Abstract: The deactivation of PdCl₂-CuCl₂-KOAc/AC catalyst for gas-phase direct synthesis of dimethyl carbonate and the effects of reaction conditions on the catalyst stability were studied.The possible active centers were Pd²⁺ and Cu⁺.Treating the catalyst with chloro-organic compounds could increase the content of Cu²⁺ and Pd²⁺ on the surface of the catalyst.Cu2+ is the oxidant of Pd⁰.The synergistic effect between Pd and Cu could complete the oxidation-reduction cycle between Pd²⁺/Pd⁰ and Cu²⁺/Cu⁺.With the loss of Cl^- anion ,the ratios of both Cu²⁺/Cu+ and Pd²⁺/Pd⁰ were changed.This change was one of the main reasons for the reversible deactivation of the catalyst.The loss of Pd component, carbon deposition and aggregation of metal particles were the main reasons for the irreversible deactivation.The stability of the catalyst could be improved by increasing the reaction temperature or by lowering the reaction pressure and the concentration of oxygen in the feed.The chloro-organic compounds added in the feed could increase the service time of the catalyst effectively.The activity could be kept stable for more than 150 h at the STY of 700～750 g•L^-1•h^-1 when the reaction pressure was 0.3 MPa and the concentration of the chloro-organic compound was 5%(vol).

摘要： 对气相直接合成碳酸二甲酯PdCl₂-CuCl₂-KOAc/AC催化剂失活问题进行了研究.结果表明：反应过程中氯的流失，使催化剂表面Cu²⁺/Cu⁺与Pd²⁺/Pd⁰比例发生变化，这是影响催化剂稳定性、造成催化剂可逆失活的一个重要因素.钯组分的流失、催化剂表面积炭和金属颗粒聚集等因素则直接造成了催化剂的不可逆失活.考察了不同反应条件对催化剂稳定性的影响，发现降低反应温度、提高反应压力和进料中氧气浓度可在一定程度上提高催化剂的稳定性.原料中配入一定浓度的含氯有机物作为补氯剂，可有效延长催化剂的寿命，当反应压力为0.3 MPa,补氯剂浓度为5％(体积分数)时，反应150 h后催化剂活性仍可稳定在700～750 g•L^-1•h^-1.