Retained products from the reaction of benzene and toluene over H-ZSM5 zeolite

Anderson, John R.

doi:10.1016/0021-9517(91)90214-o

Cited by 42 publications

(5 citation statements)

References 14 publications

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“…Various investigators have demonstrated size-exclusion product selectivity, simply by digesting spent catalyst and determining the reaction products not allowed to exit the structure …”

Section: Resultsmentioning

confidence: 99%

A Method for Characterizing Effective Pore Sizes of Catalysts

1999

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The temperature dependent effective catalytic pore size can be determined by the comparison of 13C MAS NMR spectra of heterogeneously catalyzed, shape selective reactions and data collected from GC analysis of the product stream of reactions under similar reaction conditions. The concept of effective minimum molecular dimensions has been set forth in a previous paper. (Webster, C. E.; Drago, R. S.; Zerner, M. C. J. Am. Chem. Soc. 1 998, 1 2 0, 5509−5516.) In this investigation, it is concluded that the effective catalytic channel size of HZSM-5 is between 6.62 and 7.27 Å at 300 °C, the MIN-2 dimensions of p-xylene and o-xylene, respectively. At 370 °C, the effective catalytic channel size is increased to a minimum of 7.64 Å, the MIN-2 dimension of 1,2,3-trimethylbenzene. We discuss the apparent increase in the effective catalytic channel intersection size with increasing temperature. This novel approach presents an a priori description of relative pore sizes and can be used to investigate and describe numerous catalytic and adsorbent systems as discussed in this paper. The comparison of observed isomer distributions of the trimethylbenzenes to their thermodynamic equilibrium distributions provides experimental evidence for the existence of the previously reported nest effect, which describes the shape selectivity of the exterior surface of the HZSM-5 structure.

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“…Various investigators have demonstrated size-exclusion product selectivity, simply by digesting spent catalyst and determining the reaction products not allowed to exit the structure …”

Section: Resultsmentioning

confidence: 99%

A Method for Characterizing Effective Pore Sizes of Catalysts

1999

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“…Although being merely applied to probe the molecular structure of PAHs formed in cage-structured zeolites or molecular sieves in the current work, our developed PAHs analytic strategy is expected to be of more general validity in terms of the following discussions. Coupling of aromatic species via biphenyl to form more condensed PAHs was previously hypothesized to be present in channel-structured zeolites, such as HZSM-5 46 and HFER; 47 besides, aliphatically bridged multicore PAHs were also proposed in soot formation chemistry 1 . With the similar structural feature of PAHs, the means and methodology provided here are expected to be versatile for deciphering the formation and evolution of PAHs involved other catalysis systems and fields.…”

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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“…73 Coke exhibits a detrimental effect on the activity of supported precious metal catalysts in two different ways, namely by active site coverage and by pore blockage. 74 The formation of fluorene derivatives and subsequent coke formation are kinetically controlled and a strong function of the applied catalyst material 74,75 also depends on the applied reaction conditions 67,68 For the listed reasons, the optimisation of the H0-BT/H12-BT-based LOHC technology toward technical hydrogen storage should target catalyst materials and reaction conditions that suppress the formation of fluorene derivatives as much as possible.…”

Section: Resultsmentioning

confidence: 99%

“…The thermodynamics of the dehydrocyclisation of methylene-bridged aromatic compounds has been studied in the literature and is in accordance with the here-observed behaviour. 74,75 Interestingly, Modisha et al 68 observed a reduction of fluorene derivatives during their Ni-catalysed hydrogenation of technical, hydrogen-lean H x -DBT mixtures by a C–C bond cleavage that resulted in the formation of additional H0-DBT. 82…”

Section: Resultsmentioning

confidence: 99%