高比表面大孔容TiO_2-Al_2O_3复合载体的制备与表征

采用共沉淀法和浸渍法制备了高比表面积、大孔容和具有双孔分布的TiO2-Al2O3复合载体,氧化钛掺入量分别为0、5%、10%、15%。运用X射线衍射(XRD)、N2吸附脱附、扫描电镜(SEM)对制备的TiO2-Al2O3复合载体进行了表征。结果表明,在氧化钛含量较低(共沉淀法不大于10%,浸渍法不大于15%)时,两种方法制备的复合载体都保持了γ-Al2O3的骨架结构,即氧化钛在氧化铝中高度分散,浸渍法制备的复合载体中氧化钛的分散性更好。采用共沉淀法制备的复合载体比表面积、孔容等孔结构参数减小幅度较大,而采用浸渍法制备的复合载体孔结构参数减小幅度很小,比表面积都在300m2/g左右,孔容都大于1.0cm3/g,具有双孔分布(3~7nm和20~60nm)。     

高比表面积介孔γ-Al_2O_3纳米颗粒的制备及其对Cl~-的吸附

在干法室温常压状态下,利用滚压振动磨大批量制备尺度在50~80nm的铝纳米颗粒。铝纳米颗粒在超声波作用下发生水解反应、经干燥、焙烧后制备出具有纳米结构的介孔γ-Al2O3(比表面积高达406.9m2/g)。采用X射线衍射仪(XRD)、傅里叶变换红外光谱(FT-IR)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)和比表面测定(BET)等技术对介孔纳米γ-Al2O3样品进行表征。并取0.2g不同条件下制备的介孔纳米γ-Al2O3,考察其对Cl-的吸附性能。实验结果表明,所制备的介孔纳米γ-Al2O3具有高比表面积、孔径大小均匀和高温稳定性。在焙烧温度为400℃、保温4h的条件下制备的介孔纳米γ-Al2O3对Cl-的吸附效率最高,对Cl-的去除率为14.03%。     

钛基LaxCe1-xTiyM1-yO3/γ-Al2O3催化剂的制备及催化燃烧性能

为提高钙钛矿型催化剂的活性,以γ-Al2O3为载体,采用等体积浸渍法制备负载型钙钛矿LaxCe1-xTiyM1-yO3/γ-Al2O3催化剂,考察了活性组分负载量、焙烧温度、A位元素配比和B位元素掺杂对催化剂催化燃烧甲苯性能的影响,并对催化剂进行XRD和BET表征。结果表明:催化剂的最佳制备条件是活性组分负载量为12%,焙烧温度为750℃,催化剂的最佳形式为La0.8Ce0.2 Ti0.8 Mn0.2 O3/γ-Al2 O3,在该催化剂的作用下,甲苯的起燃温度T50和完全转化温度T90分别为292℃和338℃;负载型钙钛矿催化剂保持了完整的钙钛矿结构,活性组分均匀分布在载体的孔道中,虽然会导致载体的比表面积有所降低,但催化剂可以更最大程度地分散,更有利于提高催化剂的催化活性。     

改性γ-Al_2O_3纳米颗粒的制备

在由机械研磨2 h的Al粉经超声波作用下发生水解反应、干燥、焙烧后制备Al2O3的过程中,用蔗糖、研磨13 h的Zn粉和Ag+分别作为辅助剂制得具有高比表面积的γ-Al2O3,并考察改性后对γ-Al2O3织构的影响。采用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)和比表面测定(BET)等技术对介孔纳米γ-Al2O3样品进行表征。结果表明,γ-Al2O3不但具有高的比表面积,而且孔径分布较为集中。通过改变蔗糖的用量、Zn粉纳米颗粒和Ag+,在一定程度上对γ-Al2O3的比表面积和孔结构等进行调控。     

γ-Al2O3载体研究进展

氧化铝催化剂载体领域中,γ-Al2O3应用最为广泛.综述了γ-Al2O3载体的主要研究方向方面的进展:制备工艺低成本化、孔结构控制、提高载体稳定性和制备超细γ-Al2O3,并指出结合制备方法的改善,开发出大比表面积、适宜孔径分布及热稳定性和抗水合性良好的γ-Al2O3载体,同时发展纳米γ-Al2O3以满足实际生产的需要.     

SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.     

