FORMATION OF AN INTERMEDIATE DURING THE HYDROTHERMAL SYNTHESIS OF ULM-5 STUDIED USING TIME-RESOLVED, IN-SITU X-RAY-POWDER DIFFRACTION

In situ energy dispersive X-ray diffraction studies on the hydrotherma l synthesis of the oxyfluorinated gallophosphate, ULM-5, show that whe n orthophosphoric acid is used as a starting material ULM-5 forms rapi dly after an initial induction period, whereas when phosphorus pentoxi de is used as a starting material a previously unobserved crystalline intermediate is formed, which subsequently reacts to form ULM-5; condi tions have been identified in which this intermediate is relatively lo ng lived and this has allowed the subsequent isolation of a pure sampl e of this intermediate.