Solid–state ion exchange of CoCl 2 ·6H 2 O into NH 4 + –Beta zeolite: Pathway analysis

Evaluation of Co/SSZ‐13 Zeolite Catalysts Prepared by Solid‐Phase Reaction for NO‐SCR by Methane

“…The SSIE method involves heating finely powdered mixture of a zeolite, being preferably in H + or NH 4 + cationic form, and a metal salt to make the metal ion to take over the charge balancing function of lattice cations. [10,13] In former studies a variety of Co salts were used to introduce cobalt cations into zeolites by SSIE with more or less success; [9,11,12,14,45] however, the underlying reasons behind the success or failure of getting Cozeolite with or without Co 2 + lattice cations were not fully understood. The objective of the present study was to better understand the chemistry of the SSIE process with different salts of cobalt to get Co/SSZ-13 catalyst.…”

“…Even at low concentrations the Co 2 + ions form ion pairs and bulky aqua complex that does not favor the formation of Co-rich zeolite forms. [9][10][11] In the solid-phase reaction, often referred to as solid-state ion exchange (SSIE), the temperature of finely dispersed mixture of zeolite and cobalt salt is increased to induce the reaction of the components. Using this method cobalt can be introduced into the zeolite in a single step.…”

“…It should be noted, however, that the metal incorporation by the zeolite material is often not complete and/ or not all of the Co introduced occupy ion-exchange positions in the zeolite. [9,12] A variety of Co salts, such as chloride, nitrate, acetate, etc. were suggested as potential precursors for SSIE; [9,12,14] however, the chemistry and the detailed processes are usually not well established, which makes the success of the ion-exchange process unpredictable.…”

“…The exchange level is attributed to the non‐equilibrium nature of the process due to the volatile side product of the exchange reaction. For instance, if chloride salt is mixed with the acidic form of the zeolite (H‐zeolite) HCl is formed that leaves the solid as gas [9] . Further advantage of the SSIE method is that, unlike to the APIE method, no transition‐metal‐containing waste solution is emitted.…”

“…Further advantage of the SSIE method is that, unlike to the APIE method, no transition‐metal‐containing waste solution is emitted. It should be noted, however, that the metal incorporation by the zeolite material is often not complete and/or not all of the Co introduced occupy ion‐exchange positions in the zeolite [9,12] . A variety of Co salts, such as chloride, nitrate, acetate, etc.…”