Arkema Inc.

Atofina

Stephane Lepizzera

Michel Fauconet

Jacqueline Bessalem

The invention concerns a method of purifying a (meth) acrylic monomer selected among (meth) acrylic acids and their esters, by distillation in the presence of at least a polymerisation inhibitor requiring input of oxygen and/or an inhibitor having better efficacy in the presence of oxygen for stabilizing the liquid phase. The invention is characterized in that the distillation is performed in the presence of a NOgas, with an oxygen/organic vapor (p/p) ratio ranging between 0.02 and 3%, and with a NOcondensed organic vapor (p/p) ratio ranging between 0.01 and 50 ppm.

Method for purifying (meth)acrylic monomers by distillation

2-Ethylhexyl acrylate is obtained by esterification of acrylic acid (AA) with 2-ethylhexanol (2-EtHexOH), in the presence of at least one stabilizer for AA, with H SO as catalyst, the crude reaction mixture (B1) obtained comprising the desired acrylate, 2-EtHexOH, AA, 2-ethylhexyl hydrogensulphate (2-EtHexSO H), traces of H SO and impurities. (B1) is washed with water in an extraction column C2 to remove, at the bottom, the aqueous phase (A1), the top organic phase (O2) being sent to a topping column C3 to obtain, at the top, the AA and the 2-EtHexOH, which are recycled to the esterification, the topped desired acrylate being sent to a distillation column C4, from where it exits, purified from the heavy products; a stage of hydrolysis of the 2-EtHexSO H present in (A1) being carried out to form, in this phase, 2-EtHexOH and H SO , the acidic entities resulting from the hydrolysis being neutralized by introduction of a base into the medium, and the resulting aqueous phase (A3) being sent to the recovery of the 2-EtHexOH in a distillation column C1.

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Saint Avold, France

Stephane Lepizzera