133Cs and 23Na MAS NMR studies of zeolite X containing cesium

Yagi, Fuyuki; Kanuka, Nariyasu; Tsuji, Hideto; Nakata, Shinichi; Kita, Hideaki; Hattori, Hideshi

doi:10.1016/s0927-6513(96)00113-7

Cited by 32 publications

(27 citation statements)

References 23 publications

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“…The zeolites X containing Cs in excess of the ion-exchange capacity exhibit higher activities for the base-catalyzed double bond migration of 1-butene than ion-exchanged zeolite X if the excess amount of Cs is in the range of 1.1-2.9 Cs atoms per supercage. 133 Cs NMR can distinguish the Cs located inside the cavity from the Cs located on the outer surface of zeolite and ion-exchanged Cs 36) . The active catalysts contain Cs inside the cavities, indicating that Cs2O particles dispersed in the cavities are the basic sites catalyzing the double bond migration of 1-butene.…”

Section: Characterization Of Basic Sitesmentioning

confidence: 99%

Solid Base Catalysts: Generation, Characterization, and Catalytic Behavior of Basic Sites

英¹

2004

J. Jpn. Petrol. Inst.

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Studies of solid base catalysis performed in our group are summarized. Strongly basic sites for most solid base catalysts are generated by removal of water and carbon dioxide by pretreatment at high temperatures from the surfaces. The nature of the surface basic sites varies with the severity of the pretreatment conditions. Rearrangement of surface and bulk atoms occurs, in addition to the removal of water and carbon dioxide, during the pretreatment. The optimum pretreatment temperature varies with the type of reaction. Characterization of basic sites by the indicator method, TPD of CO2, O exchange between adsorbed CO2 and MgO surface, NMR of 133 Cs and 19 F are described. The catalytic behaviors of solid base catalysts are described for the following reactions; (1) double bond migration, (2) hydrogenation, (3) amination, (4) aldol addition, (5) nitroaldol reaction, (6) Michael addition, (7) conjugate addition of alcohol, (8) cyanoethylation, (9) transesterification of ethyl acetate and alcoholysis of propylene oxide, and (10) the Tishchenko reaction. The strength of basic sites relevant to different reactions is discussed based on the activity order among alkaline earth oxides, and the optimum pretreatment temperatures of MgO for different reactions. Reactions with hydrocarbons need strongly basic sites, whereas reactions with compounds containing functional groups proceed even on weakly basic sites. Finally, important issues to be investigated for the development of solid base catalysis are pointed out.

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Section: Characterization Of Basic Sitesmentioning

confidence: 99%

Solid Base Catalysts: Generation, Characterization, and Catalytic Behavior of Basic Sites

英¹

2004

J. Jpn. Petrol. Inst.

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“…Samples in which only zeolite X was identified by XRD had surface areas (1.7-6.1 m 2 /g) two orders of magnitude lower than values reported in the literature (300-850 m 2 /g) (Linares et al 2005;Maurin et al 2005;Ocanto et al 2008;Yagi et al 1997). The surface area measured for the Cs-only solid at 30 days was three times higher than for the Sr-only solid.…”

Section: Particle Size and Morphologymentioning

confidence: 57%

“…Each unit cell has 8 sodalite (b) cages, 8 supercages, and 16 D6R sites. Cation-exchangeable sites are located in the hexagonal prism, b-cage, or supercage to balance the net negative charge of the aluminosilicate framework (Mon et al 2005;Sherry 1966;Yagi et al 1997). Most commonly occupied are: Site I at the center of the hexagonal prism and surrounded by 12 Al/Si atoms; Site I' located in the face of the D6R on the b-cage with 6 Al/Si atoms; and Sites II and II' adjacent to six-membered rings that form the supercages and b-cages (Frising and Leflaive 2008).…”

Section: Structural Observationsmentioning

confidence: 99%

Cesium and strontium incorporation into zeolite-type phases during homogeneous nucleation from caustic solutions

