Preparation of Fe-char catalyst from tank cleaning oily sludge for the catalytic cracking of oily sludge

As a hazardous organic waste, the disposal and utilization of oily sludge discharged from crude oil storage tank have received widespread attention. In this study, a novel method was proposed that Fe-char was prepared from oily sludge and was further applied to the catalytic cracking of heavy oil in oily sludge. The char exhibited a porous structure and the inherent iron oxides were directly reduced to metallic iron (Fe degrees) at 900 degrees C after carbonization. The catalytic effects of the char prepared at 600 degrees C (Char600) and 900 degrees C (Char900) were compared in terms of oil conversion efficiency and gas yield. The oil conversion efficiency over Char900 was higher than that over Char600 at 600 degrees C (90.2% vs. 80.1%). Meanwhile, the polyaromatics in the oil product were cracked into monocyclic aromatics and the H-2 and CO yields were increased significantly by using Char900, indicating that Fe degrees exhibited better catalytic performance for the cracking of hydrocarbons than iron oxides. The effects of catalytic temperatures (600-800 degrees C) on the performance of Char900 were also investigated. At 800 degrees C, the oil conversion efficiency reached the highest (95.8%) and the CO yield was 9.5 times higher than that under uncatalyzed conditions. Overall, the catalytic effect of Char900 can be attributed to the combined effects of char and Fe degrees. Char not only provided a porous surface for the adsorption of hydrocarbons, but also can react with moisture in the oily sludge through water gas reactions, enhancing the production of syngas. Moreover, Fe degrees played a significant role as a catalytic medium for promoting the hydrocarbons reforming and water gas shift (WGS) reactions.