Reversible interaction of NH3 with the framework of template-free zeolite-type SAPO-34

Vomscheid, R.; Briend, M.; Peltre, M.J.; Barthomeuf, D.; Man, Pascal P.

doi:10.1039/ft9959103281

Cited by 22 publications

(18 citation statements)

References 16 publications

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“…They showed that NH 3 -TPD is a good method to determine the Brønsted acidity of SAPO-34. 20 This fact encouraged us to measure the NH 3 -TPD spectra of SAPO-34 with particle sizes of less than B3 mm. The relationship between the mole fraction of Si (the value of z) and the amount of NH 3 desorption is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Influence of Si distribution in framework of SAPO-34 and its particle size on propylene selectivity and production rate for conversion of ethylene to propylene

Iwase

Motokura

Koyama

et al. 2009

Phys. Chem. Chem. Phys.

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To investigate the effect of SAPO-34 particle size (with a fixed Si mole fraction in its framework) and that of the Si mole fraction (in a SAPO-34 framework with fixed particle size) on propylene selectivity and production rate for the conversion of ethylene to propylene, SAPO-34 was prepared by hydrothermal synthesis using tetraethyl ammonium hydroxide or morpholine as a structural agent. The conversion of ethylene was carried out at 473 K using SAPO-34. The selectivity for propylene, the rate of propylene production, and the lifetime of the catalyst were strongly influenced by the catalyst crystal size. The SAPO-34 with a approximately 2.5 microm particle size had the highest selectivity for propylene (approximately 80%) up to a high conversion of ethylene (approximately 70%), while SAPO-34 with smaller particles had a longer catalyst lifetime, implying that catalyst deactivation was suppressed. The mole fraction of Si in the SAPO-34 framework with fixed particle size had little influence on the selectivity for propylene, indicating that the acid strength of SAPO-34 is independent of the Si mole fraction and all protons in SAPO-34 behave equivalently. Furthermore, the acid strength of protons determined by the measurements of NH(3)-TPD (temperature-programmed desorption) spectra did not depend on either the Si mole fraction or the SAPO-34 particle size. This result was also evident in the cracking rate of n-butane, which increased proportionally with increasing number of protons in SAPO-34.The number of protons generated by the incorporation of Si4+ into the SAPO-34 lattice increased proportionally, up to one Si atom introduced into every cage of SAPO-34, but did not continue to increase with further introduction of Si4+ into the lattice.

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Section: Resultsmentioning

confidence: 99%

Influence of Si distribution in framework of SAPO-34 and its particle size on propylene selectivity and production rate for conversion of ethylene to propylene

Iwase

Motokura

Koyama

et al. 2009

Phys. Chem. Chem. Phys.

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“…Two peaks at 3625 and 3598 cm À1 can be attributed to two types of Si(OH)Al groups differed in their localization. The bridged group with y = 3598 cm À1 is assumed to be localized in the hexagonal prism, forming an H-bond with adjacent oxygen atoms of the framework while the isolated bridged OH groups pointing towards the center of the elliptical cages give the vibration frequency at 3625 cm À1 [15][16][17][18]. These two types of OH groups have been considered to have similar acidic properties and to be the active sites for acid-catalyzing reaction [19,20].…”

Section: Resultsmentioning

confidence: 99%

New route for light olefins production from chloromethane over HSAPO-34 molecular sieve

Wei

Zhang

et al. 2005

Catalysis Today

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“…Such cleavage of the bonding metalwoxygen upon sorption of a strong base molecule has been found for cloverite24 and for aluminophosphate molecular sieves. 27 The observations with sorbed pyridine fully support the model.…”

Section: Sorption Of Strong Basesmentioning

confidence: 53%

IR microspectroscopic investigation of the acid sites in metal substituted AlPO4-5 molecular sieves Part 1.Sorption of benzene and strong bases

Müller

Bódis

Kornatowski³

et al. 1999

Phys. Chem. Chem. Phys.

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The functional groups of metal substituted aluminophosphate (MeAPO-5) materials and their interactions with probe molecules were investigated by in situ IR microspectroscopy. All metal substituted samples showed IR bands which can be assigned to the bridging hydroxy groups. Their acid strength determined from the perturbation of the bands by sorption of benzene decreased in the sequence Sorption of strong bases (ammonia and pyridine) induced the cleavage of at least one bond between the framework metal cation and oxygen at the bridging hydroxy groups leading to strong coordinative interactions of the base molecules with the framework metal cations.

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Reversible interaction of NH3 with the framework of template-free zeolite-type SAPO-34

Cited by 22 publications

References 16 publications

Influence of Si distribution in framework of SAPO-34 and its particle size on propylene selectivity and production rate for conversion of ethylene to propylene

Influence of Si distribution in framework of SAPO-34 and its particle size on propylene selectivity and production rate for conversion of ethylene to propylene

New route for light olefins production from chloromethane over HSAPO-34 molecular sieve

IR microspectroscopic investigation of the acid sites in metal substituted AlPO4-5 molecular sieves Part 1.Sorption of benzene and strong bases

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