Catalytic Performance of Bimetallic Systems (Cu-Fe, Cu-Mn, Fe-Mn) Based on Spherical MCM-41 Modified by Template Ion-Exchange in NH3-SCR Process

Abstract

Mesoporous silica of MCM-41 type with spherical morphology was modified with copper, iron, or manganese as well as pairs of these metals by template ion-exchange (TIE) method. The obtained samples were characterized with respect to their structure (XRD), morphology (SEM-EDS), textural parameters (low-temperature N2 sorption), surface acidity (NH3-TPD), transition metal loadings (ICP-OES), their deposited forms (UV-vis DRS) and reducibility (H2-TPR). The catalytic performance of monometallic and bimetallic samples in the selective catalytic reduction of NO with ammonia (NH3-SCR) was tested. The best catalytic results presented a bimetallic copper-manganese sample, which was significantly more active than the mechanical mixture of monometallic copper and manganese catalysts. The synergistic cooperation of manganese and copper species is possibly related to charge relocation between them, resulting in activation of the catalyst in oxidation of NO to NO2, which is necessary for the fast NH3-SCR reaction.

Heat Treatment Improves the Activity and Water Tolerance of Pt/Al2O3 Catalysts in Ammonia Catalytic Oxidation

“…Ammonia (NH 3 ) is a harmful alkaline gas, which can cause serious harm to human health and the ecological environment. , Vehicle emissions are considered a major source of NH 3 in the urban atmosphere, especially ammonia leakage from diesel vehicles using selective catalytic reduction (SCR) technology. − Ammonia selective catalytic oxidation (NH 3 -SCO) technology is widely recognized as an efficient and environmentally friendly method for NH 3 elimination. ,, Generally, an ammonia oxidation catalyst (AOC) is expected to completely oxidize NH 3 to harmless N 2 and H 2 O at low temperatures. , Unfortunately, the AOCs with superior low-temperature activity usually will over-oxidize NH 3 to form undesired N 2 O and NOx, thus inducing poor N 2 selectivity. − Hence, investigating the reaction mechanism of NH 3 oxidation is critical for designing highly efficient AOCs.…”

“…Ammonia (NH 3 ) is a harmful alkaline gas, which can cause serious harm to human health and the ecological environment. 1 , 2 Vehicle emissions are considered a major source of NH 3 in the urban atmosphere, especially ammonia leakage from diesel vehicles using selective catalytic reduction (SCR) technology. 3 − 5 Ammonia selective catalytic oxidation (NH 3 -SCO) technology is widely recognized as an efficient and environmentally friendly method for NH 3 elimination.…”

Studies of NO Reduction with Ammonia Over Copper Species Deposited on MCM‐41 Nanospheres ‐ Experimental Evidence of Reaction Mechanism

“…Template ion-exchange (TIE) method, which is relatively easy and cheap, is very effective for deposition of metal species, such as copper, iron, or manganese, into mesoporous silica materials in highly dispersed forms. [26] TIE method is based on the exchange of cationic alkylammonium surfactants attached into negatively charged silica walls in freshly prepared (non-calcined) mesoporous silica for metal cations. More precisely, in the templatecontaining MCM-41 type material, the silica framework is built around pore-filling cationic surfactants (S + ), that interact with each other by means of Coulombic forces.…”

“…On the other hand, deposition of metals by impregnation methods, especially in the case of their higher loadings, results in formation of metals species of various aggregation. Template ion‐exchange (TIE) method, which is relatively easy and cheap, is very effective for deposition of metal species, such as copper, iron, or manganese, into mesoporous silica materials in highly dispersed forms [26] . TIE method is based on the exchange of cationic alkylammonium surfactants attached into negatively charged silica walls in freshly prepared (non‐calcined) mesoporous silica for metal cations.…”