La—Ba—Cu复合氧化物在催化消除NO反应中催化性能的研究

合成了具有钙钛石结构的复合氧化物ＹＢａ２Ｃｕ３Ｏ７、ＬａＢａ２Ｃｕ３Ｏ７、ＬａＢａＣｕ２Ｏ５、Ｌａ２ＢａＣｕ３Ｏ７和Ｌａ４ＢａＣｕ５Ｏ１２。考察了它们对ＮＯ分解和ＮＯ＋ＣＯ反应的催化性能。结合化学分析、ＸＲＤ、ＴＰＤ和ＴＰＲ对催化剂的表征结构，探讨了该系列复合氧化物对ＮＯ分解和ＮＯ＋ＣＯ反应的催化机理。     

La-Ba-Cu复合氧化物在催化消除NO反应中催化性能的研究

合成了具有钙钛石结构的复合氧化物YBa₂Cu₃O₇、LaBa₂Cu₃O₇、LaBaCu₂O₅、La₂BaCu₃O₇和La₄BaCu₅O₁₂.考察了它们对NO分解和NO+CO反应的催化性能.结合化学分析、XRD、TPD和TPR对催化剂的表征结果,探讨了该系列复合氧化物对NO分解和NO+CO反应的催化机理.     

层状复合氧化物La4BaCu5-xMxO13+λ的制备、表征及对CO还原NO的活性

 采用柠檬酸爆炸法合成了系列层状钙钛矿型复合氧化物La4BaCu5-xMxO13+λ(M=Mn, Co; x=0~5)催化剂. 用TPD, TPR和化学分析法对催化剂进行了表征,考察了催化剂在CO还原NO中的催化活性.结果表明,掺杂Mn, Co后催化剂中的活性氧含量及氧化还原性质发生了变化. 掺杂少量Mn, Co可使催化剂在CO还原NO中的催化活性明显提高,且掺杂Co的样品比掺杂Mn的样品活性提高更明显.这是由于Cu-Mn与Cu-Co之间的协同作用不同导致的结果.     

La2CuO4的制备及其对催化消除NO活性的影响

用四种制备方法：柠檬酸络合爆炸法,聚乙二醇凝胶法,聚丙烯酰胺凝胶法,DTPA络合法合成了La2CuO4.比较了四种方法的特点及其对La2CuO4结构的影响,并对所得La2CuO4在NO-CO反应中的催化活性的影响进行了研究．结果发现聚乙二醇凝胶法和DTPA络合法有利于形成好的晶形,而聚乙二醇凝胶法和聚丙烯酰胺凝胶法对NO-CO反应有较好的活性,这是由于不同制备方法得到的样品中的缺陷的种类和含量不同所致     

NO在Sm2—xSrxNiO4上的催化还原

在具有Ｋ２ＮｉＦ４型结构的Ｓｍ２－ｘＳｒｘＮｉＯ４（ｘ＝０．４，０．５，０．６，０．８，１．０，１．２，１．４，１．５）化合物上进行了ＣＯ催化还原ＮＯ的研究。结果表明，低温、低Ｓｒ＾２＋取借代量与高温、高Ｓｒ＾２＋取代量的反应途径不同，这可从化合物的结构、化合物中金属－氧键的标准生成焓的总和、ＮＯ还原的表现活化能及化合物上Ｏ２的脱附行为等得到解释。     

K2NiF4型Eu2—xSrxCuO4稀土复合氧化物的合成、结构及还原特性

研究了具有K2NiF4型结构的Eu2-xSrxCuO4复合氧化物合成,物相结构及其还原特性。发现用络合凝胶法制备时,Eu2-xSrxCuO4复合氧化物的生成温度为1100℃左右,粉末XRD表明Eu2-xSrxCuO4复合氧化物属四方 晶系,空间群为I4／mmm,其晶胞参数随x的增加而增加,当x≥0.7时,多余的Sr不能进入晶胞而呈游离的SrO形式存在,同时在物相中也存在一定数量的CuO物相,Eu2-xSrxCuO4系列复合氧化物对CO和甲烷的催化氧化反应的活性在x较小随着x的增加而增加。     

