TiO2/BiVO4复合光催化剂的微波辅助水热法合成及催化性能研究

以硝酸铋和偏钒酸铵为原料,采用微波-辅助水热法合成了BiVO4和TiO2/BiVO4复合光催化剂,借助XRD、UV-Vis和FE-SEM等测试手段对样品进行表征。XRD分析表明,所得BiVO4粉体为单斜晶系,且与TiO2复合后,特征衍射峰宽化,强度降低;FE-SEM显示,所得样品为具有多级结构的球状纳米结构体系;UV-Vis吸收光谱表明,BiVO4粉体和TiO2/BiVO4在400～600 nm的可见光区域对光响应。根据光吸收特性,选择罗丹明B为模型污染物,考察了样品可见光催化活性。结果表明,TiO2/BiVO4相比BiVO4,具有更高的可见光催化活性。     

Catalytic degradation of aqueous Fischer–Tropsch effluents to fuel gas over oxide‐supported Ru catalysts and hydrothermal stability of catalysts

BACKGROUND: The catalytic degradation of aqueous Fischer–Tropsch (FT) effluents to fuel gas over Ru/AC has been investigated. In order to understand the catalytic performance and stability of oxide‐supported Ru catalysts, several oxide supports (titania, zirconia, γ‐alumina and silica) were selected for study, with a focus on the hydrothermal stability of catalysts. RESULTS: The catalytic efficiency for transforming the oxygenates in aqueous FT effluents to C₁–C₆ alkanes decreased in the order: Ru/ZrO₂～ Ru/TiO₂ > Ru/SiO₂ > Ru/Al₂O₃. The conversion of alcohols was greatly suppressed over Ru/γ‐Al₂O₃. The former two catalysts (Ru/ZrO₂ and Ru/TiO₂) exhibited enhanced efficiency and long‐term stability (400 h) relative to Ru/SiO₂ and Ru/Al₂O₃. N₂‐physisorption, XRD and SEM showed that titania and zirconia exhibited high structural stability in an aqueous environment. However, the structures of γ‐alumina and silica were unstable due to significant drop in surface area and adverse changes in surface morphology. Especially for the case of the Ru/γ‐Al₂O₃ catalyst, the γ‐alumina was transformed into boehmite structure after reaction, and metal leaching and carbon deposition were extensive. CONCLUSION: Ru/ZrO₂ or Ru/TiO₂ may be a promising alternative for degrading aqueous FT effluents due to their long‐term stability. Copyright © 2012 Society of Chemical Industry     

核壳结构Co3O4水热法制备及其电化学性能

以硝酸钴为原料,柠檬酸三钠为模板,六次甲基四胺为成沉淀剂水热制备了核壳结构Co3O4,X射线衍射(XRD)、扫描电镜(SEM)测试表明,柠檬酸三钠的加入使制备的Co3O4呈现核壳状结构,循环伏安等电化学研究表明该材料的电化学电容性能较好,单电极比电容达到333 F/g。     

Hydrothermal modification of natural zeolites to improve uptake of ammonium ions

The modification of natural zeolites was carried out under hydrothermal conditions to improve the effectiveness of the uptake of ammonium ions. Natural zeolites originating in Japan, such as mordenite and clinoptilolite with quartz, feldspar and a trace of layered silicate, were treated with 0.1, 0.3, 1.0 and 3.0 M NaOH solutions at temperatures from 25 to 150 °C under autogenous pressure for 7 days. After the hydrothermal treatment, the transformation of the zeolites to phillipsite, hydroxyl‐sodalite and analcime was observed, depending on the temperature and NaOH concentration. The amounts of ammonium ions taken up into the hydrothermally‐treated zeolites were compared with those of the starting materials. The treated products, containing mainly phillipsite, took up twice the amount of ammonium ions as the starting materials. The maximum uptake of ammonium ions was 1.92 mmol g^?1. The number of ammonium ions taken up into phillipsite was equal to the number of Na⁺ ions released from phillipsite. These results indicate that the uptake of ammonium ions proceeds by an ion‐exchange mechanism with Na⁺ ions. Copyright © 2005 Society of Chemical Industry     

