Shen Meiqing

Dynamic Oxygen Storage Capacity Measurements on Ceria-Based Material

Abstract Dynamic oxygen storage and release capability (OSC) measurement apparatus was designed to evaluate the OSC performance of ceria-based oxygen storage material. The optimum measurement condition was at a frequency of 0. 1 Hz with the inlet gas-flow sequence CO (5S)→O2(5S)→CO→O2 and a flow rate of 300 ml·min −1 . Under this condition, similar regular square wave in the inlet and outlet of the reactor was obtained to guarantee the reliability of the dynamic OSC results. The dynamic OSC performance of the CeO 2 and Ce o . 67 Zr 0.33 O 2 mixed oxide prepared using the citric sol-gel method was studied at the optimum measurement condition with focus on both quantitative and qualitative analyses. The results reveal distinctly that Ce 0.67 Zr 0.33 O 2 had better dynamic OSC performance because of its higher oxygen migration rate than CeO 2 . Under dynamic conditions, two CO 2 production peaks occurred corresponding to the CO pulse and the O 2 pulse, respectively, during the entire cycle. The intensity and ratio between the two CO 2 productions were highly influenced by temperature and frequency indicating complex surface phenomena during the oxygen storage/release process. As a result, this set-up can be applied to the evaluation of ceria-based material on the OSC performance.

Influence of Supports on Catalytic Performance and Carbon Deposition of Palladium Catalyst for Methane Partial Oxidation

Abstract The catalytic performance of methane partial oxidation was investigated on Pd/CeO 2 -ZrO 2 and Pd/α-Al 2 O 3 catalysts. The catalysts were characterized by XRD, Raman spectra, and TG-DTA techniques. The results show that CeO 2 -ZrO 2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al 2 O 3. TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite, which is the main reason for the deactivation of catalysts after a 24-hour reaction. Moreover, CeO 2 -ZrO 2 had positive effect on inhibiting carbon deposition.

Complete Oxidation of Ethanol and Thermal Stability of Ceria-Based Materials Modified by Doping Cu

The complete oxidation of ethanol (COE) was studied over Cu0.1Ce0.9Ox and Cu0.1Ce0.6Zr0.3Ox catalysts prepared by the sol-gel method. Samples were characterized by X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) adsorption, Raman spectroscopy, hydrogen temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). Results show that for fresh samples, the activity of COE is found to be superior over Cu0.1Ce0.9Ox than over Cu0.1Ce0.6Zr0.3Ox whereas this is reversed for aged samples. The thermal stability improves after the introduction of Zr. Furthermore, the relationship between the active species and the activity for COE was investigated.