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[Review]物理化学学报(Wuli Huaxue Xuebao )Acta Phys.-Chim.Sin.2015,31(5),817-828May Received:January 19,2015;Revised:March 23,2015;Published on Web:March 25,2015.∗Corresponding authors.YAO Xiao-Jiang,Email:yaoxj@;Tel/Fax:+86-23-65935924.YANG Fu-Mo,Email:fmyang@;Tel/Fax:+86-23-65935901.The project was supported by the Chongqing Science &Technology Commission,China (cstc2013jcsf20001,cstc2014pt-gc20002)and Open Project Program of the Chongqing Key Laboratory of Environmental Materials and Remediation Technology from Chongqing University of Arts and Sciences,China (CEK1405).重庆市科学技术委员会项目(cstc2013jcsf20001,cstc2014pt-gc20002)和重庆文理学院环境材料与修复技术重庆市重点实验室开放课题基金(CEK1405)资助©Editorial office of Acta Physico-Chimica Sinicadoi:10.3866/PKU.WHXB201503253铈基催化剂用于NH 3选择性催化还原NO x 的研究进展姚小江1,*贡营涛1,2李红丽1杨复沫1,3,*(1中国科学院重庆绿色智能技术研究院,水库水环境重点实验室,重庆400714;2重庆工商大学,催化与功能有机分子重庆市重点实验室,重庆400067;3长江师范学院,重庆408100)摘要:源自固定源(如燃煤电厂烟气)和移动源(如机动车尾气)排放的氮氧化物(NO x )造成了严重的大气污染,对其进行减排控制已迫在眉睫.研究表明,氨选择性催化还原(NH 3-SCR)技术是消除NO x 的最有效手段之一.铈基催化剂因其良好的氧化还原性能、适当的表面酸性、较高的储/释氧容量以及丰富的资源储备而被广泛用于NH 3-SCR 反应.探讨铈基组分在该反应中发挥的具体作用,有助于了解相关催化过程的本质,为现有催化剂的优化和新型催化剂的设计提供科学参考.基于CeO 2在NH 3-SCR 催化剂中扮演的不同角色,本文从CeO 2作为载体、铈基复合氧化物、表面负载组分(助剂和活性组分)以及特殊结构的铈基催化剂等方面系统地介绍了近年来铈基催化剂在NH 3-SCR 反应中的最新研究进展,并对该领域未来可能的发展方向进行了展望.关键词:铈基催化剂;氮氧化物;NH 3选择性催化还原;载体;复合氧化物;表面负载组分;特殊结构中图分类号:O643Research Progress of Ceria-Based Catalysts in the SelectiveCatalytic Reduction of NO x by NH 3YAO Xiao-Jiang 1,*GONG Ying-Tao 1,2LI Hong-Li 1YANG Fu-Mo 1,3,*(1Key Laboratory of Reservoir Aquatic Environment of CAS,Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,P .R.China ;2Chongqing Key Laboratory of Catalysis and FunctionalOrganic Molecules,Chongqing Technology and Business University,Chongqing 400067,P .R.China ;3Yangtze Normal University,Chongqing 408100,P .R.China )Abstract:Nitrogen oxides (NO x ),which are emitted from stationary sources (such as coal-fired power plant flue gases)and mobile sources (such as motor vehicle exhausts),cause serious atmospheric pollution.As a result,it is very important to control the emissions of NO x .Some studies have suggested that NH 3-selective catalytic reduction (NH 3-SCR)of NO x is one of the best techniques for this purpose.Ceria-based catalysts are widely used in the NH 3-SCR reaction because of their good redox ability,suitable surface acidity,high oxygen storage or release capacity,and rich resource reserves.Investigating the role of ceria component in this reaction is important to understand the nature of the related catalytic process,and provides a valuable scientific reference for the optimization of existing catalysts and the design of novel catalysts.Based on the different roles of ceria in NH 3-SCR catalysts,we have performed a systematic review of the latest research progress of ceria-based catalysts in the NH 3-SCR reaction for the following aspects:CeO 2used as supports,ceria-based mixed oxides,surface loading components (additives and active species),and ceria-based catalysts with special structures.Finally,we discuss the future directions of this field.817Acta Phys.-Chim.Sin.2015V ol.311引言近年来,随着工业化和城镇化步伐的加快,我国的大气污染问题频发(如2013年1月以来出现了多次大范围灰霾天气),引起了公众的日益关注和政府部门的高度重视.如何有效治理大气污染成为当前的当务之急.我国是典型的酸雨地区,为了缓解酸雨污染,从“六五”规划就开始花大力气进行脱硫方面的研究.通过不懈的努力,二氧化硫(SO2)的排放得到了较好的控制,但是近年来酸雨污染并未得到根本解决,并且出现了由硫酸型酸雨向硝酸型酸雨转变的趋势,这主要是由于氮氧化物(NO x)的排放量快速增加所致.NO x除了造成酸雨污染外,还可与碳氢化合物在光照作用下产生光化学烟雾以及破坏臭氧层等.1,2研究表明,NO x还是颗粒物(PM,特别是PM2.5)的主要前驱物之一.3在此背景下,我国“十二五”规划首次将NO x增列为约束性指标,这意味着NO x已成为我国今后一段时间内的减排重点.NO x的来源可分为自然源和人为源,在人为源NO x排放中,固定源(如燃煤电厂烟气)和移动源(如机动车尾气)分别占据了大约60%和40%的NO x排放份额.4众多研究结果表明,氨选择性催化还原(NH3-SCR)技术是消除固定源和柴油车尾气中NO x 的最有效手段之一.5-10其反应过程主要涉及以下化学反应:4NH3+4NO+O2→4N2+6H2O(标准NH3-SCR 反应),4NH3+2NO2+O2→3N2+6H2O,以及4NH3+ 2NO+2NO2→4N2+6H2O(快速NH3-SCR反应).该技术的核心在于催化剂的研发.商业化的NH3-SCR催化剂V2O5-WO3/TiO2在300-450°C具有较好的催化效果,11但还存在如下缺点:低温活性差;V2O5在高温下易升华脱落且具有生物毒性;高温下N2选择性差;在500°C以上时由于TiO2从锐钛矿型向金红石型转变导致催化剂性能急剧下降等.4,12-16目前,欧洲、美国和日本等发达地区和国家都已相继停用V2O5-WO3/TiO2催化剂.相关的研究重点逐渐转移到非钒基NH3-SCR催化剂上,9其中,金属氧化物NH3-SCR催化剂是一个重要发展方向.尽管此类催化剂还未投入商业应用,但由于其具有制备方便、性能可调且适于大规模生产等优点而成为研发的热点,值得重点关注.稀土金属氧化物由于具有未充满电子的4f轨道和镧系收缩等特征,表现出独特的性能.研究表明,稀土组分的存在可以有效地调节催化剂的表面酸碱性、修饰催化活性中心的结构、提高催化剂的储/释氧能力、增强其结构稳定性和提高活性组分的分散度等.16-21二氧化铈(CeO2)作为稀土催化材料中的最重要组成,由于具有优异的氧化还原性能和较高的储/释氧容量以及良好的Ce3+/Ce4+切换能力,在NH3-SCR反应中有着广泛的应用.5,22-25作为稀土资源大国,我国正从稀土原材料的开发向稀土推广应用转变,稀土材料的应用已开始带动传统产业的升级,加强稀土催化在环境治理方面的基础研究既可提高生产效率,又能高效利用资源和减少环境污染,符合当今可持续发展的战略方向.对铈基催化剂在NH3-SCR反应中的现有研究成果进行梳理、归纳和总结,将有助于本领域的研究者更清楚地了解铈基组分所发挥的作用和催化反应机理,从而科学地设计相关实验体系.因此,基于CeO2在NH3-SCR催化剂中扮演的不同角色,本文将从CeO2作为载体、铈基复合氧化物、表面负载组分(助剂和活性组分)以及特殊结构的铈基催化剂等方面系统地介绍近年来铈基催化剂在NH3-SCR反应中的最新研究进展,并对该领域未来可能的发展方向进行展望.2CeO2作为载体负载型金属氧化物催化剂因其良好的催化性能和低廉的成本而广泛应用于众多重要催化反应,这在我们前期撰写的几篇综述文章中都有专题探讨.26-28人们早已发现在负载型金属氧化物催化剂中,表面负载组分的性质常常不可避免地会受到载体的影响,29研究表面负载组分与载体之间的相互作用,已成为多相催化领域多年来持续研究的热点.负载型金属氧化物催化剂的载体通常可分为刚性载体(如Al2O3、SiO2等)和活性载体(如CeO2、TiO2等),其中活性载体与表面负载组分之间的相互作用更丰富,因此成为关注的焦点.2.1CeO2纯载体以CeO2为纯载体的负载型金属氧化物催化剂在NH3-SCR反应中的研究引起了人们的极大关注.