Well-defined (supra)molecular structures in zeolite methanol-to-olefin catalysis

Haw, James F.; Marcus, David M.

doi:10.1007/s11244-005-3798-0

Cited by 253 publications

(275 citation statements)

References 32 publications

(37 reference statements)

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“…[4] The generally accepted reaction mechanism for MTO is based on a hydrocarbon pool (HP) mechanism, meaning that organic molecules trapped within the inorganic zeolite framework act as co-catalysts. [5] For small-pore chabazite catalysts these organic reaction scaffolds consist mainly of methylated aromatics, with hexamethylbenzene (HMB, see Figure 1) showing the highest activity as demonstrated by GC-MS analyses of 13 C-labeled methanol experiments and computational studies. [6][7][8][9][10] Starting from this compound, aromatic-based cycles have been proposed for olefin formation, in particular the side-chain and paring mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34

Wispelaere

Hemelsoet

Waroquier

et al. 2013

Journal of Catalysis

106

154

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ABSTRACT:The methanol to olefins process is an alternative for oil-based production of ethene and propene. However, detailed information on the reaction mechanisms of olefin formation in different zeolite is lacking. Herein a first principle kinetic study allows elucidating the importance of a side-chain mechanism during methanol conversion in H-SAPO-34. Starting from the experimentally observed hexamethylbenzene, a full low-barrier catalytic cycle for ethene and propene formation is found. The olefin elimination steps exhibit low free energy barriers due to a subtle interplay between an sp 3 carbon center of the organic intermediate, stabilizing non-bonding interactions and assisting water molecules in the zeolite material.

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Section: Introductionmentioning

confidence: 99%

Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34

Wispelaere

Hemelsoet

Waroquier

et al. 2013

Journal of Catalysis

106

154

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show abstract

“…If not limited by space restrictions, as is the case in H-SAPO-34 or H-Beta, the aromatic HP species are known to be the higher methylated benzene derivatives [13,14,15]. Recently Wang et al…”

Section: Introductionmentioning

confidence: 99%

“…In H-SAPO-34, the aromatic HP species can readily age into larger aromatic compounds which block the active sites and severely restrict mass transport [15,25,26]. Haw and Marcus outlined possible aging routes that lead to less active, aromatic species which are entrapped in the zeolitic pore and will remain there until regeneration of the catalyst [15].…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical IR study of methanol and ethanol conversion over H-SAPO-34

Hemelsoet

Ghysels

et al. 2011

Catalysis Today

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Theoretical and experimental IR data are combined to gain insight into the methanol and ethanol conversion over an acidic H-SAPO-34 catalyst. The theoretical simulations use a large finite cluster and the initial physisorption energy of both alcohols is calculated.Dispersive contributions turn out to be vital and the final adsorption of ethanol is predicted to be stronger compared to methanol (difference of 14 kJ mol −1 ). Calculated IR spectra of the alcohols and of formed aromatic cations upon conversion are also analyzed and support the peak assignment of the experimental in situ DRIFT spectra, in particular for the C-H and C=C regions. Theoretical IR spectra of the gas phase compounds are compared with those of the molecules loaded in a SAPO cluster and the observed shifts of the peak positions are discussed. To get a better understanding of these framework-guest interactions, a new theoretical procedure is proposed based on a normal mode analysis.A cumulative overlap function is defined and enables the characterization of individual peaks as well as induced frequency shifts upon adsorption.

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“…그러나 HMB 의 추가 축합 고리화 반응으로 다고리 방향족 화합물(polyaromatic hydrocarbons: PAHs)이 생성되면서, 활성 물질인 HMB가 줄어들고 세공이 PAHs로 채워져 반응물과 생성물의 이동이 억제되어 활성이 저하된다 [15].…”

Section: Mto 반응 중 둥지 내에 생성된 헥사메틸벤젠(Hexamethylbenzeneunclassified

Methanol-to-Olefin Reaction over MWW and MFI Zeolites: Effect of Pore Structure on Product Distribution and Catalyst Deactivation

Song¹,

Seo²,

Shin³

2011

Korean Chemical Engineering Research

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− Methanol-to-olefin (MTO) reaction was studied over MWW zeolite with independently developed two pores (circular and straight) and MFI zeolite with intercrossed sinusoidal and straight pores in order to investigate the effect of pore structure on their catalytic behavior. MWW and MFI zeolites with similar acidity exhibited commonly high conversion and slow deactivation in the MTO reaction, but their product selectivities were considerably different: linear hydrocarbons of C 3 -C 9 were mainly produced on MWW, while the yield of C 2 = and aromatics were high on MFI.Polyaroamatic hydrocarbons (PAHs) were accumulated on MWW, but a small amount of benzene and aromatics on MFI. The impregnation of phosphorous on MWW caused significant decreases in the catalytic activity and toluene adsorption, but the decreases were relatively small on MFI. Although the straight pores of MWW were inactive in the MTO reaction due to the accumulation of PAHs, its circular pores which suppressed the formation of PAHs sustained catalytic activity for the production of linear hydrocarbons. Therefore, the impregnation of phosphorous on the circular pores of MWW caused a significant decrease in catalytic activity. The phosphorous impregnation on the cross sections of MFI altered the product selectivity due to the neutralization of strong acid sites, but catalytic deactivation was negligible. The difference of MWW and MFI zeolites in the MTO reaction was explained by their difference in pore structure.

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Well-defined (supra)molecular structures in zeolite methanol-to-olefin catalysis

Cited by 253 publications

References 32 publications

Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34

Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34

Experimental and theoretical IR study of methanol and ethanol conversion over H-SAPO-34

Methanol-to-Olefin Reaction over MWW and MFI Zeolites: Effect of Pore Structure on Product Distribution and Catalyst Deactivation

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