关键词: 大分子硫醇, 催化裂化汽油, 烯烃, 过程强化

Abstract:

Selective removal of heavy molecular mercaptan from FCC gasoline after hydrodesulfurization is an effective method for low-cost and efficient production of clean gasoline in China. CoMo/Al₂O₃ hydrodesulfurization catalysts with different pore sizes were prepared using pore saturation impregnation method. After crushing to different particle sizes, they were subjected to sulfurization treatment. Simulated and real FCC gasoline after hydrodesulfurization were evaluated in a fixed bed reactor, and the reaction effect of catalyst removal of heavy molecule mercaptans was investigated under different process conditions. The in-situ adsorption reaction process intensification method was used to enhance the selective removal of heavy molecule mercaptans. The results showed that mercaptans are heavy molecular mercaptans formed by the combination of olefins and hydrogen sulfide in gasoline, with various types and low content of each mercaptan. The removal reaction of regenerated mercaptan is limited by mass transfer at low temperature, and the chemical reaction of hydrogen sulfide and olefin to regenerate mercaptan reaches thermodynamic equilibrium, which cannot be effectively removed by current MoS₂ catalysts. By reducing the catalyst particle size and increasing the catalyst pore size, the diffusion limit of mercaptan removal reaction can be effectively reduced. At the same time, the in-situ adsorption reaction process intensification method is used to remove the hydrogen sulfide generated during the mercaptan removal reaction process, avoiding the recombination reaction between hydrogen sulfide and olefins. It can efficiently remove heavy molecule mercaptan under mild conditions and produce clean gasoline with low-cost.

Key words: heavy molecular mercaptan, FCC gasoline, olefin, process intensification