钠助剂对Fe/SiO_2催化剂结构及其催化甲烷氧化偶联反应性能的影响(英文)

以二氧化硅担载铁氧化物（１ｗｔ％ Ｆｅ／ＳｉＯ２）为探针,结合ＸＲＤ、ＸＡＮＥＳ以及ＥＸＡＦＳ分析结果首次从表面配位几何的观点讨论了钠助剂对Ｆｅ／ＳｉＯ２催化剂结构及其甲烷氧化偶联反应性能所产生的影响。ＸＲＤ分析表明,Ｆｅ／ＳｉＯ２经８００℃焙烧后仍保持无定形特征,添加钠助剂并经８００℃焙烧后,Ｎ２Ｆｅ／ＳｉＯ２已转化为α－方石英结构。Ｆｅ／ＳｉＯ２的ＥＸＡＦＳ拟合结果显示,铁中心被５个近邻氧环绕,平均Ｆｅ－Ｏ键长为０．１９４ｎｍ。与Ｆｅ／ＳｉＯ２相比,Ｎａ－Ｆｅ／ＳｉＯ２的径向结构函数谱中最强峰的相对强度提高了１／４,表明形成了一个更加密集的Ｆｅ－Ｏ壳层。拟合结果表明围绕中心铁原子０．１８９ｎｍ处平均有４．１个氧近邻。Ｆｅ－Ｋ边ＸＡＮＥＳ谱表明钠的参与使催化剂的活性组分由配位不饱和的八面体位逐渐向四配位四面体位迁移。甲烷氧化偶联反应结果显示,添加钠助剂后甲烷转化率有所下降,但是Ｃ２烃的选择性提高了近４２个百分点,ＣＯｘ的选择性则明显下降。说明钠的引入使催化剂的表面结构发生变化,所形成的多数四面体／少数八面体混合结构有效地抑制了甲烷的深度氧化,乙烯乙烷的选择性明显提高。     

硫酸亚铁对两种烟煤直接液化的催化作用

用饱和浸渍法把ＦｅＳＯ４直接担载于山东兖州和山西汾西两种烟煤上。在实验的基础上,结合人工神经网络模型考察了ＦｅＳＯ４浸渍量、反应温度和反应时间对烟煤液化行为的影响,并通过ＸＲＤ和热力学计算探索了ＦｅＳＯ４在煤直接液化反应中可能发生的化学形态变化。结果表明,训练完全的人工神经网络不仅可较好地拟合实验结果,而且可较好地预报反应条件对ＦｅＳＯ４催化活性的影响,ＦｅＳＯ４在煤液化反应时存在着临界浸渍量,当     

铁酸锌纳米晶体材料的制备

以ＦｅＳＯ４·７Ｈ２Ｏ和ＺｎＳＯ４·７Ｈ２Ｏ为原料，首先制备出晶粒细小的碱式碳酸盐前驱体，在３００—７００℃焙烧１ｈ后，制备出ＺｎＦｅ２Ｏ４纳米粒子。经ＸＲＤ和ＴＥＭ检测，粒径约５－２５ｎｍ，粒度均匀。     

载铁煤焦中铁化学形态的研究

利用ＥＸＡＦＳ，ＸＡＮＥＳ和ＸＲＤ方法对负载三氯伦铁的地焦中铁化学形态进行了表征，并着重考察煤的铁负载量对铁化学形态的影响。在６００℃热解条件下，两种褐煤载铁半焦中铁主要以晶相Ｆｅ３Ｏ４存在，而烟煤载铁半焦中以Ｆｅ３Ｏ４，ＦｅＯ和α－Ｆｅ混合物相存在。     

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．     

纳米晶La_（1－_x）Sr_xFeO_3的合成及气敏特性的研究

用柠檬酸盐法合成出Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３（ｘ＝０．１，０．２，０．３，０．４）原粉，再经固相反应得到纳米晶粉末，用ＴＧ、ＤＴＡ、ＸＲＤ、ＩＲ进行了表征，确证复合氧化物Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３为钙钛矿型结构，粒径在１０～２５ｎｍ之间。实验结果表明，随着固相反应条件不同，产物粒径呈规律性变化．气敏特性研究表明，该纳米晶材料对乙醇有较高的选择性和灵敏度，其选择性顺序为Ｌａ_（０．９）Ｓｒ_（０．１）ＦｅＯ_３＞ＬａＦｅＯ_３＞ＬａＦｅＯ_３（大晶粒）。     

