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1.
Inorganic ion-exchangers with a layered structure such as γ-zirconium and γ-titanium phosphates, intercalated with organic
diamines, are able to exchange Pt2+ ions to give new intercalation compounds that can be utilized in heterogeneous catalysis. The experiments performed at different
temperatures (25 and 45°C), show different ion uptakes, greater at 45°C and for the materials derived from γ-zirconium phosphate.
After platinum exchange, all the materials show an amorphization in the XRD if compared with their precursors. The thermal
behaviour of the platinum materials is specific, depending on the exchanger used and the ligand inside the exchanger. Pt2+ ion has a catalytic effect on ligand elimination in the γ-zirconium phosphate platinum compounds, but not in those derived
from γ-titanium. All the obtained yellow materials show a small step in the TG curves and simultaneously we have the Pt2+→Pt0 reduction: this is confirmed by XRD registered at the temperatures of the thermal effect, showing peaks at dhkl=2.27 and 1.95 Å.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Marco Arfelli Giovanni Cossu Giulia Mattogno Carla Ferragina Maria Antonietta Massucci 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(2):161-170
X-ray photoelectron spectroscopy provides evidence that when [Cu(phen)2]2+(phen = 1,10-phenanthroline) is diffused between the layers of -zirconium phosphate, the complex species does not remain intact after intercalation, but some Cu-N bonds are broken, replaced with Cu-O bonds and the released nitrogen atoms can now interact with the PO3-OH groups of the host. XPS also provides evidence for coordination of the Cu2+ ions when they are diffused by ion exchange in the phenanthroline--zirconium phosphate intercalation compound. Although Cu2+ and phen are in a 1 : 1 molar ratio in the interlayer region of the host, so that a 1 : 1 coordination could be expected between the two species, the characteristic peaks of the uncoordinated phenanthroline, even though at a low intensity, are still present. The differences between the two Cu(II)-intercalation compounds are discussed. 相似文献
3.
Zinc ions can be exchanged in sol-gel zirconium phosphate by using the batch or hydrothermal method. The zinc materials obtained that undergo thermal treatment after complete dehydration, can rehydrate fully or partially depending on whether half or all the zinc ions are exchanged. At high temperature syntherization is evident. By flowing sulfide acid over the zinc forms, zinc sulfide particles are formed and their amount depends on the length of time of the gas flow and on the state of hydration of the original material. This is not the case in the half exchanged zinc zirconium phosphate material. The decomposition temperature of the ZnS particles depends on their position in the exchanger: whether on the surface or between the layers of the host matrix. The XRD patterns of the materials obtained are similar to those of the sol-gel zirconium phosphate. The presence of ZnS particles is evident. 相似文献
4.
Paolo Ferragina Roberto Grossi 《Journal of Algorithms in Cognition, Informatics and Logic》1999,31(2):291
In the dynamic text indexing problem, a text string has to be maintained under string insertions and deletions in order to answer on-line queries about arbitrary pattern occurrences. By means of some new techniques and data structures, we achieve improved worst-case bounds. We show that finding allpoccoccurrences of a pattern of lengthpin the current text of lengthntakesO(p + pocc + updlog p + log n) time, whereupdis the number of text uptakes performed so far; inserting or deleting a string of lengthsfrom the current text takesO(s log(s + n)) time. 相似文献
5.
Carla Ferragina Romolo Di Rocco Potenzo Giannoccaro Pasquale Patrono Lucantonio Petrilli 《Journal of inclusion phenomena and macrocyclic chemistry》2009,63(1-2):1-9
Intercalation compounds such as the ruthenium trisbipyridyl complex in inorganic layered ion-exchangers (α- and γ-zirconium phosphate) have been synthesized using the batch method. There is no loss of bipyridyl ligand from the metal ion during the exchange of the ruthenium trisbipyridyl complex in these host matrices. The materials obtained are thermally stable up to ~330 °C (γ-phase) or ~380 °C (α-phase). The complex decomposition occurs in one or more steps and at ~600 °C the complex decomposition is complete. The X-ray patterns of ruthenium materials show a new phase with an increase in the interlayer distance with respect to the initial phase. Microanalysis measurements confirm the fact that the ruthenium complex is not modified when exchanged and the complex decomposition depends on its position in the host matrices. 相似文献
6.
