Petroleum refinery has been developed for production of transportation fuel with light alkenes and benzene, toluene, ethylbenzene, and xylenes (abbreviated BTEX), but global market demands are shifting to chemicals produced from light alkenes and BTEX. Additionally, the sort of feedstock oil becomes more multifaceted. Fluid catalytic cracking mainly produces gasoline from residual oil over the catalyst matrix including USY zeolite. Addition of ZSM-5 zeolite to the catalyst can increase yield of propylene. The activity and stability are improved by the incorporation of phosphine, alkali earth metal, and transition metal. Hydrocracking principally produces light saturated hydrocarbons over bifunctional catalyst, which are composed of hydrogenation/dehydrogenation catalyst loaded on solid acid. Ultraheavy oil contaminated by sulfur, nitrogen, and metals can be converted into synthetic crude oil by hydrocracking. In addition, the novel process with dealkylation is introduced for the production of chemicals. Dealkylation of alkylpolycyclic aromatic hydrocarbons in crude oil is made solely to proceed, and then the produced alkane keeping the long chain length and polycyclic aromatic hydrocarbon with no alkyl branch are separated by solvent extraction. Alkanes are utilized as diesel fuel and kerosene, whereas polycyclic aromatic hydrocarbon is converted into benzene and its derivatives through partial hydrogenation and ring opening.