Pillaring of montmorillonite by organotin cationic complexes

Petridis, D.; Bakas, Thomas; Simopoulous, A.; Gangas, N. H.

doi:10.1021/ic00311a037

Cited by 27 publications

(16 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The steric and electronic constraints prevailing in this super-zeolitic structure (Vaughan, 1988) render to these novel materials a high selectivity. The list of metal oxides used in pillaring various smectites has rapidly expanded and already comprises quite a few metals, e.g., A1 (Lahav et al, 1978), Zr (Bartley, 1988), Si (Endo et al, 1980), Cr (Tzou and Pinnavaia, 1988), Fe (Yamanaka et aL, 1984), Ti (Sterte, 1986), Nb and Ta (Christiano et aL, 1985), Mo (Christiano and Pinnavaia, 1986), Sn (Petridis et aL, 1989). Furthermore, the synthetic route to PILCs shows a new way to engineer out of swelling clays a multitude of nanophases.…”

Section: Introductionmentioning

confidence: 99%

“…(Vaughan and Lussier, 1980;Occelli, 1983;Bergaya et al, 1991) has stimulated research not only for the synthesis of new PILCs, but also for their extensive microscopic characterization. A wide spectrum of analytical techniques, e.g., magic-angle spinning NMR (Plee et al, 1985;Tillak et aL, 1986), EPR (Harsh and Doner, 1984;Braddell et aL, 1987), neutron scattering (Pinnavaia et al, 1984), NMR and HzTPR (Bergaya et al, 1993) and M6ssbauer spectroscopy (Gangas et aL, 1985;Lee Woo et al, 1989;Petridis et al, 1989), has been used for unravelling the structure and the properties of these novel materials. However, in spite of the substantial advance made up to now in the synthesis and characterization of PILCs, the elucidation of additional aspects of the pillared structure (e.g., the diameter of the pillars) is of cardinal importance for understanding the role of their morphology in physicochemical processes occurring in the interlayer space, as well as developing applications,…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Bakas

Moukarika

Papaefthymiou

et al. 1994

Clays and clay miner.

Self Cite

View full text Add to dashboard Cite

Abstract--Pillared structures with an interlayer opening of ~ 0.3 nm were obtained after successive heat treatments of the PILC precursor in reducing and oxidizing conditions. This precursor was prepared by reacting a Na+-montmorillonite with an intercalant containing A1 and Fe oxo-hydroxides (A1/Fe = 1). Powder X-ray diffraction, elemental analysis, 57Fe Mrssbauer spectroscopy, catalytic activity measurements and surface area data were used to characterize the samples. On the basis of M6ssbauer spectra taken at temperatures between 4.2 and 300 K, it is deduced that oxidizing steps produce A1 substituted maghemite which converts into A1 substituted magnetite upon reducing heat treatment. Firing the precursor in oxidizing atmosphere forms pillars of few nm in diameter. However, heating under reducing conditions yields pillars of smaller diameter. This later behaviour is maintained even after reheating the material in oxidizing atmosphere. From the temperature dependence of M6ssbauer spectra it is deduced that the diameter of the Fe oxide particles in the pillars is smaller than 10 nm.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Bakas

Moukarika

Papaefthymiou

et al. 1994

Clays and clay miner.

Self Cite

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…Abdo et al (1980) investigated a Sn-porphyrin complex sorbed on hectorite, Molloy etal. (1986) produced a high spacing intercalate using N-methyl-(3-triphenylstannyl)pyridinium iodide, and Petridis and co-workers (Simopoulos et al, 1988;Petridis et al, 1989) have studied the behaviour of cationic dimethyltin(IV) species exchanged on to a Wyoming montmorillonite. A tin-exchanged clay does, however, offer some potentially interesting characteristics, given the high Lewis acidity of Sn as well as its ability to produce acid media from coordinated water molecules.…”

mentioning

confidence: 99%

Mössbauer spectroscopic and thermogravimetric studies of tin-clay complexes

1992

View full text Add to dashboard Cite

Complexes of SnCIJmontmorillonite have been prepared from solutions which contained 10, 20, 40 and 200 times the cation exchange capacity of the clay, resulting in complexes which contained 1.7, 1.6, 2.8 and 4-6 wt% of tin. Detailed thermogravimetric and variable temperature llgsn M6ssbauer spectroscopic studies of these complexes, both as prepared and following back exchange with Ca2+-ions, have shown that (i) the complexes are quite acidic in nature, and (ii) the majority of the Sn forms an oxy/hydroxy coating over the montmorillonite surface in which the vibrational freedom of Sn depends upon both the Sn content and the state of hydration of the coating. Adams (1987) has shown that layered silicates with small, highly charged cations residing on the exchange sites can impart considerable catalytic activity to the host structure. The small, highly charged cations polarize the water molecules held in the primary coordination sphere resulting in an acidic proton. Consequently, the clay acts as a solid source of protons and can efficiently catalyse a number of novel and industrially significant reactions such as the hydration of ethene (Atkins et al., 1983), the esterification of organic acids by alkenes (Ballantine et al., 1984) and the low temperature synthesis of tert-methylbutylether from 2-methylpropene and methanol (Adams et al., 1982). More recently, Ni 2+, Co 2+ and Cu e+-exchanged clays have proven to be efficient Diels-Atder cycloaddition catalysts (Adams et al., 1987).Recent investigations into the acidity and catalytic activity of a variety of cationexchanged clays (Breen et al., 1987; Breen, 1991a,b) have shown that when H +, A13+ and Fe 3 § reside on the exchange sites the acidity is predominantly Bronsted in nature, whereas Ni z+ and Co z+ ions result in predominantly Lewis acid centres. Only when the exchange sites are occupied by Cr 3+ is there a mixture of both Lewis and Bronsted acid sites. Clearly, the type of interlayer cation can have a profound influence on the nature of the acid sites and the resulting catalytic activity, insofar as Ni 2+ and Co 2+ are only effective acid catalysts at temperatures above 200~ whereas the other exchange forms referred to are active at temperatures below 100~To our knowledge, no previous attempts have been made to exchange Sn n+ (n = 2,4) cations between the layers of montmorillonite, although several groups have studied tin complexes on clays. Abdo et al. (1980) investigated a Sn-porphyrin complex sorbed on hectorite, Molloy etal. (1986) produced a high spacing intercalate using N-methyl-(3-triphenylstannyl)pyridinium iodide, and Petridis and co-workers (Simopoulos et al., 1988;Petridis et al., 1989) have studied the behaviour of cationic dimethyltin(IV) species 9 1992 The Mineralogical Society

