2,012,022 research outputs found
Trust e legittimazione passiva tributaria
No full textLa questione della soggettività giuridica del trust si riflette sul profilo della legittimazione passiva del trust ovvero del trustee ai fini della valida notificazione degli atti di accertamento per il pagamento di imposte. Il contributo si propone come obiettivo quello di esaminare la giurisprudenza, tanto di merito quanto di legittimità, formatasi sul punto, nonché di far emergere quale sia il criterio per individuare correttamente il soggetto passivo d’imposta in relazione a fattispecie di trust
Fourier-transform Ir Detection of Adsorbed Hydrogen On A Cu-Zn-Cr Low-temperature Methanol Synthesis Catalyst
No full textAcidity and basicity of zeolites: A fundamental approach
No full textThe main data concerning acidity and basicity characterization of protonic and cationic zeolites are described and discussed. In particular, experimental data concerning IR studies of the adsorption of pyridine, CO and CO2on Na-zeolites (Na-X, Na-A, Na-MOR) and on protonic zeolites (with emphasis on H-Y and USY) are described and discussed. The nature of the Lewis acid and basic sites as well as of the Brà ̧nsted acid sites is discussed with a fundamental chemical approach
A FT-IR study of the adsorption of indole, carbazole, benzothiophene, dibenzothiophene and 4,6-dibenzothiophene over solid adsorbents and catalysts
No full textThe adsorption of benzothiophene (BT), dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (DMDBT), dibenzofuran (DBF). indole (IND) and carbazole (CARB) on alumina, zirconia and magnesia has been studied by IR spectroscopy. The main adsorption process is due to adsorption on Lewis sites or on acid-base pairs. On alumina the adsorption is strongest, desorption being not obtained above 723 K. BT also undergoes a transformation with likely the heteroaromatic ring opening. Adsorption of 4,6-DBT is definitely limited in extent likely due to steric hindrance. The N-containing compounds IND and CARB are adsorbed dissociatively with breaking of the NH bond. (C) 2002 Elsevier Science B.V. All rights reserved
An ultraviolet–visible–near infrared study of the electronic structure of oxide-supported vanadia–tungsta and vanadia–molybdena
No full textThe ultraviolet-visible-near IR spectra of a series of catalysts have been recorded and discussed. In particular bulk and alumina-, titania- and silica-supported V, W, and Mo oxides have been considered. Additionally mixed V-W and V-Mo-supported oxides have been investigated. The data show that, in agreement with vibrational data and other literature data, the oxides supported on silica are similar to the corresponding bulk oxides. In contrast, the spectra of the oxides supported on alumina and titania correspond to surface oxide species where the metal stays in a lower overall coordination with respect to the bulk oxides. Finally, the spectra show that only in the case of titania-supported oxides an electronic interaction between the supported metal oxide centers through the support conduction band is possible. This allows to justify on electronic bases the activating effect of titania for vanadia, vanadia-tungsta and vanadia-molybdena catalysts used in the hydrocarbon selective oxidation catalysis and for the selective catalytic reduction of nitrogen oxide by ammonia. (C) 2001 Elsevier Science B.V. All rights reserved
Islamic Practices, Traditions and Beliefs in Egypt and the Eastern Mediterranean in the Early 16th Century: Georgius Gemnicensis’ Ephemeris
No full textThis article reports several excerpts of Georgius Gemnicensis’ Ephemeris, a travel journal in which the author recounted his experiences in Mamluk Egypt and the Eastern Mediterranean, and provided a number of details about customs, beliefs and Islamic practices in such territories at the beginning of the 16th century
An FT-IR study of the conversion of 2-chloropropane, o-dichlorobenzene and dibenzofuran on V(2)O(5)-MoO(3)-TiO(2)SCR-DeNO(x) catalysts
No full textSpectra of the adsorbed species arising from contact of a V(2)O(5)-MoO(3)-TiO(2) model SCR catalyst with ortho-dichlorobenzene (o-DCB) and dibenzofuran (DBF) and their evolution with the temperature are presented and discussed. Dichlorobenzene adsorbs weakly probably on Lewis acid sites through the chlorine atom. A very fast nucleophilic substitution on dichlorobenzene to a chlorophenate species occurs already at RT. On the contrary, adsorption of dibenzofuran is molecular, probably through the oxygen atom on Lewis sites. The aromatic rings of both molecules tend to be later oxidized to give carboxylate species. Parallel experiments with chloropropane show that dehydrochlorination occurs readily, hydrochloric acid is adsorbed quite weakly and that propene can be further oxidized. However, heavier oxidized species like cyclic anhydrides are also formed from chloropropane. The data suggest that the dechloration step of the phenyl ring could be not critical. On the contrary, the building-up of aromatic compounds from smaller molecules is possible and the oxidation of phenyl ring can be slow near reaction conditions. The possibility that the reaction between phenate species and chlorobenzenes give the "de novo" synthesis of dioxins is envisaged. (C) 2002 Elsevier Science B.V. All rights reserved
Solid acids, surface acidity and heterogeneous acid catalysis
No full textThis review begins with the historical development of the theories of acidity and of the
preparation of acids. The historical aspects of acid catalysis and catalysts are also briefly
surveyed. The fundamentals concerning acidity and acid catalysis in liquid phases and at
the solid-liquid interfaces are discussed. The factors determining acidity and activity, as
well as practical applicability, of solid catalysts such as protonic zeolites are reviewed in
detail. Methods for investigation of surface acidity of solids at both solid/vapor and
solid/liquid interfaces are briefly discussed. Finally, most of solid acid families are
considered and their properties critically reviewed
Methanol oxidation over vanadia-based catalysts
No full textThe literature data on the behavior of vanadia-based catalysts in the oxidation of methanol are briefly reviewed. The potential of vanadia-titania catalysts for the production of methyl formate through methanol oxidation is outlined, and mechanistic and technical features of this process are discussed
- …
