采用静态水热合成法,活性胶液中各组分摩尔比为n(B2O3)/n(Al2O3)/n(P2O5)/n(模板剂)/n(H2O)=r:y:1.5:2:240合成了系列硼铝磷酸盐分子筛BAPO-5。利用XRD,SEM,BET,FT-IR和MAS-NMR等方法对BAPO-5分子筛进行了多角度表征。结果表明,当活性胶液中0〈n(B2O3)/n(Al2O3)〈0.08时,可合成出不同硼含量的BAPO-5,BAPO-5与未添枷杂原子B的AlPO4-5具有相同的晶体结构;BAPO-5的比表面积和比孔容均随B含量的增加而增大,表明BAPO-5中的硼为分子筛的骨架阳离子元素;BAPO-5骨架中的A1和P的配位环境为AlO4和PO4,杂原子B的引入并未引起分子筛的骨架阳离子元素Al和P的配位环境和结构类型的改变;此外,合成的BAPO-5具有规整的六方棱柱晶体外形。
A series of boron aluminophosphate molecular sieves (BAPO-5) were synthesized by static hydrothermally method using the gel composition n(B2O3)/n(Al2O3)/n(P2O5)/n(Et3N)/n(H2O)=r:y:1.5:2:240. Based on the synthesized BAPO-5 molecular sieves, many of characterization was carried out by XRD, SEM, BET, FT-IR, MAS-NMR methods. It shows that the series of boron aluminophosphate molecular sieves with different boron contents are prepared in the range of 0〈n(B2O3)/n(Al2O3)〈0.08. And the crystal structure of BAPO-5 molecular sieves is attributed to the AFI structure type, which is the same as AlPO4-5. With the increase of the boron content, BET surface area and pore volume of BAPO-5 molecular sieves are also increased. This provides evidence of boron as heteroatom in the framework of BAPO-5 molecular sieves. It is observed that coordination environments of Al and P in the framework of BAPO-5 are AlO4 and PO4. Therefore, AlPO4-5 framework-incorporated B atoms brings no change of coordination environments of AI and P and structure type of BAPO-5 molecular sieves. In addition, SEM images show that the synthesized BAPO-5 molecular sieves have a regular hexagonal prism morphology.