超声法制备负载Cu-Fe分子筛催化剂及其催化氧化甲苯性能研究

Preparation of Cu-Fe loaded molecular sieve catalyst by ultrasonication and its catalytical oxidation performance for toluene

挥发性有机化合物(VOCs)是大气污染物的重要组成部分,可对生态环境和人体健康造成严重危害,因此设计并制备高效催化剂降解VOCs尤为重要。作为商业应用的催化剂,分子筛具有稳定性好和抗毒能力强等优点,然而单一分子筛催化活性较差,需要负载活性组分进一步提高催化性能。采用超声法,分别以ZSM-5、Beta和SAPO-34分子筛作载体同时负载Cu、Fe过渡金属氧化物制备了Cu-Fe/ZSM-5、Cu-Fe/Beta和Cu-Fe/SAPO-34催化剂并用于甲苯催化氧化。催化活性测试结果表明,Cu-Fe/ZSM-5催化剂表现出最佳催化活性,300℃下甲苯转化率可达90%。X-射线衍射(XRD)分析结果表明,同时负载Cu、Fe金属氧化物未对分子筛结构造成明显破坏,且金属氧化物具有良好的分散性。NH_(3)程序升温(NH_(3)-TPD)分析结果表明,酸性不是影响催化活性的唯一因素。原位漫反射红外(in situ DRIFT)和色谱质谱联用(GC-MS)分析结果表明,催化活性较好的催化剂上生成的中间产物较少,而催化活性较差的催化剂上会生成更多的中间产物。

Volatile organic compounds(VOCs) are important ingredients of air pollutants,which can cause serious harm to ecological environment and human health,so it is particularly important to design and prepare efficient catalysts to degrade VOCs.As catalysts for commercial application,molecular sieve exhibits the advantages of excellent stability and high resistance to toxicity.However,due to the poor catalytic activity of single molecular sieve,loading active components is needed to further improve the catalytic performance.Cu-Fe/ZSM-5,Cu-Fe/Beta and Cu-Fe/SAPO-34 catalysts were prepared by ultrasonic method using different molecular sieves(ZSM-5,Beta and SAPO-34) as carriers simultaneously loaded with Cu and Fe transition metal oxides and used for the catalytic oxidation of toluene.The results of catalytic activity test show that Cu-Fe/ZSM-5 catalyst possesses excellent catalytic activity,with the conversion rate of toluene up to 90% at 300 ℃.The X-ray diffraction(XRD) analysis results show that the molecular sieves simultaneously loaded with Cu and Fe metal oxides do not cause obvious damage to the molecular sieve structure,and the metal oxides have good dispersion.The results of NH_(3) temperature programming(NH_(3)-TPD) analysis show that acidity is not the only factor affecting catalytic activity.The results of in situ diffuse reflection infrared(in situ DRIFT) and chromatography-mass spectrometry(GC-MS) analysis show that the less intermediates are generated on the catalyst with better catalytic activity,while more intermediates are generated on the catalyst with poor catalytic activity.