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- Title
Dimethyl ether conversion to light olefins in slurry and fixed‐bed reactors: coke nature and location on Mg/ZSM‐5 catalyst.
- Authors
Obukhova, Тatiana К; Stashenko, Anton N; Batova, Тatiana I; Kolesnichenko, Nataliya V
- Abstract
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).
- Subjects
SOCIETY of Chemical Industry (Great Britain); COKE (Coal product); METHYL ether; CATALYSTS; CATALYST poisoning; SLURRY; CHEMICAL industry; ALKENES
- Publication
Journal of Chemical Technology & Biotechnology, 2021, Vol 96, Issue 9, p2696
- ISSN
0268-2575
- Publication type
Article
- DOI
10.1002/jctb.6817