不同硅铝比的Cu—ZSM—5／堇青石械催化剂的NO分解反应性能

考察了原位合成的不同硅铝比的Cu-ZSM-5/堇青石械催化剂上的NO分解反应。结果表明,在573－773K的温度范围内,铝硅比分别为60,55和40的催化剂在723K下NO的转化率最高,而硅铝比小于25的催化剂上的NO转化率很低。低温有利于N2O的生成。整体式催化剂上的NO转化率低于单纯的分子筛催化剂Cu-ZSM-5,但其催化转换频率高于后者。     

Cu-ZSM-5/堇青石整体式催化剂上NO的吸附态及分解反应机理

 用傅里叶变换漫反射红外光谱法研究了原位合成的不同硅铝比的Cu－ZSM－5／堇青石整体式催化剂上一氧化氮的吸附态,以及温度和一氧化氮浓度对吸附态的影响．结果表明,铜在整体式催化剂中主要以二价铜离子的形式存在,未发现一氧化氮在一价铜离子上的特征吸收峰;由二价铜的一氧化氮吸附物种衍生的Cu2＋（O）（NO）是与活性密切相关的物种．探讨了NO分解可能的反应机理．     

含铜MFI分子筛的H2-TPT和O2-TPD研究

 采用H2－TPR和O2－TPD手段考察了不同金属离子交换的ZSM－5分子筛催化剂上的氢还原性能和氧脱附性能．发现Cu－ZSM－5催化剂的储氧能力及氧脱附性能优于Co－ZSM－5和Fe－ZSM－5催化剂;储氧能力强、低温下氧脱附性能好的催化剂,对NO分解反应的催化活性就高．铜离子是反应的活性中心．添加Ag和Ce可使Cu－ZSM－5催化剂上氧的脱附温度大大降低．Cu－ZSM－5／堇青石整体式催化剂上Cu的存在形式与单纯的Cu－ZSM－5有差异,整体式催化剂上的一价铜数量少,但较稳定．     

晶化时间对ZSM-5分子筛物化性质及催化性能的影响

 考察了ZSM－5分子筛在晶化过程中的变化规律及其在苯与乙烯气相烷基化制乙苯反应中的催化性能．结果表明,当晶化时间为70h时,分子筛晶体开始出现;晶化90h时无定形物相基本消失．晶化时间从90h再延长至150h,ZSM－5分子筛晶粒的大小、形貌和体相硅铝比都基本不变,但分子筛表面的硅铝比逐渐降低．以晶化时间为90h的ZSM－5分子筛原粉为活性组元制备的催化剂,对苯与乙烯气相烷基化制乙苯反应表现出最佳的催化性能．     

MFI沸石上对二甲苯的热脱附

MFI沸石（ZS－5型）的骨架结构内含十氧元环的二维孔道［‘］，孔容积0．18cm‘·g－‘，硅沸石（Silicallte－1）是骨架中不合铝的ZSM－5．’‘StMASNMR话可揭示沸石的结构对称性、硅铝比和局部缺陷［习．Nagy等人间提出St－OH缺陷在含铅量高时形成．Woolery等门则认为出OH完全是由于骨架内包藏的桂的存在而产生，并随铝合量降低而增大．ZSM－5、硅沸石的结构特征和对二甲苯（Px）的性质决定了Px在ZSM－5上的吸附特性·本文用’‘StMASNLDEL表征硅沸石及不同含铅量的H、Na型ZSM－5的结构，并用＊W＊＊G巾TA分析吸附于…     

银催化剂用于氮氧化物的还原和分解

实验采用Ag2 O ,Ag3 0 Si70 合金和Ag离子交换的ZSM 5分子筛 ,研究了NO的直接催化分解和以CO ,NH3 等作为还原剂的选择还原反应 .结果表明 ,在合适的条件下 ,实验中采用的Ag基催化剂均具有一定的NO分解活性 .当反应温度低于 80 0K时 ,NO在AgZSM 5上的直接分解给出了近 2 0 %的N2 转化率 ;相似条件下 ,适量CO和NH3 的加入大大提高了反应的活性和催化剂寿命 .氧的存在促进了NO在催化剂表面的吸附 ,从而导致了选择还原温度的降低 .当气相中氧气大大过量 (O2 ∶H2 O =18∶1) ,反应温度为 6 0 0K时 ,NO在Ag ZSM 5催化剂上氨还原生成N2 的转化率仍能达到近 70 %     

