Investigation on NO reduction by CO and H2 over metal oxide catalysts Cu2M9CeOx

Composite metal oxide catalyst Cu₂M₉CeOx (M = Fe, Co, Ni) was prepared by citric acid complexation method for NOx reduction. Prepared catalysts activities were tested in a fixed bed reactor for NOx reduction by CO and H₂. The sequence of activity of the three catalysts for NOx reduction by CO is: Cu₂Co₉CeOx > Cu₂Fe₉CeOx > Cu₂Ni₉CeOx. The catalytic efficiency of Cu₂Co₉CeOx increased to 100% at 250 °C. For NO reduction by H₂, the sequence of activity follows: Cu₂Fe₉CeOx > Cu₂Co₉CeOx > Cu₂Ni₉CeOx. The catalytic activity of Cu₂Fe₉CeOx was ranged from 60% to 100% during 250–325 °C. Additionally, characterization was conducted to investigate the physical and chemical properties of Cu₂M₉CeOx catalysts. In-situ Fourier transform-infrared spectra was also used to study the mechanism of the reaction. The results indicated that Cu-□-Co synergistic oxygen vacancies in Cu₂Co₉CeOx and unstable CuFe₂O₄ (spinel) in Cu₂Fe₉CeOx promote NO reduction. The reasons of activities over different Cu₂M₉CeOx catalysts were then carefully explored.     

应用于微波场的温度测量方法的研究进展

在微波加热过程中,由于温度的准确性会直接影响到化学反应速率与制备样品的性能,所以微波场中温度的准确测量具有十分重要的意义。综述了微波场中传统的温度测量方法包括热电偶测温、光纤测温和红外测温方式在微波场中应用时的局限性。鉴于传统测温手段的局限性,一种新型的温度测量方式-有机金属框架材料(MOFs)温度计因具有高度的可调性以及纳米级的MOFs颗粒能够实现微米级甚至亚微米级的温度测量而受到了广泛的关注,对近年来双发射MOFs温度计以及膜式温度计的研究成果进行了分析,并综述了优化MOFs温度计的方法,讨论了微波场测温技术未来的发展方向。     

Enhanced SO2 fluidized adsorption dynamic by hierarchically porous activated coke

Porous materials such as activated cokes have been widely utilized in the adsorption removal of atmospheric SO₂ emission. Pore configuration of coke is a key factor affecting its SO₂ rapid adsorption dynamics, which is critically important for fluidization adsorption craft. Herein, activated coke adsorbents with typically microporous structure and hierarchically porous structure were prepared by a catalytic physical activation method from Chinese large-reserve Zhundong coal, which were used as model adsorbents to investigate the effect of pore configuration on SO₂ fluidized adsorption dynamics. SO₂ fluidized-state adsorption experiments indicate that hierarchically porous coke has a more rapid initial adsorption dynamic than microporous type coke, and coke with 44.2% meso-/macropores volume shows the highest initial adsorption rate of 7.37 mg g⁻¹·min⁻¹. Additionally, the fitting of Weber-Morris model provides the dominate factors for SO₂ adsorption kinetics in each sub-process: SO₂ adsorption capacity of microporous-dominated adsorption stages account for 70%–80% of total, and when it comes close to adsorption saturation, the main dominant factor of kinetic becomes the ratio of meso-/macropores volume. This work is of significance for the application of SO₂ adsorption craft in fluidized bed and also provides insight into the role of hierarchically porous configuration in gas molecule rapid adsorption.     

I.r. studies on the acidity of dealuminated Y zeolite with different probe molecules

Dealuminated HY zeolites (D-HY), which are partly reexchanged by La ions (D-LaHY), show two i.r. bands at 3625 cm⁻¹ (high frequency) and 3550 cm⁻¹ (low frequency). In contrast to the findings in D-HY and nondealuminated La-exchanged Y zeolite (LaHY), the LF band of D-LaHY is considerably affected by the adsorption of butadiene, in connection with a strongly increased coking. Sorption experiments with pyridine and ammonia confirm the OH groups belonging to the LF band to be acidic and accessible even to pyridine. This can be further confirmed by an HD exchange reaction with C₆D₆ at room temperature.