Adsorption properties of α-type layered and pillared zirconium phosphite phosphonates with high specific surface areas and porosities

Abstract

Single-phase mixed zirconium phosphite phosphonates with layered and pillared structures were prepared by direct reaction of a zirconyl salt and phosphorous acid with phenylphosphonic or p-xylenediphosphonic acid, respectively. Materials with different chemical compositions were prepared by changing the phosphorous acid/phosphonic acid molar ratio in the mother solution between 1 and 4. The compounds were characterised by XRPD, ³¹P MAS NMR, SEM, and FTIR analyses. The adsorption/desorption properties toward nitrogen and hydrogen at 77 K and the dichloromethane (DCM) uptake from the vapor phase at 30 °C were studied. All materials exhibited a Specific Surface Area (SSA) of ≥ 200 m² g⁻¹, due to the contribution of micro-, meso- and macropores. The estimated micropore volume, V_micro, increased with increasing SSA and affected the hydrogen uptake that reached 1.43 mmol g⁻¹ at 77 K with the zirconium phosphite phenylphosphonate compound having the highest V_micro value. The DCM uptake reached 1300 mg g⁻¹ with the zirconium phosphite p-xylenediphosphonate having the highest macroporosity. The zirconium phosphite phenylphosphonate in the gel form was proved to disperse well in a PLA matrix, even at high filler loadings, affecting its physico-chemical properties.