In Situ Comparison of Ionothermal Kinetics Under Microwave And Conventional Heating

We have used in situ energy dispersive synchrotron X-ray diffraction to study the crystallization of aluminum phosphate frameworks under ionothermal conditions with conventional and microwave heating. The reaction is shown to follow slightly different routes depending on the type of heating used and a kinetic analysis shows that the rate constant is 10 times higher under microwave heating (1.4 compared to 0.14 min(-1)). The conventionally heated reaction is shown to proceed by a transformation of SIZ-3 to SIZ-4 via an intermediate, while the microwave-heated reaction forms SIZ-4 directly. The kinetic analysis is used to rationalize the differences in reaction rate and the findings are supported by SEM images of the crystal morphologies which result from the two heating methods.