Conversion of methanol to light olefins over zeolite H‐T

Gubisch, Dietmar; Bandermann, Friedhelm

doi:10.1002/ceat.270120121

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…25 Gubisch and Bandermann found that, in HCl-exchanged zeolite Na-T, the catalyst activity decreased slowly with the number of regenerative cycles, independently of the regeneration temperature, and after 16 regenerations, the conversion of methanol dropped from 100% to 80%. 26 (2) Effect of Ni Incorporation. It is quite apparent from our experimental results that nickel substitution into the SAPO-34 framework greatly increases its selectivity toward ethylene as well as its lifetime.…”

Section: Discussionmentioning

confidence: 99%

Catalytic Study of Methanol-to-Olefins Conversion in Four Small-Pore Silicoaluminophosphate Molecular Sieves: Influence of the Structural Type, Nickel Incorporation, Nickel Location, and Nickel Concentration

2000

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The selectivity of four small-pore silicoaluminophosphate molecular sieves, including , , , and SAPO-18 (AEI), toward light olefins in general and ethylene in particular has been investigated for the methanol-to-olefins reaction using gas chromatography. This study was prompted by earlier electron spin resonance and electron spin-echo modulation results on nickel-modified SAPO materials in which Ni(I) was incorporated into both framework and ion-exchanged sites. These seemingly similar materials behaved significantly differently with respect to reducing agents and adsorbates. Attention was focused on whether the catalyst performance is influenced by the structural type, the presence of a transition metal ion (Ni) either in the framework or at ion-exchanged positions, or the amount of incorporated transition metal ion. Our results show that these factors indeed play an important role in the catalytic behavior. Among the protonated H-SAPO-n materials, the highest combined distribution of ethylene, propylene, and butenes (C 2 -C 4 olefins) was obtained with H-SAPO-34, and the lowest with H-SAPO-35, which also had the shortest lifetime for catalytic activity. H-SAPO-18 turned out to be the best catalyst in terms of lifetime for catalytic activity. Incorporation of Ni(II) into the framework increased the lifetime, the overall distribution of C 2 -C 4 olefins (in the case of NiAPSO-34), and the selectivity of the catalysts toward ethylene (in the cases of , whereas incorporation of Ni(II) by means of solid-state ion exchange (NiH-SAPO-n) increased only the selectivity toward ethylene. Also, the increase in ethylene selectivity was more prominent in synthesized than in ion-exchanged samples. Among the Ni-loaded samples, NiAPSO-34 was found to be the best catalyst in terms of both ethylene selectivity and lifetime, whereas NiH-SAPO-18 exhibited the worst ethylene yield and NiH-SAPO-35 the shortest lifetime. Finally, the effect of the amount of Ni was investigated in NiAPSO-34. It appears that the selectivity toward ethylene does not increase linearly with NiAPSO samples prepared with an increasing amount of Ni in the reaction gel. In fact, there seems to be an optimum Ni concentration for which ethylene selectivity reaches a maximum and above which ethylene selectivity decreases. This optimum concentration is the same as was found in earlier studies to yield the strongest Ni(I) signal, as observed by ESR.

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Section: Discussionmentioning

confidence: 99%

Catalytic Study of Methanol-to-Olefins Conversion in Four Small-Pore Silicoaluminophosphate Molecular Sieves: Influence of the Structural Type, Nickel Incorporation, Nickel Location, and Nickel Concentration

2000

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“…Examples can be found, inter alia, in the petrochemical industry, methanol to olefin conversion and production of fine chemicals. [1][2][3][4][5][6][7][8][9][10][11][12] The strength of their (catalytically active) Brønsted acid sites is a main factor determining the catalytic performance (regarding both activity and selectivity) of protonic zeolites, hence the importance of having a reliable method to evaluate relative acidity, which would help to increase the understanding and optimize the performance of these versatile solid acid catalysts; but quantifying the strength of solid acids can be a delicate task to perform.…”

Section: Introductionmentioning

confidence: 99%

Measuring the Brønsted acid strength of zeolites – does it correlate with the O–H frequency shift probed by a weak base?

Areán

Delgado

Nachtigall

et al. 2014

Phys. Chem. Chem. Phys.

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Brønsted-acid zeolites are currently being used as catalysts in a wide range of technological processes, spanning from the petrochemical industry to biomass upgrade, methanol to olefin conversion and the production of fine chemicals. For most of the involved chemical processes, acid strength is a key factor determining catalytic performance, and hence there is a need to evaluate it correctly. Based on simplicity, the magnitude of the red shift of the O-H stretching frequency, Δν(OH), when the Brønsted-acid hydroxyl group of protonic zeolites interacts with an adsorbed weak base (such as carbon monoxide or dinitrogen) is frequently used for ranking acid strength. Nevertheless, the enthalpy change, ΔH(0), involved in that hydrogen-bonding interaction should be a better indicator; and in fact Δν(OH) and ΔH(0) are often found to correlate among themselves, but, as shown herein, that is not always the case. We report on experimental determination of the interaction (at a low temperature) of carbon monoxide and dinitrogen with the protonic zeolites H-MCM-22 and H-MCM-56 (which have the MWW structure type) showing that the standard enthalpy of formation of OH···CO and OH···NN hydrogen-bonded complexes is distinctively smaller than the corresponding values reported in the literature for H-ZSM-5 and H-FER, and yet the corresponding Δν(OH) values are significantly larger for the zeolites having the MWW structure type (DFT calculations are also shown for H-MCM-22). These rather unexpected results should alert the reader to the risk of using the O-H frequency shift probed by an adsorbed weak base as a general indicator for ranking zeolite Brønsted acidity.

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“…Several paths have been followed to increase selectivity to light olefins in the transformation of methanol into hydrocarbons: (1) optimization of the operating conditions using a HZSM-5 zeolite; − (2) modifications in the HZSM-5 zeolite; − (3) testing of other natural and synthetic zeolites. ,, The review of Froment et al. approaches several aspects of these studies …”

Section: Introductionmentioning

confidence: 99%

Kinetic Modeling of Methanol Transformation into Olefins on a SAPO-34 Catalyst

Gayubo

Aguayo

Campo

et al. 2000

Ind. Eng. Chem. Res.

100

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A kinetic model for the methanol to olefins (MTO) process on a catalyst based on a silicoaluminophosphate SAPO-34 has been proposed. The model takes into account four individual steps for the production of ethene, propene, butenes, and remaining hydrocarbons (pentenes + paraffins). The kinetic parameters have been obtained by experimentation in an isothermal fixedbed reactor, in the 623-748 K range. In virtue of the results, it has been proven that the water introduced in the feed (required for attenuation of coke deactivation) inhibits olefin formation. This inhibition is taken into account in the kinetic model.

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Conversion of methanol to light olefins over zeolite H‐T

Cited by 7 publications

References 17 publications

Catalytic Study of Methanol-to-Olefins Conversion in Four Small-Pore Silicoaluminophosphate Molecular Sieves: Influence of the Structural Type, Nickel Incorporation, Nickel Location, and Nickel Concentration

Catalytic Study of Methanol-to-Olefins Conversion in Four Small-Pore Silicoaluminophosphate Molecular Sieves: Influence of the Structural Type, Nickel Incorporation, Nickel Location, and Nickel Concentration

Measuring the Brønsted acid strength of zeolites – does it correlate with the O–H frequency shift probed by a weak base?

Kinetic Modeling of Methanol Transformation into Olefins on a SAPO-34 Catalyst

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