Mechanism of SAPO-34 catalyst deactivation in the course of MTO conversion in a slurry reactor

Коннов, С. В.; Павлов, В. С.; Kots, Pavel A.; Зайцев, В. Б.; Иванова, И. И.

doi:10.1039/c7cy02045g

Cited by 29 publications

(25 citation statements)

References 36 publications

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“…Hitherto, few works detailed the structural identity and spatial location of insoluble coke on SAPO-34. Rostami et al 37 and Konnov et al 42 . speculated that the insoluble coke species was formed on the outer surface (inter-crystalline voids).…”

Section: Choosing Industrially Important Mto As a Model Reactionmentioning

confidence: 97%

Molecular elucidating of an unusual growth mechanism for polycyclic aromatic hydrocarbons in confined space

et al. 2020

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Extension and clustering of polycyclic aromatic hydrocarbons (PAHs) are key mechanistic steps for coking and deactivation in catalysis reactions. However, no unambiguous mechanistic picture exists on molecule-resolved PAHs speciation and evolution, due to the immense experimental challenges in deciphering the complex PAHs structures. Herein, we report an effective strategy through integrating a high resolution MALDI FT-ICR mass spectrometry with isotope labeling technique. With this strategy, a complete route for aromatic hydrocarbon evolution is unveiled for SAPO-34-catalyzed, industrially relevant methanol-to-olefins (MTO) as a model reaction. Notable is the elucidation of an unusual, previously unrecognized mechanistic step: cage-passing growth forming cross-linked multicore PAHs with graphene-like structure. This mechanistic concept proves general on other cage-based molecule sieves. This preliminary work would provide a versatile means to decipher the key mechanistic step of molecular mass growth for PAHs involved in catalysis and combustion chemistry.

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Section: Choosing Industrially Important Mto As a Model Reactionmentioning

confidence: 97%

Molecular elucidating of an unusual growth mechanism for polycyclic aromatic hydrocarbons in confined space

et al. 2020

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“…The DTO technologies are based largely on a fluidized bed or fixed‐bed reactor (FBR). However, the most advanced procedure for this reaction is a three‐phase system in a flow bubble slurry reactor (SLR) 43‐45 . This technology makes it possible to considerably decrease catalyst deactivation, because in the SLR catalytic suspensions based on the nanosized zeolite with a more developed surface are used; as a result, diffusion limitations are reduced.…”

Section: Introductionmentioning

confidence: 99%

Dimethyl ether conversion to light olefins in slurry and fixed‐bed reactors: coke nature and location on Mg/ZSM‐5 catalyst

Obukhova

Stashenko

Батова

et al. 2021

J of Chemical Tech & Biotech

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BACKGROUND The goal of this study was to investigate the deactivation of ZSM‐5 in the DTO process (dimethyl ether to light olefins) in a slurry reactor (SLR) in polydimethylsiloxane dispersion medium compared with its deactivation in a fixed‐bed reactor (FBR), and to unveil reasons behind the rapid deactivation of the catalyst in the SLR. RESULTS Under suspension conditions coke formation proceeds more slowly compared with fixed‐bed conditions: The amount of coke formed under suspension conditions is less than under fixed‐bed conditions, 1.4 mg versus 1.7 mg, respectively. Also, in terms of the chemical composition the coke is lighter (xylenes and trimethylbenzenes versus С4,5,6‐substituted benzenes). Using thermogravimetric analysis and gas chromatography/mass spectrometry pyrolytic system, it was shown that the decomposition products of the dispersion medium contribute to the blocking of micropores and the rapid deactivation of the catalyst in SLR. The localization of coke in both SLR and FBR occurs primarily in the microporous channels of the zeolite (>60%). In SLR, the weight fraction of coke on the external catalyst surface was 11% higher than that on the FBR. This finding can be attributed to the blocking of micropores by decomposition products of the dispersion medium. CONCLUSION Under suspension conditions, сoke formation in the DTO process proceeds more slowly compared with fixed‐bed conditions. The rapid loss of catalyst activity in the SLR was related not to coke formation, but instead to the blocking of catalyst pores by products of thermal decomposition of the dispersion medium. For the same reason, in SLR the weight fraction of coke on the external surface of the catalyst was higher than that in the FBR. © 2021 Society of Chemical Industry (SCI).

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“…As mentioned above, coking of the catalyst is a severe problem of the MTO process since it leads to pore blocking of the catalyst and severe diffusion problems . Literature reports that the presence of steam in the feed should reduce catalyst coking, thus extending its lifetime …”

Section: Introductionmentioning

confidence: 99%

“…As mentioned above, coking of the catalyst is a severe problem of the MTO process since it leads to pore blocking of the catalyst and severe diffusion problems. [22][23][24][25][26][27] Literature reports that the presence of steam in the feed should reduce catalyst coking, thus extending its lifetime. [28][29][30][31] The industrial application of the MTO reaction, a fluidized bed reactor, suffers heavily from attrition and requires the permanent exchange of the catalyst.…”

Section: Introductionmentioning

confidence: 99%

Methanol‐to‐Olefins in a Membrane Reactor with in situ Steam Removal – The Decisive Role of Coking

et al. 2019

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The reaction of methanol to light olefins and water (MTO) was studied in a fixed bed tubular membrane reactor using commercial SAPO‐34 catalyst. In the fixed bed reactor without membrane support, the MTO reaction collapsed after 3 h time on stream. However, if the reaction by‐product steam is in situ extracted from the reactor through a hydrophilic tubular LTA membrane, the reactor produces long‐term stable about 60 % ethene and 10 % propene. It is shown that the reason for the superior performance of the membrane‐assisted reactor is not the prevention of catalyst damage caused by steam but the influence of the water removal on the formation of different carbonaceous residues inside the SAPO‐34 cages. Catalytically beneficial methylated 1 or 2 ring aromatics have been found in a higher percentage in the MTO reaction with a water removal membrane compared to the MTO reaction without membrane support.

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Mechanism of SAPO-34 catalyst deactivation in the course of MTO conversion in a slurry reactor

Abstract: The mechanism of SAPO-34 deactivation in the course of the MTO conversion has been studied in a slurry reactor in polydimethylsiloxane medium.

Cited by 29 publications

References 36 publications

Molecular elucidating of an unusual growth mechanism for polycyclic aromatic hydrocarbons in confined space

Molecular elucidating of an unusual growth mechanism for polycyclic aromatic hydrocarbons in confined space

Dimethyl ether conversion to light olefins in slurry and fixed‐bed reactors: coke nature and location on Mg/ZSM‐5 catalyst

Methanol‐to‐Olefins in a Membrane Reactor with in situ Steam Removal – The Decisive Role of Coking

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