Characterization of acidity in ZSM-5 zeolites:  an x-ray photoelectron and IR spectroscopy study

Borade, Ramesh B.; Sayari, Abdelhamid; Adnot, A.; Kaliaguine, Serge

doi:10.1021/j100378a068

Cited by 160 publications

(88 citation statements)

References 3 publications

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“…Determinations of the superficial atomic ratios were made by comparing the areas under the peaks after background subtraction and corrections due to differences in escape depth and in photoionization cross sections. 23 Temperature Programmed Reduction (TPR) measurements were carried out in a Micromeritics Auto Chem II instrument equipped with a thermal conductivity detector. The calcined samples were treated at 373 K for 30 min under an argon stream in order to eliminate humidity.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

et al. 2010

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Recebido em 27/4/09; aceito em 30/10/09; publicado na web em 12/3/10 Semi-hydrogenation of alkynes has industrial and academic relevance on a large scale. To increase the activity, selectivity and lifetime of monometallic catalysts, the development of bimetallic catalysts has been investigated. 1-Heptyne hydrogenation over low-loaded Pd and Ni monometallic and PdNi bimetallic catalysts was studied in liquid phase at mild conditions. XPS results suggest that nickel addition to Pd modifies the electronic state of palladium as nickel loading is increased. Low-loaded Pd catalysts showed the highest selectivities (> 95%). The most active prepared catalyst, PdNi (1%) , was more selective than the Lindlar catalyst.

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Section: Catalyst Characterizationmentioning

confidence: 99%

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

et al. 2010

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“…Fourier transform infrared (FTIR) spectroscopy works complementary to X-ray diffraction 7,24,29,30 in search for changes in the crystallinity 31 , by comparing the peak FTIR Study of the Relation, between Extra-framework Aluminum Species and the Adsorbed Molecular Water, and its Effect on the Acidity in ZSM-5 Steamed Zeolite intensities in the region of 1300 to 300 cm -1 . These bands are grouped in two types of vibrations of the tetrahedral TO 4 units (where T = Al or Si):…”

Section: Introductionmentioning

confidence: 99%

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

Isernia

2013

Mat. Res.

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The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560-960 °C of the ZSM-5 catalyst (framework Si/Al ratio of 13), suggests an association between adsorbed molecular water and extra-framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Brönsted and Lewis sites, when treatment temperature rises, with contradicts the frequently accepted mechanism of the transformation of two bridged Si-OH-Al groups for each Lewis site generated. The gradual conversion of the octahedral extra-framework aluminum (Lewis-associated) in polymeric species with low acidity is the most probable cause of this behavior. On the other hand, the apparent decline of the acid Brönsted strength, with the increase in the temperature of the hydrothermal treatment, has two possible causes: a) the decreasing accessibility, of the pyridine molecular probe to bridged Si-OH-Al groups with the strongest Brönsted acidity, inside the channels, and b) the gradual transformation of these groups into extra framework species of weak acidity.

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Section: Catalyst Characterizationmentioning

confidence: 99%

High-Active Metallic-Activated Carbon Catalysts for Selective Hydrogenation

Carrara

Betti

Coloma

et al. 2018

International Journal of Chemical Engineering

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A series of low-loaded metallic-activated carbon catalysts were evaluated during the selective hydrogenation of a medium-chain alkyne under mild conditions. e catalysts and support were characterized by ICP, hydrogen chemisorption, Raman spectroscopy, temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR micro-ATR), transmission electronic microscopy (TEM), and X-ray photoelectronic spectroscopy (XPS). When studying the effect of the metallic phase, the catalysts were active and selective to the alkene synthesis. NiCl/C was the most active and selective catalytic system. Besides, when the precursor salt was evaluated, PdN/C was more active and selective than PdCl/C. Meanwhile, alkyne is present in the reaction media, and geometrical and electronic effects favor alkene desorption and so avoid their overhydrogenation to the alkane. Under mild conditions, nickel catalysts are considerably more active and selective than the Lindlar catalyst.

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Characterization of acidity in ZSM-5 zeolites: an x-ray photoelectron and IR spectroscopy study

Cited by 160 publications

References 3 publications

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

High-Active Metallic-Activated Carbon Catalysts for Selective Hydrogenation

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