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1.
吴泽彪  朱毅青 《催化学报》2000,21(2):129-132
考察了CO2加氢合成CH3OCH3反应中ZrO2含量对Cu-ZnO-SiO2-ZrO2催化剂的影响,采用TPR,XRD,BET和TEM等技术对催化剂的结构形态、表面性质和ZrO2的作用进行了研究,结果表明,催化剂中加入ZrO2能提高催化剂的比表面积及CO2转化率和CH3OCH3产率,降低最佳反应温度;ZrO2含量以2%~3%为佳,催化剂中的CuO以种形式存在:小晶粒CuO,聚集的无定形CuO及均匀  相似文献   

2.
CO2在Cu-Ni/ZrO2-SiO2催化剂上的吸附与反应   总被引:12,自引:3,他引:9  
采用表面反应改性法,制备了ZrO2-SiO2(ZrSiO)表面复合物,用等体积浸渍法制备了ZrSiO担载的Cu-Ni双金属催化剂,用IR和TPD技术,研究了CO2在其表面上的化学吸附与反应性能。实验结果表明:在Cu-Ni/ZrSiO催化剂CO2可形成线式吸附态、剪式吸附态和卧式吸附态;催化剂表面金属位M上的剪式吸附态CO2可与邻近的lewis酸位Zr^n+作用,形成CO2卧式吸附态M-(CO)-  相似文献   

3.
锰助剂对Co/ZrO2超细催化剂F—T合成性能的影响   总被引:8,自引:1,他引:7  
相宏伟  张永青 《分子催化》1997,11(3):196-202
制备了以气凝胶超细ZrO2为载体的Co/ZrO2及Co-MZrO2催化剂;考察了Mn助剂对Co/ZrO2催化剂结构、织构1还手、H2脱附及F-T合成性能的影响。结果表明,15%Co-4.7%Mn/ZrO2是合成重质烃(C2)的合适催化剂,每立方米合成气的C5收率可达150g。  相似文献   

4.
铜基氧化锆载体合成甲醇催化剂的结构表征   总被引:3,自引:0,他引:3  
以XRD,EXAFS和ESR等手段考察了CuO/ZrO2催化剂及其还原态的结构,结果表明,在CuO/ZrO2中铜以CuO的形式存在,ZrO2载体对所负载的CuO的结构有影响,CuO的分散度与焙烧温度有关,在适当的温度下焙烧,负载于ZrO2上的CuO可自发分散,在还原态试样中铜主要以有金属的形式存在,但是当试样中铜的含量小,铜的分散度高时有铜的氧化物存在,其Cu-O键距介于CuO与CuO2之间,Cu  相似文献   

5.
通过活性测定,XRD、TG-DTA表征,考察了共沉淀法制备的铜锌锆合成甲醇催化剂中ZrO_2对物相结构、催化活性及热稳定性的影响。结果表明,ZrO_2能显著提高CO/H_2合成甲醇的催化活性和热稳定性。催化剂母体、氧化态和还原态的物相并未发生变化,仍分别为:Cu_2(OH)_3NO_3,(Cu,Zn)_5(CO_3)_2(OH)_6,(Cu,Zn)_2CO_3(OH)_2,Zn_5(CO_3)_2(OH)_6;CuO、2nO;Cu,ZnO。ZrO_2使催化剂各组分的结晶度变得更差,晶粒更细。实验证明催化剂中ZrO_2主要以无定形状态存在,也不排除与其它组分形成固溶体。本文还探讨了ZrO_2提高催化活性和热稳定性的原因。认为ZrO_2既起了载体的高分散作用,间隔活性组分作用,又起了增加和稳定活性中心的促进剂作用。  相似文献   

