Al_2O_3-ZrO_2复合氧化物对Cu基催化剂选择加氢性能的影响

Effect of Al_2O_3-ZrO_2 composite oxide on the performance of Cu-based catalyst for selective hydrogenation

采用共沉淀法制备Al2O3-ZrO2复合氧化物,并以此为载体制备负载型Cu基催化剂,运用X射线衍射、X射线能谱、扫描电子显微镜对载体和催化剂进行表征。以糠醛气相加氢制糠醇反应为探针,考察复合氧化物对Cu基催化剂选择加氢活性的影响。结果表明,Al2O3-ZrO2复合氧化物中ZrO2的存在会减少CuO与Al2O3的接触,降低Cu基催化剂的深加氢能力;Al2O3有助于延迟ZrO2的晶化,避免活性组分Cu嵌入到ZrO2晶格中导致催化活性下降。载体中ZrO2质量分数为20%时,Cu/Al2O3-ZrO2催化剂选择加氢活性最高,与Cu/Al2O3催化剂相比,该催化剂具有较好的低温加氢活性和高温加氢选择性。

Al2O3-ZrO2 composite oxides were prepared by coprecipitation and used as supports for Cu-based catalysts prepared by impregnation. The supports and the catalysts were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,and scanning electron microscopy （SEM）. Effect of the composite oxides on the Cu-based catalysts for selective hydrogenation was studied using vapour phase hydrogenation of furfural to furfural alcohol as a probe reaction. Results showed that ZrO2 can reduce the contact between CuO and Al2O3,and therefore,decrease the deep hydrogenation capacity of the Cu-based catalysts. Al2O3 can delay the crystallization of ZrO2 and avoid Cu embedded into the ZrO2 lattice which would lead to the decrease in catalystic activity. Cu/Al2O3-ZrO2 catalyst made from Al2O3-ZrO2 support with 20% ZrO2 exhibited the highest activity for selective hydrogenation,which showed a higher low temperature activity and a higher high temperature selectivity in comparison with Cu/Al2O3 catalyst.