固相合成MAPO-5分子筛及其在甲苯催化燃烧中的应用

以二正丙胺磷酸盐(DPA·H₃PO₄)和四乙基溴化铵(TEABr)为双模板剂，采用简单、绿色、高效的固相研磨法合成了多级孔杂原子磷酸铝分子筛CeAPO-5和CoAPO-5；为提升催化性能，增加分子筛中铈离子的含量，制备了一系列不同铈掺杂量的CeAPO-5分子筛，包括CeAPO-5分子筛(w(Ce)=2%)、1.2CeAPO-5分子筛(w(Ce)=2.4%)和2CeAPO-5分子筛(w(Ce)=4%)。通过X-射线衍射(XRD)、扫描电子显微镜(SEM)、N₂吸脱附测试(BET)、固体紫外可见(UV-Vis)漫反射光谱和X射线光电子能谱(XPS)等手段对所合成分子筛进行表征，同时以甲苯为目标污染物，考察了分子筛催化剂在催化燃烧反应中的催化性能。结果表明，所合成的分子筛都具有典型的AFI结构，结晶度较高，且Ce离子和Co离子被成功引入到分子筛骨架中；CeAPO-5分子筛在甲苯催化燃烧反应中较CoAPO-5分子筛具有更好的催化性能；在将金属Ce的含量从2%提高到4%的过程中，催化剂催化氧化甲苯的活性也有所提高，当反应温度为400 ℃时，2CeAPO-5分子筛的甲苯转化率接近100%；通过对催化剂在360 ℃时催化氧化甲苯的稳定性进行研究发现，2CeAPO-5分子筛在经过30 h的反应后仍保持70%左右的甲苯转化率。

Solvent-free syntheses of aluminophosphate-based zeolites MAPO-5 and their performances in the catalytic combustion of toluene

Hierarchically porous aluminophosphate-based zeolites CeAPO-5 and CoAPO-5 have been successfully synthesized using a green solvent-free method with di-n-propylamine phosphate (DPA·H₃PO₄) and tetraethylammonium bromide as templates. In order to improve the activity of molecular sieves, the amount of cerium was increased, giving a series of cerium-doped molecular sieves, CeAPO-5, 1.2CeAPO-5 and 2CeAPO-5, with 2%, 2.4% and 4% mass fractions of cerium, respectively. The as-synthesized molecular sieves were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen sorption measurements (BET), UV-visible diffuse reflectance spectrometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS). The results indicated that as-synthesized zeolites have good crystallinity with their structure is in agreement with that of an AFI zeolite and that Ce and Co have been successfully incorporated into the frameworks. In the catalytic combustion of toluene, CeAPO-5 zeolite exhibited better catalytic properties than CoAPO-5 zeolite. Furthermore, as the Ce content was increased from 2% to 4%, the catalytic activities of CeAPO-5 zeolite improved. At a temperature of 400 ℃, toluene can eventually be almost eliminated over 2CeAPO-5 zeolite. Additionally, the 2CeAPO-5 zeolite appears to show good stability during the catalytic combustion of toluene and affords a toluene removal efficiency of about 70% after testing for 30 hours at 360 ℃.