Catalytic behavior of potassium containing compounds for diesel soot combustion

Alkali doped oxides were synthesized and tested as catalysts for diesel soot combustion using a combinatorial method. It has been found that potassium shows better promotion of the catalytic activity than other alkali elements, and most of the potassium-rich oxides showed similar catalytic behaviors when catalysts and soot were mixed in a slurry. The influence of different mixing methods, including loose contact, tight contact and slurry (wet) mixing with different soot suspensions, on the catalytic behavior of some transition metal oxides, alkali metal carbonates and potassium-containing oxides were studied through thermogravimetry and XRD. The high activity of potassium-containing catalysts is found to be due to the intimate contact between soot and potassium cations caused by polar solvents. Potassium containing catalysts degraded after repeated thermal cycles due to the loss of potassium. It was also found that the addition of transition elements can inhibit the loss of potassium.     

Factors determining gasoline soot abatement over CeO2–ZrO2-MnOx catalysts under low oxygen concentration condition

Soot oxidation under a low concentration O₂ (0.5% O₂/N₂) was investigated using CeO₂–ZrO₂-MnO_x mixed oxides with varied amounts of MnO_x, in order to gain low temperature catalytic activity and find out the main factors affecting the soot oxidation. The catalytic activity was remarkably improved over these catalysts compared to that of non-catalyst in such a low concentration of O₂. In particular, CeO₂–ZrO₂-MnO_x with 10% MnO_x doping (M10-CZ) showed the highest catalytic activity with its T₅₀ values of 340 °C under tight contact condition. The results of N₂ adsorption-desorption and X-ray diffraction (XRD) indicated that the textural and structural properties were not positive correlation with soot oxidation, are not the main factors affecting the catalytic activity of CeO₂–ZrO₂ and CeO₂–ZrO₂-MnO_x catalysts. The results of oxygen storage capacity (OSC), hydrogen-temperature programmed reduction (H₂-TPR), O₂ temperature program desorption (O₂-TPD), UV Raman spectroscopy (UV Raman) and X-ray photoelectron spectroscopy (XPS) testified that redox ability, oxygen storage capacity, oxygen desorption capacity at low temperature and surface active oxygen species are more important for soot oxidation. The enhancements of the catalytic behavior after MnO_x addition can be due to the improving of the adsorbed, activation and mobility of reactive oxygen species. In this work, these factors about generation and movement of reactive oxygen species are crucial for soot oxidation in a low oxygen concentration condition.     

Experimental Study on the Performance and Emission of Chinese Small Agricultural Diesel Engine Fuelled with Methanol/Biodiesel/DTBP

中国小型农用柴油机燃用甲醇/生物柴油/DTBP的性能与排放试验研究

李瑞娜^1,2,3,张亮¹,朱佳隆¹,华琰¹,王忠¹

（1、江苏大学汽车与交通工程学院,江苏 镇江212013;

2. 汽车测控与安全四川省重点实验室,成都 610039;

3. 四川省新能源汽车智能控制与仿真测试技术工程研究中心,成都 610039）

摘 要：

为了研究甲醇和生物柴油对小型农用柴油机性能、经济性和排放的影响,分析了甲醇和生物柴油的物理化学性质（十六烷值、低热值、粘度等）。甲醇和生物柴油的性质在一定程度上表现出良好的互补性。当在生物柴油中加入大量甲醇时,甲醇/生物柴油混合物的十六烷值将大幅度降低。由于混合燃料的十六烷值对柴油机的燃烧过程有很大影响,在对甲醇/生物柴油的混合比进行试验后,分别用5%（BM5）、10%（BM10）、15%（BM15）的甲醇添加到生物柴油中制备了混合燃料。选择过氧化二叔丁基（DTBP）作为十六烷值改进剂添加到甲醇/生物柴油混合物中。在BM15中分别加入0.25%、0.50%、0.75%的DTBP。在186FA柴油机上进行台架试验,研究了甲醇和DTBP对发动机性能和排放的影响。结果表明,在额定工况下,与生物柴油相比,BM5、BM10和BM15的NOx浓度分别降低了5.02%、33.85%和21.24%,烟度分别降低了5.56%、22.22%和55.56%,发动机功率降低了5.77%、14.23%和25.41%,比能耗提高了3.31%,7.78%和6.37%。在甲醇/生物柴油中添加DTBP可以将发动机功率恢复到柴油的水平。DTBP对降低比能耗、降低NOx、CO、HC浓度有较好的效果,但排气烟度略有增加。

关键词：甲醇、生物柴油、农用柴油机、燃烧、性能、排放