Title : Synthesis and characterization of bimetallic Ce Zr based UiO-66 and MOF-808
Abstract:
Metal Organic Frameworks (MOFs) are relatively new group of porous, crystalline materials with three - dimensional structure. They are composed of metallic cluster connected with organic ligand. The UiO-66 and MOF-808 (both containing Zr) have excellent chemical, thermal and mechanical stability but Zr4+ cations are weak Lewis acids so exchanging part of Zr cations with Ce could improve their adsorptive and catalytic properties. Cerium characterizes with very good redox properties; hence introduction of those cations to UiO-66 or MOF-808 should enhance CO2 adsorption owing to Ce3+ presence.
The aim of our work is the synthesis of bimetallic Ce/Zr-MOFs with UiO-66 and MOF-808 topology. We investigated the influence of synthesis parameters on their properties. Ce/Zr-UiO-66 and Ce/Zr-MOF-808 were obtained via solvothermal method in a Teflon-lined autoclave. Organic linker (benzene-1,3,5-tricarboxylic acid or benzene-1,4- dicarboxylic acid) and metals precursors (ZrO(NO3)2 ? XH2O and (NH4)2Ce(NO3)6) were dissolve in N,N- dimethyloforamide (DMF) and then kept at 120 °C for 0.5, 24 and 72 h. After washing with DMF and filtering off, the DMF was exchanged with chloroform. Obtained materials were dried at 120 °C for 12 h.
The structure, composition, textural properties and thermal stability of Ce/Zr-UiO-66 and Ce/Zr-MOF-808 were determined using XRD, XPS, IR, N2 sorption, SEM and TGA. The CO2 sorption capacity of these materials was also determined.