纳米晶La1—xSrxFeO3的合成及气敏特性的研究

用柠檬酸盐法合成出Ｌａ１－ｘＳｒｘＦｅＯ３（ｘ＝０．１，０．２，０．３，０．４）原粉，再经固相反应得到纳米晶粉末，用ＴＧ、ＤＴＡ、ＸＲＤ、ＩＲ进行了表征，确证复合氧化物Ｌａ１－ｘＳｒｘＦｅＯ３为钙钛矿型结构，粒径在１０～２５ｎｍ之间。实验结果表明，随着固相反应条件不同，产物粒径呈规律性变化。气敏特性研究表明，该纳米晶材料对乙醇有较高的选择性和灵敏度，其选择性顺序为Ｌａ０．９Ｓｒ０．１ＦｅＯ３＞Ｌａ     

氧化铈在非贵金属氧化物催化剂中的作用：Ⅵ.Cu—Fe—Ce—O催化剂的结 …

采用ＸＲＤ,顺磁共振（ＥＳＲ）,Ｍｏｓｓｂａｕｅｒ和或温还原（ＴＰＲ）技术对负截型Ｃｕ－Ｆｅ－Ｏ（Ⅰ）,Ｃｕ－Ｆｅ－Ｃｏ－Ｏ（Ⅱ）催化剂的固相结构及热稳定性进行了研究。结果发现,（Ⅰ）中主要存在Ｆｅ２ＣｕＯ４,ＣｕＯ和颗粒度小于１３ｎｍ的Ｆｅ２Ｏ３相。随着焙烧温度的升高,ＣｕＯ晶相逐渐消失,Ｆｅ２ＣｕＯ４的晶相长大。（Ⅱ）中Ｃｅ的存在,能提高Ｃｕ＾２＋的浓度,抑制ＣｕＯ和Ｆｅ２ＣｕＯ４晶相的生成,     

纳米复合固体超强酸SO42-/CoFe2O4的制备和表征

采用纳米化学制备技术合成了新型的纳米复合固体超强酸催化剂ＳＯ４＾２－／ＣｏＦｅ２Ｏ４。用ＸＲＤ、ＴＥＭ、ＸＰＳ、红外光谱和比表面测定等技术研究了该催化剂的结构形态,结果表明：所研制的ＳＯ４＾２－／ＣｏＦｅ２Ｏ４２催化剂为晶态纳米粒子（〈５０ｎｍ）,比表面积很大（１５７ｍ＾２．ｇ＾－１）,ＳＯ４＾２－与氧化物的金属离子呈无机齿螯合状配位化合物的结合形式。以乙酸乙酯合成为模型反应考究了该催化剂的催化活     

氧化铈对F-T反应铁锆催化剂的助催化作用

应用ＸＲＤ、ＸＰＳ、Ｍｏｓｓｂａｕｅｒ谱、ＴＰＲ、ＣＯ－ＴＰＤ、ＣＯ＋Ｈ２反应性能测量试等手段研究了ＣｅＯ２对Ｆ－Ｔ合成制低碳烯烃Ｃｅ－Ｆｅ／ＺｒＯ２催化剂催化性能的影响。结果表明，与Ｆｅ／Ｚｒ催化剂相比，加铈助剂后的催化剂Ｆ－Ｔ反应催化活性明显上升。     

Urea hard segment morphology in flexible polyurethane foam

A series of flexible polyurethane slabstock foam samples were prepared with varying water content and studied using transmission electron microscopy (TEM), video-enhanced optical microscopy (VEM), and small-angle X-ray scattering (SAXS). A new TEM sample preparation technique was developed in which the foam is impregnated with water, frozen, and microtomed, and the polyether soft segment is selectively degraded in the electron beam. Structures of two size scales were detected. A texture with grains (“urea aggregates”) 50–200 nm in size was imaged using both VEM and low-magnification TEM for foams with formulations containing more than 2 pphp water. For the first time, images of urea hard segment microdomains in polyurethane foam (approximately 5 nm in size) were obtained using high-magnification TEM. A microdomain spacing of approximately 6–8 nm was estimated from the SAXS scattering profiles. Glycerol was added to one of the formulations in order to modify the urea microphase separation and to give insight into morphology development in molded polyurethane foam systems. No structure was observed in low-magnification TEM images of the glycerol-modified foam, although smaller structures (hard segments) were detected at high magnification and by SAXS. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 573–581, 1998     

