Given the complexity of selling units to different buyers, Petrobras has decided to hire an adviser to analyze potential deals.

Petrobras, which is also interested in selling its stake in the company, has favored a sale through a share offering, but Novonor, as a controlling shareholder, prefers an acquisition because it seeks a premium for its voting shares.

Two years ago, a deal to sell Braskem to LyondellBasell Industries BV failed as Braskem faced environmental problems related to its mining activities in the northeastern city of Maceio.