众所周知,在该反应中影响催化性能的关键因素主Key Words:Ceria-based catalyst;Nitrogen oxide;Selective catalytic reduction by NH3;Support;Mixed oxide;Surface loading component;Special structure818姚小江等:铈基催化剂用于NH3选择性催化还原NO x的研究进展No.5要是氧化还原性和表面酸性等,30而对于以CeO2为纯载体的负载型金属氧化物催化剂,一方面活性组分能在CeO2表面高度分散,另一方面CeO2具有优异的氧化还原性能、较高的储/释氧容量、适当的表面酸性以及良好的Ce3+/Ce4+切换能力,可与表面负载组分产生较强的相互作用,从而促进其催化性能显著提升.8,31因此,相关研究屡见报道,如:Chen等13制备了一系列LaMnO3、LaMnO3/TiO2和LaMnO3/ CeO2催化剂,系统地考察了载体效应对其NH3-SCR 反应性能的影响,发现以CeO2为载体的样品表现出最佳的催化性能.他们认为LaMnO3和CeO2之间的相互作用在低温段(<200°C)有利于晶格氧的移动,促进部分NO氧化成NO2,使NO还原反应按快速NH3-SCR方式进行,从而显著提升其催化性能;在高温段(≥200°C)有助于催化剂表面积累的硝酸盐和亚硝酸盐的分解,进而使其脱硝性能显著提升.然而,也有研究者认为适当抑制CeO2表面氧的移动能力也可有效地提升其NH3-SCR反应性能.例如, Weng等32将WO x负载到CeO2表面用于NH3-SCR反应,研究结果表明,WO x与CeO2之间的相互作用导致催化剂表面Brönsted酸量增加以及表面氧含量减少,前者有利于NH3的吸附,后者有助于抑制NH3和NO的氧化,进而体现出优异的催化性能.Li等33分别以Ce(NO3)3∙6H2O和Ce(SO4)2∙4H2O为Ce盐前驱体采用水热法和沉淀法制备了一系列CeO2样品,深入地探讨了制备方法、表面硫酸盐和体相硫酸盐等因素对其NH3-SCR反应性能的影响.他们指出以Ce(SO4)2∙4H2O为前驱体采用水热法制备的样品(CeO2-SH)具有最佳催化性能的原因在于水热反应过程中在CeO2表面形成了键合在Ce4+上的表面硫酸盐,有利于NH3的吸附.此外,还有学者系统地研究了CeO2对NO x和NH3等反应物分子的吸附以及吸附物种之间的相互作用,为铈基脱硝催化剂的设计提供了更多的科学依据.34深入研究反应机理有助于催化剂的结构设计以及进一步的性能提升,因此,负载型铈基催化剂表面的NH3-SCR反应机理成为当今的一个研究热点.35,36例如,Shi等35详细地探讨了MnO x/CeO2催化剂表面的NH3-SCR反应机理(图1).他们指出,在NH3-SCR反应过程中,首先,气相NH3迅速地吸附在Lewis酸位上形成配位NH3,气相NO吸附在催化剂表面形成NO-;然后,两者发生反应生成活性中间体[NH3…NO-];接下来,活性中间体[NH3…NO-]再分解形成NH2NO,分解过程中多余的H转移到催化剂表面;最后,NH2NO进一步解离成最终产物N2和H2O,而气相O2则氧化催化剂表面使活性位再生,完成整个催化反应循环.他们进一步将MnO x/CeO2催化剂的物理化学性质和催化性能与MnO x/TiO2和MnO x/γ-Al2O3催化剂进行了对比,强调CeO2在上述反应机理中发挥的作用主要是有利于MnO x的分散和还原性能的提升,进而促进活性中间体[NH3…NO-]的分解,最终导致优异的催化性能.我们在之前的工作中也深入地研究了负载型铈基催化剂表面的NH3-SCR反应机理和抗硫机理.37首先,我们制备了一系列CeO2、TiO2、CeO2/TiO2和TiO2/CeO2催化剂.然后,对其物理化学性质和催化性能进行了考察,发现TiO2/CeO2催化剂在NH3-SCR反应中的催化性能略优于CeO2/TiO2样品,但两者的催化性能都明显优于单一金属氧化物CeO2和TiO2,原因在于将CeO2和TiO2结合有助于活性物种Ce-O-Ti的形成;最后,对催化剂表面的反应机理和抗硫机理进行了研究,发现TiO2/CeO2催化剂的抗硫性能显著优于CeO2/TiO2样品,并提出了如图2所示的抗硫机理.研究结果表明,当反应气氛中存在SO2时,对于CeO2样品,在反应过程中会逐渐形成表面硫酸盐和体相硫酸盐,有助于增强催化剂的表面酸性,促进NH3的吸附,从而提升催化性能;对于CeO2/ TiO2样品,催化剂表面的CeO2逐渐被硫酸盐化产生表面硫酸盐,抑制了活性物种Ce-O-Ti的形成,进而导致催化性能下降;然而,对于TiO2/CeO2样品,虽然图1MnO x/CeO2催化剂表面可能的氨选择性催化还原(NH3-SCR)反应机理35Fig.1Possible reaction mechanism of NH3-selective catalytic reduction(NH3-SCR)on the surface of MnO x/CeO2catalyst35819Acta Phys.-Chim.Sin.2015V ol.31也会产生表面硫酸盐抑制活性物种Ce-O-Ti 的形成,但是表面TiO 2的存在也抑制了体相硫酸盐的产生,NH 3-SCR 反应可通过TiO 2/CeO 2催化剂的表面硫酸盐与体相CeO 2之间的协同作用顺利进行,因此,在存在SO 2的情况下,其催化性能并没有明显下降.2.2铈基复合氧化物载体尽管以CeO 2为纯载体的负载型金属氧化物催化剂在NH 3-SCR 反应中表现出了优异的催化性能,但是CeO 2纯载体还存在比表面积较小、热稳定性较差、高温易烧结等不足,这在一定程度上限制了其广泛的应用.持续的研究发现,通过向CeO 2的晶格掺入外来金属离子形成铈基复合氧化物可有效地克服以上缺点.因此,以铈基复合氧化物为载体负载活性组分制备负载型金属氧化物催化剂用于NH 3-SCR 反应成为一个研究热点.38-40因为铈基复合氧化物有助于克服纯CeO 2的固有缺点,所以以铈基复合氧化物为载体制备的负载型金属氧化物催化剂具有明显的优势.例如,Shen 等41采用浸渍法制备了一系列MnO x /CeO 2、MnO x /CeO 2-ZrO 2和MnO x /ZrO 2催化剂,并对其物理化学性质和NH 3-SCR 反应性能进行了详细的对比研究.结果表明,MnO x /CeO 2-ZrO 2催化剂具有最佳的催化性能和抗水抗硫性能,这主要是由于CeO 2-ZrO 2复合氧化物有助于MnO x 物种的高度分散和氧化还原性能的改善,以及MnO x /CeO 2-ZrO 2催化剂对H 2O 和SO 2的吸附作用较弱所致.在此基础上,他们进一步考察了Ce/Zr 摩尔比和MnO x 负载量对MnO x /CeO 2-ZrO 2催化剂在NH 3-SCR 反应中催化性能的影响,发现Ce/Zr 摩尔比为1和Mn/(Ce+Zr)摩尔比为0.6的催化剂表现出了最佳的脱硝性能,并将其原因归属于表面酸性、比表面积、表面吸附氧和Mn 4+/Mn 3+摩尔比的增加以及氧化还原性能的改善.42类似地,Hong 等43还系统地考察了CeO 2/TiO 2质量比对MnO x /CeO 2-TiO 2催化剂催化NH 3-SCR 反应性能的影响,指出MnO x /CeO 2-TiO 2的催化性能明显优于MnO x /CeO 2和MnO x /TiO 2样品,且当CeO 2含量为4%时具有最佳的催化性能,他们认为这主要是由于在CeO 2含量为4%的铈钛复合氧化物负载MnO x 催化剂中表面Mn (特别是Mn 4+)含量增加(即促进了MnO x 的分散)以及表面酸性增强所致.此外,还有学者详细地探讨了Fe 物种对MnO x /CeO 2-TiO 2催化剂NH 3-SCR 反应性能的影响机制,研究结果表明,Fe 物种的引入主要是通过促进MnO x 的分散、比表面积和孔容的增大、氧化还原性能的改善以及活性组分与载体之间相互作用的增强,从而提升MnO x /CeO 2-TiO 2催化剂的脱硝性能.44在我们前期的研究工作中,也对以铈基复合氧化物为载体的负载型金属氧化物催化剂用于NH 3-SCR 反应进行了系统的研究.16首先,采用均相沉淀法合成了一系列CeO 2、CeO 2-TiO 2复合氧化物和TiO 2样品,进而以其为载体制备了CuO/CeO 2、CuO/CeO 2-TiO 2和CuO/TiO 2催化剂;然后,通过一系列表征手段对上述催化剂的物理化学性质进行了考察;最后,借助于NH 3-SCR 反应装置对其脱硝性能进行了评价,发现CuO/CeO 2-TiO 2的催化性能明显优于CuO/CeO 2和CuO/TiO 2催化剂.结合上述物理化学性质表征结果,我们认为CuO/CeO 2-TiO 2表现出最佳催化性能的原因有二:(1)Ce 4+掺入TiO 2的晶格使Cu 2+的配位状态由稳定的正八面体变为不稳定的扭曲八面体,有助于氧化还原性能的改善;(2)CuO/CeO 2-TiO 2催化剂中由于存在Cu 2++Ce 3+⇌Cu ++Ce 4+和Cu 2++Ti 3+⇌Cu ++Ti 4+两个氧化还原循环,使得活性组分CuO 与CeO 2-TiO 2复合氧化物载体之间的相互作用明显增强,有利于Lewis 酸的形成以及反应物分子的吸附与活化,从而促进活性中间体NH 4NO 2的生成.基于以上分析,我们针对CuO/CeO 2-TiO 2催化剂提出了一个如图3所示的涉及Cu 2++Ce 3+⇌Cu ++Ce 4+和Cu 2++Ti 3+⇌Cu ++Ti 4+氧化还原循环、Lewis酸以图2铈基催化剂表面可能的抗硫机理37Fig.2Possible sulfur-resistance mechanism on the surfaceof ceria-based catalysts 37820姚小江等:铈基催化剂用于NH 3选择性催化还原NO x 的研究进展No.5及活性中间体NH 4NO 2的可能NH 3-SCR 反应机理.3铈基复合氧化物催化剂近年来,研究发现通过向CeO 2的晶格掺入某些金属离子形成的铈基复合氧化物不仅可有效地克服其比表面积较小、热稳定性较差、高温易烧结等缺点,而且表现出可与以CeO 2为载体的负载型金属氧化物催化剂媲美的NH 3-SCR 反应性能,有的甚至更优,这为NH 3-SCR 催化剂的设计提供了另一条思路.12,45,46众所周知,催化剂的表面酸性和氧化还原性对其NH 3-SCR 反应性能影响显著,而WO 3和MoO 3是典型的酸性金属氧化物,因此成为制备铈基复合氧化物脱硝催化剂的首选对象,相关研究层出不穷.1,5,47,48例如,Li 等5通过共沉淀法制备了一系列CeO 2-WO 3复合氧化物催化剂,进而采用多种常规和原位表征手段对其在NH 3-SCR 反应中的活性位进行了系统的研究.他们发现源于CeO 2优异氧化还原性能和储释氧能力的氧化还原循环(用于活化NH 3)以及源自Ce 2(WO 4)3中W-O-W 物种表面Brönsted 酸的酸循环(用于吸附NH 3)在NH 3-SCR 反应中发挥了关键作用,这与Topsøe 30在V 2O 5/TiO 2体系中得出的结论不谋而合.在此基础上,Han 等49对CeO 2-WO 3复合氧化物催化剂在NH 3-SCR 反应中的碱金属中毒机理进行了全面的考察,发现其失活原因主要是由于碱金属K 或Na 吸附在CeO 2-WO 3(110)晶面使表面氧迁移覆盖活性W 物种,从而导致Brönsted 酸量减少所致,然而通过热水水洗可使其恢复90%以上的活性.此外,关于CeO 2-WO 3复合氧化物的协同效应及其表面的NH 3-SCR 反应机理等方面的研究也时有报道.47,50MnO x 由于具有多种可变价态,有助于调变CeO 2的氧化还原性能,从而促进其NH 3-SCR 反应性能的提升,因此也被广泛用于铈基复合氧化物催化剂的制备及相关研究,并表现出良好的低温脱硝性能.51,52a Qi 和Yang 52a 制备了一系列CeO 2-MnO x 复合氧化物催化剂,考察了Mn/(Mn+Ce)摩尔比和焙烧温度对其NH 3-SCR 反应性能的影响,发现Mn/(Mn+Ce)摩尔比为0.3,焙烧温度为650°C 的样品具有最佳的低温脱硝性能.他们进一步的动力学研究结果表明,CeO 2-MnO x 复合氧化物催化剂表面的NH 3-SCR 反应对于NH 3是零级反应,而对于NO 是一级反应,且其一级反应速率常数比文献52(b,c)报道的其它低温脱硝催化剂大好几倍.