低放热双组分聚氨酯加固材料的开发研究

以聚醚多元醇、多苯基多亚甲基多异氰酸酯、增塑剂、阻燃剂为主要原料,制备了煤岩加固用双组分聚氨酯材料。通过反应温度测试和万能材料试验机等手段研究A组分中的反应基团数量(羟值)和混合多元醇的组成对固化反应最高温度及固结体压缩强度的影响。结果表明,相同多元醇体系下最高反应温度与羟值线性相关,固结体压缩强度与最高反应温度正相关。使用平均官能度较高且平均分子量较高的聚醚多元醇Z为原料,同时减少增塑剂和液态阻燃剂总用量,可以获得最高温度较低但强度较高的聚氨酯加固材料,其性能接近矿用加固材料新标准的要求。     

Cerium based shells with palladium cores encapsulated:an efficient catalyst for carbon monoxide oxidation

Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD(X-ray diffraction) analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR(temperature programed reduction) results.Interestingly, introducing a small amount of zirconium(0.5 wt.%) exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.     

Improved sulfur-resistant ability on CO oxidation of Pd/Ce0.75Zr0.25O2 over Pd/CeO2-TiO2 and Pd/CeO2

The influence of sulfation on Pd/Ce0.75Zr0.25O2, Pd/Ce O2-Ti O2 and Pd/Ce O2 was investigated. Physical structure and chemical properties of different catalysts were characterized by N2 adsorption, X-ray diffraction(XRD), CO chemisorption, X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR) and X-ray fluorescence(XRF). After 10 h SO2 sulfation, it was found that the decrement on CO oxidation catalytic activity was limited on Pd/Ce0.75Zr0.25O2 compared to Pd/Ce O2-Ti O2 and Pd/Ce O2. It demonstrated that Pd/Ce0.75Zr0.25O2 was more sulfur resistant compared to the other two catalysts. After sulfur exposure, catalyst texture was not much influenced as shown by N2 adsorption and XRD, and surface Pd atoms were poisoned indicated by CO chemisorption results. Pd/Ce0.75Zr0.25O2 and Pd/Ce O2-Ti O2 exhibited less sulfur accumulation compared to Pd/Ce O2 in the sulfation process. Furthermore, XPS results clarified that surface sulfur amount, especially surface sulfates amount on the sulfated catalysts was more crucial for the deactivation in sulfur containing environment.