Co3O4-Bi2O2CO3催化剂的制备及其光催化性能

以Bi(NO₃)₃·5H₂O、Co(CH₃COO)₂·4H₂O为原料,采用化学沉淀-水热法制备了Co₃O₄-Bi₂O₂CO₃异质结构复合半导体光催化剂,并通过X射线衍射仪（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、紫外可见漫反射光谱（DRS）、荧光光谱（PL）等手段对所合成的复合型催化剂进行了理化性能表征。研究结果表明：引入Co₃O₄没有改变Bi₂O₂CO₃物相结构,但促进了Bi₂O₂CO₃ 对可见光的吸收能力,提高了Bi₂O₂CO₃表面吸附氧物种的数量,抑制了光生载流子复合。复合光催化剂对罗丹明B（RhB）的光催化脱色实验显示引入Co₃O₄能够明显提高Bi₂O₂CO₃催化剂的光催化脱色能力。尤其是Co₃O₄引入量为0.6%的Co₃O₄-Bi₂O₂CO₃样品对罗丹明B染料的光催化脱色率可达到97%（模拟日光照射30min）。本文为复合型光催化剂制备提供了简单易行的技术路线,制备的新型半导体复合光催化剂Co₃O₄-Bi₂O₂CO₃在环境净化方面表现出了较好的应用前景。     

Fe2O3-CuO/ZSM-5催化剂催化低浓度瓦斯制甲醇

采用催化氧化的方法,将煤矿抽采瓦斯制成高价值的化学品或液体燃料甲醇是其综合利用的一个发展方向。寻找对瓦斯转化具有较好的催化效果,且能替代贵金属催化剂的普通催化剂是瓦斯催化氧化制甲醇的研究重点。本文以硝酸铁、硝酸铜和ZSM-5分子筛为原料,采用离子交换法制备了Fe₂O₃/ZSM-5、CuO/ZSM-5和Fe₂O₃-CuO/ZSM-5催化剂,并在乙酸溶剂中考察了3种催化剂催化低浓度瓦斯部分氧化合成甲醇的性能。结果表明,Fe₂O₃/ZSM-5、CuO/ZSM-5和Fe₂O₃-CuO/ZSM-5对瓦斯部分氧化制甲醇反应均有催化活性,但Fe₂O₃-CuO/ZSM-5的催化效果最明显,且Fe、Cu负载量对催化剂的催化活性影响较为显著,Fe和Cu的最佳理论负载量分别为4.21%和3.22%。在Fe₂O₃-CuO/ZSM-5(x_Fe=4.21%,x_Cu=3.22%)添加量为0.1g、乙酸溶剂用量30mL的条件下,Fe₂O₃-CuO/ZSM-5催化甲烷体积分数为20%配制瓦斯制甲醇的最佳反应条件为初始反应压力4.0MPa、反应温度200℃、反应时间3h。     

单分散Co3O4@SiO2核壳催化剂的制备及N2O催化分解性能

N₂O是一种重要的温室气体,且对臭氧层有很大的破坏作用,而直接催化分解法是除去N₂O最经济有效的方法之一。针对目前报道较多的钴氧化物催化剂活性较差的问题,将包覆型Co₃O₄核壳材料引入N₂O直接催化分解反应,利用核壳结构的限域特性与壳层的多孔孔道使Co₃O₄分散性增加,粒径减小,金属载体相互作用与接触反应界面增强,从而提高了催化剂在N₂O直接催化分解反应中的低温活性。此外,还制备了一系列不同金属含量的Co₃O₄@SiO₂球形核壳催化剂来研究包覆结构对催化剂性能的影响,通过X射线荧光光谱（XRF）、透射电镜（TEM）、X射线衍射（XRD）、N₂物理吸附、H₂-程序升温还原（H₂-TPR）等表征,证实在保证稳定单分散核壳结构的前提下,活性Co₃O₄位点越多,催化剂反应活性越好。     

CO3O4/MPS催化氧化NO性能

微乳法制备的介孔二氧化硅（MPS）负载Co3O4构成了Co3O4/MPS催化剂,考察了负载量、焙烧温度等制备条件和反应温度、空速、NO进口浓度、O2体积分数等操作条件对Co3O4/MPS催化氧化NO性能的影响,并对载体及催化剂进行了BET和XRD表征。结果表明：MPS比表面积远大于其它载体,Co3O4呈立方晶型,MPS负载25%的Co3O4在300 ℃下焙烧3 h得到催化剂的晶体颗粒最小,分散性好,具有最佳催化氧化活性和良好的稳定性,在NO进口浓度500 μL/L、O2体积分数10%、空速12 000 h－1的条件下,250 ℃时NO氧化率可达50%～60%（此时可获得最高的NOx吸收效率）,300 ℃氧化率达到80%以上,接近热力学平衡值。     

