Hydrotreating of FCC decant oil as a needle coke feedstock

Abstract

Two levels of hydro-desulfurizing experiments using FCC decant oil were performed with a conventional petroleum hydrorefining catalyst in order to obtain detailed information on hydro-desulfurizing of feed oil and coke derived from it. Hydro-desulfurizing products and the feed decant oil were analyzed by the HPLC-MS method, and the carbonization was carried out in a small batch reactor after which properties of coke produced were measured. There is no difference with sulfur condensation ratios in cokes formed from hydro-desulfurized and unhydro-desulfurized feedstocks. Low sulfur coke clearly can be produced from low sulfur feedstocks which have been hydro-desulfurized. Coke coefficient of thermal expansion (CTE) decreases by feedstock hydro-desulfurizing, but coke CTE from the more severely hydro-desulfurized decant oil is higher than that from the mildly hydro-desulfurized decant oil. Under the severe hydro-desulfurizing conditions, hydrogenation of aromatic rings occurs, as does naphthenic ring opening and dealkylation. Severe hydro-desulfurizing also causes a decrease in hydrogen donor ability and an increase in the carbon number of alkyl side chain for one of compound classes.