Promoting Effect of ZnO on the Catalytic Performance of CoZSM-5 for CO_(2)-Assisted Dehydrogenation of Ethane

Aseries of ZnO-modified cobaltous ion exchanged ZSM-5 catalysts is prepared using incipient wetness impregnation and characterized by X-ray diffraction(XRD),N2 adsorption,transmission electron microscopy(TEM),UV-Vis diffuse reflectance spectroscopy(DR UV-Vis),X-ray photoelectron spectroscopy(XPS),pyridine-adsorbed Fourier transform infrared(Py-IR)and Raman.Their catalytic performance towards CO_(2)-assisted dehydrogenation of ethane to ethylene has been evaluated.The addition of ZnO onto CoZSM-5 obviously improved the yield of ethylene as well as the conversion of CO_(2).The promoting effect is attributed to the good activity of ZnO for the reverse water gas shift(RWGS)reaction,which enhances the coupling between RWGS and ethane dehydrogenation.

金属阳离子对高硅分子筛催化氧化NO的影响

采用离子交换法制备了Na-、K-、Co-、Ni ZSM-5分子筛催化剂.测试了它们催化氧化NO的性能并通过XRD、BET、ICP-MS和Py-IR等表征,结果表明,Co ZSM-5分子筛对NO催化氧化具有最高的活性,氧化率达到47%,主要是引入Co离子的ZSM-5表面酸性最适宜NO氧化.同时,在湿度100%条件下,考察了氧气浓度(5%~20%),空速与二氧化硫浓度(0~200×10^(-6))等对Co ZSM-5分子筛催化氧化NO性能的影响.实验结果表明,在30℃、空速14400h-1和相对湿度100%条件下,SO_2浓度在200×10^(-6)以下对催化氧化NO基本无影响.56h催化剂稳定性实验结果表明,在30℃、NO进口浓度600×10^(-6)、空速18000h^(-1)和饱和水汽(RH:100%)条件下,Co ZSM-5分子筛催化剂对NO的氧化率可维持在40%左右.因此Co ZSM-5分子筛催化剂具有良好的NO氧化稳定性、抗水性和一定的抗硫性.