此外,Baiker 等53还采用脉冲热分析结合质谱(MS)和傅里叶变换红外(FT-IR)光谱等表征手段对CeO 2-MnO x 复合氧化物催化剂的吸附性质、氧化还原性能与其脱硝性能的关联以及NH 3-SCR 反应机理进行了系统的探讨.关于CeO 2-MnO x 复合氧化物脱硝催化剂方面的研究还有很多,这里就不再一一列举.商业化V 2O 5-WO 3/TiO 2脱硝催化剂的载体TiO 2由于具有独特的抗硫性能而被选来与CeO 2结合制备铈基复合氧化物催化剂用于NH 3-SCR 反应的研究也引起了科研工作者的极大兴趣.7,45有文献指出采用优化后的均相沉淀法制备的CeO 2-TiO 2复合氧化物催化剂由于CeO 2和TiO 2之间存在强相互作用而在NH 3-SCR 反应中表现出较V 2O 5-WO 3/TiO 2和Fe-ZSM-5催化剂更优的催化性能.7在此基础上,Zhang 等54进一步通过氢气程序升温还原(H 2-TPR)、原位傅里叶变换红外(in situ FTIR)光谱、X 射线光电子能谱(XPS)、X 射线吸收精细结构谱(XAFS)和场发射透射电子显微镜(FETEM)等表征手段确定CeO 2-TiO 2复合氧化物催化剂在NH 3-SCR 反应中的活性位主要是在原子水平上具有相互作用的短程有序的Ce-O-Ti 结构单元.除此之外,研究者还对CeO 2-SiO 2、CeO 2-SnO 2、CeO 2-FeO x 和CeO 2-Nb 2O 5等铈基复合氧化物催化剂的脱硝性能进行了广泛的研究.24,46,55,56诸多研究结果显示,通过向简单的二组分铈基复合氧化物催化剂中引入第三组分对其进行改性,可有效地改善其NH 3-SCR 反应性能.18,57-64例如,Li 等59系统地考察了Ge 和Mn 掺杂对CeO 2-WO 3复合图3CuO/CeO 2-TiO 2催化剂表面可能的NH 3-SCR反应机理16Fig.3Possible reaction mechanism of NH 3-SCR onthe surface of CuO/CeO 2-TiO 2catalyst 16821Acta Phys.-Chim.Sin.2015V ol.31氧化物催化剂脱硝性能的影响,发现Ge和Mn的掺入显著提升了Ce3W2O x(Ce/W摩尔比为3/2)复合氧化物催化剂在100-250°C内的催化性能(如图4(a)所示),这主要是由于无定形相的形成和表面W/Ce 原子比的增加所致;研究结果还显示,所有催化剂经过700°C焙烧后催化性能都有所下降,但是(Ce3W2)0.9Ge0.1O x((Ce+W)/Ge摩尔比为9/1)催化剂的催化性能明显优于其它样品(如图4(b)所示),表明Ge的掺入有利于改善Ce3W2O x复合氧化物催化剂的抗烧结性能.此外,还发现Ge的掺入明显增强了Ce3W2O x复合氧化物催化剂的抗SO2中毒性能和H2还原再生性能.在另一项研究工作中,他们还指出P 的引入可显著提升CeO2-MoO3复合氧化物催化剂的NH3-SCR反应性能,并认为其原因在于P的引入增加了CeO2-MoO3复合氧化物催化剂的比表面积和表面酸性.65CeO2-MnO x复合氧化物催化剂的改性研究也屡见报道,有研究显示Sn的掺入可显著提升CeO2-MnO x复合氧化物催化剂的NH3-SCR反应性能和抗SO2中毒性能(如图5所示).6,66进一步借助于众多表征手段发现,这主要是由于Sn的改性明显增加了CeO2-MnO x复合氧化物催化剂的表面氧空位浓度和表面酸性,前者表面吸附的活性氧有利于NO氧化为NO2,后者有助于NH3的吸附,从而促进NH3-SCR 反应性能的提升;伴随着氧空位产生的Ce(III)与SO2反应生成的含Ce(III)硫酸盐有利于增加Lewis 酸和氧化NO到NO2的能力,因此表现出优异的抗SO2中毒性能.66此外,董文杰等67还详细地考察了W、Fe和Cu等掺杂对CeO2-MnO x复合氧化物催化剂NH3-SCR反应性能的影响,研究结果表明,W的改性显著提升了其催化性能,Fe的促进作用不明显, Cu的引入反而对催化性能产生了一定的抑制作用.对于CeO2-TiO2复合氧化物催化剂体系,有研究者发现CuO的掺入可有效地提升其NH3-SCR反应性能,并认为其原因在于Cu2++Ce3+⇌Cu++Ce4+和Cu2++Ti3+⇌Cu++Ti4+两个氧化还原循环的建立.68在此基础上,Weng等69借助于in situ FTIR技术进一步研究了CuO-CeO2-TiO2复合氧化物催化剂表面的NH3-SCR反应机理,指出该反应主要发生在Cu2+-NO、配位到Ce位上的硝酸盐和键合到Ti位上的NH3之间,而源于各组分间强相互作用的活性氧则有利于Cu2+-NO氧化为硝酸盐储存在Ce位上或直接参与快速NH3-SCR反应.Shen等12还系统地考察了Zr改性对CeO2-TiO2复合氧化物催化剂脱硝性能的影响,发现促进效应主要源于催化剂氧化还原性图4不同温度(500,700°C)焙烧的Ce3W2O x、(Ce3W2)0.9Mn0.1O x和(Ce3W2)0.9Ge0.1O x复合氧化物催化剂的NH3-SCR反应性能结果59Fig.4Reaction performance results of Ce3W2O x,(Ce3W2)0.9Mn0.1O x,and(Ce3W2)0.9Ge0.1O x mixed oxidecatalysts calcined at different temperatures(500,700°C)for NH3-SCR reaction59图5CeO2-MnO x复合氧化物催化剂经Sn改性前后在不存在SO2和通入SO2条件下的NH3-SCR反应性能结果66Fig.5Reaction performance results of CeO2-MnO x mixedoxide catalysts before and after modifying Sn in theabsence and presence of SO2for NH3-SCR reaction66 822姚小江等:铈基催化剂用于NH3选择性催化还原NO x的研究进展No.5能、微结构和表面酸性等的改善,而非比表面积的变化.在此基础上,他们还详细地探讨了ZrO2-CeO2-TiO2复合氧化物催化剂的碱金属K中毒机理.70此外,F等卤素元素也被用于CeO2-TiO2复合氧化物催化剂的改性研究,并表现出优异的NH3-SCR反应性能.224CeO2作为表面负载组分CeO2除了用作载体和铈基复合氧化物催化剂的重要组成部分外,也可作为负载型金属氧化物催化剂的表面负载组分(助剂和活性组分)用于NH3-SCR反应,并表现出优异的性能.4.1CeO2作为助剂诸多研究结果表明,CeO2对于脱硝催化剂来说是一种非常有效的助剂,它可促进催化性能的显著提升.71,72例如,Wu等73系统地考察了CeO2改性对MnO x/TiO2催化剂催化NH3-SCR反应性能的影响,研究结果显示,CeO2的引入使MnO x/TiO2催化剂在80°C时(空速为40000h-1)的低温活性从39%提升到84%,这主要是由于CeO2促进了催化剂表面吸附氧和表面酸性的增加以及氧化还原性能的改善所致.在此基础上,他们还对CeO2增强MnO x/TiO2催化剂的抗SO2中毒机制进行了详细的探讨,并指出CeO2的引入显著地抑制了(NH4)2SO4和NH4HSO4在催化剂表面的沉积是抗硫性能提升的根本原因.74金瑞奔等75在研究中也得到了类似的结果,并进一步指出CeO2改性还可有效地抑制MnO x/TiO2催化剂中活性组分的硫化以及降低(NH4)2SO4和NH4HSO4的稳定性,通过热水水洗即可使催化剂再生.此外,还有研究者深入地考察了CeO2改性对钛基层柱粘土负载锰基催化剂(MnO x/TiO2-PILC)在NH3-SCR反应中抗水抗硫性能的影响.76从图6中可以看出, CeO2的引入显著增强了MnO x/TiO2-PILC催化剂的抗水抗硫性能.结合氮气-物理吸附、X射线衍射(XRD)、氨气-程序升温脱附(NH3-TPD)、H2-TPR和XPS等表征结果发现这主要是因为CeO2的添加促进了MnO x/TiO2-PILC催化剂中介孔结构和比表面积的增加、提高了活性MnO x物种的分散度、增强了催化剂表面酸性和氧化还原性能,从而使其催化性能和抗水抗硫性能显著提升.76对于MnO x/Al2O3脱硝催化剂,有研究者指出CeO2的引入可同时改善MnO x在Al2O3表面的分散状态和晶相结构,从而在很宽的温度窗口内实现高效脱硝,并表现出很好的稳定性.77此外,CeO2在分子筛催化剂和钒基催化剂中的改性研究也时有报道,78-82这方面的工作由于已超出本文的讨论范畴,所以此处不再赘述.4.2CeO2作为活性组分实际上,以CeO2为负载型金属氧化物催化剂的活性组分用于NH3-SCR反应的研究也引起了科研工作者的广泛关注.11,83-86尽管单一的晶相CeO2脱硝性能较差,但是当其负载于载体表面呈高度分散状态时,催化性能得到显著提升.在以往的研究中, TiO2、Al2O3和SiO2等都被广泛用作负载型铈基脱硝催化剂的载体,并表现出了优异的催化性能.87Li 等88进一步以TiO2-SiO2复合氧化物为载体负载CeO2用于NH3-SCR反应.研究结果表明,相比于单一的TiO2和SiO2载体,CeO2在TiO2-SiO2复合氧化物载体表面的分散度更高;TiO2和SiO2之间的相互作用促进了Ce4+向Ce3+的转变,并增强了催化剂的表面酸性,有利于NH3的吸附,从而体现出优异的催化性能,特别是Ti/Si质量比为3/1的CeO2/TiO2-SiO2催化剂在250-450°C范围内具有最佳的催化活性和N2选择性.此外,他们还指出,向TiO2载体中掺入SiO2可显著提升负载型铈基催化剂的抗水抗硫性能,并认为这主要是由于SiO2的引入减弱了CeO2/ TiO2-SiO2催化剂的表面碱性,从而抑制了其表面硫酸盐的沉积所致.众所周知,变价金属氧化物和酸性金属氧化物分别有助于改善负载型铈基催化剂的氧化还原性能和表面酸性,而氧化还原性能和表面酸性在NH3-SCR反应中发挥着关键作用,因此,变价金属氧化物和酸性金属氧化物被广泛用于负载型铈基脱硝图6MnO x/TiO2-PILC和MnO x-CeO2/TiO2-PILC催化剂在NH3-SCR反应中的抗水抗硫性能76Fig.6Resistance to H2O and SO2in NH3-SCR reaction over MnO x/TiO2-PILC and MnO x-CeO2/TiO2-PILC catalysts76823。
室温下水相中的Stille 反应陆国平1,*1南京理工大学化工学院，南京孝陵卫200号，210094*E-mail: glu@卤代芳烃和有机锡试剂的Stille 反应可以在室温下水相中完成。
向水相中加入非离子型表面活性剂TPGS-750-M [1,2]，可以有效地促进水相Stille 反应的进行。
该合成方法避免了反应过程中具有潜在毒性的有机溶剂的使用，同时具有反应产率高、底物范围广、立体选择性高等优点，而这些优点大大提高了其在全合成中应用的可能性。
