CO oxidation over Co_3O_4/SiO_2 catalysts:Effects of porous structure of silica and catalyst calcination temperature

The catalytic performances of Co3O4/SiO2 catalysts prepared by incipient wetness impregnation for CO oxidation were investigated using three kinds of silica as carriers with different pore sizes of 7.7,14.0 and 27.0 nm.The effects of calcination temperature on the catalyst surface and micro structure properties as well as catalytic performance for the oxidation of carbon monoxide were also studied.All catalysts were characterized by N2 adsorption-desorption,XRD,XPS,FTIR,H2-TPR and O2-TPD.It was found that the properties and crystal size of cobalt-containing species strongly depended on the pore size of silica carrier.While the silica pore size increased from 7.7 to 27.0 nm,the Co3O4 crystal size increased from 8.5 to 13.5 nm.Moreover,it was demonstrated that if the spinel crystal structure of Co3O4 was obtained at a calcination temperature as low as 150℃,the catalyst sample would have a high Co3O4 surface dispersion and an increase of surface active species,and thus exhibit a high activity for the oxidation of carbon monoxide.     

NiO-La_2O_3-Al_2O_3气凝胶催化剂的制备

采用改进的溶胶 -凝胶法和超临界干燥技术制备出超细三元 Ni O- L a2 O3 - Al2 O3 气凝胶催化剂 .通过 BET、TEM、XRD、DTA、IR等物性表征 ,考察了煅烧温度和组成等对气凝胶催化剂制备的影响 .结果表明 ,此种方法制备的多元气凝胶催化剂不仅保留了氧化铝和 Ni O- Al2 O3 气凝胶的主要特征 ,而且 ,氧化镧的加入使气凝胶更易晶化 ,热稳定性更好和吸附能力更强 .这种改进的溶胶 -凝胶法和超临界干燥技术操作简单有效 ,适合要求组分之间相互作用强、分布均匀、结构热稳定性好的多组元负载催化剂的制备 .     

Template-assisted synthesis of hierarchically porous Co_3O_4 with enhanced oxygen evolution activity

Oxygen evolution reaction(OER) is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells(URFCs). However, the kinetically sluggishness of OER and the high prices as well as the scarcity of the most active precious metal electrocatalysts are the major bottleneck in these devices. Developing low-cost non-precious metal catalysts with high activity and stability for OER is highly desirable. A facile, in situ template method combining the dodecyl benzene sulfuric acid sodium(SDBS) assisted hydrothermal process with subsequent high-temperature treatment was developed to prepare porous Co_3O_4 with improved surface area and hierarchical porous structure as precious catalysts alternative for oxygen evolution reaction(OER). Due to the unique structure, the as-prepared catalyst shows higher electrocatalytic activity than Co_3O_4 prepared by traditional thermal-decomposition method(noted as Co_3O_4-T) and commercial IrO_2 catalyst for OER in 0.1M KOH aqueous solution. Moreover, it displays improved stability than Co_3O_4-T. The results demonstrate a highly efficient, scalable, and low cost method for developing highly active and stable OER electrocatalysts in alkaline solutions.     

非水溶液浸渍法制备TiO2—Al2O3

二氧化钛用作石油炼制的加氢脱硫(HDS)或加氢脱氮(HDN)催化剂载体具有高的活性,其缺点是比表面小,机械强度差。为克服这些缺点,近年来研究了用共胶法、浸渍法和交替成胶法制备TiO_2-Al_2O_3载体。本文报道了以TiCl_4的CCl_4溶液作浸渍液,制备单层覆盖型TiO_2-Al_2O_3载体,并用多晶X光衍射(XRD)、X光光电子能谱(XPS)、透射电子显微镜(TEM)和选区电子衍射(HEED)等实验技术进行了表征。     

