排序方式: 共有17条查询结果,搜索用时 54 毫秒
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以醋酸铜、醋酸锰、醋酸钴为主要原料,采用溶胶凝胶法制备载体,浸渍后得到用于氧化羰基化合成碳酸二苯酯(DPC)的负载型催化剂,通过XRD、TEM、EDS、XPS等仪器对催化剂进行表征,并进行催化活性评价。结果表明:载体在负载前后形成Co2MnO4晶相结构,减少了助剂流失;颗粒平均大小在40~50 nm之间;+3价的锰元素使得该晶相结构产生了晶格缺陷,促进了气相氧的吸附,增强了载体传递电子进行氧化还原的能力,有利于活性成分的再生,提高了催化活性。通过合成实验,DPC收率达到30%。 相似文献
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利用高温固相反应法制备高温质子导体BaZr0.45Ce0.45Gd0.1O3-δ.采用X射线衍射仪、扫描电子显微镜和交流阻抗谱法对不同烧结温度试样的相组成、微观形貌和导电性能进行表征,并测试试样在沸水和CO2气氛中的化学稳定性.结果表明1
600 ℃烧结的试样为纯相且致密;此温度下制备的试样具有最高的电导率,800
℃时其电导率达到0.82×10-2 S/cm,电导活化能为0.74 eV;样品对CO2表现出良好的化学稳定性,而在沸水中其稳定性稍差. 相似文献
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Effect of doping cerium in the support on the catalytic activity and side product of the reaction in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) over the catalyst Pd-Co/Cu-Co-Mn mixed oxides was studied. The specific surface areas, crystal phase, valency, and content of the element on the surface of the catalysts were determined, and the products were detected by gas chromatograph/mass spectrometry (GC-MS). It is found that the catalyst without Ce shows higher activity than that with Ce, and the yields of DPC for the two catalysts can reach 30% and 23%, respectively. However, doping cerium can prevent the formation of 2-hydroxyphenyl benzoate and p-bromophenyl phenyl carbonate. 相似文献
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采用高温固相法制备了质子-电子混合导体SrCe_0.95Tm_0.05O_(3-δ)材料.使用X射线衍射仪、扫描电子显微镜分别对1600 ℃烧结10 h后的混合导体晶型、微观形貌进行了研究.应用交流阻抗谱法测试了空气、氢气、氩气3种不同气氛中混合导体的电导率.结果表明:所制备的混合导体为单相致密斜方晶钙钛结构,气氛对晶粒电导率影响不大,而对晶界和总电导率有明显影响.800 ℃空气、氢气和氩气气氛中总电导率分别为4.65×10~(-3),3.41×10~(-3),1.87×10~(-3) S·cm~(-1). 相似文献
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以Hopcalite氧化物作为载体,浸渍后得到Pd-Co/Hopcalite混合氧化物负载型催化剂,用于氧化羰基化合成碳酸二苯酯(DPC)。通过扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对催化剂进行表征,结果表明:催化剂颗粒大小均匀,具有良好的孔结构;稳定晶相Cu Mn2O4、Co Mn2O4和Pd0.5Pd3O4的形成使反应前后催化剂表面活性组分Mn、Co的价态保持不变,有利于催化剂的重复使用;Pd0.5Pd3O4产生晶格缺陷,增加了晶格中的氧空位,可促进气相氧的吸附,加速整个催化循环,有利于活性组分再生,催化活性进一步提高。通过合成实验,DPC收率和选择性分别达到43.5%和99.6%。 相似文献
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BaCe0.45Zr0.45M0.1O3-δ (M=Y, In) and BaCe0.9Y0.1O3-δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Crystalline phase and microsa-ucture of the proton conductor before and after stability test were measured with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that all materials were quite stable in H2 atmosphere. In CO2 atmosphere, BaCe0.45Zr0.45M0.1O3-δ(M=Y, In) were relatively stable, while Bafe0.9Y0.1O3-δ decomposed. In boiling water, BaCe0.9Y0.1O3-δ was quickly decomposed into Ba(OH)2 and corresponding oxide. BaCe0.45Zr0.45M0.1O3-δ slightly reacted with boiling water and some amorphous phases were formed. However, BaCe0.45Zr0.45In0.1O3-δ was observed to exhibit better stability than BaCe0.45Zr0.45Y0.1O3-δ in water. The experimental results were interpreted in terms of thermodynamic data and tolerance factor. 相似文献