CeO2对RuO2/γ-Al2O3催化剂湿式氧化降解苯酚性能的影响

采用浸渍法制备了RuO2/γ-Al2O3和RuO2/CeO2/γ-Al2O3催化剂,并利用XRD、sEM和XPS对催化剂进行了表征,研究了Ce的加人对RuO2/γ-Al2O3催化剂表面分散性和催化剂表面元素Ru,O和Ce化学态的影响,同时考察了RuO2/γ-Al2O3和RuO2/CeO2/γ-Al2O3催化剂湿式氧化降解苯酚的活性,并深入探讨了Ce对RuO2/γ-Al2O3催化剂的助催化作用.结果表明:Ce掺杂改性后,使催化剂表面Ru的化学态降低、表面氧空位增加,并且活性组分Ru的分散性增加,从而使RuO2/CeO2/γ-Al2O3催化剂的活性提高,因此Ce起到了显著的助催化作用.     

Pd-ZrO2/Al2O3催化剂对丙烯选择性催化还原NO的催化活性研究

采用浸渍法制备了具有高比表面积的氧化铝负载的Pd-ZrO2复合物催化剂(Pd-ZrO2/Al2O3),利用BET、XRD、TEM等手段研究了该复合物催化剂的物理特性,并重点研究了该复合物催化剂对以C3H6为还原剂选择性催化还原(SCR)NO的催化反应活性,分别讨论了反应温度、组分、焙烧温度、原料气组分、空速等因素对该催化反应的影响.结果发现,少量的Pd纳米粒子均匀分散于载体氧化铝上,添加适量ZrO2后,所制备的低负载量的Pd(1wt%)-ZrO2(2wt%)/Al2O3复合物催化剂具有较高的NO选择性催化还原反应活性,在240～250℃可使NO的转化率达到50%～70%.其活性提高的机制在于适量ZrO2的添加增强了反应物中NO和C3H6在催化剂表面的吸附,同时与Pd催化剂形成一种协同催化作用.     

纳米Ti0.8Cr0.2OxNy粉体的制备与表征

以沉淀法制备的纳米TiO2／Cr2O3复合粉体为原料，采用氨解法在800℃、氮化8h制备了纳米Ti0.8Cr0.2OxNy粉体．对纳米TiO2／Cr2O3复合粉体和合成的氧氮化物粉体用俄歇电子能谱(AES)、氮吸附比表面积(BET)、X射线衍射(XRD)、透射电子显微镜(TEM)、电子探针显微分析(EPMA)等方法进行了表征．结果表明：沉淀法可以制备出组成均匀的纳米TiO2／Cr2O3复合粉体，该复合粉体在800℃氮化8h可得到粒度为20～30nm的纯立方相Ti0.8Cr0.2OxNy纳米粉体，其比表面积达46．74m^2／g．     

CaO/γ-Al2O3吸附剂吸附CO2的性能研究

采用浸渍法制备了以γ-Al2O3为载体的CaO/γ-Al2O3吸附剂,并在自制吸附剂评价装置上,研究了不同CaO负载量对CaO/γ-Al2O3吸附剂吸附性能的影响。利用XRD及BET对CaO/γ-Al2O3吸附剂的物相及结构进行了表征。实验结果表明,CaO/γ-Al2O3吸附剂对CO2有较好的吸附性能,并且CaO/γ-Al2O3吸附剂的比表面积、孔容随着CaO负载量的增大而减小。当CaO的负载量为25%(wt,下同)时,CaO/γ-Al2O3吸附剂的静吸附容量达到最大值,4.95mol/kg。     

Pt纳米颗粒负载SrTiO3/TiO2异质结结构制备及制氢性能

本文以固定n(Sr)/n(Ti)摩尔比0.4的SrTiO_3/TiO_2(金红石相)异质结纳米颗粒,通过"光催化还原沉积方法"制备不同质量分数的纳米铂颗粒(0、1%、2%、5%),探究其催化活性的变化,采用XRD、SEM、UV-vis、XPS方法对其进行表征,并做了相关光催化分解水产氢性能测试.结果表明:负载贵金属Pt纳米颗粒量越大,对应的Pt晶粒平均尺寸为40.8 nm,1%Pt纳米颗粒SrTiO_3/TiO_2异质结构的BET比表面积在23.195 m~2/g处最高,并且介孔材料的特征是平均Barrett-Joyner-Halenda(BJH)孔径为13.60 nm,总孔体积为0.079 cm~3/g;高BET表面积和大的总孔体积强烈地支持SrTiO_3/TiO_2具有介孔结构的事实;相应的催化剂催化活性越高,其中负载5%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒光催化8 h产氢量为3.574 mmol,平均产氢效率为0.447 mmol/(gcat·h),但从性价比的角度来考虑,其催化效率远不及负载1%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒催化效率的5倍,因此负载5%Pt的SrTiO_3/TiO_2纳米颗粒光催化效率最高.     