Mo/ZSM-5催化剂体系上NO的选择性催化还原研究

 首先用浸渍法在HZSM－5上负载了不同的金属元素（Mo，Sn和Ni），并比较了它们在含氧条件下对NO分解反应的影响．结果表明，Mo／ZSM－5的催化活性最高．进一步用离子扩散法、浸渍法、物理混合法及合成法制备了四种Mo／ZSM－5样品，并以NH3为还原剂，考察了它们的NO的选择性催化还原反应性能．结果表明，用离子扩散法制得的样品对NO还原反应的催化活性最高，在360℃下，NO转化率可达98％．同时，用XRD，SEM，ICP和EDS等技术对4种样品的体相和表面结构进行了测试．结果表明，用离子扩散法制得的样品，Mo元素在分子筛催化剂的内表面有很好的分散性，导致Mo／ZSM－5具有高的催化活性．这可能是由于Mo元素迁移到分子筛的孔道内，在催化剂表面形成了有利于NO选择性催化还原反应的某种特殊活性结构．     

Mg的添加对Mo／ZSM－5催化剂催化甲烷芳构化性能的影响

 通过XRD，N2吸附和吡啶FT－IR等方法考察了Mg的添加对Mo／ZSM－5催化剂物化性质的影响．吡啶FT－IR结果表明，Mo－Mg／ZSM－5催化剂上Lewis酸中心与Br¨onsted酸中心的比值随着Mg添加量的增加而增大．在甲烷芳构化反应中，虽然催化剂上的积碳量随着Mg含量的增加而减少，但只有6％Mo－0．75％Mg／ZSM－5催化剂表现出比6％Mo／ZSM－5催化剂更好的稳定性，6％Mo－2％Mg／ZSM－5和6％Mo－3％Mg／ZSM－5两个催化剂的稳定性均比6％Mo／ZSM－5催化剂差．根据催化剂稳定性与酸性的关系提出，在有足够Br¨onsted酸中心存在的前提下，可以通过调变Lewis酸中心和Br¨onsted酸中心的比值来提高催化剂的稳定性．     

Cu-ZSM-5的NH3选择性催化还原NO性能及其稳态动力学

采用浸渍法制备了一系列不同Cu载量的Cu-ZSM-5整体式催化剂.考察了该系列催化剂的NH3选择性催化还原(SCR)NO的反应特性.结果表明,当Cu质量分数为5%时,Cu-ZSM-5催化剂的SCR活性最高,此时催化剂上NO最高转化率高达96.5%,并且催化剂的活性窗口较宽,催化剂在198-470℃之间NO转化率大于80%.H2O和SO2的添加仅轻微影响Cu-ZSM-5催化剂的SCR活性.当Cu载量大于5%时,Cu-ZSM-5催化剂中出现明显的CuO物相.稳态动力学结果表明,在5%Cu载量的Cu-ZSM-5上的SCR反应中,NO的反应级数接近一级,NH3的反应级数接近零级,O2的反应级数接近1/2级.该反应的表观活化能为47.7kJ·mol-1.     

