fe catalyst increased the catalytic reducing power, which also affected the increase in acid sites. Therefore, it is expected that this catalyst can simultaneously remove NO and CO without the use of NH<sub>3</sub> gas. These results could be explained through XRD, FT-IR, TEM, BET, H<sub>2</sub>-TPR and CO-TPD analyses, and compared to single catalysts, it was confirmed that the catalyst had higher low-temperature desorption ability for CO as a reductant and reducing capability.