Decomposition of methane and its reaction with CO2 over Rh/ZSM-5 catalyst

The decomposition of methane, its conversion into higher hydrocarbons and the reaction between CH₄ and CO₂ have been investigated on Rh/ZSM-5 in a fixed bed continuous-flow reactor. Independently of the temperature at 523–973 K, the decomposition of methane gave hydrogen, surface carbon and a small amount of ethane: ethylene and benzene were not detected. The reactivity of surface carbon formed at different temperatures has been examined toward H₂, O₂ and CO₂. The carbon exhibited less reactivity toward CO₂. The reaction between CH₄ and CO₂ occurred rapidly above 673 K to give CO and H₂ with a ratio of 1.3–1.6. Very little carbon was deposited during the reaction. It is concluded that the facile reactions between CH_x and CO₂ are responsible for the lack of carbon deposition. However, a significant amount of carbon deposition and the deactivation of the catalyst occurred when more than 4–5% of ethane was added to the reacting gas mixture. The extent of deactivation can be decreased by using a large excess of CO₂. This revised version was published online in June 2006 with corrections to the Cover Date.     

Potassium-doped Co3O4 catalyst for direct decomposition of N2O

Direct decomposition of nitrous oxide (N₂O) on K-doped Co₃O₄ catalysts was examined. The K-doped Co₃O₄ catalyst showed a high activity even in the presence of water. In the durability test of the K-doped Co₃O₄ catalyst, the activity was maintained at least for 12 h. It was found that the activity of the K-doped Co₃O₄ catalyst strongly depended on the amount of K in the catalyst. In order to reveal the role of the K component on the catalytic activity, the catalyst was characterized by XRD, XPS, TPR and TPD. The results suggested that regeneration of the Co²⁺ species from the Co³⁺ species formed by oxidation of Co²⁺ with the oxygen atoms formed by N₂O decomposition was promoted by the addition of K to the Co₃O₄ catalyst.     

二氧化碳加氢合成二甲醚CuO-ZnO-Al2O3/HZSM-5型催化剂的研究

以乙醇为溶剂，草酸作沉淀剂，采用共沉淀浸渍法制备了性能优良的二氧化碳加氢合成二甲醚催化剂(CuO-ZnO-Al₂O₃/HZSM-5)，在245℃、2.0MPa、2400h-1、H₂/CO₂=2.79的条件下，CO2转化率达22.61%，二甲醚选择性为45.90%，甲醇选择性为14.81%，含氧化合物收率为13.73%。对CuO-ZnO-Al₂O₃/HZSM-5催化剂进行了反应条件及活性稳定性的初步考察。     

动物骨源羟磷灰石负载Co3O4用于N2O催化分解

通过焙烧猪骨和鸡骨获得羟磷灰石(nHAP)载体,并采用浸渍法制备Co3O4/nHAP催化剂。采用XRD、N2物理吸附-脱附、FT-IR和H2-TPR等对催化剂进行表征,在连续流动微反装置上考察催化剂催化分解N2O的性能。结果表明,相比于鸡骨源Co3O4/nHAP催化剂,以猪骨源HAP为载体的催化剂因其较大的比表面积以及较小的Co3O4粒径尺寸,提供了更多的活性位点。特别是猪骨源Co3O4/nHAP催化剂中适量的K、Na等元素促进了Co^3+到Co^2+的还原,削弱了Co-O键,使催化剂的催化活性显著提高。     

Na-Fe_3O_4/ZSM-5催化剂上CO_2加氢反应汽油烃产物的组成调控

CO_2加氢直接合成汽油不仅有利于CO_2减排,还可减轻人们对化石能源的依赖。汽油馏分烃产物组成是决定汽油燃料品质的重要因素,其调控是该过程具有挑战性的研究热点。研究NaFe_3O_4/ZSM-5催化剂中分子筛的金属(La,Ga,Zn,Cu,Co)改性对CO_2加氢产物中汽油馏分烃组成的影响,结果表明,与其他金属相比,Cu改性ZSM-5分子筛组分可在保持较高汽油收率前提下,明显提高汽油产物中异构烷烃选择性。优化改性分子筛中Cu质量分数8%时,汽油馏分烃产物中异构烷烃含量最高。当Na-Fe_3O_4和Cu-ZSM-5采用分层填装方式时,汽油馏分烃产物中异构烷烃含量达50.5%,组成调控后富含异构烷烃汽油产品更符合汽油品质升级趋势需求。     

