Morphology‐Controllable Preparation of CeO₂ Materials for CO₂ Adsorption

Abstract

Three morphology controllable CeO 2 crystals were successfully synthesized via the thermal decomposition of CeCO 3 OH precursors, which was newly prepared on the basis of a simple and template-free hydrothermal reaction between CeCl 3 solution and a CO 2 -storage material (CO 2 SM). In the formation processes of three CeCO 3 OH precursors, the CO 2 SM could be newly used as raw material and structural director. Meanwhile, the results presented the wider pH values (5.24-8.35) for isoelectric point of CeCO 3 OH precursors. After the CeCO 3 OH precursors were isolated, the filtrate could be recycled to absorb CO 2 again and prepare CeCO 3 OH precursors with two special polymorphs. Three as-prepared CeO 2 crystals by annealing three CeCO 3 OH precursors at 500 8C for 4 h showed the maximum adsorption amounts of 23.5, 18.7 and 20.5 mg/g for 8% CO 2 /N 2 mixture. As a result, this work provided the wider pH values for isoelectric point of CeCO 3 OH precursors and a simple method for the preparation of CeO 2 crystals with a short time and CO 2 adsorption properties.

Novel Core–Shell (ε-MnO2/CeO2)@CeO2 Composite Catalyst with a Synergistic Effect for Efficient Formaldehyde Oxidation

“…No impurity peaks are observed, indicating that the precursors are composed of highly crystalline MnCO 3 and CeO 2 and no CeCO 3 OH is formed. In general, the hydrothermal reaction of Ce 3+ and CO 2 SM only produces CeCO 3 OH . However, MnCO 3 is preferentially formed because of the smaller ionic radius of Mn 2+ and the higher binding energy between Mn 2+ and the CO 3 2– from the CO 2 SM.…”

“…In general, the hydrothermal reaction of Ce 3+ and CO 2 SM only produces CeCO 3 OH. 41 However, MnCO 3 is preferentially formed because of the smaller ionic radius of Mn 2+ and the higher binding energy between Mn 2+ and the CO 3 2− from the CO 2 SM. CeO 2 is formed with the small amount of oxygen in the system.…”

“…53,54 The reactions of CO 2 SM with Mn 2+ and Ce 3+ produce MnCO 3 and Ce(OH)CO 3 , respectively. 14,41 Their hydrothermal reactions form the (MnCO 3 /CeO 2 )@CeO 2 composite, possibly due to the competition between the reactions of Mn 2+ and Ce 3+ with CO 2 SM. Mn 2+ reacts with CO 3 2− to produce MnCO 3 and Ce 3+ reacts with OH − to afford Ce(OH) 3 on the surface of the MnCO 3 crystal which is then auto-oxidized to form a CeO 2 shell.…”

“…Similarly, the CeCO 3 OH precursor was synthesized by the hydrothermal reaction of 1.5 g CO 2 SM in 50 mL of 0.03 mol L −1 Ce 3+ at 120 °C for 2 h and calcinated at 500 °C for 6 h in air to yield CeO 2 crystals. 41 2.3. Preparation of (ε-MnO 2 /CeO 2 )@CeO 2 .…”

“…The MnCO 3 precursor powder was calcinated at 280 °C for 6 h in air to afford ε-MnO 2 crystals (C-0). Similarly, the CeCO 3 OH precursor was synthesized by the hydrothermal reaction of 1.5 g CO 2 SM in 50 mL of 0.03 mol L –1 Ce 3+ at 120 °C for 2 h and calcinated at 500 °C for 6 h in air to yield CeO 2 crystals …”