Development of coke texture by thermal pretreatment of petroleum residua

Thermal pretreatment of coker feeds at sub-carbonization temperatures can lead to considerable development of the optical texture of semi-cokes produced upon carbonization at 723 K. The extent of the development is dependent upon the nature of the residual feed and pretreatment time-temperature history. Under suitable pretreatment conditions, highly reactive feed components can be induced to react and self-stabilize. During subsequent carbonization, the slower processes required for the development of carbonaceous mesophase can then proceed relatively unhindered. These same reactive species are believed to give rise to the formation of shot coke in delayed coking and cause the production of other cokes with poorly developed mesophase.