A highly efficient SAPO-34 catalyst for improving light olefins in methanol conversion: Insight into the role of hierarchical porosities and tailoring acid properties based on in situ NH3-poisoning

Wang, Qianqian; Zhang, Wenwen; Ma, Xiaosen; Liu, Yanchao; Zhang, Lichen; Zheng, Jiajun; Wang, Yan; Li, Wenlin; Fan, Bin; Li, Ruifeng

doi:10.1016/j.fuel.2022.125935

Cited by 13 publications

(14 citation statements)

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“…In that way, the decreased acidity of strong acid sites in the suitable range is conducive to improving the MTO catalytic properties because it alleviates the formation of coke deposits. 31,54 Except for that, the acid sites located on the external surfaces of SAPO-34 can also affect the catalytic performances. The reason is that these acid sites have no shape selectivity and can trigger coke formation on the surfaces that easily congest the zeolite channels, causing the crystal's inner region to be less accessible to substrates, 32,56 not only compromising catalytic lifetime but also lowering light olefins selectivity.…”

Section: Catalytic Performance Of Mto Reactionmentioning

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

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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.

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Section: Catalytic Performance Of Mto Reactionmentioning

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

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“…Pore volume: 1.307 cm 3 /g [128] Specific surface area: 514.68 m 2 /g [128] Average pore diameter: 9.69 nm [128] Bulk density: 101.423 kg/m 3 [128] Adsorption capacity: 0.02 g•g −1 [134] A series of metal aluminophosphates (AlPOs, SAPOs, VAPOs, and TAPOs, among others) presented a highly stable structure and regenerability [153][154][155], especially for AlPOs and SAPOs with high mechanical strength, and the open structures enhanced the surface areas and resulted in a good balance between hydrophobicity and hydrophilicity [156,157]. The microstructures of AlPOs, SAPOs, and VAPOs are shown in Figure 14n-p [155,158,159], respectively. In previous studies on SAPOs and AlPOs [160][161][162][163], the water adsorption mechanism was revealed, especially for structural phase-dependent water diffusivity at various concentrations and Si/Al ratios, by means of molecular dynamics (MD), density functional theory (DFT) computations [162], nuclear magnetic resonance (NMR) [160], and X-ray diffraction (XRD) [160,163].…”

Section: Silica Gelmentioning

confidence: 99%

“…Figure 14. SEM images of activated carbon fiber felt (a) [98], activated carbon foam (b) [99], expanded natural graphite (c) [102], carbon nanotubes (d) [104], activated alumina (e) [107], zeolite 13X (f) [106], attapulgite (g) [113], expanded vermiculite (h) [114], diatomite (i) [115], silica gel (j) [126], silica aero-gels (k) [127], MCM-41 (l) [130], SBA-15 (m) [128], AlPO4-5 (n) [155], SAPO-34 (o) [159], VAPO-5 (p) [158], MIL-101 (q) [166], Aluminum fumarate (r) [167], UiO-67 (s) [168], and PCN-33 (t) [169]: Reprinted with permission from Ref. [98] Copyright © 2016 Elsevier Ltd. All rights reserved; with permission from Ref.…”

Section: Peer Review 21 Of 58mentioning

confidence: 99%

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Salt Hydrate Adsorption Material-Based Thermochemical Energy Storage for Space Heating Application: A Review

et al. 2023

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Recent years have seen increasing attention to TCES technology owing to its potentially high energy density and suitability for long-duration storage with negligible loss, and it benefits the deployment of future net-zero energy systems. This paper provides a review of salt hydrate adsorption material-based TCES for space heating applications at ~150 °C. The incorporation of salt hydrates into a porous matrix to form composite materials provides the best avenue to overcome some challenges such as mass transport limitation and lower thermal conductivity. Therefore, a systematic classification of the host matrix is given, and the most promising host matrix, MIL-101(Cr)(MOFs), which is especially suitable for loading hygroscopic salt, is screened from the perspective of hydrothermal stability, mechanical strength, and water uptake. Higher salt content clogs pores and, conversely, reduces adsorption performance; thus, a balance between salt content and adsorption/desorption performance should be sought. MgCl2/rGOA is obtained with the highest salt loading of 97.3 wt.%, and the optimal adsorption capacity and energy density of 1.6 g·g−1 and 2225.71 kJ·kg−1, respectively. In general, larger pores approximately 8–10 nm inside the matrix are more favorable for salt dispersion. However, for some salts (MgSO4-based composites), a host matrix with smaller pores (2–3 nm) is beneficial for faster reaction kinetics. Water molecule migration behavior, and the phase transition path on the surface or interior of the composite particles, should be identified in the future. Moreover, it is essential to construct a micromechanical experimental model of the interface.

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“…9,10 Considerable efforts have been devoted to overcome internal diffusion limitations and prolong the lifetime of SAPO-34 catalysts for MTO reactions. [11][12][13] Previous documents have shown that decreasing the catalyst size is considered to be an effective method to decrease intracrystalline diffusion path length and thus suppress the formation rate of coke deposition, which consequently increases catalyst life span. In recent years, several synthesis methods, such as hydrothermal synthesis, 14 dry gel conversion, 15,16 rapid high temperature methods 17 and microwave and the sonochemical techniques, 18,19 have been used for fabricating nano-sized SAPO-34 catalysts by controlling synthesis parameters (crystallization time and temperature, template type and concentration, raw material type, the concentration of synthesis gel, etc.).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of nano-sized SAPO-34 using a facile micron-meter seed processing method and their enhanced performance in methanol-to-olefin reactions

Wang,

Mo,

et al. 2024

Inorg. Chem. Front.

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A highly efficient SAPO-34 catalyst for improving light olefins in methanol conversion: Insight into the role of hierarchical porosities and tailoring acid properties based on in situ NH3-poisoning

Cited by 13 publications

References 70 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

Salt Hydrate Adsorption Material-Based Thermochemical Energy Storage for Space Heating Application: A Review

Synthesis of nano-sized SAPO-34 using a facile micron-meter seed processing method and their enhanced performance in methanol-to-olefin reactions

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