PROCESS FOR PURIFYING AN OXIDATION WASTE GAS

摘要

The invention relates to a process for the purification of an off gas which originates from a reaction process operated under pressure and which is contaminated with aliphatic and/or aromatic substances, by scrubbing the off gas. The off gas to be purified originates in particular from an oxidation process operated with oxygen-containing gas, for example from the oxidation of para-xylene (p-X) with air by the so-called Witten DMT process for the preparation of dimethyl terephthalate (DMT). The off gas is subjected to purification by absorption under pressure, the absorbent consisting predominantly of an ester or of an ester mixture. The ester or the ester mixture has a higher boiling point than the substances to be washed out. The process preferably comprises the following main steps: a) Partial condensation of the substances to be washed out, at about 35-60.degree.C; b) Absorption with methyl para-toluate (p-TE) or with a mixture of p-TE and methyl benzoate (BME); c) Absorption with BME and/or methanol; d) Absorption with water; e) Combustion under pressure, if necessary with the supply of oxygen and combustible products.