ZrO2对Mn—O／γ—Al2O3催化剂中表面氧性能的影响

用ＴＰＤ－ＭＳ和ＴＰＲ技术研究了Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３和Ｍｎ－Ｏ／ＺｒＯ＋γ－Ａｌ２Ｏ３催化剂中表面氧的脱附、还原性能和再生氧化恢复性能，并用ＸＲＤ对催化剂的固相结构进行了表征。结果表明，Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３或Ｍｎ－Ｏ／ＺｒＯ２＋γ－Ａｌ２Ｏ３催化剂上存在ＭｎＯ２、Ｍｎ２Ｏ３和少量Ｍｎ３Ｏ４物种。ＺｒＯ２的存在不影响Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３的ＴＰＲ的ＴＰＤ的特征峰，但使ＭｎＯ２的量明显增加，     

掺杂ZrO2的Pt／Al2O3表面氧化性质及一氧化碳氧化性能研究

用ＴＰＤ－ＭＳ，ＴＰＳＲ－ＭＳ及ＣＯ氧化活性测定等方法研究了Ｐｔ／Ａｌ２Ｏ３和掺杂超细ＺｒＯ２的样品的表面氧脱－恢复性能，ＣＯ表面氧化性能有催化氧化性能。结果表明，在Ｐｔ／Ａｌ２Ｏ３中掺杂ＺｒＯ２后，样品表面上的氧物种脱出和氧经恢复性能明显提高，脱氧量也明显增大。     

制备方法对MoO_3／ZrO_2结构的影响及MoO_3／ZrO_2固体超强酸的结构特征 Ⅱ．活性组分存在形态的研究

ＬＲＳ，ＸＲＤ，ＸＰＳ结果表明，仲钼酸铵浸渍仅经干燥的Ｚｒ（ＯＨ）４再焙烧制得的固体超强酸（ＭｏＯ３／ＺｒＯ２（Ⅰ））与浸渍晶态ＺｒＯ２制得的部分氧化催化剂（ＭｏＯ３／ＺｒＯ２（Ⅱ）中，活性组分的存在形式明显不同．在ＭｏＯ３／ＺｒＯ２（Ⅱ）中，ＭｏＯ３以二维聚钼酸根形式单层分散在ＺｒＯ２上（其中单斜ＺｒＯ２为主），在～９５０ｃｍ－１处出现特征拉曼宽峰，超出单层分散容量的部分以晶态ＭｏＯ３形式存在．在ＭｏＯ３／ＺｒＯ２（Ⅰ）中，活性相以二维聚钼酸根和Ｍｏ—Ｏ—Ｚｒ表面物种两种表面态存在于介稳的四方ＺｒＯ２上，后者在ＬＲＳ谱中表现为～８１４ｃｍ－１的宽峰；ＭｏＯ３含量超过一定值时，多余的ＭｏＯ３在５５０℃即与四方ＺｒＯ２发生反应形成体相Ｚｒ（ＭｏＯ４）２．Ｍｏ—Ｏ—Ｚｒ表面物种中，Ｍｏ（Ⅵ）是四配位的，与四方ＺｒＯ２结合很强，它很可能与ＭｏＯ３／ＺｒＯ２具有超强酸性有密切关系．     

掺杂ZrO＿2的Pt／Al＿2O＿3表面氧性质及一氧化碳氧化性能研究

用ＴＰＤ－ＭＳ、ＴＰＳＲ－ＭＳ及ＣＯ氧化活性测定等方法研究了Ｐｔ／Ａｌ２Ｏ３和掺杂超细ＺｒＯ２的样品的表面氧脱出－恢复性能、ＣＯ表面氧化性能及催化氧化性能．结果表明，在Ｐｔ／Ａｌ２Ｏ３中掺杂ＺｒＯ２后，样品表面上的氧物种脱出和氧化恢复性能明显提高，脱氧量也明显增大；并发现在ＣＯ－ＴＰＳＲ过程中程脱物ＣＯ２的脱附量大小及峰顶温度次序与对ＣＯ的催化氧化活性也有一致的关系     

