Pd/La0.8Ce0.2MnO3/ZSM-5的制备及其甲苯催化燃烧活性

Preparation of the Pd/La0.8Ce0.2MnO3/ZSM-5 catalyst and its performance in catalytic combustion of toluene

  • 摘要: 以贵金属改性的钙钛矿为活性组分,通过等体积浸渍法制备了Pd/La0.8Ce0.2MnO3/ZSM-5催化剂,并采用XRD、BET、SEM和H2-TPR等技术对催化剂进行了表征。在固定床反应器上,对Pd/La0.8Ce0.2MnO3/ZSM-5催化剂上的甲苯为目标污染物的催化燃烧进行了研究,考察了焙烧温度、负载量及ZSM-5的性质对其催化活性的影响。结果表明,所得到Pd/La0.8Ce0.2MnO3催化剂仍保持钙钛矿型结构,Pd均匀的分布在催化剂表面,有利于催化剂活性的提高。当ZSM-5硅铝原子比为25、La0.8Ce0.2MnO3负载量为20%、焙烧温度为750℃时,La0.8Ce0.2MnO3/ZSM-5上甲苯的起燃温度和完全转化温度分别为200和279℃;加入0.3%的Pd后,Pd/La0.8Ce0.2MnO3/ZSM-5的催化活性明显提高,甲苯起燃温度下降了90℃,完全转化温度可低至230℃。

     

    Abstract: Pd/La0.8Ce0.2MnO3/ZSM-5 catalysts were prepared by incipient wetness impregnation and characterized by nitrogen physical adsorption, X-ray diffraction (XRD), scanning electron microscope (SEM), and temperature-programmed reduction (H2-TPR). The catalytic combustion of toluene as a target pollutant over the Pd/La0.8Ce0.2MnO3/ZSM-5 catalysts was investigated in a fixed-bed reactor and the effect of calcination temperature, active component loading and ZSM-5 properties on the catalytic performance was investigated. The results indicated that the Pd/La0.8Ce0.2MnO3/ZSM-5 preserves the perovskite structure and the active Pd component is evenly dispersed on the catalyst surface, which endures the catalyst with high activity in toluene combustion. Over the La0.8Ce0.2MnO3/ZSM-5 catalyst with La0.8Ce0.2MnO3 loading of 20%, ZSM-5 Si/Al atomic ratio of 25, and calcination temperature of 750℃, the ignition and complete combustion temperatures for toluene combustion are only 200 and 279℃, respectively. After being modified with 0.3% Pd, the activity of the Pd/La0.8Ce0.2MnO3/ZSM-5 catalyst is even largely enhanced; over it, the ignition temperature for toluene combustion is decreased by 90℃ and complete combustion is achieved at 230℃.

     

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