前驱体对Ru/CeO_2-ZrO_2-Al_2O_3催化剂CO选择性甲烷化的影响

以CeO_2-ZrO_2-Al_2O_3复合氧化物为载体,采用分步等体积浸渍法制备了不同Ru负载量及不同Ru前驱体的催化剂,并考察了这些因素对催化剂CO选择性甲烷化活性及为燃料电池供氢操作温度窗口的影响。结果表明,Ru负载量为1%的催化剂具有较好的CO选择性甲烷化活性及最宽的操作温度窗口;以Ru(NO)(NO_3)_3为前驱体制备的催化剂,Ru金属分散度较差,低温CO甲烷化活性较低,高温CO甲烷化选择性较差,操作温度窗口仅为15℃;以RuCl_3·xH_2O为前驱体制备的催化剂具有良好的CO选择性、甲烷化活性及60℃操作温度窗口,且水洗除氯操作对催化剂性能影响不明显。     

Ultrasound-assisted co-precipitation synthesis of mesoporous Co3O4–CeO2 composite oxides for highly selective catalytic oxidation of cyclohexane

The one-step highly selective oxidation of cyclohexane into cyclohexanone and cyclohexanol as the essential intermediates of nylon-6 and nylon-66 is considerably challenging. Therefore, an efficient and low-cost catalyst must be urgently developed to improve the efficiency of this process. In this study, a Co₃O₄–CeO₂ composite oxide catalyst was successfully prepared through ultrasound-assisted co-precipitation. This catalyst exhibited a higher selectivity to KA-oil, which was benefited from the synergistic effects between Co³⁺/Co²⁺ and Ce⁴⁺/Ce³⁺ redox pairs, than bulk CeO₂ and/or Co₃O₄. Under the optimum reaction conditions, 89.6% selectivity to KA-oil with a cyclohexane conversion of 5.8% was achieved over Co₃O₄–CeO₂. Its catalytic performance remained unchanged after five runs. Using the synergistic effects between the redox pairs of different transition metals, this study provides a feasible strategy to design high-performance catalysts for the selective oxidation of alkanes.     

共沉淀法制备Li[Ni1/3Co1/3Mn1/3]O2及电化学性能研究

采用NH3-NaOH共沉淀法合成了L[Ni1/3Co1/3Mn1/3]O2正极材料,通过改变NH3·H2O浓度及加料方式研究材料的电化学性能.采用XRD、SEM对晶体的结构和形貌作表征.将正极材料Li[Ni1/3Co1/3Mn1/3]O2制成电极极片,组装成电池进行测试.分析测试结果表明,合成的极材料Li[Ni1/3Co1/3Mn1/3]O2具有典型的α-NaFeO2结构,粒径分布较好,呈类球形.     

固体超强酸催化剂S2O2-8/Fe2O3-Al2O3的制备及其酯化性能

以硝酸铁为铁源、硝酸铝为铝源,通过共沉淀法制备固体超强酸催化剂S₂O^2-₈/Fe₂O₃-Al₂O₃。通过催化剂样品的FT-IR谱图、不同焙烧温度催化剂样品的XRD谱图、不同陈化温度的N2吸附-脱附曲线以及催化剂样品的SEM照片,研究了其晶体的形成过程。催化剂样品红外谱图表明,催化剂中的S=O有较强的共价双键特征,诱导催化剂形成超强酸性;在XRD谱图中既无Al₂O₃的晶相峰,也无Fe₂(SO₄)₃晶相峰,说明Al₂O₃与Fe₂O₃ 在催化剂样品的表面形成了Al₂O₃-Fe₂O₃ 共价键的复杂结构。采用BET方程和BJH模型计算催化剂样品的比表面积和孔径分布,经冰水陈化的催化剂样品平均孔径为9.1 nm,最可几孔径为7.5 nm,比表面积为78.9 m²·g^-1,孔容0.149 cm³·g^-1。研究了催化剂的铁与铝物质的量比、(NH₄)₂S₂O₈浸渍浓度和不同焙烧温度对硬脂酸正丁酯酯化率的影响。在反应温度85 ℃、催化剂用量0.2 g (为反应物总质量的2%)和回流反应150 min的条件下,酯化率可达84.5%。     

