CoSAPO-34分子筛的合成、表征及其光催化脱氮性能

Synthesis Characterization and Photocatalysis Denitrification Properties of CoSAPO-34 Molecular Sieve

利用水热合成法,以三乙烯四胺(TETA)为模板剂,正硅酸乙酯、磷酸、氢氧化铝及乙酸钴为原料,合成了CoSAPO-34分子筛。通过扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、热重(TG)、N2吸附-脱附和紫外-可见漫反射光谱(UV-Vis DRS)等方法对合成的分子筛进行表征。以吡啶-正辛烷体系为模拟油品对分子筛催化剂的脱氮效果进行评价,考察了样品的用量、光催化时间及循环催化次数对其脱氮性能的影响。结果表明:当合成原料的物质的量之比为n_(P_2O_5)∶n_(Al_2O_3)∶n_(SiO_2)∶n_(Co)∶n_(TETA)=1∶0.82∶0.26∶0.81∶2.05,在200℃晶化24 h,合成得到粒径约为50μm、仍保持了SAPO-34分子筛的骨架结构、形貌为立方体的Co SAPO-34分子筛,而且该分子筛具有较好的热稳定性。在500 W氙灯光照条件下反应150 min,样品对质量分数为100μg·g-1模拟油品的脱除率达到70%,循环3次光催化脱氮活性基本保持不变。

The CoSAPO-34 molecular sieve was synthesized by hydrothermal synthesis method with triethylenetetramine （TETA） as template and phosphate acid, tetraethyl orthosilicate, manganese acetate and aluminum hydroxide as raw material. The synthetic molecular sieve was characterized by scanning electron microscopy （SEM）, powder X-ray diffraction （XRD）, thermogravimetric （TG）, N2 adsorption-desorption and UV-Vis diffuse reflectance spectra （UV-Vis DRS） methods and the photocatalytic denitrification propertise of the synthetic molecular sieve was evaluated. The influences of the amount of sample and the time of light irradiation were investigated. The results show that when the raw material ratio is nP2O5：nAl2O3：nSiO2：nCo：nTETA=1：0.82：0.26：0.81：2.05, crystallization temperature is 200℃, crystallization time 24 h, the synthesized CoSAPO-34 molecular sieve is dodecahedron with about 50 μm in diameter, and the CoSAPO-34 molecular sieves show good crystallinity and still remain structure of SAPO-34 with good thermal stability. The photocatalytic degradation ratio reaches to 70% when under the irradiation of 500 W Xe lamp for 150 min. The photocatalytic denitrification activity of the sample is almost unchanged for 3 cycles.