Effect of amount of additional water during ionothermal synthesis process on physicochemical properties of vanadium phosphate catalyst material

In order to explore the effect of amount of additional water on physicochemical properties of vanadium phosphate (VPO) materials prepared in a Deep Eutectic Mixture (DES), various supernumerary amount of water (H2O: DES = 0, 0.13, 0.26, 0.39, 0.52, mass ratio) was added during synthesis. The result showed that adding appropriate quantity of water in preparation process was benefit to forming pore space framework and obtaining higher BET surface area, however, excessive quantities of water would destroy aperturestructure, seriously resulting in atresia. In addition, as the accessorial water content in a DES augmented, crystallite size of VPO materials increased and phase of that changed from amorphous to crystalline state. More than that crystalline phase types also altered. Further, the morphology of products varied from amorphous blocks to nano-particles and then to nano-sheets, finally to cuboids. What's more, VPO catalysts corresponded to reaction conversions were pretty much the same, but reaction selectivity existed a great difference under the same reaction condition. It was obvious that water played an important role in ionothermal synthesis, which may inspire us to regulate the morphology, pore space framework, crystallite size and catalytic performance of VPO materials by controlling moisture content of DES in the future.

Automated summary

Adding an appropriate amount of water is beneficial for forming pore structure in VPO materials prepared in DES, while excessive water can destroy the pore structure and morphology. The crystallite size of VPO materials increases with the additional water content, and the phase changes from amorphous to crystalline.