show abstract

“…The temperature at which these oxides appear coincides with the collapse of the basal spacing. Both complexes display BET Type IV isotherms for the adsorption of water, following thermal pretreatment at 150~ but the complex prepared at pH 4.0 has a lower sorption capacity, Both complexes, contrary to the normal behaviour of layer-silicates, have a definite pore volume and no further uptake occurs when this is filled.In two recent reports, Petridis and co-workers (Simopoulos et al, 1988;Petridis et al, 1989) have studied the behaviour of cationic dimethyltin(IV) species exchanged on to a Wyoming montmorillonite, with a view to producing SnOe pillared clays upon firing. Their preparation method (0.08 mol dm 3 Me2SnC12 at pH 5.5), chosen to generate the trimer [{(CH3)2Sn}3(OH)4] 2+ and thus maximize the Sn-loading on the clay, produced intercalates with d-spacings of 16.6 A which were stable up to 200~ in air.…”

mentioning

confidence: 99%

Organometallic cation-exchanged phyllosilicates: exchange with cations derived from (CH₃)₂SnCl₂

1992

View full text Add to dashboard Cite

Complexes formed between 0-034 M dimethyttin dichloride solutions and Namontmorillonite at pH 2.4 and 4.0 have been characterized using ngSn M0ssbauer spectroscopy, Xray diffraction, infrared spectroscopy, thermogravimetric analysis and water sorption isotherms. The dominant exchange cation at pH 2.4 is Me2Sn 2+ characterized by an isomer shift, 6, and quadrupole splitting, A values of 1.25 and 3-80 mm s l, respectively. The major exchange cation at pH 4.0 is the dimer, [Me2SnOH]22+, (6 = 1.38, A = 3.34 mm s -l) although the monomer, Me2Sn(OH) +, (6 = 0.95, A = 3.29 mm s-1) is also present. These complexes have basal spacings of 15.0 and 16.0 A, respectively, which are stable up to 200~ MOssbauer spectroscopy has shown that these ions are converted to SnO2 via Me2SnO upon thermal degradation. The temperature at which these oxides appear coincides with the collapse of the basal spacing. Both complexes display BET Type IV isotherms for the adsorption of water, following thermal pretreatment at 150~ but the complex prepared at pH 4.0 has a lower sorption capacity, Both complexes, contrary to the normal behaviour of layer-silicates, have a definite pore volume and no further uptake occurs when this is filled.In two recent reports, Petridis and co-workers (Simopoulos et al., 1988;Petridis et al., 1989) have studied the behaviour of cationic dimethyltin(IV) species exchanged on to a Wyoming montmorillonite, with a view to producing SnOe pillared clays upon firing. Their preparation method (0.08 mol dm 3 Me2SnC12 at pH 5.5), chosen to generate the trimer [{(CH3)2Sn}3(OH)4] 2+ and thus maximize the Sn-loading on the clay, produced intercalates with d-spacings of 16.6 A which were stable up to 200~ in air.In 1978 Coughlan et al. prepared and investigated the catalytic properties of several alkyltin exchanged zeolites. They reported that dibutyltin exchanged zeolite Y was more active for the dehydration of pentanol to pentene than the dimethyltin exchanged form and attributed this to the relative acidities of the aquo-diakyltin(IV) ions (Nevett & Tobias, 1963). Coughlan's dimethyltin samples, prepared from dimethyltin dichloride solutions at pH 1.8 and 3.3, were conditioned at 450~ in flowing hydrogen for six hours and the tin was thus unlikely to remain methylated.Thus, with the current interest in the utilization of various cation-exchanged clays as acid catalysts across a range of novel and industrially significant processes (Adams, 1987;Ballantine, 1986), a study of dimethyltin(IV)-exchanged clay suggested itself for several

show abstract

Pillaring of montmorillonite by organotin cationic complexes

Cited by 27 publications

References 1 publication

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Mössbauer spectroscopic and thermogravimetric studies of tin-clay complexes

Organometallic cation-exchanged phyllosilicates: exchange with cations derived from (CH₃)₂SnCl₂

Contact Info

Product

Resources

About

Pillaring of montmorillonite by organotin cationic complexes

Cited by 27 publications

References 1 publication

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Mössbauer spectroscopic and thermogravimetric studies of tin-clay complexes

Organometallic cation-exchanged phyllosilicates: exchange with cations derived from (CH3)2SnCl2

Contact Info

Product

Resources

About

Organometallic cation-exchanged phyllosilicates: exchange with cations derived from (CH₃)₂SnCl₂