Recent advances in the recovery of transition metals from spent hydrodesulfurization catalysts

Abstract

Hydrodesulfurization (HDS) catalysts are widely used in petrochemical industries, playing a crucial role in desulfurization process to get high-quality oil. The generation of Al-based spent HDS catalyst is estimated to be 1.2×10 5 tons per year around the world. The spent HDS catalysts have been regarded as an important secondary resource due to their abundant output, considerable metal value, and regeneration potential; however, if improperly handled, it would severely pollute the environment due to high content of heavy metals. Thus, the recovery of valuable metals from spent HDS catalysts is of great importance from both resource utilization and environmental protection points of view. In this work, recent advances in the spent HDS catalyst treatment technologies have been reviewed, focusing on the recovery of valuable transition metals and environmental impacts. Finally, typical commercial processes have been discussed, providing in-depth information for peer researchers to facilitate their future research work in designing more effective and environmentally friendly recycling processes.

Highly Selective Separation and Recovery of Molybdenum from Spent Catalysts by Constructing a Glass-Phase Extraction System

“…28 However, there are characteristic absorption bands of [6] Ni 2+ and [5] Ni 2+ at 7200, 13,000, and 20,000−21,000 cm −1 , respectively, which was attributed to the coextraction of 49.8% Mo 6+ with high field strength into the glass network structure to attract O 2− . 29 With the increase of melting temperature, the characteristic absorption of [6] Ni 2+ and [5] Ni 2+ in the spectra weakened and disappeared, respectively, while the band of [4] Ni 2+ at 18,300 cm −1 shifted to a higher wavelength, indicating an increase in its vibrational frequency. Based on the above results, the designed binary glass extraction system selectively extracted Al 3+ and Ni 2+ from spent catalysts at melting temperatures greater than 1400 °C, accompanied by Mo 6+…”

“…Under 1300 °C, the strong absorption bands near 8500, 15,600, and 18,300 cm −1 are diagnosed as T 1 (F) → 3 A 2 (F), 3 T 1 (F) → 3 T 1 (P), and 3 T 1 (F) → 3 T 1 (P) transitions of [4] Ni 2+ , respectively. 28 However, there are characteristic absorption bands of [6] Ni 2+ and [5] Ni 2+ at 7200, 13,000, and 20,000−21,000 cm −1 , respectively, which was attributed to the coextraction of 49.8% Mo 6+ with high field strength into the glass network structure to attract O 2− . 29 With the increase of melting temperature, the characteristic absorption of [6] Ni 2+ and [5] Ni 2+ in the spectra weakened and disappeared, respectively, while the band of [4] Ni 2+ at 18,300 cm −1 shifted to a higher wavelength, indicating an increase in its vibrational frequency.…”

“…4 Moreover, spent HDS catalysts contain higher concentrations of Mo and Ni than those in primary ores, which has led to them being classified as hazardous wastes. 5 Therefore, the extraction and recovery of Mo from spent HDS catalysts is a sustainable strategy for resources, accompanied by the reductions of the environmental burden from mining and the disposal of hazardous waste. 6 Currently, various technologies for recovering Mo from spent HDS catalysts have been reported.…”

Selective Leaching of Valuable Metals from Spent Fluid Catalytic Cracking Catalyst with Oxalic Acid

“…In view of the worldwide depletion of natural resources and ongoing environmental pollution, increased recycling is necessary, specifically for the recycling of semi-manufactured products, secondary materials, by-products, and wastes, including detrimental wastes [1][2][3]. Most industrial wastes are now regarded as recyclable substances and valuable sources of raw materials.…”

Characterization of Cobalt Oxalate Dihydrate Obtained from Spent Co-Mo/Al2O3 Hydrodesulfurization Catalyst

“…HDS catalysts account for one-third of the world's catalyst consumption. The generation of spent HDS catalyst is estimated to be 1-1.2x10 5 tons per year around the world [4,5]. Recovery of metals from spent catalysts has become more important in recent years.…”