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LaSrBO4(B=Cu、Ni、 Co、 Fe、 Mn、 Cr ) was studied with respect to their preparation, characteristics and catalytic oxidation activity by means of XRD, XPS, electric conductivity and activity evaluation. Results showed that the calcination temperature has great influence on the formation of the phases of such samples, and was associated with the radius of B ion. The greater the B ion radius, the higher the calcination temperature required for the formation of the phases. It was also found that the activity and the relative content of adsorptive oxygen and lattice oxygen on the sample surf are, the activation energy of electron conduction and the CO oxidation activity may vary with different B ions, and demonstrate a dual-peak pattern with the increase in the number of 3d electrons of the B ion. 相似文献
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超声水解法制备的纳米二氧化钛光催化性能的研究 总被引:16,自引:0,他引:16
锐钛矿型纳米二氧化钛因其优良的光催化性能在环境保护中得到广泛应用,以TiCl4为钛源,水解过程中施加超声辐照,室温条件下制得了5~6nm锐钛型TiO2.考察了施加超声、煅烧温度及粒径尺寸对甲酸降解率的影响.结果表明,催化剂制备过程中施加超声影响对催化剂的光催化性能影响显著:甲酸的降解率由68.57%提高到97.13%.用超声水解法制备的纳米二氧化钛能够在较宽的煅烧温度范围里(450~650℃)保持较高的光催化活性.随粒径的减小催化剂活性提高。当粒径小于20nm时,显示量子尺寸效应。 相似文献
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助剂钾添加方式对多乙苯脱氢催化性能的影响 总被引:1,自引:0,他引:1
The catalyst for dehydrogenation of diethylbenzene(DEB) to divinylbenzene(DVB) was studied. Potassium-promoted iron oxide catalyst was mainly used for ethylbenzene dehydrogenation. If potassium alkli or salt was used directly as promoter, it was noted that the loss of potassium component from the surface of the catalysts pellet result in deactivation. When potassium promoter was added as kaliophilite(KAlSiO4). It was shown that the latter way of adding potassium promoter not only keeps the depression of carbonaceous deposits but also controls the loss of potassium component(the value of loss of potassium component has been reduced three times) , thus making the catalyst having a higher dehydrogention activity. 相似文献
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含氧气氛下预硫化钙钛矿LaCoO3上的CO还原SO2反应 总被引:8,自引:0,他引:8
对钙钛矿LaCoO3在含氧气氛下的预硫化过程进行了研究.结果表明,在一定含氧气氛下硫化后的LaCoO3催化剂,用于含氧气氛下CO还原SO2反应具有很高的活性.XRD物相分析结果表明,硫化后的LaCoO3仍保持钙钛矿物相结构,但同时出现新的硫化物La2O2S和氧化物Co3O4物相.通过对硫化前后的催化剂进行O2-TPD和SO2-TPD分析,认为CO还原SO2反应机理可能是在一定的温度下,在钙钛矿LaCoO3上发生CO氧化燃烧反应,在硫化物La2O2S上发生CO还原SO2反应,两者相互促进. 相似文献
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掺杂纳米TiO2光催化性能的研究 总被引:64,自引:2,他引:64
利用浸渍法分别制备了Cr、Mn、Fe、Co、Ni、Cu六种过渡金属离子掺杂改性的二氧化钛光催化剂,以乙酸水溶液的光催化氧化反应和二氧化碳还原反应为探针,评价了掺杂催化剂的光催化性能.借助光电子能谱(XPS)、X射线衍射分析(XRD)等手段对掺杂催化剂进行了表征.研究结果表明,经过渡金属离子掺杂后,光催化性能均有不同程度的改善,改善程度按Cr、Co、Ni、Fe、Mn、Cu递增.掺杂后催化剂表面吸附氧的活泼性、金属离子的价态及得电子能力上的差异决定了不同离子掺杂纳米二氧化钛光催化性能的差异. 相似文献
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教学与“问题”及“问题解决”有着深厚的渊源,早在苏格拉底采用的“谈话法”中就可观察到教学的问题性现象.随着心理学的逐渐发展“问题”及“问题解决”的理论逐渐丰富起来.问题情境它是基于问题解决教学的环节之一,由于数学学科的特点本文提出的问题情境概念更偏重于它的问题性. 相似文献
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