Cu/ZnO/Al_2O_3甲醇合成催化剂AsH_3中毒热力学分析

Thermodynamics of AsH_3 poisoning on Cu/ZnO/Al_2O_3 methanol synthesis catalyst

利用HSC热力学软件对Cu/Zn O/Al_2O_3甲醇合成催化剂As H_3中毒热力学进行了计算。分析了在150°C^300°C的合成温度下催化剂可能发生的化学反应,并比较各自发反应的化学平衡常数。结果表明:合成原料气组分(CO、H_2O、N_2、O_2)能引起催化剂砷中毒。其中,O_2对催化剂砷中毒的影响最大,参与反应的热力学竞争力最强,产物Cu_3As、As_2O_5、As_2O_3和Cu_3(AsO_4)_2可能导致催化剂失活。为应对砷中毒,应在合成反应之前深度净化合成气。

Thermodynamics of poisoning on Cu/ZnO/Al2O3 methanol synthesis catalyst with AsH3 was calculated using HSC thermodynamic software. The possible chemical reactions were analyzed at the synthesis temperature ranging from 150 to 300℃, and the equilibrium constants of each spontaneous reaction were compared. Our results showed that the components （CO, H2O, N2, and O2） of feed gas for methanol synthesis cause AsH3 poisoning on catalyst, where the effect of O2 on AsH3 poisoning is mostly significant. The reaction involving O2 is the most thermodynamically competitive reaction. Catalyst deactivation is causedly mainly by the presence of Cu3As, As2O5, As2O3, and Cu3（AsO4）2 in the reaction products. To deal with AsH3 poisoning, the deep purification of the synthesis gas （syngas） is strongly suggested prior to the synthesis of methanol.