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A study of the deactivation of low loading Ni/Al2O3 steam reforming catalyst by tetrahydrothiophene

Paper ID Volume ID Publish Year Pages File Format Full-Text
50509 46797 2013 7 PDF Available
Title
A study of the deactivation of low loading Ni/Al2O3 steam reforming catalyst by tetrahydrothiophene
Abstract

•Ethanol–phenol mixture is completely steam reformed at 973 K over 5% Ni-alumina.•At lower temperature dehydration, dehydrogenation and alkylations occur.•THT deactivates the catalyst that is regenerated in the S-free stream.•THT deposes sulphur selectively on Ni centres producing butadiene and NiS.•Ni deactivation causes reappearing of dehydration and alkylation activity.

The steam reforming (SR) of ethanol/phenol mixture (168 gTOT/N m3, ethanol:phenol 2:1 mol, GHSV = 54,000 h− 1), assumed as a model for tar mixtures, has been studied over a 5% Ni/Al2O3 catalyst (155 m2/g), in the presence and in the absence of 210 ppm tetrahydrothiophene (THT) as a sulphur containing contaminant. The sulphidation of the catalyst by THT has been studied by IR spectroscopy. Infrared spectra of CO adsorbed at low temperature over the oxidized, the reduced and the sulphurized catalyst have also been recorded. The catalyst acts as a bifunctional one, with the behaviour attributed to the uncovered support (alumina modified by nickel ions) at 773 K (dehydration of ethanol to ethylene, dehydrogenation to acetaldehyde and alkylation of phenol with ethanol) that fully disappears at 973 K when steam reforming occurs very selectively. By lowering back the reaction temperature, the support behaviour reappears. THT poisons selectively the Ni component, thus causing the appearance of the support behaviour also at 973 K. IR experiments show that THT deposes sulphur at the catalyst surface with the production of gas-phase 1,3-butadiene, thus converting the catalyst into a “sulphided” SR-inactive state. The steam reforming activity of the poisoned catalyst progressively reappears upon feeding back S-free feed at 973 K. IR study suggests that steam “cleans” the catalyst surface by sulphur, generating a “disordered” surface with dispersed Ni2 + and Ni0 species, that could slowly re-approach the initial active state.

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Keywords
Steam reforming of tars; Ni/Al2O3 catalysts; IR spectroscopy; Sulphidation; Catalyst deactivation; Regeneration
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A study of the deactivation of low loading Ni/Al2O3 steam reforming catalyst by tetrahydrothiophene
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 38, 5 August 2013, Pages 67–73
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Full-text PDF Download
Online Support
Any Questions? feel free to contact us