CATALYST DESIGN OF 2-DIMENSIONAL ZIRCONIUM PHOSPHONATES

Zirconium phosphates or phosphonates, whose compounds have the general formula Zr(O3PR)2, can be obtained in crystalline forms with various layered structures. The preparation and characterization of two-dimensional zirconium phosphonate derivatives have been investigated. Two composite zirconium phosphonates in a single-crystal phase have also been investigated and characterized by XRD, C-13 and P-31 MAS NMR. These compounds are lamellar structures comprising zirconium phosphates or organophosphonates. Each layer comprising of planes of zirconium bridged through phosphonate groups that alternate above and below the Zr atom planes, oriented away from the basal surfaces in a bilayered fashion in the interlayer region. The catalytic performance over zirconium phosphonates has been evaluated by esterification of acetic acid. When the composite zirconium phosphonate includes an acidic function and a hydrophobic function in the single-crystal phase, the catalytic activity was higher than that of single-acidic-function zirconium phosphonate. The composite materials become accessible to any reactant molecule, and their hydrophobicity improves.