Formation of catalytic active sites in iron modified activated carbons from agriculture residues

• Final phase composition of Fe/AC forms by the influence of AC and reaction medium.
• Final state of Fe phase is in close relation with its dispersion and location.
• Stronger dependency of Fe state from the texture than surface functionality of AC.
• Activated carbons with well developed mesoporosity facilitate the catalytic activity.
• Variation in agriculture precursor is simple approach for Fe/AC catalysts control.

Agriculture residues (grape seeds, peach, apricot and olive stones) were used as a precursor of activated carbons with tunable textural characteristics and relatively low surface functionalities (predominantly carbonyl and hydroxyl groups). Thus obtained activated carbons were modified with iron species and tested as catalysts in methanol decomposition. Nitrogen physisorption, XRD, UV–Vis, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method were applied for complex characterization of the initial activated carbon supports, their iron modifications and the transformations during the catalytic process. The final phase composition and the related with this catalytic activity and selectivity of these materials was considered as a result of complex transformations of active phase by the influence of activated carbon support and reaction medium and this is in close relation with the dispersion and location of iron species into the porous matrix. The decisive role of activated carbon texture characteristics, which is much more significant than the surface functionalities, on the formation of iron catalytic sites is established, and the variation in the nature of the agriculture precursor is assumed as a simple approach for tailoring their properties.

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