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Here, we have examined the nanoporous activated carbon fibers (ACFs) sulfonated using the direct sulfonation and the staged method that included bromination, followed by sulfidation and oxidation. TEM confirmed the nanoporous structure of the prepared sulfonated ACFs. Nitrogen porometry and 2D nonlocal DFT simulations showed the nanoporosity reduction and variations of the pore size distribution because of the functionalization. Comparison of parameters of the SO 3 H groups confined in nanopores, e.g., the thermal stability and catalytic potential, showed that the most efficient acid sites, in the catalytic 2-propanol dehydration to propylene, are the SO 3 H groups grafted by the staged Houben-Weil methods. From the productivity of reactions used at the preparation stage, and in contrast to the one-staged aromatic substitution, the bromine addition to π sites of the edges of carbon matrix supplies enough active sites and is a reason for further high yields of the grafted thermostable SO 3 H groups. Hydrolysis of the grafted bromine and the surface oxidation of nanopores walls are parallel reactions that lowered the SO 3 H-related acidity, increasing the total acidity to 1.5 mmol g −1 . The reported nanoporous sulfonated ACFs are effective to be used in the dehydration reactions catalyzed by solid acids.

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