Study and optimization of adsorption of sulfur compounds present in fuel

Abstract

The present work investigates the performance of fly ash, coal dust, bentonite, laterite and sodium zeolite as adsorbents for desulfurization of synthetic fuel by batch adsorption experiments at 50 °C and under atmospheric pressure. A series of synthetic fuel samples containing known concentrations of thiophenol, benzothiophene and di-benzothiophene, as singular and multi component mixtures in isooctane, were prepared. The performance of coal dust was found to be the best among all the adsorbents mentioned, in removal of both single and multi sulfur compounds from synthetic fuel. The adsorbents were characterized by BET surface area analysis, XRF, XRD, FTIR, SEM and NH₃-TPD. The effects of parameters such as stirrer speed, adsorbent particle size, temperature, adsorbent amount, initial sulfur concentration and contact time between adsorbate and adsorbent were investigated for desulfurization of synthetic fuel using coal dust as adsorbent. The sulfur adsorption equilibrium with this adsorbent was fitted to Langmuir, Freundlich, BET, Halsey and Temkin isotherms. Finally Response Surface Methodology (RSM) was applied for optimizing the adsorption process parameters. The four factor Box–Behnken design (BBD) was performed, aimed at developing second order polynomial models at the optimum conditions. The objective was to find out how the output, sulfur adsorption per gram of adsorbent (q_t), is related to the inputs, initial sulfur concentration, adsorbent amount, time and temperature, in order to get a clear picture for further research.