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Benzene adsorption on Mo2C: A theoretical and experimental study

Paper ID Volume ID Publish Year Pages File Format Full-Text
42168 45913 2010 7 PDF Available
Title
Benzene adsorption on Mo2C: A theoretical and experimental study
Abstract

Continuous gas-phase benzene hydrogenation at 363 K and atmospheric pressure was studied using bulk molybdenum carbide as a catalyst. It was observed that benzene conversion to cyclohexane was initially 100%, dropping to zero after four hours of reaction. After deactivation the catalyst was submitted to a heating program under helium flow from room temperature (RT) up to 1273 K. On-line mass spectrometry showed desorption of benzene and hydrogen suggesting that the deactivation occurred due to strong absorption of benzene on the molybdenum carbide surface. Density Functional Theory (DFT) calculations support this hypothesis showing the adsorption energy of benzene on the molybdenum carbide varies from −377 kJ mol−1 to −636 kJ mol−1 depending on the surface and on the crystal phase. Based on the experimental and theoretical results, a reaction scheme is proposed with the following steps: (i) after synthesis, the molybdenum carbide surface is completely covered by chemisorbed hydrogen; (ii) when the reaction begins, benzene molecules react with the chemisorbed hydrogen via an Eley-Riedeal mechanism, producing cyclohexane and vacant sites on the surface; (iii) other benzene molecules strongly and irreversibly adsorb to these vacant sites, poisoning the surface and thus leading to deactivation of the catalyst.

Graphical abstractContinuous gas-phase benzene hydrogenation at 363 K and atmospheric pressure was studied using bulk molybdenum carbide as a catalyst. It was observed that benzene conversion to cyclohexane was initially 100%, dropping to zero after four hours of reaction. From experimental and DFT results the deactivation is attributed to strong benzene chemisorption on the surface of molybdenum carbide.Figure optionsDownload full-size imageDownload high-quality image (106 K)Download as PowerPoint slide

Keywords
Benzene hydrogenation; Molybdenum carbide; Adsorption; DFT
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Benzene adsorption on Mo2C: A theoretical and experimental study
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 379, Issues 1–2, 15 May 2010, Pages 54–60
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
You save - $31
Price after discount Only $4.95
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