Efficient hydrothermal synthesis of nanostructured SAPO-34 using ultrasound energy: Physicochemical characterization and catalytic performance toward methanol conversion to light olefins

AbstractThe effect of Zn on the catalytic performance of ZSM-5 in the methanol-to-olefin conversion was investigated. The samples were characterised by X-ray diffraction, N2 adsorption, FTIR, temperature-programmed desorption of ammonia and water, and Py-IR. The experimental results revealed Znmodified ZSM-5 to show a lower selectivity to light olefin at the higher reaction temperature of 520°C but a higher selectivity to light olefin at lower temperatures. As a comparison, the catalytic performance of Ca-modified ZSM-5 for the methanol conversion is also given. From the above results, it is concluded that Zn may play another role in the methanol conversion in addition to tuning the surface acidic property after modification.

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Short time microwave/seed-assisted synthesis and physicochemical characterization of nanostructured MnAPSO-34 catalyst used in methanol conversion to light olefins

Powder Technology ◽

10.1016/j.powtec.2017.01.017 ◽

2017 ◽

Vol 310 ◽

pp. 187-200 ◽

Cited By ~ 16

Author(s):

Ali Alizadeh Eslami ◽

Mohammad Haghighi ◽

Parisa Sadeghpour

Keyword(s):

Physicochemical Characterization ◽

Methanol Conversion ◽

Light Olefins ◽

Short Time

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Synthesis of SAPO-34 catalysts via sonochemically prepared method and its catalytic performance in methanol conversion to light olefins

Applied Petrochemical Research ◽

10.1007/s13203-018-0193-x ◽

2018 ◽

Vol 8 (1) ◽

pp. 13-20 ◽

Cited By ~ 4

Author(s):

Rana Ahmadova ◽

Hikmet Ibragimov ◽

Evgenii Kondratenko ◽

Uwe Rodemerc

Keyword(s):

Methanol Conversion ◽

Catalytic Performance ◽

Light Olefins

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Catalytic Longevity of Hierarchical SAPO-34/AlMCM-41 Nanocomposite Molecular Sieve In Methanol-to-Olefins Process

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200428092404 ◽

2020 ◽

Vol 23 ◽

Author(s):

Hossein Roohollahi ◽

Rouein Halladj ◽

Sima Askari

Keyword(s):

Molecular Sieve ◽

Molecular Diffusion ◽

Methanol Conversion ◽

Catalytic Performance ◽

Acid Sites ◽

The Other ◽

Light Olefins ◽

Initial Reaction ◽

Pore Blockage ◽

Prepared Composite

: SAPO-34/AlMCM-41, as a hierarchical nanocomposite molecular sieve was prepared by sequential hydrothermal and dry-gel methods studied for catalytic conversion of methanol to light olefins. Pure AlMCM-41, SAPO-34, and their physical mixture were also produced and catalytically compared. Physicochemical properties of materials were mainly investigated using XRD, N2 isothermal adsorptiondesorption, FESEM, FT-IR, NH3-TPD, and TG/DTG/DTA techniques. Micro-meso hierarchy of prepared composite could be demonstrated by XRD and BET analyses. Catalytic performance of materials illustrated that the methanol conversion on the prepared composite was about 98% for 120 min which showed a higher activity than the other catalysts. The initial reaction selectivity to light olefins for the composite was also comparable with those for the other catalysts. Furthermore, the results revealed that SAPO-34/AlMCM-41 preparation decreased the concentration and strength of active acid sites of the catalyst which could beneficially affect the deposition of heavy molecular products on the catalyst. However, as observed, the prepared composite was deactivated in olefins production faster than pure SAPO-34. The small mean pore diameter of composite could be mainly responsible for its pore blockage and higher deactivation rate. Meanwhile, since the SAPO-34 prepared by dry-gel method had inherently high mesoporosity, the AlMCM-41 introduction didn't promote the molecular diffusion in the composite structure. The coke content was found 15.5% for deactivated composite smaller than that for the SAPO-34 catalyst which could be due to the pore blockage and deactivation of the composite in a shorter period.

