(319f) Solution Combustion Synthesis of Iron-Based Alumina Nanocomposites for Microwave-Assisted Thermocatalytic Dehydrogenation of Fossil Fuels

Iron-based alumina nanocomposites are promising materials for microwave-assisted thermocatalytic dehydrogenation of fossil fuels, which has been proposed for the production of hydrogen with no CO₂ emissions. These powders both absorb microwave radiation and catalyze the dehydrogenation. Solution combustion synthesis (SCS) is an attractive technique for the fabrication of these materials because it has been used for synthesis of many nanoscale oxides. However, SCS can be carried out using different organic fuels and different heating equipment, and it is important to determine which fuel and heating mode generate materials with the best properties for dehydrogenation, such as maximized specific surface area.

In the present work, the iron-based alumina nanocomposites were obtained by SCS using two different fuels (citric acid and glycine) and two different heating modes (a hotplate and a muffle furnace). The precursors/oxidizers were iron nitrate and aluminum nitrate. They were mixed with the fuel according to stoichiometry and dissolved in water. Heating the solution resulted in combustion synthesis. The products were characterized by X-ray diffraction analysis, Brunauer-Emmett-Teller surface area analysis, laser diffraction particle size analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS).

XRD analysis revealed phases of hercynite, with no significant effect of the heating mode. The fuel change slightly influences the XRD pattern: products obtained using citric acid have less-crystalline spectra. SEM-EDS of the products revealed flaky structures with increased concentrations of iron in several spots on the particle surface. The products obtained using citric acid as the fuel have a narrow particle size distribution as compared to those produced using glycine, independent of the heating mode. The specific surface area of iron-based alumina nanocomposites obtained by SCS was dramatically increased by using citric acid instead of glycine, and additionally by using a muffle furnace instead of a hotplate.

This material is based upon work supported by the Department of Energy under Award Number DE-FE0032086.