加料方式对共沉淀法制Ni/Al2O3的影响

本文采用XRD研究了加料方式对共沉淀法制备的Ni/Al2O3的影响。结果表明：采用并流的方法制备的Ni/Al2O3中Ni分散度较好。     

η-Al2O3与γ-Al2O3在CS2催化水解反应中的性能比较

通过制备高纯度的前驱体湃铝石获得了η-Al₂O₃材料,采用XRD验证了η-Al₂O₃与γ-Al₂O₃在晶相结构上的差异,比较了两者的表面形貌、织构及酸碱性能,结果显示,η-Al₂O₃与γ-Al₂O₃的比表面积相当,但η-Al₂O₃具有更弱的弱碱位和较少的强碱位,并拥有丰富的中等强度酸性位。将η-Al₂O₃与γ-Al₂O₃作为催化剂应用于CS₂水解反应,结果表明,在(200~450) ℃测试温度范围内,η-Al₂O₃催化剂对CS₂的水解活性始终优于γ-Al₂O₃,两种催化剂上CS₂反应的浓度效应也明显不同,推测与它们的酸碱性质影响了对CS₂的吸附能力有关,导致两者催化CS₂水解反应遵循了不同的机制。     

溶胶-凝胶法制备分子筛／γ-Al2O3对Mn^2＋的吸附性能研究

采用溶胶-凝胶法制备分子筛／γ-Al2O3复合材料，以高碘酸钾分光光度法为检测手段，考察了分子筛／γ-AL2O3在静态条件下对Mn^2＋的吸附性能。结果表昵，pH值在7～8时，分子筛／γ-Al2O3对Mn^2＋有较好的吸附性能，吸附符合Langmuir吸附模型，吸附容量可达29mg／g，产生复合效应。     

Structural,magnetic and photocatalytic properties of Sr-doped BiFeO3 nanoparticles based on an ultrasonic irradiation assisted self-combustion method

A novel ultrasonic irradiation assisted self-combustion method was developed to prepare single-phase Bi_1−xSr_xFeO_3−δ (BSFO) nanoparticles, which were charactered by XRD, SEM, TEM and UV–vis spectra. The results show that structure, as well as magnetic and photocatalytic properties of BSFO are influenced by the particle size and the Sr²⁺ dopant content. Regarding smaller particles, even if small amount of Sr²⁺ substitution content change can result in the phase transition from the rhombohedral distorted perovskite to the cubic. The doping of heterovalent Sr²⁺ ions in BiFeO₃ (BFO) nanoparticles improves the ferromagnetic property. As ultrasonication can generate particles with larger surface area and more defections, BSFO nanoparticles exhibit efficient photocatalytic activity as a promising photocatalyst.     

Cs2O/Al2O3-ZrO2催化剂的制备及催化性能研究

本文采用醇盐-凝胶溶胶法制备Al2O3-ZrO2催化剂复合载体,并通过超声浸渍法制备Cs2O/Al2O3-ZrO2催化剂。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)等技术考察了复合载体对催化剂的晶相结构、表面形貌的影响;并以甲醛和醋酸甲酯合成丙烯酸甲酯反应为探针,讨论了单一载体及铝锆比不同的复合载体催化剂的催化活性。实验结果表明:经过500℃煅烧的催化剂具有良好的晶形;材料具有蜂窝状孔道,具有良好的通透性;Cs的负载量为4.42%;当mAl2O3∶mZrO2=1∶0.25时,所得催化剂的活性最高,收率达到14.76%。     

Pt-SO2-4/ZrO2-Al2O3催化剂的制备及其催化正戊烷异构化性能

制备了Pt-SO2-4/ZrO2-Al2O3固体超强酸催化剂,采用XRD,TG-DTA,FT-IR,TPR,SEM,BET,ICP等表征方法对催化剂进行了表征.以正戊烷异构化反应为探针,在高压固定床-色谱联合装置上,评价了催化剂的活性,考察了空速v空、反应温度t、反应压力p和氢与正戊烷摩尔比对正戊烷异构化反应的影响.在...     

