甲烷部分氧化催化剂上的积碳研究进展

积碳是影响甲烷转化制合成气的催化剂性能的重要因素.在阐述甲烷催化部分氧化过程反应机理和催化剂体系的基础上,重点论述了甲烷催化部分氧化的催化剂失活与积碳的关系及影响催化剂的积碳因素.认为提高催化剂抗积碳性能的关键在于活性组分和负载量的改变、助剂的添加、载体的调控和制备方法的改进和储氧材料的使用,并对晶格氧催化甲烷部分氧化制合成气技术提出了展望,认为该技术具有良好的工业化应用前景.     

Ni/M_xO_y/CeO_2-ZrO_2(M=Cu,Ba,Al)复合催化剂的制备及其甲烷部分氧化性能

首先采用柠檬酸络法制备了系列Mx Oy/CeO2-ZrO2(M=Cu,Ba和Al)固溶体载体,然后浸渍活性组分Ni,制得系列Ni/Mx Oy/CeO2-ZrO2复合催化剂。考察了掺杂助剂元素(Cu,Ba和Al)对CeO2-ZrO2固溶体结构和负载Ni催化剂的甲烷部分氧化生成合成气催化性能的影响。采用氮气物理吸附,X射线粉末衍射(XRD),氢-程序升温还原(H2-TPR),扫描电子显微镜(SEM),氨-程序升温脱附(NH3-TPD)和热重(TG)等技术对反应前后催化剂的理化性质进行表征。甲烷部分催化氧化表明,催化剂的活性顺序为Ni/Al2O3/CeO2-ZrO2Ni/BaO/CeO2-ZrO2Ni/CeO2-ZrO2Ni/CuO/CeO2-ZrO2。催化剂表征结果表明,掺杂助剂元素后复合载体的主要结构仍然为CeO2-ZrO2固溶体;掺杂的助剂Ba和Al能和CeO2-ZrO2固溶体产生较强的相互作用,生成Mx Oy/CeO2-ZrO2三元复合固溶体载体,并使复合载体的比表面积增大,其中掺杂Al的效果最为明显,能使CeO2-ZrO2固溶体载体颗粒细化,表面结构更丰富,从而有利于活性组分Ni的分散;虽然掺杂Al使载体的表面酸性略有增强,但是Ni/Al2O3/CeO2-ZrO2复合催化剂仍表现了最高的活性和良好的稳定性。掺杂助剂Cu后,Cu与活性组分Ni之间的"氢溢流"效应增强了催化剂中Ni的还原性,生成的Cu0与Ni0之间产生的相互作用导致CuNi合金的生成,减少了Ni0活性中心的数目,导致该催化剂对甲烷部分氧化的活性下降。     

CeO2中晶格氧直接部分氧化甲烷制取合成气的研究

介绍了一种合成气制取的新方法-熔融盐中用晶格氧直接部分氧化甲烷制取合成气技术,对该技术的概念进行了阐述.以CeO2为氧载体,对反应过程进行了热力学分析,结果表明以CeO2中晶格氧直接部分氧化甲烷制合成气是可行的.在固定床石英反应器中对非熔融盐体系下的氧载体进行了性能评价,并用XRD技术进行了氧载体的表征.在750～900 ℃温度范围内,分别对(0.462×104)/h,(0.924×104)/h,(1.386×104)/h三种空速进行了实验,同时对产物气中n(H2)/n(CO)进行了考察,结果表明,(0.924×104)/h的空速和900 ℃的温度比较适于合成气的制取,失去晶格氧的CeO2-x有着很好的氧再生能力.     

稀土在汽车尾气三元净化催化剂中的应用现状与展望

稀土在我国的汽车排放污染控制方面有着广泛的应用。介绍了稀土作为三元催化剂的助催化剂、稳定剂、贵金属和载体的表面分散剂以及稀土复合氧化物作为催化剂的组分等方面的研究现状,并对稀土在汽车尾气净化催化剂中的研究和开发提出了一些设想和建议。     

氧化镨产品的生产发展及其应用

氧化锴（Pr6O11）是轻稀土产品中的重要产品之一。因其具有独特的理化性质，故在陶瓷、玻璃、稀土永磁、稀土裂化催化剂、稀土抛光粉、研磨材料和添加剂等领域获得应用，日益广泛，前景还是看好。     

