Química Nova (Jan 2011)

The importance of pre-treatment of spent hydrotreating catalysts on metals recovery

  • Alexandre Luiz de Souza Pereira,
  • Cristiano Nunes da Silva,
  • Júlio Carlos Afonso,
  • José Luiz Mantovano

DOI
https://doi.org/10.1590/S0100-40422011000100027
Journal volume & issue
Vol. 34, no. 1
pp. 145 – 150

Abstract

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This work describes a three-step pre-treatment route for processing spent commercial NiMo/Al2O3 catalysts. Extraction of soluble coke with n-hexane and/or leaching of foulant elements with oxalic acid were performed before burning insoluble coke under air. Oxidized catalysts were leached with 9 mol L-1 sulfuric acid. Iron was the only foulant element partially leached by oxalic acid. The amount of insoluble matter in sulfuric acid was drastically reduced when iron and/or soluble coke were previously removed. Losses of active phase metals (Ni, Mo) during leaching with oxalic acid were compensated by the increase of their recovery in the sulfuric acid leachate.

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