Cu/ZrO2-Al2O3上表面氧物种脱附及其对催化性能的影响

采用ＸＲＤ,ＴＰＤ－ＭＳ和ＴＰＲ方法研究了ＺｒＯ２的改性对ＣｕＯ／γ－Ａｌ２Ｏ３催化剂上铜物种人散状态,表面氧物种的脱附和恢复性能,铜物种还原再氧行为的影响,并ＣＯ氧化反应为探针考察了催化剂的氧化活性,结果表明,ＺｒＯ２的存在的铜物种在γ－Ａｌ２Ｏ３载体上的分散容量降低,促进ＣｕＯ／γ－Ａｌ２Ｏ３催化剂上表面氧物种的脱附,同时有效地促进铜物种的还原,从而增加ＣＯ的氧化活性,实验还发现热处理条件对催     

制备方法对MoO3/ZrO2结构的影响及MoO3/ZrO2固体超强酸的结构特征Ⅱ.活性组分存在形态?

ＬＲＳ，ＸＲＤ，ＸＰＳ结果表明，仲钼酸铵浸渍仅经干燥的Ｚｒ（ＯＨ）４，再焙烧制得的固体超强酸（ＭｏＯ３／ＺｒＯ２（Ｉ））与浸渍晶态ＺｒＯ２制得的部分氧化催化剂（ＭｏＯ３／ＺｒＯ２（Ⅱ）中，活性组分的存在形式明显不同，在ＭｏＯ３／ＺｒＯ２（Ⅱ）中，ＭｏＯ３以二维聚钼酸根和Ｍｏ－Ｏ－Ｚｒ表面物种两种表面态存在于介稳的四方ＺｒＯ２上，后者在ＬＲＳ谱中表现为～８１４ｃｍ＾－１的宽峰，ＭｏＯ３含量超过一定值     

制备方法对MoO3/ZrO2结构的影响及MoO3/ZrO2固体超强酸的结构特征Ⅰ.ZrO2的形态与样品?

ＬＲＳ，ＸＲＤ，ＸＰＳ结果表明，仲钼酸铵浸渍仅经干燥的Ｚｒ（ＯＨ）４，再焙烧制得的固体超强酸（ＭｏＯ３／ＺｒＯ２（Ｉ））与浸渍晶态ＺｒＯ２制得的部分氧化催化剂（ＭｏＯ３／ＺｒＯ２（Ⅱ）中，活性组分的存在形式明显不同，在ＭｏＯ３／ＺｒＯ２（Ⅱ）中，ＭｏＯ３以二维聚钼酸根和Ｍｏ－Ｏ－Ｚｒ表面物种两种表面态存在于介稳的四方ＺｒＯ２上，后者在ＬＲＳ谱中表现为～８１４ｃｍ＾－１的宽峰，ＭｏＯ３含量超过一定值     

稀土氧化物固体碱催化剂的表面性质Ⅰ.稀土氧化物表面活性中心的表征

采用ＴＰＤ－ＭＳ，ＩＲ等技术研究了Ｌａ２Ｏ３，Ｙ２Ｏ３，Ｎｄ２Ｏ３，ＣｅＯ２及参照氧化物Ａｌ２Ｏ３ＺｒＯ２，ＭｇＯ表面的酸碱性，氧活性及表面羟基，结果表明，上述稀土氧化物表面上不仅存在着两种碱中心，还有酸中心存在，且其表面都存在的活性氧中心表面的性质同碱土氧化物ＭｇＯ类似，但与Ａｌ２Ｏ３ＺｒＯ２等有较大差别。     

ZrO2在Pd／Al2O3催化剂中的助剂作用

用流动反应法考察了富氧或贫氧气氛中添加ＺｒＯ２的Ｐｄ／Ａｌ２Ｏ３催化剂上ＣＯ的催化氧化反应，并用ＸＲＤ、ＴＰＲ和ＴＰＤ－ＭＳ等技术研究了助剂ＺｒＯ２与γ－Ａｌ２Ｏ３间的相互作用对催化剂上氧物种的还原和脱出－恢复行为的影响，结果表明，基质γ－Ａｌ２Ｏ３与ＺｒＯ２能发生相互作用，添加６％ＺｒＯ２的催化剂氧化活性最好，添加适量的ＺｒＯ２有利于催化剂上氧物种的脱出－恢复，从而促进ＣＯ氧化活性及表面活泼氧物     