6.
结晶态SO^2—4/ZrO—SiO2超强酸催化剂的制备及性能测定   总被引:4,自引:0,他引:4  
廖世军  王乐夫 《分子催化》1999,13(4):304-307
采用一种沉淀/混合沉淀的方法,制得了具有类似于分子筛结构的结晶二元二氧化物ZrO2-SiO2。用1mol/dm^3的硫酸处理经物并在550℃焙烧,制得了具有类似于分子筛结构的结晶态超强酸催化剂SO^2-4/ZrO2-SiO2。采用XRD,IR,TG,SEM等对催化剂的结构进行了表征,发现该催化剂的XRD谱图与ZSM-5分子筛的XRD谱图非常类似,用指示剂法证实了催化剂的超强酸性。还考察了催化剂对于  相似文献   

7.
以ZrO2-Al2O3为载体的Co-Mo-K耐硫水煤气变换催化剂   总被引:5,自引:0,他引:5  
李玉敏  耿云峰 《应用化学》2000,17(3):276-279
采用沉淀法和浸渍法分别制备了ZrO2-Al2O3复合载体和Co-Mo-K耐硫变换催化剂。研究了ZrO2对Co-Mo-K面硫变换催化剂活性及热稳定性的影响。利用XRD、BET、TG、XPS等手段对催化剂及其载体的结构、吸硫吸水性能和氧化还原性能进行了表征。结果表明以ZrO2-Al2O3代替传统的γ-Al2O3作为Co-Mo-K耐硫变换催化剂的载体,可提高催化剂的活性,尤其是低温活性,并可改善催化剂的  相似文献   

8.
Cu/TiO_2和Cu/ZrO_2催化甲醇脱氢反应的对比研究(英文)   总被引:1,自引:0,他引:1       下载免费PDF全文
考察了TiO_2和ZrO_2担载的铜基催化剂的结构及其催化甲醇脱氢的反应性能。氮吸附和EXAFS结果显示,两个催化剂的结构性质以及铜所处的配位环境比较接近。但X-射线光电子能谱测试结果显示,催化剂Cu/TiO_2中铜周围的电子密度较催化剂Cu/ZiO_2中的高。TiO_2结果表明,TiO_2能够降低与之接触的较大CuO的还原温度。催化剂电子结构的不同导致反应性能的差异,在Cu/TiO_2催化剂上甲酸甲酯是主要产物,而Cu/ZrO_2催化剂则催化甲醇深度脱氢生成CO。此外,Cu/ZrO_2催化剂失活较Cu/TiO_2催化剂慢得多。  相似文献   

9.
应用XPS,XAES和紫外漫反射光谱法研究了CuO-ZnO/氧化物上CO2/H2合成甲醇的反应活性中心.CuO-ZnO/氧化物催化剂上的反应活性中心是存在于CuO-ZnO固溶体中的Cu-Zn-O("□"为氧空位),活性中心的Cu价态为Cu-和Cu0.反应活性中心在CuOZnO-ZrO2催化剂上比在其它CuO-ZnO/氧化物催化剂如CuO-ZnO,CuO-ZnO-MgO,CuOZnO-Al2O3和CuO-ZnO-r2O3上更加稳定.  相似文献   

10.
CO/H2合成甲醇CuO—ZnO—ZrO2催化剂的研究   总被引:4,自引:0,他引:4  
通过活性测定,XRD、TG-DTA表征,考察了共沉淀法制备的铜锌锆合成甲醇催化剂中ZrO2对物相结构、催化活性及热稳定性的影响。结果表明,ZrO2能显著提高CO/H2合成甲醇的催化活性和热稳定性。催化剂母体、氧化态和还原态的物相并未发生变化,仍分别为:Cu2(OH)3NO3,(Cu,Zn)5(CO3)2(OH)6,(Cu,Zn)2CO3(OH)2,Zn5(CO3)2(OH)6;CuO、ZnO;Cu  相似文献   

