CO2Oxidative Dehydrogenation of Ethane to Ethylene over Cr/MCM-41 Nanocatalyst Synthesized via Hydrothermal/Impregnation Methods: Influence of Chromium Content on Catalytic Properties and Performance

Published Date
Received 29 January 2016, Revised 21 March 2016, Accepted 22 March 2016, Available online 24 March 2016.

Author
ElmiraAsgharia. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.MohammadHaghighia. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspaceOpens the author workspace. Author links open the author workspace.FarhadRahmania. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace

a

Chemical Engineering Faculty, Sahand University of Technology, P.O. Box 51335-1996, Sahand New Town, Tabriz, Iran

b

Reactor and Catalysis Research Center (RCRC), Sahand University of Technology, P.O. Box 51335-1996, Sahand New Town, Tabriz, Iran

Highlights

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Employment of Cr/MCM-41 nanocatalysts in CO2-assisted dehydrogenation of ethane.

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Investigation of Cr content effect on catalytic properties and performance of Cr/MCM-41.

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Verification of 8 wt.% chromium as the optimum content on MCM-41 support.

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Attainment of uniform dispersion and higher Cr6+/Cr3+ ratio by employing 8 wt.% of Cr.

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Attaining 53% ethylene yield and high stability at 700 °C over Cr(8%)/MCM-41.

Abstract

A series of mesoporous Cr(x)/MCM-41 nanocatalysts with 0, 2, 5, 8 and 11 wt.% content of chromium were synthesized by hydrothermal/impregnation method. The effect of chromium loading on the structure and catalytic performance of Cr/MCM-41 nanocatalysts in the oxidative dehydrogenation of ethane with CO2 was investigated. The catalysts were characterized by XRD, FESEM, EDX, DRS, BET and FTIR analysis. Various chromium species including Cr6+, Cr3+ and crystalline Cr2O3 were found in the calcined Cr(x)/MCM-41 samples. Particles of crystalline α-Cr2O3 were detected in the catalyst with Cr total content above 2 wt.%. The variation of Cr content indicates that the Cr6+/Cr3+ ratio of samples increased with the Cr loading up to 8 wt.%. However, a decreasing trend was observed with further increase of Cr content. This can be justified by Cr surface density. It was found that there is an optimum Cr content in Cr(8%)/MCM-41 for the best catalytic activity, attributable to higher active Cr6+ species, and more uniform dispersion of chromium species with monolayer coverage on MCM-41 and also, homogeneous surface morphology with smallest particle size. It was found that this catalyst effectively dehydrogenated ethane to ethylene in the presence of CO2 at 700 °C, giving 53% ethylene yield.

Graphical abstract

A series of mesoporous Cr(x)/MCM-41 nanocatalysts with 0, 2, 5, 8 and 11 wt.% content of chromium were synthesized by hydrothermal/impregnation method. The effect of chromium loading on the structure and catalytic performance of nanocatalysts in the oxidative dehydrogenation of ethane with CO2 was investigated. It was found that there is the optimum chromium content (8%) on the MCM-41 support for the best catalytic activity, attributable to higher dispersion of chromium species with monolayer coverage on MCM-41, homogeneous morphology with smallest particle size and better redox property due to higher oxidation state of chromium over the catalyst.

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