Cu对Cu—Mn—Ce—O和Cu—Mn—Ce—Pd—O催化剂三效性能的影响

利用火焰脉冲－微反装置考察了Ｃｕ－Ｍｎ－Ｃｅ－Ｏ和Ｃｕ－Ｍｎ－Ｃｅ－Ｐｄ－Ｏ两类催化剂的三效活性。结果表明Ｃｕ的加入有利Ｃｕ－Ｍｎ－Ｃｅ－Ｏ的ＮＯｘ和ＣＯ的转化，而不利于Ｃｕ－Ｍｎ－Ｃｅ－Ｐｄ－Ｏ的ＮＯｘ和ＨＣ的转化。ＸＲＤ分析结果表明在Ｃｕ－Ｍｎ－Ｃｅ－Ｏ中加入Ｐｄ，原来的ＣｕＭｎ２Ｏ３消失，生成新相ＭｎＡｌ２Ｏ４；ＴＰＲ分析结果表明Ｃｕ使Ｍｎ－Ｃｅ－Ｏ样品表面氧量增加，表面易于还原，而使Ｍｎ－     

Controlled synthesis, characterization, and catalytic properties of Mn(2)O(3) and Mn(3)O(4) nanoparticles supported on mesoporous silica SBA-15

A method established in the present study has proven to be effective in the synthesis of Mn(2)O(3) nanocrystals by the thermolysis of manganese(III) acetyl acetonate ([CH(3)COCH=C(O)CH(3)](3)-Mn) and Mn(3)O(4) nanocrystals by the thermolysis of manganese(II) acetyl acetonate ([CH(3)COCH=C(O)-CH(3)](2)Mn) on a mesoporous silica, SBA-15. In particular, Mn(2)O(3) nanocrystals are the first to be reported to be synthesized on SBA-15. The structure, texture, and electronic properties of nanocomposites were studied using various characterization techniques such as N2 physisorption, X-ray diffraction (XRD), laser Raman spectroscopy (LRS), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results of powder XRD at low angles show that the framework of SBA-15 remains unaffected after generation of the manganese oxide (MnO(x)) nanoparticles, whereas the pore volume and the surface area of SBA-15 dramatically decreased as indicated by N2 adsorption-desorption. TEM images reveal that the pores of SBA-15 are progressively blocked with MnO(x) nanoparticles. The formation of the hausmannite Mn(3)O(4) and bixbyite Mn(2)O(3) structures was clearly confirmed by XRD. The surface structures of MnO(x) were also determined by LRS, XPS, and TPR. The crystalline phases of MnO(x) were identified by LRS with corresponding out-of-plane bending and symmetric stretching vibrations of bridging oxygen species (M-O-M) of both MnO(x) nanoparticles and bulk MnO(x). We also observed the terminal Mn=O bonds corresponding to vibrations at 940 and 974 cm-1 for Mn(3)O(4)/SBA-15 and Mn(2)O(3)/SBA-15, respectively. These results show that the MnO(x) species to be highly dispersed inside the channels of SBA-15. The nanostructure of the particles was further identified by the TPR profiles. Furthermore, the chemical states of the surface manganese (Mn) determined by XPS agreed well with the findings of LRS and XRD. These results suggest that the method developed in the present study resulted in the production of MnO(x) nanoparticles on mesoporous silica SBA-15 by controlling the crystalline phases precisely. The thus-prepared nanocomposites of MnO(x) showed significant catalytic activity toward CO oxidation below 523 K. In particular, the MnO(x) prepared from manganese acetyl acetonate showed a higher catalytic reactivity than that prepared from Mn(NO(3))2.     

EPMA of interfaces applied to the solid oxide fuel cell

Chemical interactions at the phase boundaries of materials applied for the solid oxide fuel cell (SOFC) have been studied by EPMA. The chemical reactivity at the interface of La(y-x)Sr(x)MnO(3)/ZrO(2)-Y(2)O(3) is dependent on the stoichiometry (y) and the Sr content (x) of the perovskite. Typical reaction products (zirconates) and a diffusion zone in the ZrO(2)-Y(2)O(3) have been observed. The extension of cation release (Mn) is related to the increasing chemical activity of Mn oxide in the perovskite by the Sr substitution for La. The wettability of the metal/oxide interface in the anode cermet (Ni/ZrO(2)-Y(2)O(3)) has been found to be influenced by chemical reactions resulting from the applied reducing atmosphere with high carbon activity. The disintegration of ZrO(2)-Y(2)O(3) in contact with molten Ni or Ni-Ti and Ni-Cr alloys leads to the redeposition of Y(2)O(3)-enriched oxides and also to Zr-rich intermetallic compounds and eutectics.     