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Structural/Texture Evolution During Facile Substitution of Ni into ZSM-5 Nanostructure vs. its Impregnation Dispersion Used in Selective Transformation of Methanol to Ethylene and Propylene

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200825144543 ◽

2020 ◽

Vol 23 ◽

Cited By ~ 1

Author(s):

Parisa Sadeghpour ◽

Mohammad Haghighi ◽

Mehrdad Esmaeili

Keyword(s):

High Temperature ◽

Physicochemical Properties ◽

Active Sites ◽

Catalytic Performance ◽

Fixed Bed Reactor ◽

Light Olefins ◽

Isomorphous Substitution ◽

Impregnation Method ◽

Hydrothermal Temperature ◽

X Ray

Aim and Objective: Effect of two different modification methods for introducing Ni into ZSM-5 framework was investigated under high temperature synthesis conditions. The nickel successfully introduced into the MFI structures at different crystallization conditions to enhance the physicochemical properties and catalytic performance. Materials and Methods: A series of impregnated Ni/ZSM-5 and isomorphous substituted NiZSM-5 nanostructure catalysts were prepared hydrothermally at different high temperatures and within short times. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), Brunner, Emmett and Teller-Barrett, Joyner and Halenda (BET-BJH), Fourier transform infrared (FTIR) and Temperature-programmed desorption of ammonia (TPDNH3) were applied to investigate the physicochemical properties. Results: Although all the catalysts showed pure silica MFI–type nanosheets and coffin-like morphology, using the isomorphous substitution for Ni incorporation into the ZSM-5 framework led to the formation of materials with lower crystallinity, higher pore volume and stronger acidity compared to using impregnation method. Moreover, it was found that raising the hydrothermal temperature increased the crystallinity and enhanced more uniform incorporation of Ni atoms in the crystalline structure of catalysts. TPD-NH3 analysis demonstrated that high crystallization temperature and short crystallization time of NiZSM-5(350-0.5) resulted in fewer weak acid sites and medium acid strength. The MTO catalytic performance was tested in a fixed bed reactor at 460ºC and GHSV=10500 cm3 /gcat.h. A slightly different reaction pathway was proposed for the production of light olefins over impregnated Ni/ZSM-5 catalysts based on the role of NiO species. The enhanced methanol conversion for isomorphous substituted NiZSM-5 catalysts could be related to the most accessible active sites located inside the pores. Conclusion: The impregnated Ni/ZSM-5 catalyst prepared at low hydrothermal temperature showed the best catalytic performance, while the isomorphous substituted NiZSM-5 prepared at high temperature was found to be the active molecular sieve regarding the stability performance.

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Control of zeolite microenvironment for propene synthesis from methanol

Nature Communications ◽

10.1038/s41467-021-21062-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Longfei Lin ◽

Mengtian Fan ◽

Alena M. Sheveleva ◽

Xue Han ◽

Zhimou Tang ◽

...

Keyword(s):

Active Sites ◽

Inelastic Neutron Scattering ◽

Sustainable Manufacturing ◽

Methanol Conversion ◽

Acid Sites ◽

Light Olefins ◽

Carbon Bond ◽

X Ray ◽

Carbon Carbon Bond ◽

Catalytic Stability

AbstractOptimising the balance between propene selectivity, propene/ethene ratio and catalytic stability and unravelling the explicit mechanism on formation of the first carbon–carbon bond are challenging goals of great importance in state-of-the-art methanol-to-olefin (MTO) research. We report a strategy to finely control the nature of active sites within the pores of commercial MFI-zeolites by incorporating tantalum(V) and aluminium(III) centres into the framework. The resultant TaAlS-1 zeolite exhibits simultaneously remarkable propene selectivity (51%), propene/ethene ratio (8.3) and catalytic stability (>50 h) at full methanol conversion. In situ synchrotron X-ray powder diffraction, X-ray absorption spectroscopy and inelastic neutron scattering coupled with DFT calculations reveal that the first carbon–carbon bond is formed between an activated methanol molecule and a trimethyloxonium intermediate. The unprecedented cooperativity between tantalum(V) and Brønsted acid sites creates an optimal microenvironment for efficient conversion of methanol and thus greatly promotes the application of zeolites in the sustainable manufacturing of light olefins.

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