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Titolo:
ALKALI-SUPPORT INTERACTIONS ON RUBIDIUM BASE CATALYSTS DETERMINED BY XANES, EXAFS, CO2 ADSORPTION, AND IR SPECTROSCOPY
Autore:
DOSKOCIL EJ; BORDAWEKAR SV; DAVIS RJ;
Indirizzi:
UNIV VIRGINIA,DEPT CHEM ENGN CHARLOTTESVILLE VA 22903 UNIV VIRGINIA,DEPT CHEM ENGN CHARLOTTESVILLE VA 22903
Titolo Testata:
Journal of catalysis
fascicolo: 1, volume: 169, anno: 1997,
pagine: 327 - 337
SICI:
0021-9517(1997)169:1<327:AIORBC>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
ABSORPTION FINE-STRUCTURE; METAL-OXIDE SURFACES; MODIFIED ZEOLITES; SUPERBASIC CATALYSTS; MAGNESIUM-OXIDE; METHANE; ALKYLATION; ACIDITY; MGO;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
E.J. Doskocil et al., "ALKALI-SUPPORT INTERACTIONS ON RUBIDIUM BASE CATALYSTS DETERMINED BY XANES, EXAFS, CO2 ADSORPTION, AND IR SPECTROSCOPY", Journal of catalysis, 169(1), 1997, pp. 327-337

Abstract

Rubidium was supported on a variety of carriers, including magnesia, titania, alumina, carbon, and silica, by decomposition of an impregnated acetate precursor at 773 K. Except for Rb/MgO, none of the oxide-based samples contained surface carbonates as detected by IR spectroscopy after pretreatment at 773 K. The XANES and EXAFS associated with theRb Kedge indicated that the local structure around Rb was highly dependent on the support composition. For example, the Rb-O distance was significantly shorter on carbon and silica compared to more basic carriers. Results from CO2 stepwise TPD showed that Rb/MgO possessed strongly basic sites that were not present on pure MgO. The basic sites formed by Rb addition to the other supports were weaker than those on Rb/MgO. Decomposition of 2-propanol at 593 K was used to relate catalytic activity to surface basicity. As anticipated, Rb/MgO and MgO were highly active and selective for alcohol dehydrogenation. Addition of Rb toalumina and titania greatly decreased the activity of the support oxides for the acid-catalyzed dehydration of 2-propanol. Reactivity and characterization results of Rb/SiO2 were consistent with the formation of a highly disordered, weakly basic, surface silicate phase that exhibited little activity for alcohol decomposition. The overall rate of acetone formation from 2-propanol correlated with the ranking of support basicity evaluated from the Sanderson intermediate electronegativityprinciple. These results suggest that strongly basic alkali-containing catalysts should utilize basic carriers to minimize alkali-support interactions that lower base strength. (C) 1997 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/07/20 alle ore 15:10:09