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以硝酸钴和硝酸铈为前驱物,SBA-15为硬模板,利用双溶剂法制备了Co3O4-CeO2介孔复合氧化物,通过X-射线衍射、N2吸脱附测试、程序升温还原和透射电子显微镜等技术对活性组分及载体进行了表征,并且与浸渍法和共沉淀法所制备的催化剂进行了对比分析。结果表明,相比于浸渍法和共沉淀法,采用双溶剂法制备的介孔Co3O4-CeO2复合氧化物具有均匀的介孔结构、较小的颗粒尺寸、较大的比表面积和较高的活性组分分散度。此外,CO氧化脱除评价显示与常规的共沉淀法和浸渍法所制备的催化剂相比该介孔复合氧化物具有较高的反应活性和选择性,其高活性主要归因于较高的比表面积和活性组分的高分散度。 相似文献
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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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采用液相沉淀法制备了Co_3O_4催化剂,并对其进行还原-氧化预处理制得Co_3O_4-RO。通过XRD、N_2-physisorption、Raman、H_2-TPR、XPS和O_2-TPD等技术对催化剂进行表征,在连续流动微反应装置上考察了催化剂催化分解N_2O性能。结果表明,经过还原-氧化预处理,与Co_3O_4催化剂相比,Co_3O_4-RO结晶度变差,晶粒粒径减小,尤其是尖晶石结构重构过程削弱了Co-O键,增强了催化剂表面的氧物种脱附能力,降低了催化分解N_2O反应的活化能,因而显著提高了催化剂的催化活性。同时,Co_3O_4-RO对原料气中的O_22%(体积分数)和H_2O 2. 3%(体积分数)表现出较强的耐受性。 相似文献
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纳米粒子因其独特的物理化学特性成为近年来材料科学领域的研究热点 .制备方法是获得性能优越材料的关键 .Co3 O4 具有正常的尖晶石结构 ,Co2 占据八面体位置 ,在空气中低于 80 0℃时十分稳定 ,是优良的催化剂材料 [1,2 ] ,采用燃烧方法可通过控制反应条件在不发生沉淀的情况下获得化学组成均匀的复合氧化物粉体[4~ 7] .本文利用聚合物燃烧方法探索制备粒径均匀、分散性好的立方 Co3 O4 纳米粒子 .选择聚乙烯醇 ( PVA)的原因是其分子内包含大量的羟基极性基团 ,能与金属离子尤其是过渡金属离子形成良好的化学键 ,促使金属离子在 PVA… 相似文献
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研究了氧化铜的加入对锆铈复合氧化物的结构与性能的影响 ,发现氧化铜的加入可降低氧化铈的还原温度 ,稳定复合氧化物的立方结构 ,提高对CO氧化的催化活性。增加铈含量能提高催化剂的活性 ,而硫酸盐等可使催化剂的活性降低。掺铜锆铈复合氧化物催化剂的活性几乎不受高温灼烧的影响 ,是一种具有较高热稳定性的催化剂。 相似文献
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通过水热处理Co(NO3)2与(NH4)2S2O8合成了CoOOH多面体, 再经高温煅烧得到具有介孔结构的Co3O4多面体; 利用扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线衍射(XRD)和N2吸附\|脱附实验等手段对其结构和组成进行了表征; 研究了反应时间、 反应温度及(NH4)2S2O8浓度等因素对CoOOH多面体形貌的影响, 分析了CoOOH多面体的形成机理. 性能测试结果表明, 该介孔Co3O4多面体具有良好的葡萄糖电化学检测活性, 检测线性范围为0.05~1.8 mmol/L, 响应灵敏度为148 μA·cm-2·mmol·L-1, 检出限为1 μmol/L. 相似文献
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采用简单的自发氧化还原法合成了Co3O4/CeO2纳米复合材料,采用透射电子显微镜(TEM)\,X射线衍射(XRD)及X射线光电子能谱(XPS)等分析手段对样品进行了表征,并探究了反应参数对其催化CO氧化反应活性的影响.结果表明,Co/Ce摩尔比、pH值、反应温度和煅烧温度均显著影响Co3O4/CeO2纳米复合材料的催化性能;性能最优的样品用于催化CO氧化反应在140℃时即可实现100%的转化率,并且在循环测试中其催化活性保持不变,显示出良好的稳定性. 相似文献
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超微粒CO3O4的合成与表征 总被引:14,自引:0,他引:14
本文用胶溶法合成了纳米级超微粒Co_3O_4,初步探讨了合成Co_3O_4超微粒的最佳实验条件,对产品的结构性能测试表明,所得超微粒子Co_3O_4粒度均匀,平均粒度为4.0nm.200℃热处理时,产品为无定形,在许多有机溶剂中具有良好的分散性和透明性;400℃热处理得到立方Co_3O_4纳米晶体,平均粒度为6.0nm,热稳定性好。 相似文献
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铈掺杂对Co_3O_4/微孔-介孔分子筛催化剂催化性能的影响 总被引:1,自引:0,他引:1
采用水热法制备了微孔-介孔分子筛,并以Ce掺杂改性后制备了Co3O4/Ce-微孔-介孔分子筛催化剂,考察了Ce掺杂微孔-介孔分子筛催化剂对苯催化完全氧化性能的影响,并采用BET,XRD,TPR等技术对催化剂进行了表征。研究结果表明:Ce的加入有利于提高MSZ-B催化剂的催化活性。XRD分析显示Ce的加入不会阻塞Co3O4在微孔-介孔分子筛孔道内的分布;TPR分析表明:Ce的加入提高了MSZ-B催化剂的可还原性能,催化剂的可还原性能是影响催化活性的主要因素;另外,介孔的存在不利于Ce改性Co3O4/ZSM-5微孔分子筛催化剂活性的提高。 相似文献
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FANG De-ren REN Wan-zhong LIU Zhong-min XU Xiu-feng ZHANG Hui-min LIAO Wei-ping 《高等学校化学研究》2010,26(1):105-109