关键词：水相胶束；表面活性剂；TPGS-750-M ；Stille 反应参考文献：[1] Lipshutz, B. H.; Ghorai, S.; Abela, A. R.; Moser, R. J. Org. Chem. 2011, 76: 4379.[2] Lu, G.-p.; Cai, C.; Lipshutz, B. H. Green Chem. 2013, 15: 105.Stille couplings in water at room temperatureGuo-ping Lu a,*a Chemical Engineering College, Nanjing University of Science & Technology,Xiaolingwei 200, Nanjing, 210094Stille couplings can be performed in water typically at room temperature by employing nanoreactors formed from the nonionic designer surfactant TPGS-750-M. The catalyst systemPd(P(t -Bu)3)2/DABCO leads, in most cases, to a wide range of couplings between variousorganostannanes and both aryl and alkenyl halides. The newly developed procedures areenvironmentally friendly in that no organic solvent is required in these couplings, limited amountsof water are invested, and workup entails only an in-flask extraction with a minimal amount of asingle, recoverable organic solvent. These reactions take place in high yields and stereoselectivity,thereby offering considerable potential for applications to complex targets in organic synthesis.。
催化剂原位表征进展沈菊李;史鸿鑫;国海光;刘化章【期刊名称】《浙江工业大学学报》【年(卷),期】2002(030)005【摘要】评述了催化剂原位表征的进展和应用.回顾了第12届国际催化会议上有关原位表征的研究结果,阐明了原位研究对催化剂的研究和开发的重要性.分原位FT-IR、原位XAFS、"原位"XPS、联合原位表征技术及新的原位表征技术五个方面概述了原位表征的最新研究进展.原位FT-IR在催化剂原位表征仍占主导地位,是获取催化剂表面上反应物、中间体和产物结构和浓度信息的一种有力手段.原位XAFS 富含化学和结构信息.讨论了"原位"XPS的实施方法和运用.介绍了三种新的原位表征技术:流出物响应分析、镜样分析、高温高压下的原位STM研究.【总页数】7页(P505-510,519)【作者】沈菊李;史鸿鑫;国海光;刘化章【作者单位】浙江工业大学,化工学院,浙江,杭州,310032;浙江工业大学,化工学院,浙江,杭州,310032;浙江工业大学,化工学院,浙江,杭州,310032;浙江工业大学,化工学院,浙江,杭州,310032【正文语种】中文【中图分类】O643.36【相关文献】1.纳米电催化剂的原位透射电镜表征 [J], 张星;曹安民;万立骏2.甲烷氧化偶联催化剂和部分氧化反应机理的原位及非原位谱学表征 [J], 翁维正;龙瑞强;陈明树;万惠霖3.AlPW12O40@C催化剂的原位合成、表征及催化合成乙酸正丁酯 [J], 程超;曹小华;徐常龙;谢宝华;占昌朝4.二氧化铈催化剂的氧化还原和酸碱性质的原位光谱表征 [J], 王翔;李美俊;吴自力5.纳米材料蛋白冠的非原位和原位表征技术研究进展 [J], 程世超因版权原因，仅展示原文概要，查看原文内容请购买。
细胞内AhR 信号转导通路的机制研究*庞朋沙过倩萍伍会健△（大连理工大学生命科学与技术学院辽宁大连116024）摘要：芳香族化合物受体（(Aryl hydrocarbon receptor,AhR ）是一个属于碱性螺旋-环-螺旋（basic helix-loop-helix (bHLH)）Per-Arnt-Sim 同源域(Per-Arnt-Sim homology domain (PAS))家族的转录因子。
在外界环境激素2,3,7,8-四氯-二苯并-对-二恶英（2,3，7，8-tetrachlorodibenzo-p-dioxin,2,3,7,8-TCDD ）的刺激下，AhR 从细胞质中转运入细胞核中，与另一个蛋白AhR 核转运蛋白(AhR nuclear transportor ，ARNT)结合，形成异二聚体，结合在下游靶基因上，使相应基因，如细胞色素(cytochrome P4501A1/cytochrome P4501B1,CYP1A1/CYP1B1)等异常表达，从而干扰动物的内分泌，引起免疫毒性，甚至导致癌症的发生。
AhR 的激活过程，涉及多种蛋白修饰的变化，如磷酸化、泛素化等，这些修饰调控了蛋白的定位、活性、稳定性等。
AhR 信号转导通路，与其他的很多通路，如E2-ER,MAPK 通路等相互交叉。
本文旨在描述细胞内AhR 通路的激活过程，功能，以及与其他通路之间相互的调控作用，以期为TCDD 引发的相关疾病的预防和治疗提供思路。
关键词：AhR ；TCDD ；磷酸化；泛素化中图分类号：Q78文献标识码：A 文章编号：1673-6273（2010）13-2567-04Biological Role of AhR Signaling Pathway*PANG Peng-Sha,GUO Qian-Ping,WU Hui-Jian △(School of Life Science and Biotechnology,Dalian University of Technology,Dalian,116024,China)ABSTRACT:AhR (Aryl hydrocarbon receptor)is a transcription factor belongs to the basic helix-loop-helix (bHLH)Per-Arnt-Sim homology domain (PAS)family.When binds with the ligand 2,3,7,8-TCDD (2,3，7，8-tetrachlorodibenzo-p-dioxin),AhR is activated and translocates from cytoplasm to nuclear,forming heterodimer with ARNT (AhR nuclear transportor)and binding to DNA elements and leading to abnormal expression of the target genes such as CYP1A1/CYP1B1(cytochrome P4501A1/cytochrome P4501B1),which finally causes several diseases including cancer.There are several modifications during the activation of AhR,including phosphorylation and ubiquitination and so on,which are related to the localization,activity and stability of proteins.AhR signal pathway also cross-talks with E2-ER and MAPK pathways.This article aims to describe the activation and functions of AhR,and the interactions with other path-ways,hoping to give insights into the prevention and therapy of diseases caused by TCDD.Key Words:AhR ；TCDD ；Phosphorylation ；Ubiquitination Chinese Library Classification:Q78Document code:A Article ID:1673-6273(2010)13-2567-04*基金项目：国家自然科学基金(30670409；30771221)，科技部863计划(2006AA02Z120)作者简介：庞朋沙(1987-)，女，硕士研究生，主要研究方向：乳腺癌的发病机制，电话：+86-411-84709105，E-mail:pangpengsha126@ △通讯作者：伍会健，电话：+86-411-84706105，传真：+86-411-84706105，E-mail:wuhj@ （收稿日期：2010-05-05接受日期：2010-05-31）前言二恶英(Dioxin)，是一种无色无味具有强毒性的环境污染物，主要来源于城市和工业垃圾的焚烧。
第３０卷第１０期应用化学Ｖｏｌ．３０Ｉｓｓ．１０２０１３年１０月 ＣＨＩＮＥＳＥＪＯＵＲＮＡＬＯＦＡＰＰＬＩＥＤＣＨＥＭＩＳＴＲＹ Ｏｃｔ．２０１３铝离子与羟基功能化荧光碳点的相互作用方静美 刘利芹 赵希娟 李原芳（西南大学化学化工学院，发光与实时分析教育部重点实验室 重庆４００７１５）摘 要 研究了铝离子（Ａｌ３＋）与表面带有大量羟基的荧光碳点之间的相互作用。
当Ａｌ３＋的浓度在０ ２～８μｍｏｌ／Ｌ时，碳点的荧光随其浓度的增大而逐渐被猝灭；继续增大Ａｌ３＋的浓度，碳点的荧光逐渐恢复。
借助Ｚｅｔａ电位与动态光散射（ＤＬＳ），初步探讨了二者的作用机理。
Ａｌ３＋极易结合碳点表面的羟基，拉近碳点之间的距离引起碳点聚集，从而导致荧光猝灭；当碳点表面的羟基与Ａｌ３＋完全配位后，碳点表面的负电荷转变为正电荷，由于静电排斥作用和空间效应，聚集的碳点重新分散，致使荧光恢复。
对比Ｃｒ３＋和Ｆｅ３＋与荧光碳点的作用，发现它们对荧光碳点只有较强的猝灭作用，在高浓度时却未出现碳点荧光恢复的现象，这归因于Ａｌ３＋易形成两性氢氧化物。
关键词 碳点，荧光，铝离子，Ｚｅｔａ电位，动态光散射中图分类号：Ｏ６５７．３ 文献标识码：Ａ 文章编号：１０００ ０５１８（２０１３）１０ １１４４ ０５ＤＯＩ：１０．３７２４／ＳＰ．Ｊ．１０９５．２０１３．２０５５７碳点（ＣａｒｂｏｎＤｏｔｓ，ＣＤｓ）作为新型荧光碳纳米材料，近年来引起越来越多研究学者的广泛关注。
它不仅具有优良的光学性能和小尺寸特性，而且还具有良好的生物相容性与极低的生物毒性［１ ４］。
近年来，半导体荧光量子点作为荧光纳米探针在生物、医疗等领域得到了广泛的应用，然而量子点中的重金属离子对生物和环境均具有很强的毒性，所以其应用受到了一定的限制［５ ６］。
因此，碳点可有望替代量子点而被广泛应用到生物成像及检测等领域。
最近，我们报道了一种合成表面羟基化荧光碳点的新方法［７］。
所得碳点具有较好的荧光性能、强的水溶性以及低细胞毒性等优点。
3细胞自噬及其在肝纤维化中的作用代倩兰，刘绍能中国中医科学院广安门医院消化内科，北京１０００５３摘要：自噬是指真核细胞内细胞器、蛋白质等在溶酶体中被降解及其降解产物被重新利用的过程，其对细胞的增殖、分化及稳态起着重要作用。
近年来，自噬在肝纤维化中的作用受到越来越多的关注，干预自噬也许成为治疗肝纤维化的新方法。
总结了自噬的过程、功能及在肝纤维化中作用，这些研究揭示了自噬对肝纤维化作用机制的复杂性，也启示未来需要找到干预自噬更加可靠、确定的机制和靶点，进而为治疗肝纤维化提供新途径。
