Controlled synthesis of hierarchically porous SAPO-34 zeolites with tailored crystal size and morphology

Wang, Qianqian; Wang, Xuchang; Liu, Yanchao; Zhang, Lichen; Ma, Xiaosen; Zheng, Jiajun; Fan, Bin; Chen, Shuwei; Wang, Yan; Li, Ruifeng

doi:10.1016/j.cplett.2022.139513

Cited by 7 publications

(4 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This means that the contents of Si–O, Al–O, and P–O tetrahedra in the SAPO-34 crystal shell are obviously varied at different synthesis times. It can also be inferred, that compared with the Al atoms, more and more P atoms are substituted by Si atoms of the SAPO-34 framework in the shell layer with the extension of crystallization time . Furthermore, the local Si coordinate structures of the series of samples were investigated by 29 Si MAS NMR spectra (Figure C).…”

Section: Resultsmentioning

confidence: 99%

“…This means that the framework in the shell layer with the extension of crystallization time. 47 Furthermore, the local Si coordinate structures of the series of samples were investigated by 29 Si MAS NMR spectra (Figure 6C). It is well-known that silicon atoms incorporated into the SAPO-34 framework following two different substitution mechanisms, that is, SM2, in which a single P atom is substituted by a single Si atom forming a Si(4Al) structure, and SM3, in which two adjacent Al and P atoms are substituted by two Si atoms, generating Si(nAl) (n = 0−3) structures.…”

Section: Evolution Process and Formationmentioning

confidence: 99%

See 1 more Smart Citation

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Wang,

Dai,

Dai

et al. 2024

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

It is well known that low-silica SAPO-34, with an extra porosity (meso-and/or macropores) system, affords excellent catalytic performance in the methanol-to-olefins (MTO) reaction, while the direct synthesis of low-silica SAPO-34 with a hierarchical structure is difficult to achieve, principally because the crystal impurities are usually formed under a low silica content in a gel precursor. Herein, low-silica SAPO-34 nanocrystals were successfully fabricated for the first time by constructing an isomorphous core−shell structure in an epitaxial growth manner. In which, low-silica, ultrasmall nanosquare-shaped SAPO-34 crystals with the same growth orientation along the (100) crystal plane compactly grow on the monocrystal SAPO-34 cores. Crucially, the external surface acid properties of the core SAPO-34 with the Si-rich outer layer are effectively modified by the low-silica SAPO-34 shell. Furthermore, the growth process and Si-substitution mechanism of the shell zeolite were comprehensively investigated. It was found that with the prolonged crystallization time, more and more coordinated Si(4Al) and Si(3Al) structures via two substitution mechanisms (SM2 and SM3) are generated in the nanocrystalline SAPO-34 shell, which endow moderate acidity of the core−shell SAPO-34. Compared to the uncoated SAPO-34, the core−shell SAPO-34 performs a longer lifespan and a higher average selectivity of light olefins (ethylene plus propylene) when applied to the MTO reaction, which is attributed to the positive effects of the luxuriant interstitial pores offering a fast diffusion channel and the moderate acid density depressing the hydrogen transfer reaction of light olefins. This work provides new insights into the fabrication of low-silica SAPO-34 nanocrystals, which are based on the rational design of the isomorphous core−shell zeolite.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Evolution Process and Formationmentioning

confidence: 99%

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Wang,

Dai,

Dai

et al. 2024

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…It was observed the existence of several bands common to all samples in the range of 1250 -400 cm -1 , corresponding to the bands of the symmetrical and asymmetrical T-O-T bonds (T = Si, Al, P or B), highlighting sample B11_0,2B where the band at 840 cm -1 is more evident, which may correspond to boron binding, being more defined in the sample where its content is higher 37 . Still in the range of T-O-T bands, sample S11 exhibited a band at 980 cm -1 , which would correspond to the presence of asymmetric Si-O-Si, indicating that in fact there was a replacement of silicon by boron in the other samples and explaining the disappearance of this band 38 .…”

Section: Fourier Transform Infrared Spectroscopy (Ft-ir)mentioning

confidence: 96%

“…It is also observed that for samples with boron, there is a band at 1396 cm -1 , which is more evident for samples B5_0,1B e B5_0,2B, corresponding to the presence of B(OSi) 3 bonds or to trigonal asymmetric B-O bonds, indicating a higher occurrence of dehydration of the groups containing boron or structural defects similar to those that occur with aluminum 33,36 . From the range of 1250 cm -1 to approximately 400 cm -1 , samples show absorption bands corresponding to symmetrical and asymmetrical T-O-T bonds (T = Si, Al, P or B), with the band at approximately 1100 cm -1 related to the most common asymmetric tetrahedral T-O bonds in the crystal lattice 37,38 .…”

Section: Fourier Transform Infrared Spectroscopy (Ft-ir)mentioning

confidence: 99%

Boron Incorporation by Hydrothermal Synthesis Into SAPO-5 and SAPO-11 Molecular Sieves

et al. 2023

View full text Add to dashboard Cite

Silicoaluminophosphates SAPO-5 and SAPO-11 were synthesized using the hydrothermal method, 170 ºC with triethylamine and dipropylamine as the structure directing agents, respectively. This work aimed the incorporation of boron into the structures obtained by modifying the composition of the system, using as a reaction equation: Al 2 O 3 :P 2 O 5 :x SiO 2 : yB 2 O 3 :1,5TEA (or DPA):50H 2 O, with x, y=0-0.2. The phase was identified by XRD and characterized by FTIR, TGA/DTG, TPD-NH 3 and nitrogen adsorption at -196°C. The structure parameters confirmed the obtaining of pure structures, showing a slight contraction in the parameters of the unit cells, indicating the presence of boron in the crystal lattice. The Brønsted sites, were modified up to a maximum of boron (y = 0.1) and for higher content, the acidity was not significant. The modification of weak acidity related to the appearance of isolated BO 3 groups, indicating that the silicon atoms were not sufficiently distributed for the formation of sites.

show abstract

Synthesis of a phosphomolybdic acid-modified AlPO4-5/SAPO-34 composite catalyst and its catalytic performance in the MTO reaction

Zhu,

Chen,

Sang

et al. 2024

Applied Catalysis A: General

View full text Add to dashboard Cite

Controlled synthesis of hierarchically porous SAPO-34 zeolites with tailored crystal size and morphology

Cited by 7 publications

References 22 publications

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core–Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction

Boron Incorporation by Hydrothermal Synthesis Into SAPO-5 and SAPO-11 Molecular Sieves

Synthesis of a phosphomolybdic acid-modified AlPO4-5/SAPO-34 composite catalyst and its catalytic performance in the MTO reaction

Contact Info

Product

Resources

About