Flow calorimetry and adsorption study of dibenzothiophene, quinoline and naphthalene over modified Y zeolites

• Published in: Applied catalysis. B, Environmental Environmental, 2010-02, Vol.94 (3-4), p.225-233
• Main Authors: Thomas, J. Keir, Gunda, Kamalakar, Rehbein, Peter, Ng, Flora T.T.
• Format: Article
• Language: English
• Subjects: Adsorption; Adsorption capacity; Calorimetry; Catalysis; Chemistry; Desulfurization; Dibenzothiophene; Exact sciences and technology; Flow calorimetry; General and physical chemistry; Heat of adsorption; Ion-exchange; Liquid phases; Modified zeolites; Naphthalene; Quinoline; Surface chemistry; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zeolites; Zeolites: preparations and properties
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2009.11.012

The adsorptive removal of dibenzothiophene (DBT), quinoline and naphthalene in hexadecane on the zeolites, NaY, NiY and CsY, using liquid phase flow calorimetry and adsorption experiments, was studied at 30°C. NiY and CsY were prepared by the liquid phase ion-exchange method. The adsorbents were characterized by XRD, BET surface area, elemental analysis (ICP-OES) and DRIFT spectroscopic techniques. The adsorption experiments were carried out by equilibrium adsorption and flow calorimetry techniques. Modification of NaY zeolite with Ni and Cs salts resulted in the partial amorphotization of the zeolite structure which affected the adsorption properties. A higher heat of adsorption was determined for quinoline compared to DBT and naphthalene and a preferential adsorption of quinoline in a mixture containing quinoline, naphthalene and DBT was observed on NaY, NiY and CsY. The adsorption of quinoline on NiY possibly involved a direct end-on σ interaction of the Ni2+ with the lone pair of electrons of the N atom on quinoline while the adsorption of DBT and naphthalene occurs via a π interaction of the d orbitals of Ni2+ with the electrons in the aromatic rings. The equilibrium adsorption capacity of NaY was found to be the highest among the three zeolites. The decrease in the adsorption capacities of NiY and CsY appears to result mainly from the partial collapse of the zeolite structure during the ion-exchange process.