A5微孔分子筛负载V2O5催化氧化对硝基甲苯

将A₅微孔分子筛浸渍于偏钒酸铵溶液,过滤,120 ℃干燥2 h,550 ℃焙烧6 h,制备了含有V₂O₅的A5微孔分子筛催化剂。采用X射线衍射、N₂吸附-脱附和扫描电镜等进行表征,并将其用于以H₂O₂为氧化剂、乙酸酐为溶剂的对硝基甲苯催化氧化生成对硝基苯甲醇的反应。在反应温度40 ℃和反应时间4 h条件下,以质量分数35%的H₂O₂为氧化剂和V₂O₅质量分数8.5%的V₂O₅/A₅为催化剂,能够获得较好的对硝基甲苯转化率（35.54%）和较高的对硝基苯甲醇选择性(67.16%)。反应结束后,在母液中通过电感耦合等离子体原子光谱仪没有检测到V₂O₅。V₂O₅/A₅催化剂连续使用3次,对硝基甲苯转化率为34.21%,对硝基苯甲醇选择性为63.39%,催化剂活性无明显降低。     

Catalytic decomposition of N2O over CeO2 promoted Co3O4 spinel catalyst

A series of CeO₂ promoted cobalt spinel catalysts were prepared by the co-precipitation method and tested for the decomposition of nitrous oxide (N₂O). Addition of CeO₂ to Co₃O₄ led to an improvement in the catalytic activity for N₂O decomposition. The catalyst was most active when the molar ratio of Ce/Co was around 0.05. Complete N₂O conversion could be attained over the CoCe0.05 catalyst below 400 °C even in the presence of O₂, H₂O or NO. Methods of XRD, FE-SEM, BET, XPS, H₂-TPR and O₂-TPD were used to characterize these catalysts. The analytical results indicated that the addition of CeO₂ could increase the surface area of Co₃O₄, and then improve the reduction of Co³⁺ to Co²⁺ by facilitating the desorption of adsorbed oxygen species, which is the rate-determining step of the N₂O decomposition over cobalt spinel catalyst. We conclude that these effects, caused by the addition of CeO₂, are responsible for the enhancement of catalytic activity of Co₃O₄.     

Ag对Pd/Al2O3催化分解NO反应的促进作用

研究了不同含量的银对Pd/Al₂O₃催化分解NO反应活性的影响。结果表明，低温下，Pd/Al₂O₃催化剂对NO的分解反应活性不高；反应温度达到720 ℃时，NO分解活性迅速上升。O₂-TPD研究表明，Pd/Al₂O₃上氧的脱附速率也是在720 ℃左右达到最大值，因此，在温度低于720 ℃时，氧从催化剂表面的脱附是NO分解反应的速率控制步骤。Pd/Al₂O₃中添加适量的Ag对NO分解反应有促进作用。O₂-TPD研究表明，这种促进作用与Pd表面氧物种的起始脱附温度向低温移动有关。     

富氧条件下Rh/Co_3O_4催化剂对C_3H_6还原NO性能的影响

采用液相沉淀法制备Co3O4氧化物,并以其为载体制备负载型Rh催化剂。考察不同焙烧温度制备的载体和催化剂的结构、织构、氧化还原性能及其对C3H6催化还原NO性能的影响。结果发现,经600℃焙烧的载体制备的Rh/Co3O4催化剂中Rh与Co3O4的相互作用较强,促进对N—O键的削弱作用,提高对C3H6还原NO的还原能力。在相同实验条件下,当体系中C3H6为500×10-6、NO为500×10-6和O2体积分数为5%时,NO转化率50%,催化性能优于Rh/Al2O3催化剂。     

可见光增强g-C_3N_4/Co_3O_4胶体催化剂的催化产氢性能

通过水热法制备了具有可见光增产氢高性能的g-C_3N_4/Co_3O_4胶体催化剂,采用XRD、TEM、SEM和EDS等分析样品的组成和形貌结构。催化产氢结果表明,光照条件下g-C_3N_4/Co_3O_4胶体催化剂具有极高的催化产氢活性,TOF值高达58.2 min~(-1),通过拟合温度动力学曲线,得到了催化反应的活化能为15.73 kJ·mol~(-1)。对样品进行UV-vis和PL测试发现,g-C_3N_4/Co_3O_4胶体催化剂具有极高的光能利用率和电子-空穴分离率,并进一步阐述了光能促进催化产氢的作用机理。     