关键词：自噬；肝硬化；肝星状细胞中图分类号：Ｒ５７５．２ 文献标志码：Ａ 文章编号：１００１－５２５６（２０２１）０６－１４４０－０５ＲｏｌｅｏｆａｕｔｏｐｈａｇｙｉｎｌｉｖｅｒｆｉｂｒｏｓｉｓＤＡＩＱｉａｎｌａｎ，ＬＩＵＳｈａｏｎｅｎｇ．（ＤｅｐａｒｔｍｅｎｔｏｆＧａｓｔｒｏｅｎｔｅｒｏｌｏｇｙ，Ｇｕａｎｇ’ａｎｍｅｎＨｏｓｐｉｔａｌ，ＣｈｉｎａＡｃａｄｅｍｙｏｆＣｈｉｎｅｓｅＭｅｄｉｃａｌＳｃｉｅｎｃｅｓ，Ｂｅｉｊｉｎｇ１０００５３，Ｃｈｉｎａ）Ａｂｓｔｒａｃｔ：Ａｕｔｏｐｈａｇｙｒｅｆｅｒｓｔｏｔｈｅｐｒｏｃｅｓｓｉｎｗｈｉｃｈｏｒｇａｎｅｌｌｅｓａｎｄｐｒｏｔｅｉｎｓｉｎｅｕｋａｒｙｏｃｙｔｅｓａｒｅｄｅｇｒａｄｅｄｉｎｌｙｓｏｓｏｍｅｓａｎｄｔｈｅｉｒｄｅｇｒａｄａｔｉｏｎｐｒｏｄｕｃｔｓａｒｅｒｅｕｓｅｄ，ａｎｄｉｔｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｃｅｌｌｐｒｏｌｉｆｅｒａｔｉｏｎ，ｄｉｆｆｅｒｅｎｔｉａｔｉｏｎ，ａｎｄｈｏｍｅｏｓｔａｓｉｓ．Ｉｎｒｅｃｅｎｔｙｅａｒｓ，ｔｈｅｒｏｌｅｏｆａｕｔｏｐｈ ａｇｙｉｎｌｉｖｅｒｆｉｂｒｏｓｉｓｈａｓａｔｔｒａｃｔｅｄｍｏｒｅａｎｄｍｏｒｅａｔｔｅｎｔｉｏｎ，ａｎｄｉｎｔｅｒｖｅｎｔｉｏｎｏｆａｕｔｏｐｈａｇｙｍａｙｂｅｃｏｍｅａｎｅｗｍｅｔｈｏｄｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｌｉｖｅｒｆｉｂｒｏｓｉｓ．Ｔｈｉｓａｒｔｉｃｌｅｓｕｍｍａｒｉｚｅｓｔｈｅｐｒｏｃｅｓｓａｎｄｆｕｎｃｔｉｏｎｏｆａｕｔｏｐｈａｇｙａｎｄｉｔｓｒｏｌｅｉｎｌｉｖｅｒｆｉｂｒｏｓｉｓ．Ｔｈｅｓｅｄａｔａｒｅｖｅａｌｔｈｅｃｏｍｐｌｅｘｍｅｃｈａｎｉｓｍｏｆａｃｔｉｏｎｏｆａｕｔｏｐｈａｇｙｉｎｌｉｖｅｒｆｉｂｒｏｓｉｓａｎｄｐｏｉｎｔｏｕｔｔｈｅｎｅｅｄｔｏｆｉｎｄｍｏｒｅｒｅｌｉａｂｌｅａｎｄｄｅｆｉｎｉｔｅｍｅｃｈａｎｉｓｍｓａｎｄｔａｒｇｅｔｓｆｏｒａｕｔｏｐｈａｇｙｉｎｔｅｒｖｅｎ ｔｉｏｎｉｎｔｈｅｆｕｔｕｒｅ，ｓｏａｓｔｏｐｒｏｖｉｄｅｎｅｗｗａｙｓｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｌｉｖｅｒｆｉｂｒｏｓｉｓ．Ｋｅｙｗｏｒｄｓ：Ａｕｔｏｐｈａｇｙ；ＬｉｖｅｒＣｉｒｒｈｏｓｉｓ；ＨｅｐａｔｉｃＳｔｅｌｌａｔｅＣｅｌｌＤＯＩ：１０．３９６９／ｊ．ｉｓｓｎ．１００１－５２５６．２０２１．０６．０４６收稿日期：２０２０－１１－２３；修回日期：２０２０－１２－１６基金项目：国家自然科学基金（８１９７３８３２）作者简介：代倩兰（１９９１—），女，主要从事肝纤维化的基础和临床研究通信作者：刘绍能，ｌｉｕｓｈａｏｎｅｎｇ＠１２６．ｃｏｍ 自噬是机体维持内环境稳态的重要机制，也是近年来国内外研究的热点。
“原位”红外光谱追踪反应条件下催化体系的变化潘伟雄;刘金尧;李升平;夏云菊;刘殿求【期刊名称】《高等学校化学学报》【年(卷),期】1982(3)S01【摘要】为了观察和监测反应条件下中间产物和催化剂的变化,自行设计并安装了高温高压红外流动池。
池体用不锈钢制成,窗口材料为NaCl或CaF_(2)。
它可承受100atm和200℃。
整个测量系统包括高压釜、循环泵、红外池等。
用Microlab-600型红外分光光度计记录图谱。
池内温度和压力与反应釜桐同,可对反应液体、气体或气液混合物进行“原位”追踪。
当用铑膦络合物催化剂进行丙烯氢甲酰化反应时,在近于工业反应条件下(t=10O℃,P=17atm,正丁醛溶剂),检测到催化剂母体Rh(acac)(CO)(PPh_(3))转化为活性物种RhH(CO)_(2)(PPh_(3))_(2);在合成气压力较低时,只转化为RhH(CO)(PPh_(3))_(3);此活性物种随催化剂失活而消失。
催化剂加氧失活后,检测到配位体三苯基膦氧化为氧化三苯基膦,催化剂生成二聚物,丙烯氧化成丙酮,追踪到原料气CO氧化为CO_(3)的动态过程。
本文对“原位”红外光谱实验方法、高温高压红外池作了介绍,并给出有关实验数据和结果。
【总页数】7页(P107-113)【关键词】三苯基膦;气液混合物;丙烯氧化;正丁醛;红外分光光度计;反应釜;催化剂失活;窗口材料;【作者】潘伟雄;刘金尧;李升平;夏云菊;刘殿求【作者单位】清华大学化学化工系【正文语种】中文【中图分类】TQ2【相关文献】1.原位漫反射红外光谱研究氮氧化物在Ag-ZSM-5催化剂上的吸附态及选择性催化还原反应机理 [J], 张平;王乐夫2.原位Raman光谱揭示中性条件下硫化钼结构变化对其电催化析氢反应的促进作用 [J], Yamei Li;Ryuhei Nakamura3.原位漫反射傅里叶变换红外光谱研究锰铁基催化剂上低温选择性催化还原反应机理 [J], 陈婷;管斌;林赫;朱霖4.温和条件下甲醛在Pt/TiO_2上催化氧化反应的原位漫反射红外光谱研究 [J], 何运兵;纪红兵5.氧化铁系催化剂上乙苯脱氢反应机理研究(Ⅰ)——乙苯吸附态的“原位”红外光谱及脱氢反应的动力学同位素效应 [J], 陈建平;何淡云;曹守镜因版权原因，仅展示原文概要，查看原文内容请购买。
DOI：10.3969/j.issn.l674-2591.2021.01.011•综述・钙敏感受体激活性和失活性突变所致骨矿代谢异常疾病及治疗董冰子，李成乾，孙晓方［摘要］钙敏感受体(calcium-sensing receptor,CaSR)是感知细胞外钙离子浓度，调节甲状旁腺素分泌及尿钙重吸收，维持钙稳态的关键受体。
CaSR激活性和失活性突变导致钙调定点的移动，引起相应的钙矿物质代谢异常疾病和骨代谢异常表现。
本文综述CaSR突变所致疾病的发病机制、临床表现、治疗策略，通过动物实验模型阐述CaSR的病理生理功能，并探讨针对上述疾病的治疗及CaSR配体药物的研究进展。
［关键词］钙敏感受体；家族遗传性低尿钙性高钙血症；常染色体显性遗传性低钙血症；溶钙素；拟钙剂中图分类号：R589文献标志码：AGain and loss-of-function mutations of calcium-sensing receptor associated boneand mineral metabolic disorders and the therapiesDONG Bing-zi,LI Cheng-qian,SUN Xiao-fangDepartment of Endocrinology and Metabolism,The Affiliated Hospital of Qingdao University,Qingdao266003,Shandong,China[Abstract]Calcium-sensing receptor(CaSR)senses the extracellular calcium concentration,regulates the parathyroid hormone(PTH)secretion，and renal calcium reabsorption，plays an important roles in maintaining the calcium homeostasis.Gain and loss-of-function mutations of CaSR lead to the shift of calcium set-point，and result in the mineral and bone diseases.We reviewed the pathophysiology of diseases associated with activating and inactivating mutations of CaSR,and their clinical characteristics,therapeutic strategy,and animal models.To achieve better understanding of CaSR，the allosteric modulators of CaSR may become promising therapeutic options.[Key words]calcium-sensing receptor；familial hypocalciuric hypercalcemia；autosomal dominant hypocalcemia；calcilytics；calcimimetics钙敏感受体(calcium-sensing receptor，CaSR)主要表达于甲状旁腺、肾脏、骨组织、肠道等,通过感受细胞外钙离子浓度，调节甲状旁腺主细胞对甲状旁腺素(parathyroid hormone,PTH)的合成和释放，同时调节肾小管对钙的重吸收，是维持机体钙稳态的关键受体［1］。
/JPCC Green Approach To Prepare Graphene-Based Composites with High Microwave Absorption CapacityXin Bai,Yinghao Zhai,and Yong Zhang*State Key Laboratory of Metal Matrix Composites,School of Chemistry and Chemical Engineering,Shanghai Jiao Tong University, 200240Shanghai,P.R.Chinab Supporting Information’INTRODUCTIONGraphene,two-dimensional planar sheets composed by sp2-bonded carbon atoms,has drawn great attention due to its unique topological structures and interesting properties.A monolayer of graphene is a material endowed with the highest Young’s modulus (∼1000GPa)based on theoretical and experimental results.1 Thermal conductivity of graphene is5000W mÀ1KÀ1,compar-able with the highest value of reported single-walled carbon nanotubes(SWNTs).2In addition,electrical conductivity of graphene can be up to6000S cmÀ1,3and its high aspect ratio can help to constitute effective network inside graphene compo-sites at low graphene content,which promises its potential applications in microwave absorption(MA)fields.Microwave radiation is potentially harmful to biological systems,which are exposed to microwave for a considerable period of time.4,5MA materials are of great significance for their capacity of suppressing microwave radiations.High permittivity is crucial for composites with electrically conductive or dielectricfillers to raise MA capacity.SWNT/polymer composites with high real and imagin-ary permittivity in the frequency of0.5À2GHz were reported