MASNMR研究钯添加剂对SAPO-5分子筛的影响

通过在SAPO-5分子筛的前身体中加入不同含量不同形式的钯盐方式,直接合成出了分子筛上担载贵金属的双功能催化剂,X光衍射(XRD)结果表明把的加入并不影响SAPO-5分子筛的生成,但降低了分子筛结晶度。当把以碱性介质加入反应物时,使产物中有少量SAPO-34伴生,由MASNMR实验结果可见,反应物中把的加入抑制了硅进入分子筛骨架,使骨架铝配位环境更加对称,并使三乙胺模板分解,改变了其在分子筛中的存在状态。从而导致分子筛结晶度的降低.

MAS NMR STUDY ON THE EFFECT OF PALLADIUM ADDITION ON SAPO-5 MOLECULAR SIEVE

SAPO-5 molecular sicve bas been synthesized by hydrothermal method.Palladium is supported on it by adding Pd salt solution (Pd(NH₃)₄Cl₂ and H₂PdCl₄)into the mixture gel of SAPO-5 before crystallizzation in order to obtain bifunctional catalyst.The result of X-ray diffraction reveals that the introduction of palladium salt in the mixture gel does not deprcss the formation of SAPO-5. However,when palladium is added in the form of Pd(NH₃)₄Cl₂, there intergrows a little SAPO-34 in the product.MAS NMR results show that the addition of palladium obstructs silicon to enter the framework and thus makes a more symmetrical coordination environment of alumini-um and Causes partialy decomposition and polymeriZation of the template in SAPO-5.The reaction of the template during crystallization differs with the palladium precur-sors.³¹P MAS NMR result shows that the addition of palladium salt in the mixture gel has little influence on the coordination environment of phosphorus in the framework.