| 摘要 |
PURPOSE:To recover a catalyst having good activity in good yield, by removing volatile components from an oxidative coupling reaction solution by distillation and subsequently baking the formed residue containing the catalyst while treating the baked residue with an acid. CONSTITUTION:At least Pd-salt catalyst is recovered and regenerated from a reaction solution containing biphenyl tetracarboxylate formed by the oxidative coupling of ortho-phthalic ester in the presence of a catalyst containing a Pd- salt, a copper-salt and a basic bidentate ligand. In this method, volatile components containing unreacted ortho-phthalic ester and biphenyl tetracarboxylate are separated from the aforementioned reaction solution by distillation while the obtained distillation residue is baked at 400-600 deg.C and thus obtained baked substance is treated with an acid such as ritric acid. As a result, the lowering in the yield of the oxidative coupling reaction product is prevented and the regenerated catalyst shows good catalytic activity. |
