The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560-960 °C of the ZSM-5 catalyst (framework Si/Al ratio of 13), suggests an association between adsorbed molecular water and extra-framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Brönsted and Lewis sites, when treatment temperature rises, with contradicts the frequently accepted mechanism of the transformation of two bridged Si-OH-Al groups for each Lewis site generated. The gradual conversion of the octahedral extra-framework aluminum (Lewis-associated) in polymeric species with low acidity is the most probable cause of this behavior. On the other hand, the apparent decline of the acid Brönsted strength, with the increase in the temperature of the hydrothermal treatment, has two possible causes: a) the decreasing accessibility, of the pyridine molecular probe to bridged Si-OH-Al groups with the strongest Brönsted acidity, inside the channels, and b) the gradual transformation of these groups into extra framework species of weak acidity.

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Highly condensed carbons from pet-coke were first treated with Na/K hydroxides and carbonates and then with H2SO4. The esterification reaction of palmitic acid reached conversions up to 97 % on the yielded activated carbons. Results evince the relationship between the efficacy of Na/K hydroxides and carbonates as treatment agents and their lattice potential energy. Moreover, the analysis of carbonaceous solids confirms that both surface area and acidity are primary factors promoting activity in the esterification reaction. Furthermore, the results do not indicate a direct relationship between the activity and the oxidized species (SOx) arising from the treatment with H2SO4. The relatively low melting and decomposition temperature of Na/K hydroxides can improve their effect on the pet-coke matrix, leading to higher surface areas, acidities, and catalytic activities than treatment with carbonates. That supports an affinity between the carboxyl functions of fatty acid molecules and the polar and catalytically active centers of hydroxide-treated solid surface.

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