Design of high-temperature shift using waste-derived synthesis gas: Thermodynamic approach and practical reaction optimization

Herein, we verify pre-reduction conditions and H₂O/CO ratio to increase activity in the HTS using Fe-Cr catalyst. It was determined that the optimal H₂O/CO ratio was 2.5 through the result of calculated thermodynamic equilibrium analysis and performed HTS reaction. In the Fe-Cr catalyst, HTS reaction was performed at 350 ∼ 550 °C to find the condition that Fe₂O₃ convert Fe₃O₄ without over-reduction after reduced using 2% H₂/N₂, 5% H₂/N₂, and reactant gas at various temperature (400, 500, and 600 °C). The lower the pre-reduction temperature, the higher CO conversion, but the effect of the pre-reduction gas was not significant. In addition, as a result of performing a stability test that reduced using reactant gas at 400, 500, and 600 °C, all of which maintained stability without deactivation even though had a large range of CO conversion for 50 h. Thus, we identify that the appropriate H₂O/CO ratio for HTS reaction using gas produced from waste gasification is judged to be 2.5. And during the reaction using Fe-Cr, the CO conversion showed high activity when pre-reduction temperature is 400 °C. In the case of the pre-reduction gas, the activity was insignificantly affecting the pre-reduction at 400 °C, thus it is considered appropriate to use reactant gas for practical use without the need to connect the pre-reduction gas separately.