Gasoline desulfurization with two catalytic distillation columns

A new approach was proposed to remove sulfuric compounds from fluid catalytic cracking (FCC) gasoline by combining an alkylation desulfurization catalytic distillation (ADCD) column with a hydrodesulfurization catalytic distillation (HDS-CD) column. In the ADCD column, isobutylene (IB) and 3-methylthiophene (3MT) were designated as the model compounds for olefin and sulfide, respectively; NKC-9 cation exchange resin was used as the catalyst. In the HDS-CD column, dibenzothiophene (DBT) was chosen as the model sulfides; Nickel phosphide supported on the TiO ₂-Al ₂O ₃ composite oxide prepared by our laboratory were designated as the HDS catalyst. Simulations for these two CD columns were carried out by RADFRAC module of Aspen Plus. The optimization results revealed that the ADCD column had an alkylation selectivity of 96%, and the sulfur content in the overhead stream was less than 8 μg/g. The simulation results of the HDS-CD process showed that the sulfide in the bottom stream of ADCD column can be removed practically by 100% and the clean oil stream from the bottom of HDS-CD column has hardly any sulfur.