Synthesis of mesoporous aluminophosphate (AlPO) and investigation of zirconium incorporation into mesoporous AlPOs.
Mesoporous aluminophosphate materials with variable amounts of zirconium have been synthesized at room temperature using a nonionic surfactant tri-block copolymer (PEO(20)PPO(70)PEO(20)) as the structure-directing agent. Powder X-ray diffraction of as-synthesized and calcined AlPO and ZrAlPO mesoporous materials shows a single broad peak near 2theta = 2.5 degrees, indicative of the average pore-pore correlation distance. Electron probe microanalysis shows that the ratio of P/Al in the powders is approximately 0.5, far lower than 1.0 for an ideal aluminophosphate framework. XRD, TEM, and N2 adsorption data indicate that the calcined samples consist of wormlike tubular materials having surface areas >350 m2/g and pores in the mesopore range. Electron spin resonance (ESR) studies of the gamma-irradiated and evacuated ZrAlPO samples show signals due to Zr3+ that increase with Zr content in addition to signals due to framework defects (i.e., V centers) and H atoms. The line shape and g values observed for Zr3+ are best explained as arising from a trivalent zirconium ion situated at the framework tetrahedral sites.
Lü
Jian-Ming
JM
University of Houston, Houston, Texas 77204-5003, USA.
Ranjit
Koodali T
KT
Rungrojchaipan
Pesak
P
Kevan
Larry
L