Abstract
Due to the large population of vehicles, significant amounts of carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) are emitted into the atmosphere, causing serious pollution to the environment. The use of catalysis prevents the exhaust from entering the atmosphere. To better understand the catalytic mechanism, it is necessary to establish a detailed chemical reaction mechanism. In this study, the adsorption behaviors of CO and NO, the reaction of NO reduction with CO on the ZrO2 (110) and (111) surfaces was performed through periodic density functional theory (DFT) calculations. The detailed mechanism for CO2 and N2 formation mainly involved two intermediates N2O complexes and NCO species. Moreover, the existence of oxygen vacancies was crucial for NO reduction reactions. From the calculated energy, it was found that the pathway involving NCO intermediate interaction occurring on the ZrO2 (110) surface was most favorable. Gas phase N2O formation and dissociation were also considered in this study. The results indicated the role of reaction intermediates NCO and N2O in catalytic reactions, which could solve the key scientific problems and disputes existing in the current experiments.
Highlights
Heterogeneous catalysis always be used to decrease the emission of automobile exhausts (CO, nitrogen oxides (NOx) and HC), such as the Rhodium catalytic system to convert toxic gas NO to inactive productN2 [1,2]
Note that the energy barrier corresponding to TS1 (2.949 eV, Figure 6) is oxygen vacancy formation on surface is difficult at low-temperature
We found that carbon monoxide (CO) oxidation by surface lattice oxygen was the rate-determining step during the process of NO reduction with CO, the reaction barriers were 1.948 eV
Summary
Heterogeneous catalysis always be used to decrease the emission of automobile exhausts (CO, NOx and HC), such as the Rhodium catalytic system to convert toxic gas NO to inactive product. As zirconium dioxide (ZrO2 ) has high thermal stability, excellent redox properties and an acid–basic site on its surface, it is a good catalyst and support material for various reactions, such as CO2 methanation [3,4], water–gas shift [5,6], NH3 selective catalytic reduction [7,8], and hydrodeoxygenation [9,10]. The transition metal oxide dispersed onto the surface of ZrO2 exhibits powerful activity for NO reduction. Okamoto et al [11] found that Cu/ZrO2 catalysts showed high NO conversion to N2 at low temperature through a nitrous oxide (N2 O) intermediate for a NO–CO reaction. Koga et al discovered that c-ZrO2 (110) ultrathin film covering a Cu surface exhibited high NOx reduction activity [16].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