掺杂稀土BaTiO3的制备及镍基催化剂的活性

采用柠檬酸盐法和溶胶-凝胶法合成出稀土掺杂的BaTiO3,并考察了稀土离子掺杂对BaTiO3颗粒粒径的影响。测定了掺杂BaTiO3的比表面积、晶相、粒度等粉体性能,指出稀土离子有抑制BaTiO3晶粒长大的作用。稀土掺杂的BaTiO3作镍基催化剂载体,以CO2/CH4重整制合成气为探针反应,评价了这些催化剂的催化活性,实验表明掺杂稀土有助于提高催化活性。     

专利名称：一种以SBA-15为载体的合成气制低碳醇钼系硫化物催化剂制法及应用

本发明涉及一种由合成气（CO和H2）制低碳混合醇的催化剂及其制备方法和反应条件，尤其是涉及一种以SBA-15为载体的钼系硫化物催化剂。提供一种能有效提高单程转化率、低碳醇的选择性及时空产率，以SBA-15为载体的钾修饰的钴一钼硫化物催化剂及其制备方法和反应条件。载体的引入提高了催化剂活性组分分散度，该催化剂具有优异的合成气制低碳醇活性、高的醇选择性和运行稳定性，成本低且制备方便，具有实际应用价值。     

合成气制甲醇催化剂的探究新进展

利用合成气制备甲醇是代替石油的高效清洁能源,合成气制甲醇没有工业化的原因是催化剂的选择性较差。探究合成气制甲醇催化剂的研究状况,由催化剂的种类、催化剂制备工艺、助剂的作用、载体几个方面出发分析其结构与性能。超声辅助浸渍法、脉冲电沉积技术、共浸渍法、乙醇诱导的方法、共沉淀法、超声-等离子体联合法等工艺的改进或结合更有利于活性组分的分散和形成更加细小的粒径颗粒。催化剂利用合适的工艺方法和良好反应器可以获得更好的催化效果,实现合成气制备甲醇的产业化推广,解决能源匮乏问题。     

我国汽车尾气净化催化剂的研究现状

简述了我国汽车尾气净化催化剂现状,并从催化剂载体、催化剂涂层材料、催化剂助剂和催化剂活性组分四个方面作了分析。同时介绍了目前我国催化剂的主要研究和生产情况。随着各国汽车工业的迅猛发展,对催化剂的用量愈来愈多,用廉价的稀土取代贵金属催化剂将是汽车尾气催化剂新的发展方向,具有广阔的应用前景。     

盐酸优溶法回收NdFeB废料中稀土元素的研究与生产

介绍了盐酸优溶法回收NdFeB废料中稀土元素的基本工艺流程,经生产线规模萃取分离钕镝,制取的氧化镝（Dy2O3）的纯度≥99%（质量分数）,非稀土杂质符合国家标准的要求,稀土总收率大于92%,生产工艺稳定先进,具有工业生产投资少、见效快等优点。     

稀土微合金化作用研究现状分析

分析了稀土作为微合金元素在钢中的固溶量及固溶度的测定方法,并就固溶稀土的分布和其对晶界、相变及组织的影响进行了探讨,提出了稀土在钢中微合金化的发展方向     

Rare earth elements: Properties and applications to methanol synthesis catalysis via hydrogenation of carbon oxides

Methanol (CH₃OH) is an important industrial chemical with a wide variety of uses. Industrial methanol synthesis catalysts are typically composed of Cu, Zn, and Al, but the use of catalysts incorporating rare earth elements has been shown to improve the catalytic performance. Due to their unique chemical and physical properties, the use of rare earth elements (scandium, yttrium, and the lanthanides) in catalysis in general has continued to increase over the past few decades, while the use of rare earth in methanol synthesis catalysts has not, despite often improving performance. The ability of several of the rare earth elements (Pr, Ce, Eu, Tb, Yb) to easily switch between oxidation states makes them beneficial for many different types of catalysts. However, for methanol synthesis the surface basicity is an important property, and the basic nature of the rare earth elements can be used to tune the basicity of catalysts. A small number of correlations between rare earth properties and catalytic performance have been observed, but often do not apply to other catalysts. Properties such as strength of basic sites, ionic radius, and electronegativity have been found to correlate with performance results such as activity or selectivity.     

