微波辐射法制备Cu-SSZ-13催化剂及其对柴油车尾气NOx的脱除

采用微波辐射法和传统水热法分别制备了Cu-SSZ-13催化剂,用于柴油车尾气NO_x的脱除.用X射线衍射(XRD)、N₂物理吸脱附、H₂程序升温还原(H₂-TPR)、电子顺磁共振(EPR)、NH₃程序升温脱附(NH₃-TPD)、电感耦合等离子体质谱(ICP-MS)及X射线光电子能谱(XPS)等方法对样品进行表征.结果表明,微波辐射法大大缩短了SSZ-13分子筛的晶化时间,晶化9 h制得样品的结晶度与传统水热法晶化72 h制得样品的结晶度相近,同时孔结构参数也得到了一定程度的改善,微波辐射法制备样品的Brönsted(B)酸性位和Lewis(L)酸性位增多,活性组分铜的负载量也得到显著的提高,使得微波辐射法制备的催化剂呈现出优异的低温活性和水热稳定性.

Cu-SSZ-13 Catalyst Synthesized under Microwave Irradiation and Its Performance in Catalytic Removal of NOx from Vehicle Exhaust

Cu-SSZ-13 catalysts had been prepared by using a microwave irradiation (MW) method and a conventional hydrothermal (CH) method, which were applied to removal of NO_x from diesel vehicles by NH₃. The physical and chemical properties of the samples were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, H₂ temperature-programmed reduction (H₂-TPR), electron paramagnetic resonance (EPR), NH₃ temperature-programmed desorption (NH₃-TPD), inductively coupled plasma-mass spectroscopy (ICP-MS), and X-ray photoelectron spectroscopy (XPS). The MW had some significant advantages, greatly shortening the crystallization time of SSZ-13 and improving its physical and chemical properties. The sample synthesized using MW with a crystallization time of 9 h had similar crystallinity to that synthesized by the CH with a crystallization time of 72 h. The sample synthesized by the MW had improved pore structure and amounts of Lewis (L) acid and Brönsted (B) acid. The great increase in Cu load as an active component indicated that the MW enhanced the ability of SSZ-13 to perform Cu exchange. The Cu-SSZ-13 synthesized by MW had improved low-temperature activity and anti-aging ability.