DESULFURIZATION AND DENITROGENATION OF LIQUID FUELS BY MODIFIED ACTIVATED CARBON

Abstract

In the present study, nickel loaded activated carbon (Ni/AC) was synthesized and characterized by various techniques. It was further used for the adsorption of nitrogenous compound (N) (represented by quinoline) and sulfur compound (S) (represented by dibenzothiophene (DBT)). Various methods like X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, energy dispersive and scanning electron microscopy, thermo-gravimetric analysis etc. were used for physico-chemical characterization of Ni/AC before and after the adsorption of N and S. FTIR spectra of Ni/AC indicated the presence of various types functional groups on its surface. Thermo-gravimetric analysis exhibited the thermal stability of Ni/AC up to 400 oC temperature. The influence of various factors like loading, adsorbent dose, time and temperature on the adsorption of N and S from model fuel by Ni/AC were investigated. Equilibrium time for N and S was found to be 6 h and 9 h, respectively. The optimum adsorbent dose was found to be 20 g/l. It was found that adsorption of N and S followed pseudo-second-order kinetics. The adsorption of N and S was best represented by Redlich-Peterson isotherm. Taguchi’s method (L27 orthogonal array) was used to optimize various parameters for the removal of N and S simultaneously from model fuel using Ni/AC. The effect of various parameters like initial adsorbate concentration (Co,i), adsorbent dose, temperature and contact time on the adsorption of N and S has been studied at three levels to see their effect on qN, qS and qtot. It was found that the adsorbent dose is the most significant factor while the interaction between Co,i’s is also significant. For the binary system containing both S and N, equilibrium adsorption data was obtained (Co,S = 1.56-23.43 mmol/l, Co,N = 3.57-53.57 mmol/l, T= 303 K, t = 9 h, m = 20g/l). It was found that the adsorption capacity of Ni/AC was higher for N than that for S. For binary component system containing S and N, extended Freundlich isotherm best represented the isotherm data at 30 oC.