NO_x储存催化剂Pt/BaAl_2O_4-A1_2O_3的XAFS研究

采用共沉淀－浸渍法在不同载体焙烧温度下,制备了不同Ａｌ／Ｂａ原子比的Ｐｔ／ＢａＡｌ２Ｏ４－Ａ１２Ｏ３系列样品。用ＸＲＤ,ＸＡＮＥＳ,ＥＸＡＦＳ,以及ＮＳＣ（ＮＯ_ｘ　ｓｔｏｒａｇｅ ｃａｐａｃｉｔｙ）测定等手段对样品的微观结构和ＮＯ_ｘ储存性能进行了详细的表征．样品中Ｂａ物种是以ＢａＡｌ２Ｏ４和ＢａＣＯ３两种混合物相的形式存在,且伴随着载体焙烧温度和Ｂａ含量的降低,ＢａＡｌ２Ｏ４物相的分散度变高,ＮＯ_ｘ储存活性也随之提高,这表明ＢａＡｌ２Ｏ４相的分散度与样品的ＮＯ_ｘ储存性能密切相关,小颗粒的ＢａＡｌ２Ｏ４相是ＮＯ_ｘ的主要储存活性中心．在样品中,Ｐｔ物种以金属原子簇形式存在．分散度很高,其Ｐｔ—Ｐｔ壳层配位数较标样Ｐｔ粉有显著下降,Ｐｔ—Ｐｔ键长变短,出现了纳米收缩现象．高分散的小颗粒金属Ｐｔ原于簇为捕获和氧化ＮＯ_ｘ的主要活性中心．     

The design and fabrication of Co_3O_4/Co_3V_2O_8/Ni nanocomposites as high-performance anodes for Li-ion batteries

The Co_3O_4/Co_3V_2O_8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional(1D) Co_3O_4 nanowire arrays directly grew on Ni foam, whereas the 1D Co_3V_2O_8 nanowires adhered to parts of Co_3O_4 nanowires.Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network.As a result, the discharge capacity of Co_3O_4/Co_3V_2O_8/Ni nanocomposites could reach 1201.8 mAh/g after100 cycles at 100 mA/g. After 600 cycles at 1 A/g, the discharge capacity was maintained at 828.1 mAh/g.Moreover, even though the charge/discharge rates were increased to 10 A/g, it rendered reversible capacity of 491.2 mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co_3O_4/Co_3V_2O_8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.     

SO_2对Co_3O_4/Al_2O_3选择性催化氧化NO的影响

采用流动态原位IR ,TPD及XPS技术研究了NO及SO2 在Co3 O4 /Al2 O3 金属氧化物催化剂表面上的吸附及脱附行为 ,并与该催化剂上模拟烟道气中NO的选择性催化氧化活性相关联 ,考察了SO2 对该反应过程的影响及作用机理 .     

CaO-MgO-Fe2O3-Al2O3-SiO2玻璃晶化机理

玻璃晶化动力学对于理解玻璃的稳定性和制备微晶玻璃十分重要．目前，通过DTA或DSC等简单技术去研究非等温过程和等温过程的动力学已取得一定的进展[1]．这些方法虽然方便，但需要事先知道晶化机理或借助XRD等技术确定Avrami参数[2]才能得到活化能．根据动力学理论，晶体生长速度与晶体生长活化能尽有直接关系[3]，通过理论计算晶体生长速度（U）可以确定玻璃体系的活化能，再结合DTA技术和Kissinger修正方程就可能确定晶体生长机理，这方面研究还未见报导．CaO－MgO－Fe2O3－AI2O3－SiO2（CMFAS）是本文综合利用废渣和尾矿制…     

Cross metathesis of butene-2 and ethene to propene overMo/MCM-22-Al_2O_3 catalysts with different Al_2O_3 contents

A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt%were prepared and applied in the metathesis reaction of ethene and butene-2.Addition of γ-Al2O3 did not affect the structure of MCM-22 zeolite as evidenced by XRD and N2 adsorption measurements.It was deduced from TPR experiments that γ-Al2O3 phase favored the formation of polymolybdate or multilayered Mo oxide,while more Al2(MoO4)3 species were generated over MCM-22 zeolites.Alumina content in the support was directly related to the metathesis activity of ethene and butene-2 to propene.Mo species with higher valence(Mo6+or Mo5+)contributed more to the excellent performance of catalyst than metallic Mo.The best catalyst activity and stability was obtained over 3.0Mo/(MCM-22-30%Al2O3)under the reaction condition of 1.0 MPa and 125℃ using N2 as the pretreatment gas.     