Combined CO/CH4 oxidation tests over Pd/Co3O4 monolithic catalyst: Effects of high reaction temperature and SO2 exposure on the deactivation process

CO and CH₄ combined oxidation tests were performed over a Pd (70 g/ft³)/Co₃O₄ monolithic catalyst in conditions of GHSV = 100,000 h⁻¹ and feed composition close to that of emission from bi-fuel vehicles. The effect of SO₂ (5 ppm) on CO and CH₄ oxidation activity under lean condition (λ = 2) was investigated. The presence of sulphur strongly deactivated the catalyst towards methane oxidation, while the poisoning effect was less drastic in the oxidation of CO. Saturation of the Pd/Co₃O₄ catalytic sites via chemisorbed SO₃ and/or sulphates occurred upon exposure to SO₂. A treatment of regeneration to remove sulphate species was attempted by performing a heating/cooling cycle up to 900 °C in oxidizing atmosphere. Decomposition of PdO and Co₃O₄ phases at high temperature, above 750 °C, was observed. Moreover, sintering of Pd⁰ and PdO particles along with of CoO crystallites takes place.     

V2O5/Al2O3上异丁烷脱氢反应研究

用浸渍法制备了质量分数为12%V₂O₅/Al₂O₃负载型催化剂，考察了催化剂的活化气氛，反应中异丁烷与氢气的比例和反应温度对异丁烷脱氢活性的影响。结果表明，用N2作活化气，反应中异丁烷与氢气的体积比为1∶1时，在质量分数为12%的V₂O₅/Al₂O₃催化剂上异丁烷脱氢转化率和选择性较好，在625 ℃时，转化率达到52%，选择性为80%。     

Microwave discharge-assisted NO reduction by CH4 over Co/HZSM-5 and Ni/HZSM-5 under O2 excess

Microwave discharge-assisted reduction of NO by CH₄ in the presence of excess O₂ over Co/HZSM-5 and Ni/HZSM-5 catalysts was studied. By comparing the activities of the catalysts in the microwave discharge mode with that in the conventional reaction mode, it is demonstrated that microwave discharge enhanced greatly the conversion of NO to N₂, and expanded the reaction temperature range of the catalysts. For the Co/HZSM-5 catalyst, the conversion of NO to N₂ increased by 30%, and the optimum temperature decreased by 200°C. With the Ni/HZSM-5 catalyst, the highest activity was close to 100%, and the optimum temperature decreased by 325°C. The conversion of CH₄ also increased in the microwave discharge mode over both of the catalysts.     

焙烧温度对CuO/Co_3O_4-CeO_2催化剂CO优先氧化性能的影响

采用浸渍法制备了Cu O/Co3O4-Ce O2(Cu Co Ce10)催化剂,考察了在不同温度(250、300、350、400和450℃)焙烧后的样品在富氢气氛中对CO优先氧化反应的催化性能。应用BET、XRD、H2-TPR及XAFS技术详细表征了催化剂的结构与性能。结果表明,不同温度焙烧的催化剂中,铜物种均主要以Cu O相存在;350℃焙烧的Cu Co Ce10催化剂具有最大的比表面积和最好的氧化还原性能,在98~173℃的温度范围内能够将CO完全转化为CO2,呈现出最宽的CO优先氧化可操作温度窗口,以及良好的催化活性稳定性。     

An ultrafast synthesis method of LiNi1/3Co1/3Mn1/3O2 cathodes by flash/field‐assisted sintering

LiNi_1/3Co_1/3Mn_1/3O₂ as a promising cathode material in lithium‐ion batteries was synthesized by flash/field‐assisted sintering technique for the first time. This study showed that the current‐limited synthesis of LiNi_1/3Co_1/3Mn_1/3O₂ could be carried out at temperatures less than 400°C for only 8 minutes, compared with the conventional pressureless sintering at 850°C for 12 hours. X‐ray diffraction results showed the phase evolution from precursor mixtures to the final LiNi_1/3Co_1/3Mn_1/3O₂ products during flash/field‐assisted sintering process and a well‐layered structure without undesirable cation mixing in the as‐formed LiNi_1/3Co_1/3Mn_1/3O₂. Combined with the lowered sintering temperatures and reduced sintering time, the excellent electrochemical performance of flash/field‐assisted sintered LiNi_1/3Co_1/3Mn_1/3O₂ materials suggested that this technique could be an energy‐efficient approach for the synthesis of lithium‐ion battery cathode materials and other materials requiring high‐temperature heat treatment.