Resumo

PEREIRA, Alexandre Luiz de Souza; SILVA, Cristiano Nunes da; AFONSO, Júlio Carlos  e  MANTOVANO, José Luiz. The importance of pre-treatment of spent hydrotreating catalysts on metals recovery. Quím. Nova [online]. 2011, vol.34, n.1, pp. 145-150. ISSN 0100-4042.  http://dx.doi.org/10.1590/S0100-40422011000100027.

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.

Palavras-chave : spent catalyst; metals recovery; foulant elements.