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Catalytic performance of different carbon materials for hydrogen production in sulfur–iodine thermochemical cycle

Paper ID Volume ID Publish Year Pages File Format Full-Text
45735 46421 2015 10 PDF Available
Title
Catalytic performance of different carbon materials for hydrogen production in sulfur–iodine thermochemical cycle
Abstract

•Four carbon catalysts are investigated for HI decomposition.•The AC catalysts present the best catalytic performance.•Structural analysis indicates that AC possesses the largest amount of edge sites.•Quantity of the edge sites relates to disordering and content of aliphatic carbon.•A detailed mechanism of HI decomposition over carbon materials is established.

This study examines four carbon materials through a series of characterization methods and a hydrogen iodide (HI) decomposition test. Applying a traditional structure to carbon materials facilitates the quantitative analysis of the four samples. The X-ray diffraction and Raman spectroscopy results indicate that lesser stacked graphite-like layers and shorter lateral diameter La result in higher disordering structure. However, the quantity of active sites is not determined only by the degree of disordering. The aliphatic carbon in the inter-layer correlations decreases the amount of graphite carbon and occupies its edge, thereby inhibiting the formation of edge sites in carbon materials. A low ratio of amorphous carbon with a high degree of disordering corresponds to a high concentration of surface active sites associated with the edges of graphite-like layers. The catalytic performance combined with characterization results demonstrates that the edges of graphite carbon are active sites in HI decomposition. A computational chemistry study is also conducted to illustrate the dominant role of edge sites in the reaction. The calculation results build a detailed mechanism of the catalytic decomposition of HI over the carbon materials and verify that the adsorbed I on the edge sites facilitate the HI decomposition.

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Keywords
Sulfur–iodine cycle; HI decomposition; Catalytic activity; Carbon materials; Hydrogen production
First Page Preview
Catalytic performance of different carbon materials for hydrogen production in sulfur–iodine thermochemical cycle
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 166–167, May 2015, Pages 413–422
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis