用晶型超细粒子ZrO2制备SO4^2^—／ZrO2超强酸催化剂的研究

用超临界流体干燥法制备了超细粒子晶型ZrO_2,并用稀H_2SO_4溶液对其进行处理,制得了对甲醇转化反应具有高活性的SO_4~(2-)/ZrO_2超强酸催化剂.首次发现,晶型金属氧化物ZrO_2,当它是超细粒子(粒径<0.1μm)时,同样可以用H_2SO_4溶液浸渍的方法制得SO_4~(2-)/ZrO_2固体超强酸.这一事实同时还说明,超细粒子与非超细粒子不仅在某些物理性质上有较大区别,而且在化学性质上也有差别.     

S~2O~8^2^-处理的ZrO~2固体超强酸上的正丁烷异构化反应

首次报道了由浸渍过硫酸根的方式制备固体超强酸.讨论了焙烧温度、浸渍浓度以及ZrO_2前驱体沉淀条件对样品性质的影响,并研究了它们对正丁烷异构化反应性能.实验结果表明,600～650℃焙烧、0.25～0.50mol/LS_2O_8~(2-)浸渍反加沉淀的ZrO_2具有最高超强酸性.与相同条件下制备的SO_4~(2-)/ZrO_2相比,S_2O_8~(2-)/ZrO_2上正丁烷250℃异构化活性是SO_4~(2-)/ZrO_2的2倍,可能是由于它具有较多的中强酸位并具有与SO_4~(2-)/ZrO_2不同的活性位结构.     

掺杂物对负载型ZrO_2/Al_2O_3的催化性能的影响

用浸渍-沉淀法分别制备了负载型ZrO_2/Al_2O_3和ZrO_2-(MgO、 K2O、 CeO_2、La_2O_3)/Al_2O_3催化剂. 用XRD、 BET、 TPD对催化剂的晶相结构、比表面积、孔径分布、表面酸碱性等进行了表征;同时以CO_2和CH_3OH为探针用原位红外对催化剂的吸附行为进行研究. 结果表明, 掺杂氧化物有效的阻止ZrO_2晶粒的团聚, 并提高了催化剂的比表面积和平均孔径;CeO_2的添加有利于碱性中心数的增多, La_2O_3有利于酸性中心数的提高. 原位红外结果表明CH_3OH能在ZrO_2-(CeO_2、 La_2O_3)/Al_2O_3催化剂表面发生解离吸附, 而CO_2在催化剂表面均出现单齿态吸附. CO_2和CH_3OH在常压下直接合成碳酸二甲酯(DMC)反应中ZrO_2-(CeO_2、 La_2O_3)/Al_2O_3催化剂表现出较好的催化活性和选择性.     

ZrO_2表面上Zr~(3+)中心上的O_2吸附平衡

以ESR为主要研究手段,研究了一种最可几粒径为9.8 nm的ZrO_2样品在室温不 同气体（He,H_2,O_2,空气,温空气）中及经不同温度处理后ZrO_2中Zr~(3+)中 心信号的变化。根据ZrO_2样品中Zr~(3+)浓度在室温下对于介质气体中O_2分压改 变的响应极快及Zr~(3+)浓度在室温下对于介质气体变化可逆性等特点提出, ZrO_2中Zr~(3+)中心绝大多数存在于样品的表面上,Zr~(3+)是ZrO_2晶体表面上那 些O~(2-)配位不饱和的Zr原子点位。ZrO_2表面上ESR活性Zr~(3+)中心的数目与其 上氧吸附平衡有关。由ESR法对ZrO_2样品中Zr~(3+)中心的定量和对ZrO_2晶体的粒 度分析,推测ZrO_2表面上Zr~(3+)中心是那些位于ZrO_2微晶的晶角处O~(2-)配位 不饱和的Zr原子。     

ZrO2酸碱性质的TPD表征 I. 单组分吸附研究

以NH_3、吡啶、Et_3N、CO_2和苯酚为探针，用TPD-MS方法对ZrO_2催化剂的酸碱性质进行了表征．ZrO_2上碱性探针（NH_3、吡啶和Et_3N）的脱附温度远低于在强酸性SiO_2－Al_2O_3上；而酸性探针CO_2的脱附温度远低于在强碱性MgO上的结果．为ZrO_2的弱酸弱碱性质提供了证明．NH_3吸附IR结果表明ZrO_2表面配位不饱合Zr~(4＋)为酸（Lewis酸）中心．NH_3、吡啶和Et_3N与这些酸中心作用的方式和能量分布相似．NH_3和CO_2的TPD谱图均存在三个脱附峰，且相应脱附峰的温度范围相近．表明ZrO_2的酸中心和碱中心具有匹配相当的酸、碱强度，ZrO_2为典型的酸－碱双功能催化剂，在苯酚的TPD过程中，ZrO_2的特征表现为对苯酚的强吸附和对苯酚分解的高活性．文中结合IR结果，对与NH_3和CO_2的脱附相联系的表面吸附物种分别进行了讨论.     

