Production of low sulfur diesel fuel via adsorption: an equilibrium and kinetic study on the adsorption of dibenzothiophene onto NaY zeolite

Abstract

The adsorption of dibenzothiophene (DBT) in hexadecane onto NaY zeolite has been studied by performing equilibrium and kinetic adsorption experiments. The influence of several variables such as contact time, initial concentration of DBT and temperature on the adsorption has been investigated. The results show that the isothermal equilibrium can be represented by the Langmuir equation. The maximum adsorption capacity at different temperatures and the corresponding Langmuir constant (K L ) have been deduced. The thermodynamic parameters ( G 0 , H 0 , S 0 ) for the adsorption of DBT have also been calculated from the temperature dependence of K L using the van't Hoff equation. The value of H 0 , S 0 are found to be −30.3 kJ mol −1 and −33.2 J mol −1 K −1 respectively. The adsorption is spontaneous and exothermic. The kinetics for the adsorption process can be described by either the Langmuir model or a pseudo-second-order model. It is found that the adsorption capacity and the initial rate of adsorption are dependent on contact time, temperature and the initial DBT concentration. The low apparent activation energy (12.4 kJ mol −1 ) indicates that adsorption has a low potential barrier suggesting a mass transfer controlled process. In addition, the competitive adsorption between DBT, naphthalene and quinoline on NaY was also investigated. NomenclatureDBT dibenzothiophene t contact time, min c 0 initial concentration of adsorbate in the solution, mmol L −1 c t the concentration of adsorbate at contact time t, mmol L −1 c e equilibrium concentration of adsorbate in the solution, mmol L −1 c DBT the concentration of DBT, mmol L −1 k 0 temperature independent factor, g mmol −1 min −1 k 2 pseudo-second-order rate constant, g mmol −1 min −1 k ads adsorptive constant, L g −1 min −1 k d desorptive constant, mmol g −1 min −1 K L Langmuir constant, L mmol −1 q e adsorptive amount of adsorbate after equilibrium, mmol g −1 q L a solution of the second-order polynomial expression, mmol g −1 q m adsorptive amount of adsorbate to its maximum, mmol g −1 q t adsorptive amount of adsorbate at time t, mmol g −1 θ dimensionless ratio of coverage of the surface of adsorbent v 0 initial adsorptive rate, mmol g −1 min −1 v ads rate of adsorption, mmol g −1 min −1 v d rate of desorption, mmol g −1 min −1 v t rate of adsorption at time t, mmol g −1 min −1 V the volume of solution, L W the mass of adsorbent, g R 2 regression coefficient E a activation energy of adsorption, kJ mol −1 550 Adsorption (2010) 16: 549-558 R g the universal gas constant, 8.314 J mol −1 K −1 T temperature,°C T K temperature in Kelvin, K G 0 Gibbs free energy, kJ mol −1 H 0 enthalpy, kJ mol −1 S 0 entropy, J mol −1 K −1

Kinetic and thermodynamic studies on adsorption of thiophene and benzothiophene onto AgCeY Zeolite

“…Our results showed that the activation energy for the adsorption of TP on AgCeY zeolite is 13.218 kJ/mol and for the adsorption of BT is 9.302 kJ/mol, which are lower than 21 kJ/mol, suggesting the adsorptions are diffusion controlled. Similar results were obtained by others [20,[23][24][25] . Jiang and Ng [20] have studied adsorption kinetic of dibenzothiophene onto NaY Zeolite.…”

“…Similar results were obtained by others [20,[23][24][25] . Jiang and Ng [20] have studied adsorption kinetic of dibenzothiophene onto NaY Zeolite. The activation energy determined to be 12.4 kJ/mol, suggesting the adsorption is mass transfer controlled.…”

“…Although the Langmuir model is widely used to describe the adsorption isotherm, it may also be used to describe the adsorption kinetics [20,21] . The adsorptive rate at any time can be described by Eq.…”

Heterogeneous Photocatalytic Reactions of Sulfur Aromatic Compounds

“…In a recent report, the adsorption of DBT from hexadecane solution onto NaY zeolite was studied by equilibrium and kinetic adsorption measurements. [137] For adsorption to reach equilibrium, tens of hours are required and the low apparent activation energy (12.4 kJ mol…”

Adsorptive removal of refractory sulfur compounds by tantalum oxide modified activated carbons

“…We have previously reported on the use of zeolites and metal modified zeolites for the adsorptive desulfurization of liquid fuels. Liquid phase micro flow calorimetry was successfully used to determine the heat of adsorption of various adsorbate compounds (thiophene, DBT, quinoline, naphthalene) over metal modified zeolites . This study is focused on the study of the effect of metal ions on activated carbons for the removal of refractory sulfur compounds such as DBT and 4,6‐DMDBT in hexadecane as activated carbons have been reported to be good sorbents for refractory type sulfur containing compounds.…”