Synthesis of heteropolyoxometalate-pillared Mg/Al, Mg/Ga, and Zn/Al layered double hydroxides via LDH-hydroxide precursors

We report the synthesis of acidic (Zn/Al-POM) and basic (Mg/Al-POM and Mg/Ga-POM) materials by a general route previously demonstrated only for basic LDH materials. In each case, H2W12O406- or PW11O397- pillared materials with significant BET surface areas were obtained. Stringent control over the M2+:M3+ ratio in the layers of the POM-pillared products was not possible, and loss of M2+ was found to be the most severe for the Mg/Ga and Zn/Al materials. Infrared analysis indicated that complete exchange of adipate anions in the precursor material by POM anions was achieved except for the Zn/Al analogues. Removal of the residual adipate anions after washing the product with a dilute base solution was possible, but a concomitant decrease in surface area could not be avoided.