有机添加物对Cu-Co-Fe合成醇催化剂的修饰作用

 采用并流共沉淀法制备了Cu-Co-Fe合成醇催化剂,通过改变有机添加物,对Cu-Co-Fe催化剂前驱物的结构和表面状态进行修饰和改性,考察了不同有机添加物对催化剂结构的影响规律. 不同添加物可以修饰调节催化剂的晶粒大小、比表面积和孔径分布. 加入草酸或丙烯酰胺,可使CuO(111)和Co3O4(110)晶粒度增大,比表面积减小,孔径较大的过渡孔分数增大. 柠檬酸为添加物时,催化剂中CuO和Co3O4晶粒度较小,比表面积较大,孔径主要分布在小于10 nm的细孔区.     

Studies on the structure and catalytic performance of S and P promoted Na-W-Mn-Zr/SiO2 catalyst for oxidative coupling of methane

A series of Na-W-Mn-Zr/SiO2 catalysts promoted by different contents of S or/and P were prepared and their catalytic performance for oxidative coupling of methane was investigated to clarify the effect of S and P on the Na-W-Mn-Zr/SiO2 catalyst. The catalysts were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). From the characterization results, it is found that the addition of S and P to the Na-W-Mn-Zr/SiO2 catalyst helps the formation of active phases, such as α-cristo...     

助剂对Ru/C催化剂的表面性质及氨合成催化性能的影响

以碱金属、碱土金属硝酸盐作为助剂前体，活性炭为载体制备了系列负载型钌催化剂，采用物理吸附、化学吸附和XRD等表征手段，考察了助剂对Ru/C催化剂的比表面、孔分布和钌分散度的影响，并在430 ℃、10.0 MPa和10 000 h－1条件下进行氨合成活性评价。结果表明，单助剂Ru/C催化剂，碱金属助剂的促进作用与其相应氢氧化物碱性变化规律一致，碱土金属助剂的促进作用与其相应氧化物碱性变化规律一致。在同类化合物中，铯和钡均是最有效的助剂，钡比铯具有更强的促进作用。以硝酸钡和硝酸铯制备双助剂Ru/C催化剂，先钡后铯分步浸渍制备钌催化剂的活性不仅明显高于钡、铯共浸渍钌催化剂，而且也高于先铯后钡分步浸渍钌催化剂。     

The role of urea in Cu–Zn–Al catalysts for methanol steam reforming

Abstract  

Impregnated Cu–Zn over Al₂O₃ exhibits high activity with the use of a lower amount of active metal relative to conventional co-precipitation catalysts. The activity of the catalyst could be enhanced by addition of urea to the metal salt solution during impregnation. The H₂ yield from Cu–Zn catalysts with urea is 42%, while the H₂ yield from catalyst without urea is only 28% in a continuous system at 250 °C and 1.2 atm. The H₂ yield of the catalyst with urea in this study could compete with that of commercial catalysts. The role of urea in the Cu–Zn catalysts was investigated. X-ray diffraction (XRD) analysis of the catalysts shows that the crystal size of CuO could be reduced by the addition of urea. The XRD diffractogram of the catalyst prior to calcination also shows the formation of NH₄NO₃, which could aid in dissociation of metal clusters. Scanning electron microscopy (SEM) images of catalysts show the size of Cu–Zn compound clusters and also their dispersion over the Al₂O₃ surface on the impregnated catalysts. The addition of urea could also yield smaller Cu–Zn compound clusters and better dispersion compared with the impregnated catalyst without urea. Such impregnated Cu–Zn catalysts with urea could be alternative novel catalysts for methanol steam reforming.     

乙烯氧气法氧氯化反应中铜催化剂的研究

用微分固定床和沸腾床反应器考查了在乙烯氧气法氧氯化制二氯乙烷反应中,浸渍法制备的铜催化剂的反应活性及其应用的可能性,并与共沉淀法制备的铜催化剂进行了比较。用x射线衍射分析,程序升温还原和乙烯脉冲反应探讨了乙烯氧氯化催化剂的活性相结构与反应机理。     

