Reaction of Benzene and Pyridine on Metal-Promoted Sulfated Zirconia Catalysts

Srinivasan, Ram; Keogh, Robert A.; Ghenciu, Anca; Fǎrcaşiu, D.; Davis, Burtron H.

doi:10.1006/jcat.1996.0049

Cited by 47 publications

(18 citation statements)

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“…It has been reported that other compounds may evolve from the surface than just the original probe molecule. In some cases probe or the sulfate decomposes when acidity of metal ion promoted S-ZrO 2 is determined by ammonia-TPD [16,17]. However, decomposition of sulfate is observed above 600 • C during TPD analysis for unpromoted sulfated zirconia by using NH 3 as a probe [18,19].…”

Section: Ammonia-tpdmentioning

confidence: 97%

Preparation of a novel catalyst UDCaT-5: enhancement in activity of acid-treated zirconia—effect of treatment with chlorosulfonic acid vis-à-vis sulfuric acid

Yadav

Murkute

2004

Journal of Catalysis

130

100

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Section: Ammonia-tpdmentioning

confidence: 97%

Preparation of a novel catalyst UDCaT-5: enhancement in activity of acid-treated zirconia—effect of treatment with chlorosulfonic acid vis-à-vis sulfuric acid

Yadav

Murkute

2004

Journal of Catalysis

130

100

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“…Besides an ongoing debate as to which promoter is best [12,13], their exact function is even more controversial. Initially these promoters were believed to boost the acidity [14]but the evidence did not hold [15][16][17]. It has been proposed that a redox functionality is introduced with the promoters, and alkanes might be activated via oxidative dehydrogenation [18] but corresponding reduction of the promoter is not always detected [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Rapid genesis of active phase during calcination of promoted sulfated zirconia catalysts

Hahn

Jentoft

Ressler

et al. 2005

Journal of Catalysis

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Amorphous sulfated zirconium hydroxide was promoted with iron or manganese via the incipient wetness technique, to give 0.5-3.5 weight% promoter in the final catalyst. An exothermic reaction during the calcination temperature ramp (to 823 or 923 K) leads to a rapid overheating ("glow") of the sample. XRD shows that crystallization starts before and progresses during the overheating. The surface area shrinks during the glow, and its final size (85-120 m 2 ·g -1 ) and the porosity appear to be largely determined by the glow event. Manganese and iron ions prevent the coalescence of particles and lead to high surface areas. Variation of the batch volume (2.2, 8.4, or 17.1 ml) for calcination produced different catalysts from the same precursor. For both promoters, samples calcined in large batches exhibited the highest surface areas, interconnected mesopores (2.2-3.8 nm), and the highest maximum rate in n-butane isomerization (338 K, 1 kPa n-butane). Long term performance was independent of surface area and morphology. The concentration of the active sites depended on the calcination batch size, indicating that the active phase is formed in kinetically controlled reactions during the rapid overheating. The catalytic and textural properties of sulfated zirconia catalysts can be reproduced through controlling the batch size used for calcination.

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“…The first row transition metal promoters have thus qualitatively the same effect, which suggests a common yet unknown mode of operation. The promoting effect of Mn and Fe (and others) on sulfated zirconia has been ascribed to (i) increase of acid strength, 10,20 some of these experiments were later proven misleading; 11,15,16 (ii) facilitated formation and stabilization of carbenium ion and alkene intermediates on the surface, 12,13 increased dehydrogenation ability, 7,30 strengthened interaction with carbenium ions, 32 stabilization of the transition state complex on the surface, 7 (iii) a redox trigger of the acid catalyzed process, 2 a different degree of synergism between redox and acid sites, 22 a combination of a redoxactive metal site and an acid site in close proximity with oxidative dehydrogenation as initiating step; 25 and (iv) formation of 'less oxidized' Zr species. 33 Many of these suppositions point towards an interplay between redox and acidic sites, but no clear-cut picture has evolved, and the evidence for the promoter action is mainly indirect.…”

Section: Introductionmentioning

confidence: 99%

Incorporation of manganese and iron into the zirconia lattice in promoted sulfated zirconia catalysts

Jentoft

Hahn

Kröhnert

et al. 2004

Journal of Catalysis

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Two series of Mn-or Fe-promoted zirconia samples were prepared, (i) a series of sulfated-free reference compounds via co-precipitation of aqueous solutions containing zirconium and the promoter cation, and (ii) a series of catalysts via incipient-wetness impregnation of a sulfated zirconium hydroxide. The promoter content was varied between 0 and 5 wt% metal. All promoter-containing materials were calcined at 923 K. The reference materials contained mainly isolated Mn or Fe species incorporated into the zirconia lattice as evidenced by stabilization of the tetragonal zirconia phase, EPR (isolated ions in highly symmetric environment), and a shrinking unit cell volume (XRD) of the tetragonal zirconia phase with increasing promoter content. Only the Mn-promoted catalysts showed such shrinkage in unit cell volume with increasing promoter content. At 2 wt% promoter content, Fe could, and Mn could not be detected by ion scattering spectroscopy on the surface of the catalysts. The Fepromoted catalysts contained Fe2O3-like surface species (EPR, XANES), which could at least in part be removed by washing with oxalic acid. Catalysts were tested for isomerization at 338 K using 1 kPa n-butane in balance of N2. At 0.5 wt% promoter content the maximum rates produced by the 0.5 wt% Mn-promoted and Fe-promoted sulfated zirconia were about 80 and 20 µmol g -1 h -1 , respectively. Mn was thus more effective as a promoter for n-butane isomerization than Fe, despite the more extensive incorporation into the zirconia lattice.

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Reaction of Benzene and Pyridine on Metal-Promoted Sulfated Zirconia Catalysts

Cited by 47 publications

References 0 publications

Preparation of a novel catalyst UDCaT-5: enhancement in activity of acid-treated zirconia—effect of treatment with chlorosulfonic acid vis-à-vis sulfuric acid

Preparation of a novel catalyst UDCaT-5: enhancement in activity of acid-treated zirconia—effect of treatment with chlorosulfonic acid vis-à-vis sulfuric acid

Rapid genesis of active phase during calcination of promoted sulfated zirconia catalysts

Incorporation of manganese and iron into the zirconia lattice in promoted sulfated zirconia catalysts

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