Al2O3对AIPO4催化剂的结构及其缩醛化反应活性的影响

采用溶胶-凝胶法制备了系列AlPO4-Al2O3催化剂,利用XRD、TG-DTA、NH3-TPD和催化剂评价等方法,研究了制备条件对催化剂结构和缩醛化反应催化性能的影响,结果表明,Al2O3的存在不仅能提高AlPO4的热稳定性,而且可以调节催化剂的表面酸性性能.在适宜的缩醛化反应条件下,400℃焙烧和Al2O3质量分数为15%的AlPO4-Al2O3催化剂样品具有较好的催化活性,1,2-丙二醇转化率达28.1%,AlPO4-Al2O3催化剂的缩醛化反应活性与表面弱酸中心的酸量成顺变关系.     

纳米光催化剂TiO_2/Fe_3O_4的制备及表征

采用两步法制备磁性负载纳米光催化剂TiO2/Fe3O4。首先用液相共沉淀法制备磁性纳米Fe3O4颗粒;然后用溶胶-凝胶法,以钛酸四正丁酯为先驱体,通过水解缩聚在Fe3O4纳米颗粒表面包覆TiO2层,得到易于磁分离回收的复合纳米光催化剂TiO2/Fe3O4,粒径大约为30 nm。利用TEM、XRD、FT-IR、VSM对Fe3O4和TiO2/Fe3O4的结构和性能进行了表征,结果表明,制备的Fe3O4为面心立方晶体(FCC)结构,具有超顺磁性;TiO2为锐钛矿相,包覆在Fe3O4的表面,形成了核-壳式结构的TiO2/Fe3O4复合光催化剂。     

溶胶-凝胶法制备氧化硅-氧化铝体系凝胶及合成过程研究进展

氧化硅-氧化铝（SiO₂-Al₂O₃）体系凝胶不仅应用广泛,而且其制备及反应机理还可借鉴到碱激发胶凝材料等领域。通过对溶胶-凝胶法合成氧化硅-氧化铝体系凝胶的制备过程及影响因素和影响规律、凝胶的性质和结构表征及合成机理研究进展进行综述,提出目前仍缺乏有关碱（土）金属离子对凝胶结构性能的影响研究以及硅铝含量变化的定量描述数据,建议拓宽研究范畴,结合核磁共振等检测方法,得出该体系结构性能变化准确数据,为氧化硅-氧化铝体系凝胶的设计和应用夯实基础。     

Reusable high performance of calcined Mg/Al hydrotalcite for the removal of Navy Blue and Yellow F3G dyes

Water pollution with dye chemicals from apparel industries is a serious problem in the world.Since most of dyes are potentially have toxic and carcinogenic effects on human,it is important to remove them before they are discharged to the environment.Among many methods available for dyes removal in water,adsorption is the easiest and economically feasible that has no major obstacle for practical appli-cations.In the present study,we tested calcined Mg/Al hydrotalcite (Mg/Al CHT) prepared by co-precipitation technique as an adsorbent for the removal of Navy Blue (NB) and Yellow F3G (YF3G) dyes.Mg/Al CHT was characterized by using a Fourier transform infrared (FTIR) spectrometer,an X-ray diffrac-tometer (XRD) and a scanning electron microscope (SEM).The results showed that Mg/Al CHT was highly effective as an adsorbent for the removal of NB and YF3G under mild-acidic condition (pH 4) with removal capacities (b) according to Langmuir isotherm model were 7.97 × 10-4 and 5.80 × 10-4 mol·g-1,respectively.Kinetics study showed that the adsorption of NB and YF3D on Mg/Al CHT followed pseudo-second order with rate constant (kp2) 11.57 × 103 and 11.75 × 103 g·mol-1·min-1,respectively.The spent adsorbent can be easily regenerated by simply calcining it at 450 ℃ for 3 h.Adsorption test on the mix-ture of NB and YF3G showed that the adsorption capacity of Mg/Al CHT was eightfold higher than that of Mg/Al HT and the value was maintained with repeated use.     