11.
The total conductivity (σT) in bcc γ-Bi2O3 doped with V2O5 system has been measured in the composition range between 1 and 7 mol% V2O5 at different temperatures. Phase transitions for different addition amounts depending on the temperature were investigated by quenching the samples. According to the XRD and DTA/TG results, this bcc type solid solution was stable up to about 720°C and the solubility limit was found at ˜7 mol% V2O5 in γ-phase. This system showed predominantly an oxide ionic conduction. As the V2O5 addition increased, the ionic conduction increased up to 5 mol% V2O5 at which the highest conductivity was found to be 8.318·10-2 Ω-1 cm-1 at 700°C and then decreased. It has been proposed that γ-Bi2O3 phase contains a large number of oxide anion vacancies and incorporated vanadium cations at tetrahedral sites which affect the oxygen sublattice of the crystal structure. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
采用水热稳定的MgAl2O4尖晶石对-αAl2O3载体表面进行修饰,采用具有较强亲水性能的SnO2对活性组分Nb2O5进行修饰,制备了SnO2-Nb2O5/MgAl2O4/-αAl2O3催化剂,并用于环氧乙烷水合制乙二醇反应.采用X射线衍射、红外光谱和程序升温脱附研究了Sn/Nb摩尔比对催化剂酸性、环氧乙烷在催化剂表面的吸附状态和吸附强度以及催化剂性能的影响.结果表明,Sn/Nb摩尔比明显影响催化剂的组成和结构;催化剂的结构不同,环氧乙烷在催化剂表面的吸附强度存在明显差别,催化剂的催化性能明显不同.  相似文献   

13.
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。  相似文献   

14.
研究了高温煤气中的H2 和H2 O(g)对铁钙氧化物高温脱硫行为的影响。结果表明 ,对还原态和非还原态脱硫剂 ,气氛中的H2 的影响有所不同。对前者 ,硫化气体中的H2 不利于脱硫 ;对后者 ,由于H2 首先会部分还原脱硫剂 ,提高其活性 ,因而有利于脱硫。H2 O(g)的存在对硫化和还原过程均起阻碍作用。  相似文献   

15.
The thermal stability and material properties of HfO2 thin films on Si substrates with and without H2O2 wet chemical oxidation were investigated. The HfO2 samples were deposited through plasma-enhanced atomic layer deposition and subjected to thermal annealing. They were then examined using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy, and conductive atomic force microscopy. For the Si substrate without H2O2 wet chemical oxidation, a native oxide (~1.8 nm) was formed on the substrate before HfO2 deposition. After the annealing process at 600°C, the band gap (Eg) of the HfO2 films increased from 6.0 to 6.2 eV due to the diffusion of Si into HfO2. Furthermore, the conduction and valence band offsets (ΔEc and ΔEv, respectively) between HfO2 and Si changed from 1.02 to 1.42 and 3.86 to 3.66 eV, respectively. After the H2O2 wet oxidation of the Si substrate, a 1.5-nm chemical oxide was formed instead of a native oxide. The band offset and Eg values of HfO2 were similar before and after 600°C annealing (ΔEv = 3.86 eV, ΔEc = 1.02 eV, and Eg = 6.0 eV), implying the high thermal stability of the HfO2 films. Accordingly, wet oxidation not only prevents diffusion from chemical oxide but also markedly improves the oxide leakage current, which is useful for developing highly efficient and thermally stable HfO2 gate oxides in Si-based integrated circuit devices.  相似文献   

16.
用沉淀-浸渍法制备了NOx储存-还原(NSR)催化剂Pd/TiO2/γ-Al2O3,通过NOx吸附储存实验和对催化剂进行XRD、TPD和TPR等表征分析,考察了添加BaO对催化剂的NOx储存性能和抗硫性能的影响.研究表明,催化剂Pd/TiO2/γ-Al2O3中TiO2的高含量和高分散均可提高NOx储存能力.少量BaO(3%)提高了催化剂Pd/TiO2/γ-Al2O3的NOx储存能力而抗硫能力基本不受影响,当BaO含量超过一定值(5%)时,随催化剂中BaO含量进一步增加,NOx储存量增多,但催化剂的抗硫能力下降.催化剂表面上形成的硫化物易还原,则催化剂的抗硫能力高.  相似文献   

