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Enhancing the resistance of SCR (Selective Catalytic Reduction) catalyst to K poisoning can be effectively achieved through modification. This study investigated the impact of transition metal modification on improving the ability of Ce/TiO 2 (CT) catalysts to resist K poisoning by DFT (Density functional theory) calculations. Mo-, Nb-, and W-doping could effectively suppress the adsorption of K. O v (oxygen vacancy) formation and hydrogenation reactions were both facilitated due to the modification of Cu, Co and Sb. The Cu-doping had a significant contribution to the adsorption of NH 3 and NO, and showed the best resistance to K poisoning in the adsorption of reactive species. Additionally, Cu-doping decreased the energy barriers for NH 3 dehydrogenation, NH 2 NO generation and decomposition, and NO 2 formation on CT catalyst, and weakened the inhibition effect of K on the above elementary reactions. Consequently, this provided an effective improvement in the k-poisoning tolerance of the CT catalysts. [Display omitted] • A method for screening modified elements based on DFT calculation was reported. • M-doping benefits hydrogenation, oxygen vacancy formation, and adsorption of NH 3 /NO. • M-doping mitigated the toxic effect of K in adsorption energy and energy barrier. • The modification effect of Cu was better than that of Co, Sb, Mo, Zr, Nb, W. • CCuT extremely weakened the inhibition of E-R and L-H mechanisms by K. [ABSTRACT FROM AUTHOR]

• Na poisoning mechanism on Ce/TiO 2 (001) surface was studied by DFT calculations. • Ce/TiO 2 (001) surface was easily poisoned due to the high affinity with Na. • Na doping changed the catalyst structure and reduced the reactivity of the surface. • Na poisoning significantly increased the energy barrier of elementary reactions. • Both Eley-Rideal and Langmuir-Hinshelwood mechanisms were inhibited. The presence of alkali metal Na in flue gas can significantly impair the reactivity of Ce/TiO 2 (CT) SCR (Selective Catalytic Reduction) catalyst. This study investigates the deactivation mechanism of Na on the Ce/TiO 2 catalyst using Density Functional Theory (DFT) calculations, focusing on the adsorption of surface species and the pathway of elementary reaction. Due to the high affinity between Na atom and the catalyst surface, Na poisoning readily occurs on Ce/TiO 2 (001) surface. The presence of Na on the catalyst surface hampers hydrogenation, oxygen vacancy formation, and NH 3 adsorption, while also reducing the catalyst's acidity and reducibility. Additionally, Na impedes the NH 3 dehydrogenation reaction, as well as the formation and decomposition of NH 2 NO and the dissociation of O 2 on the catalyst surface, thereby inhibiting the NH 3 -SCR reaction. The inhibition of NO 2 formation further affects the fast SCR reaction, which may explain the low-temperature deactivation of the catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

CeO 2 /TiO 2 catalyst is a promising material for realizing the integration of denitrification and mercury removal to reduce mercury emissions. Oxidation mechanism of Hg0 on CeO 2 /TiO 2 (001) surface in the presence of HCl and O 2 was studied by density functional theory (DFT). The results indicated that Hg0 was physically adsorbed on CeO 2 /TiO 2 (001) surface. As an important intermediate, HgCl was adsorbed on the surface of CeO 2 /TiO 2 (001) utilizing enhanced chemisorption, while the adsorption energy of HgCl 2 was only −57.05 kJ/mol. In the absence of HCl, mercury oxidation followed the Mars-Maessen mechanism with a relatively high energy barrier, and the product (HgO) was difficult to desorb, which hindered the reaction process. When HCl existed, reactive chlorine (Cl*) would be produced by the dissociation of HCl, and the mercury oxidation would follow the Langmuir-Hinshelwood mechanism. The co-existence of HCl and O 2 had no significant effect on the adsorption of Hg0, but reduced the reaction energy barrier and the final product (HgCl 2) was more easily desorbed from the catalyst surface. In addition, two complete cyclic reaction pathways for catalytic oxidation of Hg0 on CeO 2 /TiO 2 (001) surface were constructed to clarify the detailed reaction process. [Display omitted] • Hg0 oxidation mechanism on CeO 2 /TiO 2 (001) surface was studied by DFT calculation. • Difficult formation and desorption of HgO result in low oxidation efficiency. • HCl and O 2 could significantly reduce the reaction energy barrier. • Hg0 oxidation by HCl followed Langmuir-Hinshelwood mechanism. • Two complete catalytic cycles were constructed to understand the reaction pathway. [ABSTRACT FROM AUTHOR]