Additional acid site on HZSM-5 treated with basic and acidic solutions as detected by temperature-programmed desorption of ammonia

Utilizing full-exchange capacity of zeolites by alkaline leaching: Preparation of Fe-ZSM5 and application in N2O decomposition

“…Thus the exchange capacity of the material increases per unit of weight. These results on leaching are in agreement with the literature [32][33][34][35][36][37][38][39][40][41][42].…”

“…In contrast to acid leaching, which removes framework Al [30,31], alkaline treatments preferentially extract Si, as initially reported by the Mobil Research & Development team [32][33][34]. Subsequently, several groups applied this technique in a more extended fashion [35][36][37][38][39][40][41][42]. There have been two major topics of interest: (i) aluminum zoning coupled with desilication and (ii) intracrystalline mesoporosity development to create hierarchical porous systems.…”

IR studies of Fe modified ZSM-5 zeolites of diverse mesopore topologies in the terms of their catalytic performance in NH3-SCR and NH3-SCO processes

“…The fabrication of mesopore system is usually detected as a distinct increase of the silanols amount on mesopore surfaces. In the spectra of microporous H-P a band at 3660 cm -1 is also discernible being ascribed to OH groups associated with extraframework aluminium species[24]. The main characteristic of Fe-exchanged zeolites is a decrease of the intensityof the bridging Si(OH)Al groups which is attributed to the substitution of protons for positively charged Fe(III) species.…”

Catalyst Design by NH4OH Treatment of USY Zeolite

“…Matsuura et al also applied an NH 4 OH treatment on H-ZSM-5 zeolites, resulting in the formation of an additional acid site type, the pore architecture of the zeolite being fully retained. [ 26 ] Furthermore, a mesostructured zeolite USY was successfully synthesized by a hydrothermal NH 4 OH treatment. [ 27 ] However, cetyltrimethyl ammonium (CTA + ) addition as a structure-directing agent was necessary, which needs to be removed by combustion.…”