by Grimes et al.6Micheli et al.7studied the effect of carbon inclusion size and geometry on electromagnetic properties of epoxy com-posites in X-band(8.2À12.4GHz),in which SWNTs and carbon nanofibers showed high dielectric permittivity and MA capability, while granular graphite of microsize showed limited MA capacity. Liang et al.8reported the high electromagnetic interference(EMI) shielding efficiency for epoxy resinfilled with graphene.But up to now,few studies have been realized insofar as the MA capacity of graphenefilled polymer composites is concerned.So far,large volume production of high electrically conductive graphene remains a big challenge in graphene researchfield.Among various synthesis approaches toward graphene,chemical reduction approach is favorable for its scalable productivity and flexible functionalization of graphene.Hydrazine was much more frequently used to reduce graphene oxide(G-O)due to its high reduction efficiency.9À14Unfortunately,hydrazine and their derivatives are toxic and harmful to human as well as the environment.Zhang et al.15and Gao et al.16reported a green method to reduce G-O with L-ascorbic acid(L-AA)in aqueous media,which is environmentally friendly.Their researches were both conducted in aqueous media showing environmentally friendly.Meantime,L-AA possessed higher reduction efficiency concerning the electrical conductivity of the as-prepared chemi-cally reduced graphene(CR-G)in comparison with such re-ductants as ammonia and potassium hydroxide,etc.17If G-O is highly reduced without surfactants,it will cause inevitable aggregation,11,18À20making it difficult to be uniformly dispersed in polymers.In our research,composites of G-O and poly-(ethylene oxide)(PEO)were prepared by a simple aqueous mixing method,and then G-O was in situ reduced by L-AA.X-ray diffraction(XRD)analysis showed CR-G sheets were dispersed in PEO matrix with exfoliated structure.Microwave measure-ment showed CR-G/PEO composites had high complex per-mittivity on account of large aspect ratio and uniform dispersionReceived:March15,2011Revised:May10,2011prevent agglomeration during the process of reduction.CR-G/PEOdispersion of electrically conductive CR-G with high aspect ratio.CR-capacity as its minimum reflection loss isÀ38.8dB.CR-G sheets microwave energy into heat effectively as well as dielectric relaxationPublished:May19,2011of CR-G along with large interface between CR-G and PEO.The composites had excellent MA capacity with reflection loss of À38.8dB,which could be attributed to the pronounced con-duction loss,dielectric relaxation,and interface scattering.’EXPERIMENTAL SECTIONPreparation of Graphite Oxide(GO).GO was prepared using a modified Hummers method21from flake graphite.Briefly, flake graphite(5g)and NaNO3(3g)were put into a flask,and concentrated H2SO4(120mL,98%)was added under stirring in an iceÀwater bath.KMnO4(22.5g)was slowly added to the above mixture over1h and followed by continuously stirring at 23°C for2h.Then H2SO4aqueous solution(700mL,5wt%) was slowly added under stirring,and the temperature was kept at 98°C.When the temperature was decreased to60°C,H2O2 aqueous solution(15mL,30wt%)was added.The product was washed with HCl solution(5wt%)and distilled water several times and freeze-dried.Preparation of G-O/PEO Composites.GO(25mg)was dispersed in water(50mL)in an ultrasonic bath for1h at23°C to yield a clear solution.In this process,GO was completely exfoliated down to individual sheets to form a stably dispersed G-O/H2O solution.Meanwhile,PEO(2.5g,molecular mass, 1.5Â106)was dissolved in water(80mL)at room temperature. The G-O dispersion was gradually added to the PEO solution and sonicated for1h at23°C to form uniform solution of G-O/PEO composite(1/100w/w).G-O/PEO composite (5/100w/w)was prepared following the same procedure.The densities of GO and PEO are2.2and1.2g cmÀ3,so the volume ratios of G-O/PEO composites(1/100w/w)and(5/100w/w) are0.54and2.6vol%,respectively.Preparation of CR-G/PEO Composites.G-O was in situ reduced by L-AA in the G-O/PEO solution.Typically,L-AA (250mg)was added into G-O/PEO(0.54vol%)aqueous solution and stirred at50°C for24h.When the reaction ended, the color of the solution turned from yellow to dark black, indicating G-O was successfully reduced into CR-G.The solu-tion was dried under vacuum at60°C until its weight kept unchanged.CR-G/PEO composites were press-molded at80°C under the pressure of5MPa for testing.Characterization.Atomic force microscopy(AFM)images of CR-G were taken in the tapping mode by carrying out on NanoNavi II,with samples prepared by spin-coating sample solutions onto freshly exfoliated mica substrates and dried at 80°C under vacuum.Transmission electron microscopy(TEM) was carried out on a JEOL JEM-2010electron microscope at200 kV,and samples were prepared by depositing a drop of solution containing CR-G on a carbon-coated copper grid and dried at ambient temperature prior to analysis.UVÀvis absorption spectra were recorded at room temperature on a Perkin-Elmer Lambda20UVÀvis spectrophotometer.Raman spectra