✍ Scribed by Ziyu Liu; Yingxu Wei; Yue Qi; Xianbin Liu; Yinfeng Zhao; Zhongmin Liu
No coin nor oath required. For personal study only.
A kind of mesoporous Zr-P-Al materials was synthesized by a three-step method, in which a hexagonal zirconium oxide-sulfate composite was prepared and subsequently treated with a phosphoric acid solution followed by the treatment with AlCl 3 solutions. These materials had ordered cylindrical pores, and their textual data depended on the amount of AlCl 3 and calcination temperature. Small amount of Al incorporation (Al/Zr = 0.49) leaded to a microporous material with a Brunauer-Emmett-Teller (BET) specific surface area of 314 m 2 /g and a pore size of 0.6 nm. Increasing the Al/Zr ratio resulted in mesoporous materials with higher BET specific surface area. The mesoporous Zr-P-Al material exhibited a BET specific surface area of 462 m 2 /g and a pore size of 2.9 nm after calcination at 773 K. 973 K calcination led to a BET specific surface area of 416 m 2 /g and a pore size of 2.7 nm. Even after calcination at 1073 K, a BET specific surface area of 227 m 2 /g and a pore size of 3.2 nm could still be observed. The pentacoordinated aluminium species seemed to be indispensable for the synthesis of mesoporous Zr-P-Al materials because of their effective reduction of the lattice contraction. NMR results showed that a hexacoordinated aluminium layer, a (HO) 2 P(O-Zr) 2 layer and a Zr(OH) layer combined with each other were formed after AlCl 3 treatment. Upon calcination, the layers of Al 2 O 3 , (Zr-O) 2 PO 2 and ZrO 2 formed the walls of the mesoporous Zr-P-Al materials. This unique structure was suggested to be responsible for the high thermal stability (up to 1073 K).
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