Synthesis and dye-sensitized solar cell performance of nanorods/nanoparticles TiO2 from high surface area nanosheet TiO2

High surface area nanosheet TiO2 with mesoporous structure were synthesized by hydrothermal method at 130 degrees C for 12 h. The samples characterized by XRD, SEM, TEM, SAED, and BET surface area. The nanosheet structure was slightly curved and approximately 50-100 nm in width and several nanometers in thickness. The as-synthesized nanosheet TiO2 had average pore diameter about 3-4 nm. The BET surface area and pore volume of the sample were about 642 m(2)/g and 0.774 cm(3)/g, respectively. The nanosheet structure after calcinations were changed into nanorods/nanoparticles composite with anatase TiO2 structure at 300-500 degrees C (10-15 nm in rods diameter and about 5-10 nm in particles diameter). The solar energy conversion efficiency (eta) of the cell using nanorods/nanoparticles TiO2 (from the nanosheet calcined at 450 degrees C for 2 h) with mesoporous structure was about 7.08% with Jsc of 16.35 mA/cm(2), Voc of 0.703 V and ff of 0.627; while eta of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm(2), Voc of 0.704 V, and ff of 0.649.     

Effect of Microstructure on Electrorheological Property for Pure TiO2 Particle Material

Pure titanium dioxide （TiO2） particle materials were prepared by hydrolyzing titanium tetrachloride （TiCl4）. The microstructures of these materials were determined by X-ray diffraction （XRD）, accelerated surface area and porosimetry apparatus （BET）, and transmission electron microscopy （TEM）. The TiO2 materials obtained by calcinations under different temperatures distinctly revealed different microstructures in crystal structure type, surface area, pore size, pore volume and grain size. The relationship between the microstructure of the TiO2 materials and their electrorheological （ER） activity was investigated. Anatase titania particles have better ER performance than rutile titania particles. Amorphous TiO2 materials display higher ER activity than the crystalline titania materials. A large pore volume can be more advantageous in improving the ER effect of a particle material.     

合成条件对晶态介孔TiO2结构和性能的影响

采用sol-gel法合成了锐钛矿相介孔氧化钛，利用XRD、BET、TEM和PL对介孔TiO2的结构和光致发光性能进行了表征及分析。结果表明，采用预制TiO2溶胶为钛源，所得介孔氧化钛具有良好的锐钛矿晶型、较大的孔径和比表面积，具有高的光致发光活性。     

介孔SO42-/TiO2的一步法制备及其光催化性能

通过对TiOSO4溶液热水解用一步法制备出大比表面积、高活性的介孔SO42-/TiO2光催化剂.用低温氮吸附-脱附等温线、XRD、Hammett指示剂、艾氏卡等方法对SO42-/TiO2催化剂进行了表征,以亚甲基蓝的光催化氧化降解反应考察了催化剂的光催化性能.结果表明,在焙烧过程中硫酸根和偏钛酸孔壁上的自由羟基键合,不仅有效地抑制了TiO2晶粒的长大和晶相转变,而且起到了孔结构形成的导向及支撑作用,使TiO2保持了介孔结构、较高的比表面积和锐钛矿相,同时S=O键的强电子诱导效应还使邻近的Ti成为超强酸中心,促进了TiO2光生电子-空穴对的分离,延长了电子-空穴对的寿命,从而有效地提高了TiO2的光催化活性.     

