Abstract
Metal-free catalysts based on carbon powder modified with reduced graphene oxide (rGO) were prepared and investigated in the ethylene hydrogenation reaction. The samples were characterized by Raman and FTIR spectroscopies, SEM, TEM, thermogravimetric analysis, and N2 adsorption-desorption. SEM and TEM analyses showed that rGO deposition leads to the formation of wrinkled graphene-derived structures covering the external surface of the carbon support. Raman spectra confirmed the presence of defect-rich sp²-hybridized carbon domains, while FTIR analysis revealed oxygen-containing functional groups associated with partially reduced graphene oxide. Textural analysis demonstrated that rGO incorporation mainly affects the external surface area without significantly changing the microporous structure of the support.
The catalytic properties of the obtained materials were studied in ethylene hydrogenation within 50–400 °C under continuous-flow conditions. The pristine carbon powder provides the highest catalytic activity, whereas deposition of rGO results in a decrease in activity compared with the unmodified support. However, within the rGO/CP series, catalytic activity increased with increasing rGO loading, reaching 18% conversion for rGO(0.1)/CP at 400 °C.
At the same time, normalization of the reaction rate to the mass of deposited rGO showed a decrease in specific activity at higher rGO contents, attributed to partial restacking of graphene sheets and blocking of active surface sites.
The obtained results indicate that the catalytic behaviour of the investigated composites is governed by the balance between the intrinsic activity of carbon powder and the contribution of defect-rich graphene-derived domains. The findings highlight the importance of controlling graphene loading and surface accessibility in the design of efficient metal-free carbon catalysts.
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