铈离子引进方法对其在Y型分子筛中定位的影响

对离子交换法和一步沉积法引进铈离子的系列Y分子筛进行了铈离子定位研究。建立了铈离子在Y分子筛中定位的简便有效的基础表征体系：利用Ce3d XPS谱获得Ce4+/Ce3+摩尔比，通过Ce3d谱及XPS定量结果分析铈离子在分子筛笼内外的存在情况；利用XRD和Py IR确定铈离子在笼内的定位。研究了不同方法引进不同含量铈离子的定位规律。结果表明，离子交换法较沉积法利于铈离子迁移进分子筛笼内，从而进一步迁移进β笼；Ce2O3质量分数为4%、8%、12%和14%时，离子交换法引进的铈离子基本能迁移进β笼。一步沉积法引进的Ce2O3质量分数为4%时，易进入β笼；更多的铈离子则易留在分子筛笼外，可用于防止重金属中毒。

Effects of Introduction Methods of Cerium Cations on Its Location in Y Zeolites

A series of Y zeolites modified with cerium cations using different introduction approaches, including ion exchange process and one step deposition process, were investigated. The location of cerium cations was determined based on comprehensive routine practical characterization methods. The molar ratio of Ce4+/Ce3+ was obtained from Ce3d XPS spectra. XPS Ce3d spectra and quantitative results were utilized to identify the cation location inside or outside the cages of zeolite Y, while XRD and Py IR were presented to determine the cation location inside cages. The cation location features with different cerium contents among different introduction methods were elucidated. Results reveal that ion exchange process benefits the migration of cerium cations to the zeolite cage and therefore favors its migration to sodalite cage. Cerium cations can migrate to sodalite cage successfully on occasion that the mass fractions of Ce2O3 are 4%, 8%, 12% and 14%. Cerium cations introduced via deposition process tend to locate in sodalite cage in case of 4% mass fractions of Ce2O3. However, more cerium cations are prone to remain outside the zeolite cage, which can prevent the poisoning of heavy metal on zeolite.