Dataset Information

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite.

ABSTRACT: Cobalt-loaded MFI zeolite showed distinct activity for direct methylation of benzene with methane into toluene. High activity was found at around 0.6 of Co/Al molar ratio. Incorporation of carbon from methane into the methyl group of toluene was confirmed with isotope tracer experiments and mass spectroscopy. Ammonia infrared-mass spectroscopy temperature-programmed desorption, transmission electron microscopy, X-ray absorption near edge spectroscopy and extended X-ray absorption fine structure indicated that Lewis acidic divalent (+II of oxidation state) Co species mono-atomically dispersed on the ion exchange site of MFI zeolite was the active species.

SUBMITTER: Nakamura K

PROVIDER: S-EPMC6282706 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite.

Nakamura Koshiro K Okuda Akihito A Ohta Kiyotaka K Matsubara Hitoshi H Okumura Kazu K Yamamoto Kana K Itagaki Ryosuke R Suganuma Satoshi S Tsuji Etsushi E Katada Naonobu N

ChemCatChem 20180711 17

Cobalt-loaded MFI zeolite showed distinct activity for direct methylation of benzene with methane into toluene. High activity was found at around 0.6 of Co/Al molar ratio. Incorporation of carbon from methane into the methyl group of toluene was confirmed with isotope tracer experiments and mass spectroscopy. Ammonia infrared-mass spectroscopy temperature-programmed desorption, transmission electron microscopy, X-ray absorption near edge spectroscopy and extended X-ray absorption fine structure ...[more]

PMID: 30546494

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Project description:Because of the small particle size, orientation-dependent diffusion measurements in microporous materials remains a challenging task. We highlight here the potential of micro-imaging by interference microscopy in a case study with MFI-type crystals in which, although with different accuracies, transient concentration profiles in all three directions can be observed. The measurements, which were performed with "rounded-boat" shaped crystals, reproduce the evolution patterns of the guest profiles recorded in previous studies with the more common "coffin-shaped" MFI crystals. The uptake and release patterns through the four principal faces (which in the coffin-shaped crystals extend in the longitudinal direction) are essentially coincident and there is no perceptible mass transfer in the direction of the long axis. The surface resistances of the four crystal faces through which mass transfer occurs are relatively small and have only a minor effect on the mass transfer rate. As a result of the pore structure, diffusion in the crystallographic c direction (which corresponds to the direction of the long axis) is expected to be much slower than in the transverse directions. This could explain the very low rate of mass transfer observed in the direction of the long axis, but it is also possible that the small end faces of the crystal may have high surface resistance. It is not possible to distinguish unequivocally between these two possibilities. All guest molecules studied (methyl-butane, benzene and 4-methyl-2-pentyne) show the same orientation dependence of mass transfer. The long 4-methyl-2-pentyne molecules would be expected to propagate at very different rates through the straight and sinusoidal channels. The coinciding patterns for uptake through the mutually perpendicular crystal faces therefore provide clear evidence that both the coffin shaped crystals and the rounded-boat-shaped crystals considered in this study, must be intergrowths rather than pure single crystals.

Dataset Information

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite.

Publications

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite.

Similar Datasets

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