Bi2O3／γ—Al2O3系助燃剂的性能研究

负载性Pt助燃剂已被广泛应用。由于助燃剂能促进CO的转化成CO_2,对焦炭本身的燃烧速度无明显影响,故欲强化催化剂再生过程应提高其表面结焦的燃烧速度。我们制备了一系列Bi_2O_3/γ-Al_2O_3助燃剂以取代较为昂贵的Pt系助燃剂,并考察了Bi系助燃剂的物相结构、表面吸附性能、抗硫性及CO催化氧化活性和烧碳速度。结果表明,在高温实用区域,Bi系和Pt系对CO催化氧化活性相近,Bi系尚具有较好的去焦性能,有利于催化剂再生。     

超微粒CO3O4的合成与表征

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。     

添加Y_2O_3的ZrO_2-Al_2O_3复相陶瓷力学性能的研究

采用工业ZrO2,Al2O3原料,以Y2O3作为稳定剂,通过适当的工艺制备出ZrO2 Al2O3复相陶瓷。研究结果表明,Y2O3添加量为3.5%(摩尔分数)的ZrO2基陶瓷中加入Al2O3可有效地抑制ZrO2晶粒的生长,有利于使ZrO2晶粒以亚稳四方相存在,从而提高材料的强度与断裂韧性。Al2O3含量为20%(质量分数)时,复相陶瓷的抗弯强度、断裂韧性分别为676.7和10MPa·m1 2,其值接近湿化学法制备的复相陶瓷的力学性能。相变增韧与颗粒弥散增韧作用相互叠加提高了复相陶瓷材料的力学性能。     

TiO2-Al2O3复合载体的比较研究

对用混胶法和共沉淀法分别制备的ＴｉＯ２－Ａｌ２Ｏ３复合载体（ＴｉＯ２含量为０．０８ｇ／ｇγ－Ａｌ２Ｏ３）进行了对比研究，采用的表征方法有ＸＲＤ，ＸＲＳ，ＬＲＳ等，得出的结论如下：两种载体均保持了γ－Ａｌ２Ｏ３的骨架结构，但ＴｉＯ２的分散状态不尽相同，混胶样品中ＴｉＯ２主要以表面富集的形式分散在γ－Ａｌ２Ｏ３表面，这有利于集二者的优点于一体，共沉淀样品中ＴｉＯ２趋于整个体相均匀分散，这有利于相互作用     

Studies of Nano-sized Co_3O_4 as Anode Materials for Lithium-ion Batteries

Introduction　　Thelargecapacityandhighcellvoltageoflithium basedcells ,coupledwiththeirrelativelylowenvironmen talimpactmakethemanidealcandidateforportablepowersupplies .Studyonpresentmaterialsforlithiumionbatter iesfocusesonimprovingcycleabilityandincreasingca pacityofelectrodematerials.Asoneoftheimportantpartsoflithium ionbatteries ,anodematerialshavebeeninvestigatedintensively .Now ,carbonaceousmaterialsareusedinnearlyalllithiumionbatteriesbecauseoftheirhighcapacity (theoreticalcapaci tyof…     

第四组元对Y_2O_3-Al_2O_3-SiO_2钎料连接氮化硅陶瓷的影响

在Y2 O3 Al2 O3 SiO2 (YAS)钎料中添加TiO2 (YT)和Si3N4(YN) ,并进行氮化硅陶瓷的连接。用四点弯曲方法测定不同连接工艺下的连接强度 ,并对连接界面进行SEM ,EPMA和XRD分析。接头强度随着保温时间、连接温度的增加 ,而逐渐增加。在达到峰值后 ,连接强度逐渐降低。在YAS中添加TiO2 ,可以形成Si3N4/Y Sialon玻璃 TiN/TiN/Y Sialo玻璃的梯度层界面 ;而在YAS钎料中添加Si3N4,可以降低接头界面的热应力 ,改善接头强度。微观分析表明 :接头强度的变化主要与界面反应有关。     

