The Quantitative Study of Brönsted Acidity in Sapo-37

Макарова, М. А.; Ojo, Adeola F.; Al-Ghefaili, Khalid M.; Dwyer, John

doi:10.1016/b978-1-4832-8383-8.50116-1

Cited by 14 publications

(8 citation statements)

References 6 publications

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“…This fact can be interpreted in terms of the increasing likelihood of SM3+SM2 substitution for the samples synthesized from the nonaqueous media [18]. For SAPO molecular sieves, simple SM2 substitution will lead to the formation of one Bronsted acid site per Si atom, while SM3+SM2 substitution will result in less than one acid site per Si atom [16,17].…”

Section: Acidity and 29 Si Cp/mas Nmr Characterizationmentioning

confidence: 99%

“…The acidity of the SAPO molecular sieves depends strongly on the Si content and the mechanism of Si substitution [15][16][17][18]. When Si atoms are introduced to the phosphorous sites of a theoretical AlPO 4 framework (SM2 substitution), Bronsted acid sites will be formed [16].…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, simultaneous replacement of a pair of Al and P atoms by two Si atoms (SM3 substitution) will lead to a neutral framework. In addition, the Bronsted acid sites can also be generated by a combination of the SM3 substitution with the SM2 substitution [18]. The resulting acidic strength is usually stronger than that arising by a simple SM2 substitution [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Hydroisomerization of Long-Chain Alkane Over Pt/SAPO-11 Catalysts Synthesized from Nonaqueous Media

et al. 2005

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SAPO-11 molecular sieves were synthesized from nonaqueous media. The effects of Si and Al sources as well as solvents on the catalytic performance of SAPO-11 were investigated by the hydroisomerization reaction of n-dodecane. The samples were characterized by XRD, XRF, N 2 -adsorption, SEM, NH 3 -TPD, IR-NH 3 and 29 Si CP MAS NMR. The SAPO-11 samples synthesized with tetraethoxysilane as the Si source showed higher Si incorporation contents than the SAPO molecular sieves prepared with polymeric Si sources (fumed silica and Si colloidal gel). The reaction results showed that Pt/SAPO-11 catalysts synthesized from ethylene glycol and glycerol media with the monomeric Si and Al sources (tetraethoxysilane, aluminum isopropoxide) exhibited higher catalytic activities than those catalysts with the polymeric Si or Al (pseudo-boehmite) sources, due to the larger external surface area and higher acidity of the former ones. Especially, the catalyst synthesized in an ethylene glycol medium possessed the highest catalytic activity. Over this catalyst, 88% conversion of n-dodecane was achieved at a low temperature of 250°C.

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Section: Acidity and 29 Si Cp/mas Nmr Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydroisomerization of Long-Chain Alkane Over Pt/SAPO-11 Catalysts Synthesized from Nonaqueous Media

et al. 2005

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“…Since the 3660 cm q band was only present in the spectrum of No.4 SAPO-11 sample containing relatively high Si (0.08 molar content), it might be due to vibrations of hydroxy groups in or around Si domains in the framework lattice. These bands were also found at similar frequencies for SAPO-5 [28,31] and SAPO-37 [27,32,33], and may be common features of SAPOs. The intensities of these bands increased with increase of Si content in SAPO-11 samples except for the one at 3677 cm q, which decreased due to the reduction of P in the framework lattice by Si-P exchange.…”

Section: Aciditymentioning

confidence: 57%

“…The 1455 cm "l band was assigned to carbon chain stretching of coordinatively bonded pyridine complexes and indicated the presence of Lewis acidity. The 1490 cm -1 band was common to both species and related to Br0nsted and Lewis acidity, while the bands at 1635 and 1624 cm -1 belonged to BrOnsted and Lewis acidity, respectively [33].…”

Section: Aciditymentioning

confidence: 90%

Catalytic behavior in skeletal isomerization of linear butenes and acidic properties of ani-Pr2NH-templated sapo-11 molecular sieve

Tian¹,

Shi

Yuan

et al. 1998

React Kinet Catal Lett

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SAPO-11 samples were synthesized with i-Pr2NH as a novel template, and applied in catalytic skeletal isomerization of linear butenes. More linear butenes were converted with increasing Si content in SAPO-11 samples, while the iso-butene selectivity was proportional to the Si content only in the lower reaction temperature region. The maximum yield of iso-butene was achieved around 763 K. The acidic properties of SAPO-11 samples were studied by NH3-TPD and IR spectroscopy. The strong acidity was due to the formation of Si domains in the framework lattice.

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