CuO/ZrO_2催化水煤气变换反应制氢:ZrO_2载体焙烧温度的影响

以经不同温度(120、250、350、450℃)焙烧处理的ZrO_2为载体,采用沉积-沉淀法制备了系列CuO/ZrO_2催化剂;考察了富氢气氛下催化剂的水煤气变换反应(WGS)催化性能。结果表明,CuO/ZrO_2催化剂的催化活性随ZrO_2载体焙烧温度的升高呈现先升高后降低的"火山型"变化趋势,在焙烧温度为250℃时取得最高值。采用X射线粉末衍射、N_2物理吸附-脱附、N_2O滴定、H_2程序升温还原和CO程序升温还原及质谱跟踪等技术研究了系列ZrO_2载体及CuO/ZrO_2催化剂的结构和还原性能。结果表明,随着ZrO_2焙烧温度的升高,一方面,CuO/ZrO_2催化剂的Cu分散度逐渐降低,与ZrO_2具有强相互作用的高分散活性Cu-[O]-Zr物种("[]"表示ZrO_2表面氧空位)逐渐减少;另一方面,Cu-[O]-Zr物种的还原能力逐渐增强,并诱导催化剂活性表面羟基的还原能力也相应增强(CO为还原剂),即降低了催化剂对WGS反应的起活温度。两方面的综合作用使得ZrO_2载体焙烧温度为250℃(中等温度)时,CuO/ZrO_2催化剂的WGS催化活性最高。     

ZrO2催化剂上吸附CH3NO2的分解

用TPD和IR谱研究了CH_3NO_2在ZrO_2催化剂上的吸附活化和分解反应。结果表明,室温下CH_3NO_2在ZrO_2表面发生不可逆化学吸附,它们在TPD过程中可完全分解生成HCN、CO_2、CO、NH_3、H_2O和微量NO。其中H_2O和NO的脱附峰出现在383K附近。其它产物在543K附近出现极大值。IR结果表明,CH_3NO_2在ZrO_2上吸附形成诸如[CH_2NO_2],和/或吸附物种。这些吸附物种在升高温度时转化为表面态“HCN”。“HCN”或脱附,或进一步向表面“HCONH_2”和/或“HCOO~-”转化,后两种表面物种分解可产生CO_2、NH_3和CO。将这些结果与CH_3NO_2在SiO_2-Al_O_3和MgO催化剂上的结果进行了比较,讨论了酸-碱双功能性ZrO_2催化剂上CH_3NO_2活化分解的特点。     

ZrO_2改性对Ni/SBA-15催化二苯并呋喃加氢脱氧的促进作用研究

以二苯并呋喃为煤焦油中含氧组分的模型化合物,在280℃、氢气压力6.5 MPa条件下于反应釜中考察了Ni/ZrSBA-15催化剂的加氢脱氧性能,分析了ZrO_2改性对Ni/SBA-15催化剂结构特性与反应活性的影响。结果表明,ZrO_2的添加会增强活性金属Ni与载体间相互作用,促进Ni颗粒的分散,同时会在催化剂中引入氧空位,氧空位与活性金属Ni的协同作用可以促进含氧中间产物的转化,提高目标产物联环己烷的收率。但过量ZrO_2(30%)的添加会降低催化剂的比表面积、孔容,不利于Ni颗粒分散,不利于反应的进行。研究发现,当ZrO_2添加量为10%时,二苯并呋喃反应速率最高,为9.21 mmol/(min·g);当ZrO_2添加量为20%时联环己烷生成速率最高,为3.74 mmol/(min·g);两者均高于未改性的Ni/SBA-15催化剂。     