Effects of Dissipation on Contact Angle Measurements Using a Dynamic Method

We report studies of the effect of hydrothermal treatment on physical properties such as crystalline phase, size, and morphology of nanosized cadmium sulfide (CdS) particles. CdS precipitates have been synthesized by the reaction of Cd(NO(3))(2) with Na(2)S at room temperature. These CdS precipitates have been hydrothermally treated in the range 120-240 degrees C with variation of the treatment time. The effects of acid catalysts and other additives were also investigated. The particles prepared were characterized by XRD, TEM, and BET methods. With increased hydrothermal treatment temperature and time, crystallization from amorphous to crystalline form, cubic or hexagonal, and an increase of particle size occurred. CdS particles of well-developed hexagonal form were obtained at a hydrothermal treatment temperature of 240 degrees C; the primary hexagonal grain size was on the order of 20-30 nm. The addition of an acid catalyst, HCl, or of Cd(NO(3))(2) into the precipitate sol promoted crystal growth and phase transformation during the hydrothermal treatment, but another additive, Na(2)S, showed the opposite trend. It appears that hydrothermal treatment combined with proper additives could be an effective method for preparation of nanosize crystalline CdS particles. Copyright 2001 Academic Press.     

反应条件对聚苯乙烯复合硫化铅纳米微粒粒度及分布的影响

用新的方法将ＰｂＳ纳米微粒复合在聚苯乙烯光学塑料中，并利用吸收光谱、小角Ｘ－光散射和透射电镜等方法研究了不同反应条件对复合的硫化铅（ＰｂＳ）纳米微粒粒度及分布的影响．结果表明，在一定范围内Ｈ２Ｓ的量和初始含铅聚合物浓度对纳米微粒的粒度影响很小，但对其粒度分布影响较大；当Ｈ２Ｓ与Ｐｂ２＋的摩尔比及初始含铅聚合物浓度均较大时，纳米微粒的粒度分布变宽．实验结果表明复合于聚苯乙烯中的ＰｂＳ的粒度分布是由溶液中反应决定的，本体聚合反应时对ＰｂＳ微粒的粒度分布影响很小．因此控制适当反应条件，可以得到粒度分布均一、分散均匀且透明性好的ＰｂＳ纳米微粒复合有机光学材料．     

Identification of solvated species present in concentrated and dilute sodium silicate solutions by combined 29Si NMR and SAXS studies

Both concentrated and diluted sodium silicate solutions have been investigated by combining (29)Si NMR spectroscopy and SAXS experiments. The chemical nature of the entities responsible for the high siliceous species solubility observed in such alkaline concentrated sodium silicate solutions and their evolution according to dilution have been identified. For the most concentrated solution ([Si]=7 mol/l; pH=11.56; Si/Na atomic ratio=1.71), the results evidence the preponderant presence of neutral Si(7)O(18)H(4)Na(4) complexes, which behave like colloids of about 0.6-0.8 nm able to form very small aggregates with an average size lower than 3 nm. Addition of distilled water to this initial concentrated solution leads, on one hand, to a doubling of the colloid size, i.e. 1.2-1.5 nm, and, on the other hand, to a progressive decrease of the aggregate size until their total disappearance. Such a behavior could be explained by considering, first, the dissociation of the neutral Si(7)O(18)H(4)Na(4) complexes present in the concentrated solution into Na(+) ions and charged (Si(7)O(18)H(4)Na(4-n))(n-) complexes (with 1 ≤ n ≤ 4) and, second, the condensation of these siliceous charged species in order to form larger (Si(7y)O(18y-z)H(4y-2z)Na((4-n)y))(ny-) colloids. The mean size of these colloids suggests that the condensation occurs between 2 and 8 (Si(7)O(18)H(4)Na(4-n))(n-) groups.     

金属间化合物电催化剂Pt1Te1/XC-72的制备及其电催化氧化甲醇性能

以氯铂酸和亚碲酸钠为前驱体,采用两步法在醇水体系下得到负载型Pt1Te1金属间化合物前驱体,通过热处理得到负载型金属间化合物电催化剂Pt1Te1/XC-72.采用X射线衍射（XRD）、透射电子显微镜（TEM）、选区电子衍射（SAED）、电子能谱（EDS）和循环伏安方法（CV）对催化剂进行表征.结果表明：所得产物呈有序金属间化合物Pt1Te1结构,平均粒径4.5nm,在碳载体上具有很好的分散性;负载型金属间化合物电催化剂Pt1Te1/XC-72具有较高的电催化氧化甲醇活性,其优秀的催化氧化甲醇活性与Pt形成金属间化合物后所带来的几何及电子结构改变密切相关.