机械研磨燃烧法制备Cu/ZnO/Al2O3甲醇合成催化剂

引言Cu/ZnO/Al2O3催化剂近年来广泛应用于低压甲醇合成、二甲醚合成和水煤气变换等领域[1-2],该催化体系具有活性高、使用寿命长、反应温度及     

Structural and optical properties of MoO3 and V2O5 thin films prepared by Spray Pyrolysis

MoO₃ and V₂O₅ thin films were prepared on glass substrates by Spray Pyrolysis technique at a substrate temperature of 423 K. The precursor solutions were obtained by varying the concentrations of MoCl₅ and VCl₃ in bi-distilled water. The structural investigation conducted by X-ray diffraction showed that MoO₃ and V₂O₅ thin films were polycrystalline with orthorhombic structure. The optical properties studied in the 300–2500 nm range suggest that the thin film behaviours are related to bound electronic states. The optical band gaps have been estimated from slopes of ln(hν) versus hν plots of MoO₃ and V₂O₅ films were 3.35 and 2.44 eV, respectively. The electrical conductivity was measured using four probes method.     

填料型La2O3/Al2O3-Al催化剂的制备及其催化性能

以n水硝酸镧[La(NO3)3·n H2O]为原料,阳极氧化铝(Al2O3-Al)为载体,采用水热合成法将活性组分负载在Al2O3-Al上,制备了填料型固体碱催化精馏元件La2O3/Al2O3-Al,以丙酮缩合制备二丙酮醇为探针反应,考察了制备条件对催化剂性能的影响。采用XRD、SEM对催化剂的性能进行了表征。结果表明,活性组分La2O3均匀分散在载体Al2O3-Al表面上。当La(NO3)3·n H2O与氨水(NH3·H2O)的摩尔比为1∶8,油浴温度为160℃,油浴时间10 h,N2保护下焙烧温度为550℃,焙烧时间为2 h时,催化剂的活性最高,此时丙酮转化率为4.1%,二丙酮醇选择性98%。     

Synthesis, characterization and catalytic properties of NiMo/Al2O3–MCM-41 catalyst for dibenzothiophene hydrodesulfurization

Ni–Mo/Al₂O₃–MCM-41 supported catalysts have been investigated for modification of MCM-41 by using sol–gel alumina incorporation method. Different catalysts were synthesized with variation of Si/Al molar ratios of 10, 50, 100 and 200. High specific surface area ordered meso-porous solid (MCM-41) was synthesized by using organic template method. In order to modify the low acidity of silica solid, the surface of MCM-41 was modified by incorporation of alumina. The surface acidity of solids modified significantly with variation of alumina content in the supports. The sol–gel method of alumina incorporation was used, which does not modify extensively the pore characteristics of MCM-41 material during the preparation of Al₂O₃–MCM-41. The X-ray diffraction intensities indicated that alumina as well as MCM-41 were present in the synthesized supports. Additionally, the hydrothermal stability of the Al₂O₃–MCM-41 materials was maintained up to 873 K using sever conditions like 100% water vapor stream. The catalytic activity of the catalysts was tested in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Selectivity was oriented mainly to the production of biphenyl (BP) and for high Si/Al ratios toward cyclohexylbenzene (CHB) and showed a higher conversion and better selectivity to hydrogenation (cyclohexylbenzene).     

Performance and characterization of Ru/Al2O3 and Ru/SiO2 catalysts modified with Mn for Fischer–Tropsch synthesis

Mn effect and characterization on γ-Al₂O₃-, -Al₂O₃- and SiO₂-supported Ru catalysts were investigated for Fischer–Tropsch synthesis under pressurized conditions. In the slurry phase Fischer–Tropsch reaction, γ-Al₂O₃ catalysts showed higher performance on CO conversion and C₅⁺ selectivity than -Al₂O₃ and SiO₂ catalysts. Moreover, Ru/Mn/γ-Al₂O₃ exhibited high resistance to catalyst deactivation and other catalysts were deactivated during the reaction. From characterization results on XRD, TPR, TEM, XPS and pore distribution, Ru particles were clearly observed over the catalysts, and γ-Al₂O₃ catalysts showed a moderate pore and particle size such as 8 nm, where -Al₂O₃ and SiO₂ showed highly dispersed ruthenium particles. The addition of Mn to γ-Al₂O₃ enhanced the removal of chloride from RuCl₃, which can lead to the formation of metallic Ru with moderate particle size, which would be an active site for Fischer–Tropsch reaction. Concomitantly, manganese chloride is formed. These schemes can be assigned to the stable nature of Ru/Mn/γ-Al₂O₃ catalyst.