Enhanced Fe2O3/Al2O3 Oxygen Carriers for Chemical Looping Steam Reforming of Methane with Different Mg Ratios

Synthesis and characterization of micro-/nano-α-Fe2O3 for photocatalytic dye degradation

Photocatalytic activity using micro-/nano-α-Fe2O3 on a large scale was carried out using a sol-gel autocombustion method. A degradation time of 60 min was noted for 50 mg of the catalyst. Post characterization, this catalyst system showed a degradation of about 53% (rate = 2.60 × 10-3 min-1) and 17% (rate = 1.38 × 10-2 min-1) under sunlight and up to 45% (rate = 1.13 × 10-3 min-1) and 7% (rate = 1.20 × 10-2 min-1) under a 400 W UV lamp for rhodamine 6G (R6G) and crystal violet (CV), respectively. Sunlight has a broad spectrum of light; it greatly accelerates the degradation process and creates ideal conditions for the reaction to occur. The rate of photocatalytic dye degradation of α-Fe2O3 without Fenton's reagent was found to be 7.84 × 10-3 min-1 in the presence of external air provided (in the photocatalytic setup) through a bubbler and 3.23 × 10-3 min-1 in the absence of the bubbler.

Pressure-Induced Enhancement in Chemical Looping Reforming of CH4: A Thermodynamic Analysis with Fe-Based Oxygen Carriers

Chemical looping reforming of methane (CLRM) with Fe-based oxygen carriers is widely acknowledged as an environmentally friendly and cost-effective approach for syngas production, however, sintering-caused deactivate of oxygen carriers at elevated temperatures of above 900 °C is a longstanding issue restricting the development of CLRM. Here, in order to reduce the reaction temperature without compromising the chemical-looping CH4 conversion efficiency, we proposed a novel operation scheme of CLRM by manipulating the reaction pressure to shift the equilibrium of CH4 partial oxidation towards the forward direction based on the Le Chatelier's principle. The results from thermodynamic simulations showed that, at a fixed reaction temperature, the reduction in pressure led to the increase in CH4 conversion, H2 and CO selectivity, as well as carbon deposition rate of all investigated oxygen carriers. The pressure-negative CLRM with Fe3O4, Fe2O3 and MgFe2O4 could reduce the reaction temperature to below 700 °C on the premise of a satisfactory CLRM performance. In a comprehensive consideration of the CLRM performance, energy consumption, and CH4 requirement, NiFe2O4 was the Fe-based OCs best available for pressure-negative CLRM, especially for an excellent syngas yield of 23.08 mmol/gOC. This study offered a new strategy to address sintering-caused deactivation of materials in chemical looping from the reaction thermodynamics point of view.