The palladium-incorporated catalyst, (0.5% Pd/C) (nanospace engineering KOH-activated carbon material) catalyst with macro-structured carbon nanofibers aggregates and micro-nano-porous activated carbons, has been studied as a candidate for hydro purification of crude terephthalic acid containing of 4-carboxybenzaldehyde (4-CBA) as an impurity. The efficiency of different carbon structures (macro/micro) was investigated over selectivity catalyst. The reaction products were analyzed by HPLC to determine the amounts of 4-CBA, benzoic acid (BA), 4-Hydroxymethyl benzoic acid (4-HMBA) and paratoluic acid (p-tol). It has been confirmed that 0.5% Pd/microporous catalyst gave an excellent performance to catalyze the hydrogenation of 4-CBA to para-toluic acid due to high micro-porous surface area and the most desirable selectivity to 4-HMBA was obtained with macro-structured carbon nanofibers. Pd/AC catalyst with more micro surface area (85.26%) achieved a maximum yield to the intermediate product of 4-HMBA only 30% whereas the macro-structured CNFs achieved typically 66%. The desired selectivity to paratoluic acid was found to be deep dependent on the micro-porous structure. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.