The evaluation of properties of core-shell CuMgAl of layered double hydroxides and their potential for Guerbet reaction

Abstract

Diploma thesis is focused on so-called core-shell systems, solid-state materials used in heterogenous catalysis. In detail, core-shell SiO2 CuMgAl LDH (layered double hydroxide) based materials are studied. The materials are synthesized with various Cu/Mg molar ratio (0.05-0.50) while keeping (Cu+Mg)/Al molar ratio at a constant value of 2. Original core shell materials are treated in 0.25 M NaOH solution to partially dissolve SiO2 core (synthesis of hollow shell CuMgAl LDH materials). Prepared core shell SiO2 CuMgAl LHD and hollow shell CuMgAl LHD materials have been characterized with respect to their structural properties (XRD), morphology (SEM, TEM), composition (EDX) and textural properties (N2 adsorption). Finally, hollow shell materials are calcined at 450 °C for 4 hours resulting in the formation of CuMgAl mixed oxides used as catalysts in Guerbet reaction with ethanol. CuMgAl mixed oxides are additionally characterized for acid-base properties (TPD) and redox properties (TPR). Core shell and hollow shell materials are described in the introduction. In detail, their preparation and utilization are discussed. The main attention is focused on the process of removing the core from the core-shell material to obtain hollow shell materials. There, possibilities of their characterization are also discussed. Catalytic behavior of mixed oxides prepared from hollow shell CuMgAl LHD materials in Guerbet reaction with ethanol is also considered. The aim of this work is (i) to determine whether or not it is possible to prepare core shell materials with CuMgAl layered double hydroxides perpendicularly onto a nonporous silica core, (ii) to find if it is possible to remove silica core and leave the shell intact, (iii) to evaluate the benefits of hollow shell CuMgAl LDHs in contrast to classical CuMgAl LDHs, and (iv) to evaluate the potential of CuMgAl mixed oxides obtained by thermal treatment of hollow shell CuMgAl LDHs for Guerbet reaction.