CoMo／Al_2O_3和CoMo／TiO_2－Al_2O_3加氢脱硫催化剂的研

研究了ＣｏＭｏ／Ａｌ２Ｏ３和ＣｏＭｏ／ＴｉＯ２－Ａｌ２Ｏ３催化剂的加氢脱硫性能，并用ＬＲＳ，ＸＲＤ和ＴＰＳ等方法表征其表面相结构和硫化行为．结果表明，以ＴｉＯ２－Ａｌ２Ｏ３为担体的Ｍｏ和ＣｏＭｏ催化剂的活性均比相应的Ａｌ２Ｏ３为担体的高；少量Ｃｏ，Ｎｉ助剂的引入可显著提高ＭｏＯ３在担体上的分散度和改进催化剂的活性；Ｃｏ助剂还有降低Ｍｏ物种硫化温度的作用．     

聚合物燃烧方法制备Co_3O_4纳米粒子

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…     

固体超强酸SO_4~(2-)/SnO_2-Al_2O_3的红外光谱研究

以四氯化锡、硫酸铝为原料,氨水为沉淀剂,采用共沉淀法制得新型固体超强酸SO42-/SnO2-A l2O3。采用FT-IR技术考察了金属元素摩尔比、焙烧温度、浸渍液以及掺杂稀土氧化物对该固体超强酸结构和性能的影响。FT-IR结果表明在该固体超强酸中,锡和硫酸根是以螯合和桥式两种方式配位结合,其中起催化活化作用的主要是和硫酸根以螯合双齿结合的锡;和SO42-/ZrO2型超强酸相比,SO42-/SnO2-A l2O3超强酸的硫酸根FT-IR特征吸收峰发生蓝移,显示出更强的酸性。锡铝摩尔比为9∶1、焙烧温度为773K、焙烧时间为3h时,制得的SO42-/SnO2-A l2O3样品对酯化反应的催化性能最好。     

CeO_2-ZrO_2-Al_2O_3稀土储氧材料制备工艺的研究

采用化学沉淀法制备了系列CeO2-ZrO2-Al2O3稀土储氧材料,并用BET,XRD和储氧性能测定等表征手段考察了陈化时间、La2O3含量、反应pH和沉淀方式等工艺因素对CeO2-ZrO2-Al2O3比表面积、储氧性能和结构的影响。结果表明:当陈化时间为12 h,反应pH=10时,掺杂2%(质量分数)La2O3的CeO2-ZrO2-Al2O3样品在老化前后均具有很高比表面积和良好的储氧性能,并且pH为影响样品比表面积及热稳定性能的主要因素。与一步法沉淀相比,二步法制得的CeO2-ZrO2-Al2O3样品具有很高的热稳定性能,1050℃老化5 h后的样品比表面积高达46.4 m2.g-1,但储氧性能略差,这与Al2O3对CeO2-ZrO2的结构影响程度有关。     

MoO3/TiO2-Al2O3催化剂表面结构的LRS研究

负载型Mo和Co-Mo催化剂由于工业上的广泛应用,多年来一直是催化工作者的重要研究课题.工业上应用的Mo和Co-Mo催化剂多以活性Al_2O_3和SiO_2-Al_2O_3为载体,近年来也有用TiO_2,ZrO_2和活性碳作为催化剂载体的研究报导.有关催化剂活性组分与载体之间相互作用对催化剂表面相结构和催化性能的影响方面研究已引起人们的重视。我们多年来在金属-载体相互作用研究基础上,以石油加氢精制催化剂为应用背景,开