were measured on a Jobin Yvon LABRAM-1B multichannel confocal microspectrometer with632.8nm laser excitation.X-ray photo-electron spectroscopy(XPS)spectra were collected on a Perkin-Elmer PHI5000C ESCA system using Al K R radiation.XRD spectra were acquired by D/max-2200/PC using Cu K R radia-tion.Scanning electronic microscopy(SEM)images were taken on a JSM-7401F field-emission SEM system.For microwave measurement,cylindrical toroidal specimens with an outer diameter of7.0mm,inner diameter of3.04mm,and thickness of4.0mm were set in a coaxial line.Microwave scattering parameters(S parameter,S ij,i,j=1,2)were measured using an Agilent8722ES vector network analyzer in the frequency range of2À18GHz.Then complex permittivity(εr=ε0Àjε00) was calculated from the S parameters according to the literature.22Since no ferromagnetic materials were involved in our experiment,complex permeability was considered to be that of free space(μr=1).Electrical conductivity test was performed on SB100A/2digital four-point probe system(Shanghai,P.R. China).’RESULTS AND DISCUSSIONIn our study,GO was prepared by a modified Hummers method.After mild sonication,GO was homogenously dispersed in water to form G-O and further reduced by L-AA.AFM was applied to determine the aspect ratio of CR-G.An AFM image of typical CR-G sheets is shown in Figure1a with the height profile. CR-G sheets wereflat with a lateral size of∼1.5μm and thickness of∼1nm,implying CR-G sheets existed in water with exfoliated structure and the aspect ratio of CR-G sheets were∼1500. UVÀvis spectra are effective to trace the reduction process.As shown in Figure1b,typical absorbing peaks appeared at234and 298nm in the curve of G-O,corresponding to theπÀπ* transitions of aromatic C d C bonds and nÀπ*transitions of C d O bonds,respectively.The CR-G had a peak at261nm that was red-shifted from234nm for G-O.The absorption intensity of the entire spectrum increased dramatically,indicating that the G-O might be reduced and the aromatic structure might be restored gradually,which was in agreement with the reported article.12The reduction process could also be proved by XPS. Figure1c,d shows the C1s XPS spectra of GO and CR-G.GO had three different peaks centered at284.6,286.5,287.1,andFigure1.(a)A tapping mode AFM image of CR-G sheets with the height profile,(b)UVÀvis spectra of CR-G,(c)the C1s peak in the XPS spectra of GO,and(d)CR-G.288.4eV,corresponding to C d C/C ÀC in aromatic rings,C ÀO (epoxy and alkoxy),C d O groups,respectively.Although the three types of carbon remained in Figure 1d,the intensity of the peaks corresponding to oxygen-containing groups decreased to a large extent compared with GO,showing the high reduction e fficiency of L-AA.TEM with selected area electron di ffraction (SAED)pattern of CR-G and Raman spectra of GO and CR-G results also proved the reduced exfoliated structure of CR-G when prepared with this approach (Supporting Information S1and S2).To obtain CR-G composites,CR-G was prepared in the presence of PEO.G-O/PEO composites were prepared through a simple aqueous mixing method and further reduced by L-AAin situ as described in the Experimental Section.XRD is a powerful tool to determine the dispersion of fillers in polymer matrix.23,24As shown in Figure 2,a di ffraction peak of pristine graphite is observed at 26.4°,indicating the distance between layers of graphene was 0.35nm according to the Bragg equation.After graphite was oxidized,the di ffraction peak shifted to 11.0°,indicating the distance between layers was expanded to 0.8nm,which made it possible for polymers to intercalate into GO sheets.PEO is a typical crystalline polymer showing strong peaks at about 19°and 24°.The peak at 24°was a combination of the (112)and (032)re flections,and the peak at 19°corresponded to the (120)re flection.Similar to poly(vinyl alcohol),23PEO could interact with G-O through hydrogen bonding,25giving rise to exfoliated structure of G-O in polymer matrix,and the XRD pattern of CR-G/PEO composite (2.6vol %)only showed the di ffraction peaks similar to PEO.Neither the di ffraction peak of graphite nor the peak of GO appeared,indicating CR-G sheets have been exfoliated into monolayers in the PEO matrix,which is in accordance with SEM results (Supporting Information S3).That may be attributed to PEO acting as a barrier for CR-G,which prevented the agglomeration of CR-G during the reduction process.As important parameters for microwave electromagnetic proper-ties,the real part (ε0)and imaginary part (ε00)of complex permittivity of PEO and its composites were measured in the frequency range of 2À18GHz (Figure 3a,b).The composites had much higher ε0and ε00than PEO.In X-band that was frequently studied,CR-G/PEO composite (2.6vol %)had ε0ranged from 8.0to 7.3and ε00about 3.1,while PEO had ε0ranged from 3.1to 3.0and ε00about 0.4.CR-G/PEO composites had higher permittivity than most carbon nanotube/polymer composites,while high ε00was of great importance for electrical loss.7,26The ε0of PEO and its composites decreased with increasing frequency in 2À18GHz.The