铜锰铝水滑石的合成、表征及衍生复合氧化物酸碱催化活性研究

采用低过饱和共沉淀法合成了铜锰铝不同摩尔投料比的碳酸根型水滑石,通过XRD、IR、TG-DTA等手段对样品进行测试和表征。X-衍射结果显示,其M2 /M3 摩尔投料比为2-4得到的水滑石为较满意构型。红外的结果进一步证实了碳酸根离子柱撑CuMnA l水滑石的成功合成,热重-差热分析结果显示随M2 /M3 比的增加,水滑石热稳定性减弱。经焙烧后,发现其复合氧化物催化活性随着Cu含量的增加而增大,随着Mn含量的增加对乙醛的选择性增大,可达到91.6%。     

CuO—ZrO20—CeO2复合氧化物的催化性能研究

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。     

TiO2负载Mn-Co复合氧化物催化剂上NO催化氧化性能

氮氧化物(NO_x)是大气主要污染物之一, 主要来源于化石燃料的燃烧, 其中NO不溶于水难以去除, 催化氧化技术可以将NO氧化为易溶于水可被脱硫装置去除的NO₂, 具有十分重要的实际意义. 本文采用浸渍法制备了不同Mn掺杂量的Mn-Co/TiO₂复合金属氧化物催化剂, 考察了其催化NO氧化的活性. 结果表明, Mn的掺杂对Co/TiO₂催化剂催化NO氧化的活性有明显促进作用, 掺杂量为6%时, Mn(0.3)-Co(0.7)/TiO₂催化剂NO的转化效率最高, 300℃达到88%. 采用X射线衍射(XRD)、N₂吸附/脱附、H₂程序升温还原(H₂-TPR)、O₂程序升温脱附(O₂-TPD)和原位漫反射傅里叶变换红外(in-situ DRFTIR)光谱等技术对催化剂的物理化学特征进行了表征. 结果发现, 当掺杂量为6%时, Mn一方面促进了催化剂表面活性组分的分散, 增加了催化剂的比表面积和孔径; 另一方面提高了催化剂的还原性能, 促进氧的低温脱附, 此外还促进了反应中间产物桥式NO-3向NO₂的反应, 从而提高了Co/TiO₂催化剂的NO氧化活性.     

钙钛矿型复合氧化物在甲烷部分氧化反应中催化性能的研究

自 1 990年以来 ,由甲烷部分氧化制合成气 ( POM)的反应作为对传统甲烷水蒸气重整反应的一个重大改进而受到高度重视 [1] .目前 ,在 POM反应中 ,研究较多的催化剂体系大致可分为贵金属 ( Pt,Pd,Rh,Ru及 Ir) [2 ,3] 以及以 Ni和 Co为主的 B族过渡金属催化剂[4～ 6 ] .最近 ,Hayakawa等 [7,8] 报道了具有钙钛矿结构的复合氧化物 Ca1- x Srx Ti1- y My O3-δ( M=Cr,Fe,Co或 Ni)在甲烷部分氧化制合成气反应中具有一定的催化活性 .本文以本组开发的钙钛矿型复合氧化物 Ba0 .5Sr0 .5Co0 .8Fe0 .2 O3-δ(简称BSCFO)和 Ba0 .5Sr0 .5…     

Co?Cu?Al mixed oxides derived from hydrotalcite-like compound for NO reduction by CO

Various hydrotalcite based catalysts were prepared for catalytic removal of NO (NO reduction by CO). The general formula of hydrotalcite compounds (HTLc) was Co−Cu−Al-HTLc. Precalcination of these materials at 450°C for NO reduction by CO, was necessary for catalytic activity. All catalysts except Co−Al and Cu−Al have very good activity at lower temperature for NO reduction by CO. All samples were characterized by XRD and BET. The tentative reaction mechanism was also proposed.     

