Sodium hydroxide-assisted desulphurization of petroleum fluid coke

Abstract

Desulphurization of a fluid coke produced commercially from a conventional petroleum crude oil was attempted. Direct hydrodesulphurization of the coke at 700°C resulted in ≈31 wt% sulphur removal; however, impregnation of the fluid coke with trace amounts of sodium hydroxide and subsequent hydrodesulphurization resulted in > 80 wt% sulphur removal primarily as H 2S. A significant part of the alkaline reagent could be recovered by hot water leaching of the desulphurized coke. The calorific value of the desulphurized coke is slightly lower than that of the starting material. The mechanism appears to be complex as the change in surface area was negligible upon impregnation and hydrodesulphurization. Economic evaluation of the desulphurization process, carried out at the Alberta Research Council, indicates that it has significant economic advantages over fluidized-bed combustion of the coke with limestone or combustion of the coke with flue gas desulphurization.