甲烷氧化偶联制乙烯Li—ZrO2,Li—La2O3催化剂的研究

研究了添加Li的La_2O_3和ZrO_2两种催化剂对甲烷氧化偶联催化性能的影响,并用XRD,LRS和XPS等方法对催化剂进行了表征。结果表明,Li~+的加入提高了催化剂的C_2选择性,但两类催化剂上Li~+的添加作用机制不同。La_2O_2加入Li~+达40mol％时,样品可获得34.4％的甲烷转化率和60.4％的C_2选择性。Li~+在La_2O_3表面分散,表面O/(Li+La)比随Li~+添加量增加而下降。催化剂对C_2选择性的提高可能是因为Li~+覆盖了La_2O_3表面部分完全氧化中心所致。ZrO_2中添加Li~+有Li_2ZrO_3生成,75mol％Li-ZrO_2仅检测到Li_2ZrO_3晶相,该样品可得34％甲烷转化率和63％C_2选择性。样品的XRD及XPS研究表明,随Li~+加入量增加,表面Li/Zr比接近2:1,没有Li的富集,样品表面存在两种氧物种,其O_1s结合能分别为530.3和531.9eV。对75mol％Li—ZrO_2样品,后者占95％,该表面氧物种可能与C_2选择性提高有关。     

ZrO2／SO4^2—超强酸体系形成过程的研究

本文用XRD、TG-DTG-DTA、SEM和化学分析等多种实验手段研究了浸渍H_2SO_4的无定形ZrO_2在不同焙烧温度下的晶化和相变,失水和失硫等过程.实验结果表明,这些过程与超强酸的形成密切相关,在ZrO_2/SO_4~(2-)超强酸体系中不存在水和游离H_(2)SO_(4),体系超强酸强度最高时ZrO_2呈四方晶相,晶体表面约有略少于1/3的Zr原子与SO_4~(2-)根相结合.     

单层型氧化铁催化剂的制备及其前体的表征:Ⅰ.催化剂前体的制备

尝试用（ＮＨ４）３［Ｆｅ（Ｃ２Ｏ４）３］·ＸＨ２Ｏ的过量水溶液含浸法制备不同载体上单层型氧化铁催化剂．为了比较，也采用Ｆｅ（ＡｃＡｃ）３的甲苯溶液热吸附以及Ｆｅ（ＮＯ３）３溶液饱和浸渍两种方法制备样品．特别对合浸法，考察了含浸溶液的ｐＨ值、浓度及含漫时间对吸附过程的影响，确定了不同载体催化剂前体的适宜制备条件．     

制备高比表面负载型催化剂的一种新方法

In this paper, a new way to increase the specific surface areas of supported catalysts has been suggested. The results for MoO_3/ZrO_2, WO_3/ZrO_2, CuO/ZrO_2, SO_4~(2-)/ZrO_2, NiO/ZrO_2, Fe_2O_3/ZrO_2, Fe_2(SO_4)_3/ZrO_2, MoO_3/TiO_2, WO_3/TiO_2, SO_4~(2-)/TiO_2, NiSO_4/TiO_2, NiO/TiO_2, V_2O_5/TiO_2 etc. systems show that the specific surface areas of the samples, prepared by impregnating some hydroxides then calcinating at high temperature, are much larger than those of the samples prepared with a traditional method——impregnating their oxides calcinated at the same temperature. Using this way, the specific surface areas of some supported catalysts can increase by several times. The surface areas of some supports such as zirconia and titania are not large enough, and they are easy to sinter at high temperature. In these cases, the advantage of of this preparation method is fully displayed, and the specific surface areas of the resulting zirconia-or titania-supported catalysts can compare favourably with those of the catalysts prepared from some classical supports (such ar γ-Al_2O_3, SiO_2).In addition, it has been proved by means of XPS, XRD, LRS, and DTA that as an active component disperse on a support as a monolayer and its content comes up to its monolayer dispersion capacity, the specific surface area of the obtained catalyst would be the largest. We suggest a mechanism that an active component covered on a support can not only segregate its particles, but also hinder the surface diffusion of support, and as a result, its crystalline growth, an accompanying phase transformation and inter-crystalline sintering are all retarded.     

