Exxon Mobil Corp. is selling its troubled Southern California refinery for $537 million to a New Jersey energy company more than six months after an explosion crippled the plant and led to higher gas prices in the Golden State, according to an announcement Wednesday. PBF Energy Inc., one of the largest independent oil refiners in North America, said it will purchase the Torrance plant that can produce 155,000 barrels of oil a day.