Catalytic reduction of NOx by CO on hydrotalcites-derived mixed oxides CoAlM and MgAlM (M=Cr,Mn, Fe,Co, Ni,Cu)

Two series of mixed oxides, GIAlM and MgAlM (M= G, Mn, Fe, Co, Ni, Cu), were prepared by calcining their corresponding hydrotalcite-like compounds (HTLc). The ratio of Mg: Al: M (or Co: Al: M) was 3:1:1. The catalytic activity of all samples for the reaction of NO + CO was investigated. The results showed that the activity of CoAlM was much higher than that of MgAlM. The structure and the property of redox were characterized by XRD and H₂-TPR. The results indicated that only MgO phase was observed after calcining MgAlM hydrotalcites, and the transition metals became more stable. The spinel-like phase appeared in all of CoAlM samples after the calcination, and the transition metals were changed to be more active, and easily reduced. The activities of three series of mixed oxides CoAlCu obtained from different preparation methods, Different ratio of Co: Al: Cu and at different calcination temperatures. were studied in detail for proposing the mechanism of reaction. The ability of adsorption of NO and CO were investigated respectively for supporting the mechanism.     

Catalytic reduction of NO_x by CO on hydro-talcites-derived mixed oxides Co AIM and MgAlM (M = Cr, Mn, Fe, Co, Ni, Cu)

Two series of mixed oxides, CoAlM and MgAlM (M= Cr, Mn, Fe, Co, Ni, Cu) , were prepared by calcining their corresponding hydrotalcite-like compounds (HTLc) . The ratio of Mg: Al: M (or Co: Al: M) was 3:1:1. The catalytic activity of all samples for the reaction of NO CO was investigated. The results showed that the activity of CoAlM was much higher than that of MgAlM. The structure and the property of redox were characterized by XRD and H2-TPR. The results indicated that only MgO phase was observed after calcining MgAlM hydrotalcites, and the transition metals became more stable. The spinel-like phase appeared in all of CoAlM samples after the calcination, and the transition metals were changed to be more active, and easily reduced . The activities of three series of mixed oxides CoAlCu obtained from different preparation methods, different ratio of Co:Al:Cu and at different calcination temperatures, were studied in detail for proposing the mechanism of reaction. The ability of adsorption of NO and CO     

层状复合氧化物La4BaCu5-xMxO13(M=Mn, Co)的物化性质和结构中活性氧的研究

合成了一系列结构为层状ＡＢＯ３的复合氧化物Ｌａ４ＢａＣｕ５－ｘＭｘＯ１３（Ｍ＝Ｍｎ，Ｃｏ），并利用ＸＲＤ、Ｘ射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。ＸＲＤ分析结果表明：它们的结构为五层的ＡＢＯ３结构。活性氧种的研究表明Ｌａ４ＢａＣｕ５Ｏ１３中掺杂Ｍｎ或Ｃｏ之后，样品中明显存在的ＭＣｕ（Ｍ＝Ｍｎ，Ｃｏ）之间的协同作用，并且ＣｕＭｎ之间协同作用明显比ＣｕＣｏ的强。     

锰锆复合氧化物CO催化还原NO性能研究

采用柠檬酸络合法制备了锰锆复合氧化物催化剂,用XRD、H_2-TPR、XPS和SEM等技术进行了表征,研究了其CO催化还原NO性能。结果表明,MnO_x主要以Mn_3O_4物相存在,Zr占比的增加会促进Mn_3O_4物相的分散,引起Mn_3O_4平均晶粒粒径减小;Mn主要有Mn~(2+)、Mn~(3+)、Mn~(4+)离子价态形式,添加Cu和Ce后,(Mn~(3+)+Mn~(4+))含量和表面吸附氧(OA)含量增加,H_2-TPR还原峰温度向低温区偏移,有利于催化活性的提升。Mn-Zr-O复合氧化物的CO催化还原NO活性较低,加入Cu后的Mn-Cu-Zr-O复合氧化物其CO催化还原NO的活性得到改善,而添加Ce后所制备的Mn-Cu-Ce-Zr-O复合氧化物的催化活性进一步提高;在350℃下、反应空速为18000 h~(-1)时,Mn-Cu-Ce-Zr-O复合氧化物表现出较好的CO催化还原NO活性,CO转化率达到了89.17%,NO转化率达到了91.70%。     

Copper oxide on Cu/Al2O3-TiO2 catalystsTG,FTIR-CO absorption and catalytic activity in the NO reduction by CO