催化裂化装置中催化剂平衡活性的数学模拟

依据催化裂化催化剂水热失活过程伴随着超稳化过程，确定了催化剂自抑制水热失活动力学模型方程。利用催化裂化催化剂水热失活实验数据进行参数估值，确定了模型参数，以及模型参数与老化温度和水蒸气分压的关联式，建立了催化裂化催化剂水热失活动力学模型。考虑工业装置中催化裂化催化剂呈全混流，建立了催化裂化催化剂平衡活性数学模型，并且成功地模拟计算了装置平衡催化剂的微反活性。该模型的预测结果表明，随着再生器温度或催化剂藏量的提高，平衡剂的微反活性逐步降低；平衡剂微反活性随催化剂单耗的增加而提高，但提高的幅度逐渐降低。     

Flower-like Sc2Mo3O12 nanosheet clusters: Synthesis,thermal expansion and photocatalytic properties

In this work, Sc₂Mo₃O₁₂ has been synthesized via one-pot hydrothermal reaction. The effects of process conditions on the crystal structure, morphology, photocatalytic activity and negative thermal expansion (NTE) behaviors of flower-like Sc₂Mo₃O₁₂ were systematically investigated. Results indicate that orthorhombic flower-like Sc₂Mo₃O₁₂ assembled by nano-size flaky crystal grains can be synthesized by one-pot hydrothermal reaction at a temperature as low as 120 °C for 2 h. The hydrothermal reaction temperature and time have no obvious effects on the crystal structure and morphology. However, the photocatalytic property of synthesized Sc₂Mo₃O₁₂ is sensitive to the above parameters. The sample synthesized at 200 °C for 2 h shows the best photocatalytic degradation of methyl orange, and the degradation rate is 73.32% in 2 h ¹The coefficient of thermal expansion (CTE) of Sc₂Mo₃O₁₂ is ?1.99 × 10^?6 °C^?1 in 50–500 °C tested using TMA. The high-temperature XRD analysis reveals that Sc₂Mo₃O₁₂ exhibits anisotropic NTE and the intrinsic CTE is measured to be ?2.09 × 10^?6 °C^?1 in 25–800 °C.     

Microstructure and photocatalytic activity of Ni-doped ZnS nanorods prepared by hydrothermal method

Pure ZnS and Ni²⁺-doped ZnS nanorods (Zn_1-xNi_xS, x=0, 0.01, 0.03, 0.05 and 0.07, mole fraction, %) were synthesized by hydrothermal method. The effects of Ni²⁺ doping on the phase-structure, morphology, elemental composition and optical properties of the samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (EDS) and ultraviolet-visible spectroscopy (UV-Vis), respectively. The photocatalytic activity of Zn_1-xNi_xS nanorods was evaluated by the photodegradation of organic dyes Rhodamine B (RhB) in aqueous solution under UV light irradiation. The results show that all samples exhibit wurtzite structure with good crystallization. The morphologies are one-dimensional nanorods with good dispersion, and the distortion of the lattice constant occurs. The band gap of Zn_1-xNi_xS samples is smaller than that of pure ZnS, thus red shift occurs. Ni²⁺-doped ZnS nanocrystals can enhance photocatalytic activities for the photodegradation of RhB. Especially, Zn_0.97Ni_0.03S sample exhibits better photocatalytic performance and photocatalytic stability for the decomposition of RhB.     

Effect of cosolvent and addition of catalyst (HZSM‐5) on hydrothermal liquefaction of macroalgae

The present study aimed to evaluate the effect of the direct liquefaction of macroalgae in an autoclave reactor (50 mL) possessing water and ethanol as cosolvent. The reaction conditions such as duration, temperature, algae/solvent ratio, the composition of cosolvent (ethanol‐water) on product distribution, and bio‐oil characterization were studied. The optimum conditions such as 300°C of temperature, 45 minutes of reaction time, 75% of ethanol, and algae to solvent ratio of 4/40 g/mL supported the bio‐oil yield of 46.75% with a conversion rate of 95.5%. The composition and concentration of the compounds in the bio‐oil produced under various doses of catalyst were described using GC‐MS. The bio‐oil characterization showed that the esters were most predominant in hydrothermal liquefaction with a catalyst (HZSM‐5) compared with hydrothermal liquefaction in the absence of the catalyst.