Removal of sulfur compounds in FCC raw C₄ using activated carbon impregnated with CuCl and PdCl₂

Fluid catalytic cracking (FCC) is one of the most important refinery processes for economical efficiency that produces commercial fuels with acceptable concentrations of sulfur. Several activated carbon (AC) based adsorbents were studied to develop a more efficient adsorbent for removal of mercaptanes and sulfides during the FCC C4 refinery process. The adsorbents were prepared by impregnating AC with CuCl and PdCl₂. To evaluate the degree of metal halide impregnation into the AC support, each adsorbent was characterized by N₂ adsorption, elemental analysis (EA) and XRF. Three types of ACs were used to investigate the effect of the structural properties such as surface area, total pore volume and pore size distribution. From this analysis, an AC micro pore size of 0.7 nm was found to be the most effective support material for FCC C₄ removal of sulfur compounds. The experimental adsorption isotherms were compared with Langmuir and Freundlich models and were found to fit the Freundlich model much better than the Langmuir model. The sulfur removal performance of the prepared adsorbents was tested using the breakthrough experiments. The sulfur adsorption capacities of adsorbents decreased in the following order: AC impregnated PdCl₂, AC impregnated CuCl and non-impregnated AC (NIAC). The saturated adsorbents were regenerated by toluene treatment and reactivated at 130 °C under a vacuum.