Hydrodesulphurization of gasoils: advantages of counter-current gas-liquid contacting

Abstract

Hydrodesulphurization (HDS) of gasoils is conventionally carried out in the petroleum industry in co-current trickle bed reactors. The important disadvantage of co-current operation is that the build-up of H₂S along the reactor height is detrimental to the desulphurisation reaction; this is because of inhibition effects. In this paper we examine the benefits of carrying out the HDS reaction in a counter-current mode. We carried out simulations of the co- and counter-current configurations using an equilibrium stage model and taking dibenzothiophene (DBT) as a model sulphur compound. Our simulations show that counter-current operation can significantly reduce the requirements in the total amount of catalyst when ultra low levels of S are demanded in the product steam. For the same amount of catalyst, the conversion of DBT is significantly higher.