The impact of synthesis method on the properties and CO2 sorption capacity of UiO-66(Ce)

Abstract

A series of cerium-based UiO-66 was obtained via hydrothermal and sonochemical methods, using the same quantities of reagents (cerium ammonium nitrate (CAN), terephthalic acid (H2BDC)) and solvents) in each synthesis. The impact of synthesis method and metal to linker ratio on the structural and textural properties of obtained UiO-66(Ce), as well as their composition in terms of Ce4+/Ce3+ ratio, structure defects resulting from missing linker, and CO2 adsorption capacity was discussed. By using typical characterization techniques and methods, such as XRD, N2 and CO2 sorption, TGA, XPS, and SEM, it was shown that the agitation of reacting mixture during synthesis (caused by stirring or ultrasounds) allows to obtain structures that have more developed surfaces and fewer linker defects than when MOF was obtained in static conditions. The specific surface area was found to be of minor importance in the context of CO2 adsorption than the contribution of Ce3+ä ions that were associated with the concentration of linker defects.