金属离子交换分子筛的NO吸附性能

在固定床流动吸附装置上利用吸附一脱附法测定了各种金属离子交换分子筛上NO吸附性能．结果表明，在ZSM－5上NO的可逆吸附量（qrev）与不可逆吸附量（qiir）随交换金属离子的不同而不同．单位交换金属离子的NO可逆吸附量（qrev）与不可逆吸附量（qiir）随分子筛铝含量的减少而增加．qrev与qiir在ZSM－5分子筛上不随交换度变化，而在丝光沸石上却随交换度的变化而改变．     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/₂, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of⁹⁹Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/₃, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

Direct synthesis of dimethyl carbonate ?from CH3OH AND CO2 by H3PW12O40/CexTi1-xO2 catalyst

Summary Ce_xTi_1-xO₂ and H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ showed a better catalytic performance than the corresponding Ce_xTi_1-xO₂, due to the bifunctional catalysis of Br?nsted acid sites (provided by H₃PW₁₂O₄₀) and base sites (provided by Ce_xTi_1-xO₂). H₃PW₁₂O₄₀/Ce_0.1Ti_0.9O₂ showed the highest catalytic performance among the H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts.     

An investigation of the promotional effect of propylene or propane traces on the activity of sulfatedPt/g-Al2O3andPt-Sn/g-Al2O3inCH4combustion

Summary A strong promoting effect of the presence of C₃H₈or C₃H₆was determined for the combustion of CH₄in excess oxygen, over pre-sulfated 1%Pt/g-Al₂O₃and pre-sulfated 1%Pt-2%Sn/g-Al₂O₃catalysts.</o:p>     

LixNi0.8-yCo0.2ZnyOp的合成及电化学性能研究

A series of single-phase Li_xNi_0.8-yCo_0.2Zn_yO_p(0.96 ≤x≤ 1.10， 0 ≤y≤ 0.05， 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method， in which LiOH·H₂O， Zn-doped spherical Ni(OH)₂ and Co₂O₃ were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD， SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine， narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity， but also a better cycling stability characterization than the un-doped one. The Li_1.06Ni_0.75Co_0.22Zn_0.03O_2.03 material has an initial reversible capacity as high as 160.5mAh·g^-1; and a first discharge efficiency 89.2%， and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles.     

Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

Visible light-sensitive yellow TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx anatase photocatalysts

Nitrogen substituted yellow colored anatase TiO_2−xN_x and Fe-N co-doped Ti_1−yFe_yO_2−xN_x have been easily synthesized by novel hydrazine method. White anatase TiO_2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe³⁺ in the lattice. TiO_2−xN_x has higher conductivity than TiO_2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO_2−x extends in the visible region in N, Fe and Fe-N co-doped TiO₂, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO₂ and Fe-doped TiO₂ show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO₂ consist may cause this discrepancy in their photocatalytic activities.     

Carbon black and propylene oxidation over Ru/CoxMgyAl2Oz catalysts

The effects of Co_xMg_yAl₂O_z mixed oxides composition and ruthenium addition on the oxidation of propylene and carbon black (CB) were investigated. Different reactive cobalt and ruthenium oxide species were formed following calcination at 600 °C. The addition of ruthenium was beneficial for the CB oxidation under “loose contact” conditions and for propylene oxidation when the cobalt content was intermediate to low. The calculated activation energy for CB oxidation was decreased from 151 kJ mol⁻¹ for the uncatalyzed reaction to 111 kJ mol⁻¹ over the best catalyst.     

Structure refinement, dielectric, pyroelectric and Raman characterizations of Ba1−xLax(1−y)/2Euxy/2Nax/2TiO3 solid solution

The perovskite-type oxides Ba_1−xLa_x(1−y)/2Eu_xy/2Na_x/2TiO₃ (0?x?0.5 and xy=0.04) were synthesized and characterized by X-ray diffraction as well as dielectric measurements and Raman spectroscopy. The crystal structure of these ceramics has been determined by the Rietveld refinement powder X-ray diffraction data at room temperature. These compounds crystallize at room temperature in tetragonal space group P4mm for 0?x?0.1 and in the cubic group for 0.2?x?0.5. The phase transition temperature T_C (or T_m) decreases as x content increases. The degree of diffuseness of the phase transition is more pronounced for higher x content, implying the existence of a composition-induced diffuse phase transition of the ceramics with x?0.1. The evolution of the Raman spectra was studied as a function of various compositions at room temperature. The polarization state was checked by pyroelectric measurements.