17.
La2NiO4/Al2O3催化剂上CH4/CO2的重整   总被引:9,自引:1,他引:8  
 通过溶胶-凝胶方法制备了尖晶石结构的La2NiO4/Al2O3催化剂,采用BET,XRD和TG表征了催化剂的孔分布、比表面积、体相组成以及凝胶样品的热失重和热分解过程.将催化剂应用于CH4/CO2重整反应制合成气,考察了惰性气体和反应温度对转化率、选择性以及积碳的影响.结果表明,在高空速(GHSV=4.8×104ml/(g·h))下,CH4和CO2转化率分别为51%和60%,CO和H2的选择性约为98%和92%,惰性气体He的引入明显地提高了CH4和CO2的转化率.  相似文献   

18.
We report here a novel method to prepare high-quality samples of the three layered oxides ASrBi2Nb2TiO12ACa, Sr or Ba using the pre-formed intermediates ABi2Nb2O9 and SrTiO3. The room temperature structures were refined using synchrotron X-ray and Neutron powder diffraction data in the orthorhombic space group B2cb. This symmetry arises as a consequence of cooperative tilting of the BO6 octahedra in the [ASrNb2TiO10]2− perovskite-like slabs and a polar displacement of the cations. The structure is characterized by extensive cation disorder but lacks appreciable oxygen vacancies.  相似文献   

19.
La—Cu—Fe—O/γ—Al2O3催化剂的抗烧结研究   总被引:4,自引:0,他引:4  
张学文  俞寿明 《应用化学》1992,9(4):107-110
  相似文献   

20.
Two Modifications of Dy2OS2 Oxidation of DyCl2 with sulfur in the presence of NaCl (tantalum capsule, 800°C, 7 d) results in the formation of single-crystalline U2S3-type Dy2S3 as the main product. Oxidic impurities (e.g. DyOCl) react to yield Dy2OS2 in two different types of single crystals, i.e., almost colourless needles (I: orthorhombic, Pnma (no. 62), a = 1542.71(9); b = 380.07(2); c = 674.49(3) pm; Vm = 59.540(6) cm3/mol, Z = 4; R = 0.023; Rw = 0.021) and faint yellow face-rich prisms (II: monoclinic, P21/c (no. 14), a = 825.09(6); b = 691.06(5); c = 686.25(5) pm; β = 99.612(7)°; Vm = 58.082(7) cm3/mol, Z = 4; R = 0.026; Rw = 0.025). According to its by 2.5% lower density (Dx = 6.80 for I vs. 6.97 g/cm3 for II), the orthorhombic form of Dy2OS2 should be addressed here as “ambient-pressure” type (I). Both crystal structures are built up from O2-centered tetrahedra [O(Dy)4]10+ which are cis-edge connected via two common edges to form zig-zag chains of the composition [O(Dy1)3/3 (Dy2)1/1]4+ in Dy2OS2—I, or singly edge-bridged to dimers and further connected via two corners to form puckered layers of the composition [O(Dy1)3/3(Dy2)1/1]4+ in Dy2OS2—II. Three-dimensional interconnection occurs via two crystallographically different S2? anions for charge neutrality which are surrounded by five nearest Dy3+ neighbours in both cases as tetragonal pyramid (C.N. = 5) each. Dy2OS2—I contains Dy1 in eightfold (3O and 5S, bicapped trigonal prism) and Dy2 in sixfold anionic coordination (1O and 5S, “octahedron”). In form II, both Dy3+ are surrounded by seven anions (Dy1: 3O and 4S, Dy2: 1O and 6S) as monocapped trigonal prisms.  相似文献   

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