Mesoporous indium oxide synthesized via a nanocasting route

The synthesis of crystalline mesoporous indium oxide by using a mesoporous carbon (CMK-3) as hard template is described. Transmission electron microscopy (TEM) exhibits the presence of mesoporous structure in our sample and the corresponding wide-angle X-ray diffraction (XRD) pattern confirmed the crystalline wall of sample. N₂ adsorption measurement exhibits the synthesized crystalline mesoporous indium oxide possesses a specific surface area of 39 m²/g and the total pore volume of 0.17 cm³/g, and the corresponding pore size distribution curve reveals the presence of a mesopore of 7.0 nm in maximum. Our work demonstrates that the maintenance of the ordered structure of carbon template is very significant for obtaining high quality replicas via the nanocasting route.     

Investigation of Eu-doped mesoporous titania phosphor with enhanced luminescence

A novel mesoporous TiO2 phosphor doped with Eu was synthesized through a facile hydrothermal synthesis method using cetyltrimethylammonium bromide as structure template reagent. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, scanning electron microscope, high-resolution transmission electron microscopy, ultraviolet visible diffuse reflectance, X-ray photoelectron spectroscopy, and three dimensional Photoluminescence. The X-ray diffraction results demonstrated that the products were anatase type with polycrystalline. N2 adsorption-desorption analysis showed that the samples were of high ordered double mesoporous structures. Eu-doped mesoporous TiO2 indicated the typical fluorescent spectra of Eu3+ ion occurred: the excited-states at 5L6 (394 nm), 5D2 (465 nm) and 5D1 (535 nm); the main emission peaks at 592 and 617 nm, corresponding with the transitions 5D0 --> 7F1 and 5D0 --> 7F2, respectively. Meanwhile, the phenomena of Eu(3+)-doped mesoporous TiO2 phosphor with efficient nonradiative energy transfer from the mesoporous TiO2 host to the activator Eu3+ ions was observed and possible emission mechanism was proposed. High dispersion of Eu in mesoporous TiO2 matrix was responsible for enhanced luminescence.     

A two-step sol-gel method for synthesis of nanoporous TiO2

This article reports a study of the effects of synthesis parameters on the preparation and formation of mesoporous titania nanopowders by employing a two-step sol-gel method. These materials displayed crystalline domains characteristic of anatase. The first step of the process involved the hydrolysis of titanium isopropoxide in a basic aqueous solution mediated by neutral surfactant. The solid product obtained from step 1 was then treated in an acidified ethanol solution containing the same titanium precursor to thicken the pore walls. Low pH and higher loading of the Ti precursor in step 2 produced better mesoporosity and crystallinity of titanium dioxide polymorphs. The resultant powder exhibited a high surface area (73.8 m2/g) and large pore volume (0.17 cm3/g) with uniform mesopores. These materials are envisaged to be used as precursors for mesoporous titania films as a wide band gap semiconductor in dye-sensitized nanocrystalline TiO2 solar cells.     

The direct synthesis of mesoporous structured MnO(2)/TiO(2) nanocomposite: a novel visible-light active photocatalyst with large pore size

A series of visible-light-driven mesoporous structured MnO(2)/TiO(2) nanocrystal photocatalysts have been synthesized through a modified sol-gel method, and the N(2) adsorption-desorption isotherm confirms that the mesoporous materials possess large pore size (up to 9.2?nm) and a narrow pore size distribution. X-ray powder diffraction (XRD) analyses and complementary x-ray photoelectron spectroscopy (XPS) measurements reveal that the doping of the transition metal Mn inhibits the growth of TiO(2) anatase nanocrystals and the Mn species are highly dispersed on the surface of TiO(2). The ultraviolet (UV)-vis spectrum demonstrates the excellent adsorption properties of MnO(2)/TiO(2) over the whole region of visible light, which enables this novel photocatalysis material to possess remarkable activity in the photocatalytic degradation of methylene blue under visible light radiation. Moreover, a 'coating mechanism' based on the nucleation of titania nanocrystals along with the interaction between the dopant precursors and titania clusters has been suggested.     

有序介孔二氧化钛粉体研究进展

主要综述了高度有序六方相和立方相孔道结构介孔二氧化钛以及具有低有序蠕虫状孔道结构介孔二氧化钛的制备方法及其结构特征。总结了后处理法、模板剂脱除法在制备稳定、具有有序介孔和锐钛矿相孔壁的介孔二氧化钛粉体中的应用,指出采用直接合成法制备孔壁结晶的介孔二氧化钛原粉,之后用萃取法脱除模板剂并用钛酸异丙酯蒸气增强骨架,将是得到高稳定性有序介孔二氧化钛材料的良好途径。