A. La Ginestra C. Ferragina P. Patrono R. Dl Rocco 《Journal of Thermal Analysis and Calorimetry》1981,20(1):205-213
The thermal and redox behaviours of some Ag-low-converted zirconium phosphates have been investigated by thermoanalytical and X-ray methods: the conditions for obtaining Ag solid solutions in
phases are reported.
Paper in part presented at the 6th ICTA, in Bayreuth (Germany), July 1980.
We thank Dr. M. A. Massucci, of our Institute, for helpful discussions and suggestions. 相似文献
Zusammenfassung Das thermische und Redoxverhalten einiger Zirkoniumphosphate niedriger Ag-Konversion wurde durch thermoanalytische und Röntgenmethoden studiert; über die Bedingungen zum Erhalten von Ag-Festphasenlösungen in HH-Phasen wird berichtet
Résumé On a étudié le comportement thermique et oxydo-réducteur de quelques phosphates de zirconium faiblement converti par Ag, en se servant des méthodes d'analyse thermique et des rayons X: on communique les conditions permettant d'obtenir des solutions solides d'Ag dans les phases .
- Ag- . HH.
Paper in part presented at the 6th ICTA, in Bayreuth (Germany), July 1980.
We thank Dr. M. A. Massucci, of our Institute, for helpful discussions and suggestions. 相似文献
7.
Ferragina C. Cafarelli P. De Stefanis A. Di Rocco R. Petrilli L. 《Journal of Thermal Analysis and Calorimetry》2003,71(3):1023-1034
Long chain trimethylammonium salts can be successfully used as guest molecules to produce mesoporous layered materials when
intercalated in sol-gel zirconium phosphate, an inorganic ion-exchanger. The obtained materials are very similar independently
of the chain length and the synthesis method batch (B) or direct intercalation (DI). They show a good thermal stability, and
a very high interlayer distance if compared with their precursor. By the thermal characterization it can be observed that
the surfactant is lost in two or three steps depending on its position in the host. The layered structure with the expanded
interlayer distance is maintained up to 300°C. From the IR spectra the different surfactant release models for (B) and (DI)
are confirmed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Carla Ferragina Maria Antonietta Massucci Giulia Mattogno 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(5):529-536
The host-guest interactions of 2,2-bipyridyl, 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline intercalated between the layers of crystalline-zirconium monohydrogen phosphate have been studied by X-ray photoelectron spectroscopy. Evidence that, on average, only one of the two nitrogen atoms of each aromatic diamine is protonated by the P-OH groups of the host is given. The acid-base interaction is strongly reduced on dehydration of the materials. The role of the cointercalated water is discussed, together with the probable disposition of the guests within the interlayer region. 相似文献
9.
Ferragina C. Di Rocco R. Fanizzi A. Giannoccaro P. Petrilli L. 《Journal of Thermal Analysis and Calorimetry》2004,76(3):871-881
Long chain alkylammonium cations can be exchanged into a preswelled phase of g-zirconium phosphate, a layered inorganic ion-exchanger.
The derived materials are used as templates to give organic-inorganic composite materials. The cationic exchange occurs very
quickly. These intercalation compounds behave in a very similar way. They are still layered and exhibit an interlayer distance
d notably greater than that of its precursor whose behavior depends on the chain length. By thermal and microanalyser characterizations
it can be observed that the surfactant is lost in two stages, the second one as a result of the fragmentation of the chain.
The layered structure with the expanded interlayer distance is maintained up to ~350°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Carla Ferragina Romolo Di Rocco Pasquale Patrono Lucantonio Petrilli 《Central European Journal of Chemistry》2009,7(1):31-34
Layered compounds with CdS particles supported on the ion-exchanger, γ-titanium dihydrogen phosphate, were prepared by the
stepwise reaction of the ion-exchanger and cadmium solution, followed by reaction with H2S gas. The CdS content on the ion-exchanger is dependent on the timeframe of the H2S gas flow. The materials obtained were layered, as shown by the X-ray measurements that exhibit both precursor and CdS diffraction
peaks. The thermal treatment of the material obtained gives evidence of its stability (≤ 320°C) before the CdS decomposition,
which occurs in a single step.
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