کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
212385 | 462047 | 2012 | 7 صفحه PDF | دانلود رایگان |
Spent hydrodesulphurisation (HDS) catalysts from petroleum refineries, mostly constituted by aluminium (Al), molybdenum (Mo), nickel (Ni) and cobalt (Co), are classified as hazardous wastes and disposal is restricted by environmental regulations; thus, the recovery of valuable metals is the most attractive option in the processing of these residues. Selective Mo leaching from two spent HDS (Ni–Mo or Co–Mo) catalysts, roasted at 500 °C, was studied using three different approaches: conventional, ultrasound- and microwave-assisted methods. For the Ni–Mo or Co–Mo catalysts, 77% and 84% of Mo extraction, respectively, was achieved when a conventional (10 g/L NaOH, 80 °C, 120 min, S/L = 50 g/L) approach was used. For both catalysts, ultrasound-assisted leaching (pulse 0.5 s and 20% amplitude) with 10 g/L NaOH and S/L = 50 g/L led to 66% Mo dissolution after 10 min. Under microwave-assisted (four cycles of 30 s) conditions, Mo leaching reached 89% and 91% for Ni–Mo and Co–Mo catalysts, respectively. The latter conditions represent the best compromise between Mo extraction and selectivity, since Al dissolution was between 6% and 9%.
Figure optionsDownload as PowerPoint slideHighlights
► Selective leaching of Mo from spent Ni–Mo and Co–Mo catalysts using NaOH solution
► Application of ultrasound and microwaves to improve Mo dissolution
► Ultrasound leaching is faster than conventional process.
► For NaOH 10 g/L, microwave leaching leads to a better and more selective Mo extraction.
Journal: Hydrometallurgy - Volumes 129–130, November 2012, Pages 19–25