Detailed Study of Cu Migration in the Course of NH3-Facilitated Solid-State Ion-Exchange into *BEA Zeolites

Cu migration into *BEA zeolite in the course of NH3-faciliated solid-state ion exchange (SSIE) was studied using CuIIO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{II}} {\text{O}}$$\end{document} and Cu2IO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{I}}_{ 2} {\text{O}}$$\end{document} as the Cu sources. It was found that CuIIO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{II}} {\text{O}}$$\end{document} and Cu2IO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{I}}_{ 2} {\text{O}}$$\end{document} are equally effective when SSIE is carried in the presence of 500 ppm NO and 500 ppm NH3. Removal of NO significantly reduces the efficiency of SSIE for [CuIIO+NH4-∗BEA\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{II}} {\text{O }} + {\text{ NH}}_{ 4} {\text{-}}^{*}{\text{BEA}}$$\end{document}] since the process becomes limited by CuIIO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{II}} {\text{O}}$$\end{document} → Cu2IO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{I}}_{ 2} {\text{O}}$$\end{document} reduction. When Cu2IO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{I}}_{ 2} {\text{O}}$$\end{document} is used as the Cu source the rate of SSIE is no longer limited by the reduction, but becomes limited by the formation and migration of mobile [Cu(NH3)2]+ complexes. A time-resolved study of SSIE with NH3 and a Cu2IO+NH4-∗BEA\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}^{\text{I}}_{ 2} {\text{O }} + {\text{ NH}}_{ 4} {\text{-}}^{*}{\text{BEA}}$$\end{document} mixture at 200 and 250 °C reveals two distinctly different stages during Cu migration, which are tentatively attributed to non-random occupation of different cationic positions that the Cu-species occupy upon consecutive exposure to the atmosphere in the selective catalytic reduction of nitrogen oxides with ammonia.