Catalytic Combustion of Methane over MnOx／ZrO2-Al2O3 Catalysts

MnOx/Al2O3 and MnOx/ZrO2-Al2O3 catalysts were prepared by incipient wetness impregnation of Mn(CH3COO)2 on the corresponding supports, followed by the characterization using X-ray diffraction (XRD). temperature programmed reduction (TPR) and BET surface area techniques. The result shows the BET surface area of ZrO2-Al2O3 is lower than that of Al2O3 due to the loading of ZrO2.However tile resulted MnOx/ZrO2-Al2O3 catalyst exhibits higher activity for methane combustion than MnOx/Al2O3, because the addition of ZrO2 onto Al2O3 is beneficial for the dispersion of Mn species and the improvement of the lattice oxygen activity in MnOx. subsequently the activation of methane during combustion. The optimum loading of Zr in MnOx/ZrO2-Al2O3 is in the range of 5%-10% correlated with the calcination temperatures of catalyst supports.     

MnOx／TiO2催化剂的表面状态与氧化活性

研究了不同负载量的MnO_2/TiO_2系列催化剂的表面状态及CO氧化活性。结果表明,当MnO_2负载量低于5.7wt％时,MnO_2呈Mn_2O_3相;高于5.7wt％时,MnO_2则为Mn_2O_3+MnO_2混合相。Mn_2O_3由分散态到聚集态的分散阀值为0.028g Mn_2O_3/100mm~2 TiO_2。催化剂氧化活性与其表面状态密切相关。当Mn~(3+)、Mn~(4+)共存时,有利于提高氧化活性。     

净化丙烯腈废气催化剂的研究

研究了贵金属Ｐｄ，Ｐｔ，非贵金属Ｃｕ－Ｍｎ氧化物沸石等催化剂对含－ＣＮ有机物丙烯腈的氧化活性，结果表明，以Ｃｕ－Ｍｎ作活性组分、ＺｒＯ２作助活性组分的催化剂对丙烯腈有较高的氧化活性，较强的控ＮＯｘ能力、较低的起燃温度、较宽的浓度处理范围和较魇空速处理能力，３００ｈ稳定性试验后催化剂活性仍在９９％以上。Ｏ２－ＴＰＤ及扫描电镜表征结果很好地支持了反应结果。     

Manganese oxides: parallels between abiotic and biotic structures

A large number of microorganisms are responsible for the oxidation of Mn(2+)((aq)) to insoluble Mn(3+/4+) oxides (MnO(x)()) in natural aquatic systems. This paper reports the structure of the biogenic MnO(x)(), including a quantitative analysis of cation vacancies, formed by the freshwater bacterium Leptothrix discophora SP6 (SP6-MnO(x)()). The structure and the morphology of SP6-MnO(x)() were characterized by transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), including full multiple-scattering analysis, and powder X-ray diffraction (XRD). The biogenic precipitate consists of nanoparticles that are approximately 10 nm by 100 nm in dimension with a fibrillar morphology that resembles twisted sheets. The results dem-onstrate that this biogenic MnO(x)() is composed of sheets of edge-sharing of Mn(4+)O(6) octahedra that form layers. The detailed analysis of the EXAFS spectra indicate that 12 +/- 4% of the Mn(4+) layer cation sites in SP6-MnO(x)() are vacant, whereas the analysis of the XANES suggests that the average oxidation state of Mn is 3.8 +/- 0.3. Therefore, the average chemical formula of SP6-MnO(x)() is M(n)()(+)(y)()Mn(3+)(0.12)[ square(0.12)Mn(4+)(0.88)]O(2).zH(2)O, where M(n)()(+)(y)() represents hydrated interlayer cations, square(0.12) represents Mn(4+) cation vacancies within the layer, and Mn(3+)(0.12) represents hydrated cations that occupy sites above/below these cation vacancies.     

