Two-dimensional composite zirconium phosphonates: preparation and catalytic activities

Composite zirconium phosphonates in single crystal phase have been investig ated and characterized by XRD, C-13-, and P-31-MASNMR. These compounds are lamellar structures comprising zirconium organophosphonates. Each layer con sists of planes of zirconium bridged through phosphonate groups that altern ate above and below the Zr atom planes, oriented away from the basal surfac es in a bilayered fashion in the interlayer region. The catalytic performan ce over zirconium phosphonates is evaluated by esterification of acetic aci d. When the composite zirconium phosphonate includes an acidic function and with a hydrophobic function in single crystal phase, the catalytic activit y showed a higher activity than that of sulfonic acid catalyst. The composi te zirconium phosphonates become accessible to any reactant molecule and im prove hydrophobicity around acidic sites. (C) 1999 Elsevier Science B.V. Al l rights reserved.