Method for recycling hydrogen from refined benzene dicarboxylic acid plant discharge airflow

The invention discloses a method for recovering hydrogen in exhaust air stream of a refined terephthalic acid plant. The method comprises the following steps that: exhaust gas is subjected to alkali cleaning treatment to remove phenylformic acid, ethylic acid, methyl benzoic acid and other acidic or high boiling point benzene structure substances, and is introduced into a converter and a pressure varying adsorption device, so that the substances cannot damage sour corrosion destroyed a catalyst bed and crystal blocked bed in subsequent process. The method carries out pretreatment on an organic substance which is possibly condensed and crystallized and an acidic substance which possibly destroy the subsequent catalyst bed in the exhaust gas, thereby ensuring the operability of hydrogen recovery and utilization in the subsequent process.