CO氧化反应中H2O对MOx和Au/MOx催化性能的影响

过渡金属氧化物［1,2］及负载型贵金属催化剂［3～13］是催化氧化消除CO的有效催化剂,一直是研究的热点. 虽然对MOx和Au/MOx上CO的氧化性能研究得较多,但大多是在无水条件下进行的;涉及催化剂抗水性能的报道较少［3,9,10］,且仅限于对催化剂活性的研究. Haruta等［3］对Au/Fe2O3,Au/Co3O4和Au/TiO 2等体系开展了一些工作, 认为水对CO氧化活性有促进作用. 本文重点考察了水对MOx(M=Al,Ca,Co,Cr,Cu,Fe,La,Mn,Ni和Zn)催化剂上CO氧化活性的影响,以及水对Au/MOx 催化剂活性及稳定性的影响.     

Preparation and formation mechanism of a n-butylammonium/MnO2 layered hybrid via a one-pot synthesis under moderate conditions

The preparation of organic/inorganic layered hybrids has relied on multistep processing. Thus, shortening the synthetic procedure is important for possible future applications, but only a few studies report one-pot syntheses. In this work, we established a simple one-pot solution process to synthesize layered alkyl ammonium/MnO(2) hybrids, by stirring MnCl(2) and alkyl amine/H(2)O(2) aqueous solutions at 40 °C; the reaction concept is a chemical oxidation of Mn(II) ions in the presence of alkyl amine in aqueous solution. Furthermore, the formation mechanism of the layered n-butylammonium/MnO(2) hybrid was examined by following the structural and optical changes during the reaction, revealing that the one-pot reaction includes 3 steps; formation of β-MnOOH, topotactic oxidation of β-Mn(III)OOH to form the protonated layered manganese oxide H(x)Mn(III, IV)O(2)·yH(2)O, and ion-exchange of interlayer H(+) (or H(3)O(+)) with n-butylammonium to form layered n-butylammonium/MnO(2).     

低温等离子体场内复合不同晶型氧化锰催化降解甲苯性能和机理

作为典型的挥发性有机化合物,甲苯通常来源于建筑涂料、交通运输和各种工业生产过程,是PM2.5、臭氧和光化学烟雾的重要前驱体,对环境和人类健康造成巨大影响.近年来,低温等离子体技术因具有在常温常压下就能通过高能电子、活性氧物种和羟基等活性粒子有效降解挥发性有机物的优点而受到广泛关注.然而,高能耗和大量副产物的产生是等离子体技术工业化应用的巨大障碍.当前最有效的策略之一是将等离体技术与催化技术结合,从而加快反应速率,提高产品的选择性和能源利用率.在所应用的催化剂中,MnO2因具有较好的O3分解效率而成为最有潜力的催化剂之一.但是MnO2具有不同的晶型结构、隧道结构和形貌,这些均会显著影响MnO2的催化活性.本文通过一步水热法制备了α-,β-,γ-和δ-MnO2四种MnO2催化剂,并将其用于等离子体催化降解甲苯研究,在此基础上系统考察了等离子体催化降解性能和MnO2不同晶型之间的关系.结果表明,当能量密度为160 J/L时,等离子体单独降解甲苯去除效率为32.5%.引入催化剂能够显著提高甲苯的降解效率,其中α-MnO2效果最显著,甲苯降解效率能够提升至78.1%,β-,γ-和δ-MnO2能够相应提升至47.4%,66.1%和50.0%.采用X射线衍射、拉曼光谱、扫面电子显微镜、透射电子显微镜、比表面积-孔结构分析、氢气程序升温还原和X射线光电子能谱等手段研究了催化剂的理化特性.结果表明,隧道结构、催化剂在等离子体中的稳定性、Mn–O键能和催化剂表面吸附氧均在等离子体催化降解甲苯中发挥了重要作用.在此基础上,通过GC-MS分析降解产生的气相副产物推断甲苯在等离子体和等离子体催化体系中的降解机理.在等离子体催化体系中,通过Mn4+,Mn3+和Mn2+价态的变化,等离子体产生的O3,O2*和其他活性自由基会被吸附到催化剂表面,随后与催化剂吸附的甲苯或中间副产物发生氧化还原反应,将甲苯氧化为CO2等小分子物质.此外,MnO2作为分解O3最有效的催化剂,可以吸附O3并将其分解为O?或者与H2O生成?OH参与到反应中,从而提高甲苯的降解效率.