Rivera

Choi

Strepka

et al. 2011

American Mineralogist

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Formation of faujasite-and sodalite/cancrinite-type phases associated with caustic waste reactions in the environment may structurally incorporate contaminant species such as radioactive Sr 2+ and Cs + , and thus provide a mechanism of attenuation. To investigate mineral evolution and structural incorporation of cations in simplified experiments, aluminosilicate solids were precipitated homogeneously at room temperature from batch solutions containing a 1:1 molal ratio of Si to Al and 10 -3 molal Sr and/or Cs, and aged for 30 or 548 days. Syntheses were done with solutions in equilibrium with atmospheric CO 2 and with gas-purged solutions. Experimental products were characterized by bulk chemical analyses, chemical extractions, XRD, SEM/TEM, TGA, solid-state 27 Al NMR, and Sr EXAFS. Chemical analysis showed that solids had a 1:1 Al:Si molar ratio, and that Sr was sequestered at higher amounts than Cs. After 30 days of aging in purged solutions, XRD showed that zeolite X (faujasite-type) was the only crystalline product. After aging 30 and 548 days in solutions equilibrated with atmospheric CO 2 , a mixture of sodalite, cancrinite, and minor zeolite X were produced. Surface areas of solids at 30 days were much lower than published values for zeolite phases synthesized at high temperature, although particle aging produced more crystalline and less aggregated phases with higher bulk surface areas. Characterization of products by 27 Al NMR indicated only tetrahedrally coordinated Al. Measured isotropic shifts of primary resonances did not change substantially with precipitate aging although the primary mineral phase changed from zeolite X to sodalite/cancrinite, indicating local ordering of Al-Si tetrahedra. Analysis of reaction products by Sr EXAFS suggested Sr bonding in hexagonal prisms and six-membered rings of the supercages of zeolite X that may be more site specific than those of monovalent cations. For samples aged for 548 days, interatomic distances from Sr-EXAFS are consistent with partial Sr dehydration and bonding to framework oxygen atoms in sodalite cages or in large channels in cancrinite. Incorporation of Sr into both faujasite and sodalite/cancrinite phases is favored over Cs during room-temperature synthesis, possibly because of increased cation site competition between Cs + and Na + . Results of this study help to constrain cation incorporation into sodalite/cancrinite mineral assemblages that form at caustic waste-impacted field sites and may aid in the predictive modeling of contaminant release.

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“…Cs(add)-β, which was not washed, exhibited a higher Cs introduction ratio than Cs-β due to the presence of Cs2O outside the zeolite skeleton 2) . The basic strength of ABZ was assessed by the Knoevenagel reaction.…”

Section: Resultsmentioning

confidence: 97%

“…A flavanone derivative (3) is generally prepared by Claisen-Schmidt condensation of a 2'-hydroxyacetophenone (1) and a benzaldehyde over a homogeneous catalyst such as sodium hydroxide aqueous solution, pyridine or L-proline 1) , followed by intramolecular cyclization of the obtained 2'-hydroxychalcone derivatives (2). However, this preparation method can hardly be called environmentally friendly or green because the 2 and 3 formation rates cannot be controlled and catalyst reuse is difficult.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Chalcone and Flavanone Derivatives from Condensation of 2’-Hydroxyacetophenones and Benzaldehyde over Basic <i>β</i>-Zeolites

崇

廣大

寛次

et al. 2010

J. Jpn. Petrol. Inst.

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133Cs and 23Na MAS NMR studies of zeolite X containing cesium

Cited by 32 publications

References 23 publications

Solid Base Catalysts: Generation, Characterization, and Catalytic Behavior of Basic Sites

Solid Base Catalysts: Generation, Characterization, and Catalytic Behavior of Basic Sites

Cesium and strontium incorporation into zeolite-type phases during homogeneous nucleation from caustic solutions

Synthesis of Chalcone and Flavanone Derivatives from Condensation of 2’-Hydroxyacetophenones and Benzaldehyde over Basic <i>β</i>-Zeolites

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