Improved lifetime and stability of copper species in hierarchical, copper-incorporated CuSAPO-34 verified by catalytic model reactions

Abstract

The first successful synthesis of hierarchical CuSAPO-34 (3.9 wt.% Cu) is reported using the polymer Pluronic F127 as mesoporous structure directing agent (SDA). X-ray absorption spectroscopy (XAS) proved single site...

Pinpointing basic sites formed upon incorporation of iron in hierarchical SAPO-11 using catalytic model reactions

“…S2-2 †), indicated that calcined FeSAPO-11 had 4 Fe-O neighbors at 1.95 Å whereas calcined FeCTAB-11 had 3 Fe-O neighbors at 1.93 Å. While these distances are slightly longer compared to those of previously studied Fe(III)-incorporated zeolites (∼1.85 Å), [32][33][34] they are similar to previously reported distances of iron-(1.91 Å) 35 and other transition metal-incorporated SAPOs (1.95 Å) 16 and do not correspond to Fe-O bonds in iron oxides. Furthermore and importantly, no Fe-Fe or Fe-O-Fe contributions could be found, indicating that isolated, single-site Fe(III) is present in calcined FeSAPO-11 and FeCTAB-11.…”

“…9,10 Indeed, while there are many studies on hierarchical SAPOs, [10][11][12][13][14][15] research on the incorporation of transition metals into hierarchical SAPOs is scarce. [13][14][15][16] A critical issue in the incorporation of transition metals into hierarchical SAPOs is the topological location of the metal. 16 Indeed, similar to the location of the Brønsted acid sites, the location of the transition metal dictates the contributing effect of the mesopores in the hierarchical structure.…”

“…[13][14][15][16] A critical issue in the incorporation of transition metals into hierarchical SAPOs is the topological location of the metal. 16 Indeed, similar to the location of the Brønsted acid sites, the location of the transition metal dictates the contributing effect of the mesopores in the hierarchical structure. For shape selective reactions (e.g.…”

“…SCR of NOx), transition metal sites in mesopores would lead to a longer lifetime. 16 Previously, we have demonstrated that the methanol-to-hydrocarbons (MTH) model reaction can function as a characterization technique for locating the Brønsted acid sites and probing the pore connectivity of high acid density hierarchical SAPO-5 (12-membered ring, 0.7 nm pore apertures). 17,18 Likewise, the corresponding properties of the low acid density hierarchical SAPO-11 (10-membered ring, 0.4 nm × 0.6 nm pore apertures) 17 were successfully investigated by using the vapor phase isomerization of cyclohexanone oxime (Beckmann rearrangement, BMR) model reaction.…”

“…9,10 Indeed, while there are many studies on hierarchical SAPOs, 10–15 research on the incorporation of transition metals into hierarchical SAPOs is scarce. 13–16…”