Cationic surfactant-assisted hydrothermal synthesis: an effective way to tune the crystalline phase and morphology of SAPO molecular sieves

Yang, Miao; Tian, Peng; Liu, Lin; Wang, Chan; Xu, Shutao; He, Yanli; Liu, Zhongmin

doi:10.1039/c5ce01702e

Cited by 13 publications

(8 citation statements)

References 37 publications

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“…21 As a result, many efforts have been made to develop new synthetic routes to control the growth of zeolite crystals. 22 One effectual way is the introduction of metal ions in the zeolite synthesis. The germanosilicate molecular sieve is a successful example in this context, 23,24 which implies that some metal additives may favor the formation of ultra-high silica zeolites.…”

Section: Introductionmentioning

confidence: 99%

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

et al. 2016

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Mg 2+ -derived mesoporous ultra-high silica twelve-membered-ring zeolites with multiple topologies (MOR, BEA and MTW) were straightforwardly synthesized by a one-pot route, where the crucial step was the cohydrolysis/condensation of silica source and magnesium salt under moderate acidic conditions. SiO 2 /Al 2 O 3 ratios can be adjusted from ∼30 to as high as 410, thus generating superior basicity that was further improved by the incorporation of Mg species. A mesoporous structure was self-formed without the assistance of any template or special strategy. Catalysis tests showed high activity of these zeolites in a typical base reaction, Knoevenagel condensation, even for the bulky substrates due to the enhanced mass transfer arising from the mesopores. This methodology provides a promising approach towards target synthesis of valuable Mg 2+ -derived mesoporous ultra-high silica zeolites with tunable acid/base properties, which can even act as an efficient mesoporous zeolitic solid base.

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Section: Introductionmentioning

confidence: 99%

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

et al. 2016

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“…The role of the surfactant in the D r a f t crystallization was investigated previously. 40 The literature finding suggests that although the presence of cationic surfactant is not essential for DNL-6 formation, the surfactant does affect the crystal morphology and phase purity by inhibiting the formation of competing SAPO-34. Our DGC results seem to suggest that the surfactant molecules are part of the structure of the layered intermediate as it is known that mesostructured AlPO lamellar and tubular materials can be prepared using cationic surfactants.…”

Section: Discussionmentioning

confidence: 99%

“…30 Previous work also examined the role of the surfactant used in the synthesis of DNL-6. 40 At the present time, the formation of DNL-6 is still not understood completely on a molecular level. In this study, we examined the formation of DNL-6 under both the DGC and HTS conditions.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the crystallization of molecular sieve DNL-6

Goldman

Huang

2022

Can. J. Chem.

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Crystallization of DNL-6, a silicoaluminophosphate (SAPO) based molecular sieve with the RHO topology, was investigated under both the hydrothermal synthesis (HTS) and dry-gel conversion (DGC) conditions. Crystallization of DNL-6 under the HTS conditions is rather fast. But a combination of crystallization under the DGC conditions and reducing reaction temperature slow down the reactions, allowing for intermediates to be captured. Under the DGC conditions, DNL-6 crystallizes through a semi-crystalline layered phase. The nature of this intermediate is aluminophosphate (AlPO) rather than SAPO with most P atoms having a local environment of P(–O–Al)3(OH). The surfactant (cetyltrimethylammonium chloride) used for synthesis appears to be part of the layered intermediate. Si is directly incorporated in the DNL-6 framework via SM II mechanism when the semi-crystalline AlPO phase is transforming to DNL-6 with the assistance of a very small amount of water. Both the structure directing agent and the surfactant play a role in the formation of DNL-6, as they were found within the final synthesized products. SEM data show that hydrothermal synthesis produces a much more crystalline product. The facts that the semi-crystalline layered phase was also observed in the powder X-ray diffraction patterns of the solid samples obtained under the HTS conditions and that the evolution of the local structure around P and Al in the intermediate phases are similar imply that under the reaction conditions employed in the present study, the formation pathways of DNL-6 under the HTS and DGC conditions appear to have some similarities.

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“…SAPO-RHO zeolite materials were synthesized by Liu’s method . The molar composition of the initial precursor was 1.0 Al(i-C 3 H 7 O) 3 /0.8H 3 PO 3 / x TEOS/1.5 DEA/50H 2 O/0.2C 18 TAB ( x = 0.4; 0.6; 0.8; 1.0).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Cu-SAPO-RHO Catalysts by Template-Assisted Ion Incorporation and Their Catalytic Performance for NH₃-SCR of NO_x

Hou

Yin

Zhong

et al. 2022

Ind. Eng. Chem. Res.

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A series of Cu-SAPO-RHO zeolite catalysts were prepared using a straightforward template-assisted ion incorporation process for NH3-SCR of NO x . The Si content and Cu loading amount were changed, and the effects of Si and Cu contents were investigated by physical and chemical measurements. Interestingly, catalysts prepared by this direct ion exchange method show higher activity than those obtained by conventional ion exchange. Significantly, the Cu-SAPO-RHO catalyst with 0.8 Si and Cu exchanged 3 times exhibits excellent NH3-selective catalytic reduction (SCR) performance, which is due to the amounts of moderate and strong Brønsted acid sites, more isolated Cu2+, and relatively less CuO species. Moreover, the reaction mechanism over the best-performance catalyst was studied. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results indicate that the Cu-SAPO-RHO sample conforms to both Eley–Rideal (E–R) and Langmuir–Hinshelwood (L–H) paths, and the L–H reaction is dominant at low temperatures.

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Cationic surfactant-assisted hydrothermal synthesis: an effective way to tune the crystalline phase and morphology of SAPO molecular sieves

Cited by 13 publications

References 37 publications

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Investigation into the crystallization of molecular sieve DNL-6

Synthesis of Cu-SAPO-RHO Catalysts by Template-Assisted Ion Incorporation and Their Catalytic Performance for NH₃-SCR of NO_x

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Cationic surfactant-assisted hydrothermal synthesis: an effective way to tune the crystalline phase and morphology of SAPO molecular sieves

Cited by 13 publications

References 37 publications

Mg2+-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Mg2+-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Investigation into the crystallization of molecular sieve DNL-6

Synthesis of Cu-SAPO-RHO Catalysts by Template-Assisted Ion Incorporation and Their Catalytic Performance for NH3-SCR of NOx

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Product

Resources

About

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Mg²⁺-derived mesoporous ultra-high silica twelve-membered-ring basic zeolites: straightforward synthesis and catalytic performance

Synthesis of Cu-SAPO-RHO Catalysts by Template-Assisted Ion Incorporation and Their Catalytic Performance for NH₃-SCR of NO_x