镍钴复合氧化物的制备和析氧活性

用浸碱热分解法制备了具有较高析氧活性和稳定性的复合氧化物ＮｉＣｏ＿２Ｏ＿４。考察了涂液成分、热分解温度和涂覆次数对ＮｉＣｏ＿２Ｏ＿４析氧活性的影响；测定了氧在ＮｉＣｏ＿２Ｏ＿４从电极上的稳态电化学行为。     

不同温度下生成的过渡金属表面氧化物的热稳定性研究

不久前本文作者等首次观察到金属钴表面氧化物的热稳定性与其氧化温度密切相关。研究对象包括多晶钴片和蒸镀的钴薄膜。它们无论是被纯氧氧化或是被空气氧化,其结果相同:室温表面氧化钴在真空中300℃加热时很容易被还原成金属钴,而对250℃形成的表面氧化钴作同样的真空热处理则不能被还原成金属钴,鉴于该现象在多相催化、金属氧化和腐蚀,电子学表面器件等研究领域中的意义,本文用X射线光电子能谱(XPS)等方法研究     

Preparation of ultrafine high density gamma ferric oxide using aerosol OT microemulsions and its characterization

Ultrafine gamma ferric oxide has been prepared by controlled heating of ferrous oxalate at a temperature range of 225° to 300°C in moist air. Ferrous oxalate was prepared both in aqueous as well as in Aerosol OT microemulsion systems. It has been observed that the product is always a mixture of alpha and gamma ferric oxides which were characterized by TGA, DTA and XRD studies. Microemulsion mediated ferrous oxalate was found to yield more gamma ferric oxide than that from ferrous oxalate prepared in aqueous solution. However, the yield of gamma ferric oxide prepared through microemulsion mediated system depends on the size of the microemulsion droplets in which precursors have been participated as well as calcination temperature.     

单层型氧化铁催化剂的制备及其前体的表征:Ⅱ.催化剂前体的表征

用三种方法，即草酸络铁（Ⅱ）酸铵的过量水溶液含浸，三乙酰丙酮铁的甲苯溶液热吸附和硝酸铁溶液饱和浸渍法制备了种载体上氧化铁的负载样品，对用不同方法制备的催化剂前体中表面铁物种的存在形式，结构和分散度等进行了细致的表征和详细的讨论，并与焙烧后样品中Ｆｅ＾３＋的最终形态进行了关联。     

Effects of Composition on the Structure and Capacitive Properties of Ti/(ZrO2)x(RuO2)1-x Electrodes

<正>A series of nominal composition Ti/(ZrO_2)_x(RuO_2)_(1-x) (0.1≤x≤0.9) coatings chan- ged in 10% steps was deposited on titanium substrate from RuCl_3·nH_2O and ZrCl_4 containing ethanol solution by thermal decomposition method. The X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM) and electrochemical tests were performed to clarify the effects of ZrO_2 content on the structure and capacitive property of Ti/(ZrO_2)_x(RuO_2)_(1-x). The results show that by adding ZrO_2 into the coatings the degree of crystallization of RuO_2 decreases. The specific capacitance firstly increases and then deceases with the increase of ZrO_2 content in the mixed oxide coatings. The film of Ti/(ZrO_2)_(0.6)(RuO_2)_(0.4) consisting of amorphous matrix and fine nano-crystalline RuO_2 (about 4 nm) has the maximum specific capacitance of 713.27 F/g(RuO_2).     

Catalytic performance of iron oxide loaded on electron-rich surfaces of carbon nitride

Carbon nitride(CN) in CN encapsulated Ni/Al_2O_3(denoted as CN/Ni/Al_2O_3) catalyst was evidenced previously as a material in electron-rich state and possessed H2-dissociative adsorption activity due to the electron doping effect from underlying nickel. In this report, iron oxide loaded on the CN/Ni/Al_2O_3 was synthesized and investigated by Fischer-Tropsch(F-T) synthesis to test the special effect of electron-rich support on the catalytic activity of iron oxide. The Fe/CN/Al_2O_3 and CN/Ni/Al_2O_3 samples were accordingly synthesized for comparison. In Fe/CN/Ni/Al_2O_3, the iron oxide was reduced to magnetite by syngas as evidenced by the in-situ XPS measurements and XRD pattern of used catalyst. Compared with Fe/CN/Al_2O_3, more light hydrocarbons over Fe/CN/Ni/Al_2O_3 were observed. It should be understood by the interaction between iron oxide and support mainly due to the effect of electron-rich state and thus enhanced H_2 adsorption ability. In addition, such a novel support facilitated the CO conversion and retarded the water-gas shift reaction and CO2 formation. The new type of adjustment on electronic state should be useful for novel catalyst design.