Directly Producing Clean and Low Softening Point Diesel Using Integrated Hydrotreating and Hydroisomerizing Catalysts

摘要

A novel hydrotreating (HT) catalyst of Mo-W-Ni-P supported on γ-Al_2O_3 modified by a Group IVA element and a hydroisomerizing (HI) catalyst of W-Ni supported on modified zeoliteβ with mesopores were prepared by the impregnation method. An integrated process using HT and HI catalysts was designed, and its advantages were well-investigated for directly producing clean diesel from various feedstocks. An industrial application shows that the integrated catalysts have flexible operating modes and are suitable for a wide range of feedstocks. For the HT operating mode, the integrated catalysts showed better hydrodesulfurization (HDS) performance for upgrading the poor quality diesel with a sulfur content of 1000 ppmw and a nitrogen content of 1131 ppmw. The sulfur content of diesel product is less than 40 ppmw, coupled with a hydrodenitrogenation (HDN) rate of 85.76% and an HDS rate of 96.3%. The cetane index increases by 7 units, and the diesel yield is more than 98.0 wt %. For the hydro-dewaxing operating mode, the integrated catalysts showed excellent catalytic performance for upgrading the feeds, with a sulfur content of 990 ppmw and a nitrogen content of 805 ppmw. The HDN rate of 99.42% and HDS rate of 99.99% were also achieved. More importantly, while retaining the cetane index, the diesel yield was as high as 88.72 wt % and the sulfur content and solidifying point of diesel were less than 10 ppmw and -29.3 ℃, respectively. The higher HDS and HDN activities of the integrated catalysts are associated primarily with enhanced hydrogenation activity and increased acidity of the HI catalyst.