TG, FTIR-(CO absorption), and catalytic activity in the NO reduction by CO were used to characterize Cu/Al₂O₃-TiO₂ catalysts prepared by co-gelling aluminum tri-sec-butoxide and titanium iso-propoxide at pH 9 and at pH 3 gelling conditions. Under nitrogen flow, copper oxide decomposition, oxygen storage capacity (OSC) and sample dehydroxylation (total mass loss) was followed by TG. The CuO decomposition forming Cu⁰, Cu⁺¹ was observed by means of FTIR (CO absorption) spectra. In pH 9 sample the large amount of Cu⁰ was observed. At low total mass loss and high Cu⁰/Cu⁺¹+Cu⁺² ratio (pH 9 sample) a lowest light-off in the NO reduction by CO was observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of sol-gel derived Al2O3-ZrO2 and Al2O3-TiO2 oxides on the selectivity of NO reduction by CO under oxidizing conditions

The role of Al₂O₃-ZrO₂ and Al₂O₃-TiO₂ sol-gel prepared supports in the activity of platinum for the NO reduction by CO under oxidizing conditions has been studied. ²⁷Al MAS-NMR spectra have shown the formation of pentacoordinate Al^V in alumina-zirconia support. ZrO₂ or TiO₂ crystalline phases cannot be identified by XRD diffraction, suggesting the formation of nanosized structures supported on alumina. When the reaction was carried out in presence of oxygen, large amounts of NO₂ were observed on Pt/Al₂O₃-ZrO₂catalyst, while the formation of N₂O is more prononced on Pt/Al₂O₃-TiO₂ catalyst. The effect of water during NO reduction is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

甲烷在金属铁及氧化铁表面还原NO的研究

在程序控温电加热水平陶瓷管反应器、N₂气氛和模拟烟气气氛及300~1 100℃时,对甲烷在金属铁及其氧化铁表面还原NO的特性进行了实验研究。为使甲烷在脱硝反应后完全燃尽以及脱硝反应过程生成的CO等中间产物完全燃尽,在第一段加热炉后串联了第二段加热炉,补充氧气,实现燃尽。结果表明,甲烷在金属铁及氧化铁表面能够高效地还原NO。在N₂气氛中,在900℃以上温度范围内甲烷在金属铁表面的脱硝效率超过95%,与甲烷在氧化铁表面的脱硝效率差别很小。在模拟烟气条件下,当过量空气系数小于1.0时,在900℃以上时,甲烷在金属铁和氧化铁表面的脱硝效率都能超过90%,且未燃尽和燃尽两种条件下NO的还原率相差不大。NO同时通过金属铁的直接还原和甲烷的再燃还原两种反应机理脱除。而甲烷则通过还原氧化铁为金属铁,从而使金属铁直接还原NO可持续进行。同时,甲烷再燃反应的中间产物HCN/NH₃等被氧化铁还原,从而使燃尽后的脱硝效率不下降。研究结果表明,甲烷和金属铁或氧化铁在富燃料条件下可有效地还原NO。     

Characterization and catalytic behavior of La2 - x (Sr, Th)xCuO4 ± λ in reaction NO+CO

Two mixed oxide systems La₂-_xSr_xCuO_{4± λ} (0.0⩽x⩽1. 0) and La_2-xTh_xCuO_{4± λ} (O. O⩽x⩽ 0.4) with K₂NiF₄ structure were prepared by varyingx values. Their crystal structures were studied by means of XRD and IR spectra. The average valence of Cu ion at B site, nonstoichiometric oxygen (λ) and the chemical composition in the bulk and on the surface of the catalysts were measured by means of chemical analysis and XPS. The catalytic behavior in reaction CO+NO was investigated under the regular change of average valence of Cu ion at B site and nonstoichiometric oxygen (λ). Meanwhile, the adsorption and activation of the small molecules NO and the mixture of NO+CO over the mixed oxide catalysts were studied by means of MS-TPD. The catalytic mechanism of reaction NO+CO over these oxide catalysts were proposed; and it has been found that, at lower temperatures the activation of NO is the rate determining step and the catalytic activity is related to the lower valent metallic ion and its concentration, while at higher temperatures the adsorption of NO is the rate determining step and the catalytic activity is related to the oxygen vacancy and its concentration. Project supported by the National Natural Science Foundation of China.