Pd-Na/Al2O3催化剂的表征及室温下催化氧化甲醛的性能

Characterization of Pd-Na/AlO catalyst and its catalytic oxidation of formaldehyde at room temperature

为获得一种可在室温下完全氧化甲醛且价格较低的催化剂,选取商用的γ-Al2O3为载体,以价格相对较低的Pd为活性组分,以Na^+为助剂,采用共浸渍法制备了一系列0.5%Pd-x%Na/Al2O3(x=0、1、2和4)催化剂。采用N2吸附脱附、XRD、H2-TPR、O2-TPD和XPS对催化剂物理化学性质进行了表征,对催化剂室温催化氧化甲醛性能进行了评价。结果表明:Pd与Na之间的协同作用促进了部分带负电荷Pd物种的形成,有利于O2物种的吸附;Pd与Na之间的强相互作用,显著改善了催化剂的低温还原性,促进了表面吸附氧活化,有利于催化氧化甲醛;0.5%Pd-2%Na/Al2O3催化剂具有较好的催化活性和良好的稳定性,在室温(25℃)下,甲醛体积分数为0.025%时,甲醛转化率为100%;连续使用60 h后,甲醛的转化率仍维持在99.0%以上。0.5%Pd-2%Na/Al2O3催化剂载体易得、Pd负载量低,合成工艺简单,催化氧化甲醛性能优异,有望成为一种去除室内甲醛的新型催化剂。上述结果可为室内空气中甲醛的催化氧化治理提供参考。

In order to obtain a catalyst that can completely oxidize formaldehyde at room temperature with a low price,a series of 0.5%Pd-x%Na/Al2 O3(x=0,1,2 and 4)catalysts with different mass fraction of Na were successfully prepared by co-impregnation method using commercialγ-Al2 O3 as the support,low-cost Pd as the active component and Na+as the promotor.The as-prepared catalysts were characterized by various methods of N2 adsorption and desorption,XRD,H2-TPR,O2-TPD and XPS and evaluated the performance on HCHO catalytic oxidation at room temperature.The results showed that the synergetic effect between Pd and Na could lead to the formation of partial Pd species with negative charge,which enhanced O2 adsorption.Meanwhile,the strong interaction between Pd and Na significantly improved the low-temperature reducibility and promoted the activation of the surface chemisorbed oxygen,which was beneficial for the catalysis oxidation of HCHO.The catalyst with 0.5%Pd and 2%Na/Al2 O3 had better catalytic activity and stability,which could lead to 100%HCHO conversion within initial volume fraction of 0.025%at 25℃;after 60-hour continuous usage,the HCHO conversion maintained above 99.0%.It has demonstrated that the 0.5%Pd-2%Na/Al2 O3 is a promising potential catalyst for indoor removal of HCHO,due to its readily available catalyst support,the low Pd loading amount,the facile synthesis process,and excellent catalytic performance.This study provides a theoretical reference for the catalytic oxidation of formaldehyde in indoor air.