A series of mesoporous Cu-Mn-Al2O3(CMA) materials was synthesized at moderate temperature and their structures were characterized by XRD, N2 physical adsorption and TPR techniques. It was found that using metal complex ion[Cu(NH3) 42+-Mn(NH3)62+] as raw materials is easier to form good-structure mesoporous Cu-Mn-Al2O3 materials than using its nitrate salt [Cu(NO3)2-Mn(NO3)2]. The TPR tests results indicate that CuO and MnOx were homogeneously dispersed in the mesoporous materials. Their catalytic application to preferential catalytic oxidation of CO in a hydrogen-rich stream was studied. The activity varies in the order of CMA(1:1, molar ratio) CMA(1:2)CMA(2:1)CMA(CP)CMA(1:0)≈CMA(0:1). The CMA(1:0) and CMA(0:1) have lower activity compared to other samples, implying that there existed coordination effect between Cu-Mn in the samples. The selectivity varied in the order of CMA(0:1)≥CMA(1:2)CMA(1:1)CMA(2:1)CMA(1:0) at higher temperature (≥120 °C), indicating that increasing the Cu content enhanced the conversion of H2. The sample CMA(CP) made by coprecipitation method has a lower CO oxidation activity and selectivity than its counter-parts of mesoporous Cu-Mn-Al2O3 materials[CMA(1:2)], this attributed to the lower surface area of the former and poor interaction of CuO with MnOx. 相似文献
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通过电化学沉积方法在三维结构泡沫镍基体上沉积金属钴层, 利用固相氧化方法制备了三维结构泡沫Co3O4负极. XRD和SEM结果显示, 电化学沉积制备得到具有纳米结构的金属钴层, 经固相氧化处理, 在泡沫镍基体表面形成了Co3O4微米级的致密活性氧化层. 通过充放电和循环伏安以及电化学阻抗等方法研究了电极的电化学性能, 结果表明, 当放电电位区间为0.05~3.2 V时, 三维泡沫Co3O4于0.2 C倍率下充放电, 初始容量损失为29%, 经50次循环后, 质量比容量为824 mA·h/g, 三维泡沫结构提高了Co3O4电极的循环容量保持性能和倍率性能. 相似文献
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Anne M. Garrido Pedrosa Marcelo J. B. Souza Joana D. G. Fernandes Dulce M. A. Melo Antonio S. Araujo 《Reaction Kinetics and Catalysis Letters》2003,79(2):391-396
The present study reports the catalytic behavior of Co3O4-CeO2 in the oxidation of n-heptane. The results obtained showed that the catalyst give good activity in n-heptane oxidation with high selectivity to carbon dioxide.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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IntroductionMaterialsbasedoncobaltoxideshaveattractedagreatinterestinviewoftheirpotentialapplicationsinscientificandtechnologicalfields .1Theyhavebeenusedfortheproductionofsolid statesensors ,2 heterogeneouscatalysts ,3electrochromicdevices (ECDs) 4andasinte… 相似文献
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Identification of the Active Sites for Low Temperature CO Oxidation over Nanocrystalline Co3O4 Catalysts
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The microstructural properties of dry‐grinding derived Co3O4 catalysts pretreated under different atmospheres, in relation to the activities on CO oxidation were investigated. The Co3O4 synthesized by soft reactive grinding and pretreated with O2 resulted in the best activity, with 100% conversion of CO at ?52 °C, superior to that of Co3O4 pretreated with He. To find out the active sites on Co3O4 for low temperature CO oxidation, the characterizations of the cobalt oxides had been investigated by means of N2 physisorption, XRD, TEM, H2‐TPR, CO‐titration, XPS and O2‐TPD technologies. XPS of Co2p results show that it is difficult to ascribe the difference in catalytic performance to the surface concentration of active Co3+ sites. A correlation between the activity and the CO‐titration and O2‐TPD results for Co3O4 reveals that a high abundance of readily accessible superficial electrophilic oxygen (O?) species is important for achieving a high activity. Therefore, CO oxidation takes place on the surface active oxygen sites in Co3O4 crystallites via the suprafacial mechanism. 相似文献