CeO_2改性的Pd/Al_2O_3催化剂在加氢脱硫反应中的抗硫性能

Sulfur Tolerance of CeO_2 Promoted Pd/Al_2O_3 Catalyst on Hydrodesulfurization Reaction

采用浸渍法制备CeO2改性的Pd/Al2O3催化剂,以噻吩加氢脱硫为探针反应,考察了Pd/Al2O3和Pd-CeO2/Al2O3催化剂的活性和抗硫性能,并运用CO吸附、FT-IR、TG等分析测试技术研究表征了催化剂性质。结果表明,Pd-CeO2/Al2O3催化剂比Pd/Al2O3催化剂具有较低的硫化度。在连续反应中,Pd-CeO2/Al2O3催化剂的抗硫失活能力较强。CeO2的加入导致了Pd—S键能的减弱,在Pd-CeO2/Al2O3催化剂上H2S主要吸附在CeO2上而不是Pd原子上。Pd-CeO2/Al2O3抗硫能力的提高是由于Pd-Ce结合导致Pd缺电子状态,减少了Pd的硫化失活而引起。CeO2对H2S的竞争吸附造成与CeO2结合作用的Pd处于较低的H2S分压,减少了Pd失活的几率。

CeO2 promoted Pd/Al2O3 catalyst was prepared by impregnation method.Its activity and sulfur tolerance was investigated in the hydrodesulfurization of thiophene.CO adsorption,FT-IR and TG were used to characterize the catalyst.The results of deactivity with time and sulfide degree showed that Pd-CeO2/Al2O3 catalyst had much better sulfur tolerance than Pd/Al2O3 catalyst.The FT-IR results indicated the addition of CeO2 caused the bond energy of Pd-S to weaken and H2S to be adsorbed on CeO2.TG revealed that H2S was mainly adsorbed on CeO2 and not on Pd.Enhanced sulfur tolerance of Pd-CeO2/Al2O3 was attributed to the Pd electron deficient state which inhibitd the formation of sulfided palladium.In addition,competitive adsorption of H2S on CeO2 resulted in the lowering of partial pressure of H2S around the Pd phase in close contact with CeO2.