A simple and low cost method for the synthesis of metallic cobalt nanoparticles without further reduction as an effective catalyst for Fischer–Tropsch Synthesis

In this research work, a simple, one-step and environmentally friendly method is reported for synthesizing metallic Co nanoparticles (NPs) and its application in Fischer–Tropsch Synthesis. In this attractive method, metallic CoNPs decorated on the alumina surface are prepared by auto-reduction of cobalt (II) formate dihydrate at 380 °C for 4 h under high-pure nitrogen atmosphere. During the thermal decomposition process, hydrogen and carbon monoxide gases, which are reducing agents, are released. The decomposed samples were directly used in the reaction without typical hydrogen pretreatment. For comparison, the Co/γ-Al2O3 catalyst was also prepared by the traditional impregnation method, which includes the calcination and reduction steps. Different characterization techniques including TGA-DTA, XRD, FESEM, EDX mapping and BET were carried out to investigate the structural and textural properties of samples. CO conversion of the auto-reduced Co/γ-Al2O3 catalyst was almost twofold of the reduced catalyst by H2. The characterization data indicated that auto-reduction method leads to better dispersion and smaller CoNPs production than those prepared by H2 reduction pretreatment. Therefore, the active sites for the reaction increased, leading to an increase in CO conversion. The results suggested that the catalyst reduction under H2 stream is unnecessary.