ε00of PEO and CR-G/PEO composite (0.54vol %)decreased with increasing frequency,but the ε00of CR-G/PEO composite(2.6vol %)kept unchanged around 3.1after 11GHz,which may be related to a resonance behavior that was reported for SWNT/polyur-ethane composites when the nanotube concentration was higher than 15wt %.26And a change in dielectric loss factor of composites filled with multiwalled carbon nanotubes was also attributed to resonance.27The dielectric loss factor (tan δe =ε00/ε0)indicates the inherent dissipation of electromagnetic energy for dielectric materials.The frequency dependency of tan δe of PEO and its composites is shown in Figure 3c.The composites have much higher tan δe than PEO.CR-G/PEO composite (2.6vol %)and CR-G/PEO com-posite (0.54vol %)had nearly the same tan δe in low frequencies (2À7.6GHz),but the former had increasing tan δe while the latter had decreasing tan δe at frequencies over 7.6GHz.The re flection loss (RL)of a metal-backed single absorb layer was calculated as follows:RL ðdB Þ¼20logZ inÀ1Z in þ1ð1ÞFigure 2.XRD patterns of PEO,CR-G/PEO composite (2.6vol %),GO,and graphite.Figure 3.Electromagnetic characteristics of CR-G/PEO composites in the 2À18GHz range:(a)real part of complex permittivity,(b)imaginary part of complex permittivity,and (c)dielectric loss factor.while the normalized input impedance (Z in )was calculated byZ in ¼ffiffiffiffiμr εr r tanh j 2πfd c ffiffiffiffiffiffiffiffiμr εr p ð2Þwhere f is the microwave frequency,d is the thickness of theabsorb layer,c is the velocity of electromagnetic wave in vacuum,and εr and μr are the complex relative permittivity and perme-ability,respectively.RL is expected to be as low as possible at a given sample thickness.The calculated RL curves of the CR-G/PEO compo-sites with di fferent thickness are shown in Figure 4.Interestingly,the CR-G/PEO composite (0.54vol %)had the minimum RL less than À10dB,and CR-G/PEO composite (2.6vol %)had the minimum RL of À38.8dB at the optimal sample thickness of 1.8mm and the À10dB absorption frequency ranged from 13.9to 18GHz.The minimum RL of CR-G/PEO composite (2.6vol %)at the thickness of 2.0mm reached À32.4dB,and the À10dB absorption frequency ranged from 12.4to 18GHz.RL of CR-G/PEO composite (2.6vol %)with wide range of thickness (1.8À4.0mm)was less than À25dB,indicating its excellent MA capacity.Considering the low graphene content in the CR-G/PEO composite (2.6vol %),this kind of composites should be a promising light-weighted,high-absorption MA material with potential applications.The high MA capacity of CR-G/PEO composites is attributed to electrical conduction loss,dielectric relaxation,interface scattering,and multiple re flections (as shown in Figure 5),while the absorbed energy is dissipated as heat.When electromagnetic waves propagated within the composites,the directional motion of charge carriers on CR-G formed oscillatory current,and boundary charges induced dielectric relaxation and polarization.7Besides,due to the di fference in complex permittivity betweenCR-G and PEO,pronounced interface scattering would be generated.28The well-dispersed exfoliated CR-G sheets with high aspect ratio could constitute conduction network within the PEO matrix,resulting in high conduction loss.The dielectric relaxation and polarization were mainly induced by interfacial multipoles,which existed along the boundaries between CR-G sheets and PEO matrix.29,30They were related to the interface area,which was the same as the interface scattering.High surface area of CR-G sheets with well dispersion could enhance the attenuation caused by relaxation and scattering.Furthermore,multiple re flections could be induced due to the huge aspect ratio and layered structure of CR-G (Figure 5);thus,the routes of electromagnetic waves propagate in the layer are extended,which brings more e fficient absorption.’CONCLUSIONSA novel MA material CR-G/PEO composite was prepared through a green approach.G-O was in situ reduced by L-AA in PEO aqueous solution to form CR-G/PEO composites.CR-G was uniformly dispersed in the composites as exfoliated structure and conductive filler.The CR-G/PEO composites had high permittivity and very low microwave re flection loss,with great potential to be used in the field of protecting people from microwave radiation.’ASSOCIATED CONTENTbSupporting Information.Raman spectra,TEM of CR-G,and SEM image of CR-G/PEO composite (0.54vol %).This material is available free of charge via the Internet at .’AUTHOR INFORMATIONCorresponding Author*E-mail:yong_zhang@.Tel:þ862154743257.Fax:þ862154741297.’ACKNOWLEDGMENTThis work was financially supported by the National Natural Science Foundation of China (No.50773036and No.51073092).’REFERENCES(1)Lee,C.;Wei,X.;Kysar,J.W.;Hone,J.Science 2008,321,385.(2)Balandin,A.A.;Ghosh,S.;Bao,W.;Calizo,I.;Teweldebrhan,D.;Miao,F.;Lau,C.N.Nano Lett.2008,8,902.(3)Du,X.;Skachko,I.;Barker,A.;Andrei,E.Y.Nature Nanotechnol.2008,3,491.Figure 4.Re flection loss curves for the CR-G/PEO composites with di fferent 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