The oxidation behavior of an iron-nickel alloy containing yttrium or rare earth elements between 900°C and 1200°C

A study of oxidation of an iron-nickel alloy with and without yttrium or rare earth additions is made to provide information over a range of temperature. The additions improve the oxidation resistance in air. The microfractograph features of oxide scale are discussed. It is suggested that pores existing in the interface between oxide scale and substrate may be an important factor for the good adherence which is obtained. In addition the pegging mechanism of rare earth element oxides may improve the adherence of oxide scale to substrate. An incubation period of oxidation in the alloys containing yttrium or rare earth elements is described and discussed in terms of net weight gain and weight loss due to gas evaporation.     

钼基催化剂技术发展现状

钼基催化剂广泛用于原油加氢、加氢脱硫,氨氧化丙烷为丙烯腈,气相催化氧化丙烯醛为丙烯酸,1-丁烯氧化脱氢生产1,3-丁二烯,从合成气生产乙醇或混合醇,甲烷干式重整,催化热解含碳气体生产碳纤维或纳米碳管,煤液化或气化和含氮氧化物废气净化等。     

Migration behavior,separation and recycling of rare earth during thermal decomposition of Zhijin phosphorus ore

Zhijin phosphorus ore is a moderate and low-grade phosphorus rare-earth ore contained in mines. The separation and extraction of associated rare earth are important research topics. In this study,the migration behavior of rare earth during the thermal decomposition of Zhijin phosphorus ore and the separation and extraction of rare earth in phosphorus slag are discussed systematically. During the thermal decomposition process of phosphorus ore, almost all of the associated rare earth enters into the phosphorus slag phase but does not enter into the ferrophosphorus or gas phases. Amorphous calcium metasilicate and calcium fluosilicate are major components of phosphorus slag, and rare earth mainly exists as a calsil solid solution. Hydrochloric acid was used for acidolysis of the phosphorous slag.Under the following conditions, 96% of the rare earth in the phosphorous slag can be dissolved in the acidolysis solution: acid excess coefficient of 1.5, reaction time of 50 min and reaction temperature of 50℃. The rare earth in the acidolysis solution was separated and recycled using oxalic acid as a precipitator and NaOH as a pH modifier. At pH of 1.7, rare-earth-enriched matter with rare-earth content of 2.1 wt% was obtained, and the recovery of the rare earth was 88%.     

三溴偶氮胂在稀土元素光度分析中的应用

在综合分析大量文献的基础上，全面评述了三溴偶氮肿在光度法测定稀土总量、铈组稀土分量和某些单一稀土元素中的应用情况，包括吸光光度法、固相光度法、动力学光度法、计算光度法等。     

High-efficiency simultaneous extraction of rare earth elements and iron from NdFeB waste by oxalic acid leaching

Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C₂O₄)3^3- were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC₂O₄-2H₂O).     

稀土元素对高速钢组织和性能的影响

概述了稀土元素在高速钢中净化晶界、固溶强化、改善碳化物等作用的研究现状,阐述了其相应的作用机制;着重介绍了稀土元素对高速钢组织和性能的影响,主要包括:稀土元素参与形成氧硫化物的过程,稀土元素与其他元素相互作用实现高速钢微合金化,净化晶界,细化晶粒以及稀土元素改善高速钢中碳化物形貌、尺寸与含量。研究发现,过量添加稀土元素会使钢中夹杂物增多,影响高速钢的性能,针对目前存在的问题,对稀土元素的引入方式以及含量进行了讨论,并对在粉末冶金高速钢中引入稀土元素的方式提出进一步展望。     

基于协同体系的磁性材料在稀土吸附中的应用研究

通过二氧化硅溶胶—凝胶法,将2-乙基己基膦酸单(2-乙基己基)酯（P507）与二(2,4,4’-三甲基戊基)膦酸（C272）的协同体系引入磁性固体吸附材料中,并将其用于吸附低浓度稀土离子。吸附剂的吸附试验结果表明,当溶液pH值为2时,吸附剂具有较优的协同效果,协同系数高达22,最大吸附量为0.07 mmol/g,但由于离子强度的增加会产生竞争吸附,使得稀土吸附量降低;吸附热力学分析表明,吸附为自发的吸热过程,且吸附量随着温度的升高而增大;动力学试验研究结果表明,吸附过程与二级动力学模型具有最高的拟合度,在吸附90 min后基本达到平衡。