超大孔磷酸铝分子筛的合成及性能

1988年Davis等首次报道了以二正丙胺和四丁基氢氧化铵为结构导向剂合成出一种命名为VPI-5的新型磷酸铝超大孔分子筛。它是一族具有相同三维拓朴学骨架的磷酸铝系分子筛,该结构的对称性属六方晶系,P6_3cm空间群,单位晶胞由36个TO_2组成,晶胞参数α=1.8989nm,c=0.8112nm,其主孔道由18员环构成,孔直径约为1.2-1.3nm。

SYNTHESIS AND CHARACTERIZATION OF ALUMINOPHOSPHATE AND SILICOALUMINOPHOSPHATE WITH EXTRA-LARGE PORES

Aluminophosphate and silicoaluminophosphate molecular sieves VPI-5 and Si-VPI-5 with extra-large pores have been synthesized using di-isopropylamine(DIPA), di-propylamine(DPA), and di-butylamine (DBA) as structure directing agents. It is emphasized that we synthesized DIPA-VPI-5 with high crystallinity shown in XRD pattern without peaks of impurities. The hydroxyl and their acidic properties of VPI-5 and Si-VPI-5 have been examined by means of IR spectroscopy using the adsorption of D2O and pyridine as probes. The experimental results indicate that both of Bronsted and Lewis acid sites are examined on the Si-VPI-5 with moderate acid strength. The adsorption of nitrogen gas under liquid nitrogen temperature at p/ PO = 0.928 was measured on VPI-5 and Si-VPI-5 samples. Their adsorption capacities are 0.2284 and 0.2236cm3 / g respectively, consistent with Davis's data. The adsorbed velocities of 1,3,5-trimethylbenzene on VPI-5 and Si-VPI-5 are extremely larger than that on AlPO4-5 at 393K. From above results it further gives evidences that VPI-5 and Si-VPI-5 possess extra-large pore in their topology.