Influence of residual cations (Na+, K+ and Mg2+) in the alkylation activity of benzene with 1-octene over rare earth metal ion exchanged FAU–Y zeolite

Abstract

Influence of residual cations (Na", K+ and Mg2+) AbstractThe effect of residual cations in rare earth metal modified faujasite-Y zeolite has been monitored using magic angle spinning NMR spectral analysis and catalytic activity studies. The second metal ions being used are Na", K+ and Mg". From a comparison of the spectra of different samples, it is concluded that potassium and magnesium exchange causes a greater downfield shift in the 29Si NMR peaks. Also, lanthanum exchanged samples show migration behavior from large cages to small cages, which causes the redistribution of second counter cations. It is also observed that Mg2+ causes the most effective migration of lanthanum ions due to its greater charge. The prepared systems were effectively employed for the alkylation of benzene with l-octene in the vapor phase. From the deactivation studies it is observed that the as-exchanged zeolites possess better stability towards reaction condition over the pure HFAU zeolite.

Impact of Low-Temperature Water Exposure and Removal on Zeolite HY

“…The recent literature discusses the location of important rare-earth cations that stabilize the HY framework against framework hydrolysis during high-temperature steaming steps. ,,, Other recent reports suggest that the small-pore sodalite units in HY can be accessed through strategic “opening up” of the caged subunits. , These reports demonstrate that there is still significant interest in understanding and extending the use of zeolite HY to many new applications, as well as optimizing their use for increased selectivity in known gas-phase hydrocarbon chemistries. Many HY applications involve postsynthetic ion exchange in aqueous salt solutions to introduce rare-earth cations, probe the acid site location and proximity with mono- and divalent probe cations, and impart new functionality through metal intercalation, hydrophobization, or other specific chemical modifications. − ,− While many of these chemistries begin with the NaY or NH 4 Y form, some begin with the acidic HY catalyst, particularly those in which the goal is to interrogate the Brønsted acid site location and paired acid site proximities, as well as modify acid site densities via partial cation exchanges or selectively “poisoning” very strong acid sites. In all cases, zeolite crystallites are suspended in excess liquid water at 25–80 °C for extended time periods.…”

“…In the interim, between these apparently conflicting reports, excess liquid water has routinely been used as the solvent for modifying Y-type zeolites via ion-exchange procedures at temperatures ranging from room temperature to ca. 80 °C. ,− While most procedures involve starting with the NaY or NH 4 Y form of the zeolite, the latter of which affords significant protection against deleterious water effects as indicated by the data in Figure (vide infra), many begin with the HY form.…”

Catalytic acetalization of carbonyl compounds over cation (Ce3+, Fe3+ and Al3+) exchanged montmorillonites and Ce3+-exchanged Y zeolites

“…Zeolites in the present investigation were purchased or prepared via cationic exchange. The detailed characterization of the present catalyst systems has already been reported elsewhere (Thomas and Sugunan, 2004. The physiochemical properties of the catalysts, including, the nSi/nAl ratio, the BET surface area, the pore volume, the number and distribution of the acid strength and the crystallite size (μm) are presented in Table 1.…”

“…A response factor of unity was used for GC-FID product analysis. The % conversion of the carbonyl compounds and the selectivity towards the corresponding acetals were calculated as reported in our previous communications (Thomas and Sugunan, 2004;Thomas et al, 2009).…”

Effect of Transition Metal Ion‐Exchanged into the Zeolite Y on Electrical Conductivity and Response of PEDOT‐PSS/MY Composites toward SO2

“…The M 2+ zeolites studied in this work are zeolite Y (Zeolyst, Si/Al = 5.1, hydrated form) with different compensating cations (Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ). The Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ‐exchanged zeolite Y were carried out using the conventional ion‐exchange procedures . Zeolites NaY was used as the starting material for the ion exchange.…”