Adsorption and thermal transformation of lignin model compound (ferulic acid) over HY zeolite surface studied by temperature programmed desorption mass-spectrometry, FTIR and UV-Vis spectroscopy

The adsorption of an aqueous solution of ferulic acid (FA) on protonic zeolites was studied. Three different types of zeolites and adsorption parameters (time, solid/liquid ratio, temperature and pH) were analyzed and opti-mized. The HY zeolite (SiO2/Al2O3 = 12) showed an adsorption percentage of 90% at 30 degrees C, 5 min, 10 g L-1 and pH <= 3. The adsorption complexes structures on the molecular adsorbates were determined by UV-Vis DRS and FTIR spectroscopies. The FA molecule interacted through phenol and carboxyl group forming monodentate and bidentate surfaces complexes (bridge and chelate). Temperature programmed desorption mass-spectrometry (TPD MS) has been used to study the decarboxylation, demethoxylation, and transalkylation processes during pyrolysis of FA surface complexes with the formation of carbon dioxide, 4-vinylguaiacol, methanol, methane, polyaromatic hydrocarbons, phenols and others.

Automated summary

The adsorption of aqueous ferulic acid (FA) solution on protonic zeolites was investigated. Three types of zeolites and various adsorption parameters were analyzed and optimized. The HY zeolite with a SiO2/Al2O3 ratio of 12 exhibited a high adsorption percentage of 90% at 30°C, 5 minutes, 10 g L-1, and pH <= 3. UV-Vis DRS and FTIR spectroscopies revealed the structures of the adsorption complexes formed by the interaction between the FA molecule and the zeolite surface, involving phenol and carboxyl groups.