On sorption and thermal properties of the zirconium phosphate fluoride [(H₂en)_0.5][Zr₂(PO₄)₂(HPO₄)F]H₂O

Abstract

The thermal behavior of the title compound (ZrPO-1) has been investigated using conventional thermal analysis techniques as well as coupled TG–MS, TPD and XRD. Owing to the channel structure, ZrPO-1 reveals zeolitic properties in the dehydration range (up to 200 °C) whereas the removal of the organic template above 400 °C results in a complete loss of the sorptive activity. Water may be substituted by ammonia which is then released in two well separated steps atca. 150 and 300 °C, respectively. The stronger differentiation of the water sites by the ammonia sorption allows attribution of the desorption ranges to the channels and the cavities, respectively, that exist in the structure. X-Ray characterization of the product after removal of the template above 400 °C did not yield any known zirconium phosphate or oxide. EXAFS measurements show that no significant changes occur in the short-range order around zirconium neither by dehydration nor by annealing. However, the environment of zirconium becomes increasingly disordered at higher temperatures.

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