焙烧温度对WVOx/SiO2催化甘油气相脱水性能的影响

以工业级介孔SiO2为载体,通过浸渍法制得系列不同焙烧温度下的WVOx/SiO2催化剂(CatT,T=350、400、450、500、600)用于甘油气相脱水反应。BET、XRD、NH3-TPD和XPS结果显示CatT具有发达的介孔结构（d0 为5.1~6.8 nm）,比表面积达到215-235 m2/g;焙烧温度有效地调控了WVOx在SiO2表面的分布、化学组成及酸强度。300 ℃时,Cat400（用量7 ml）上甘油（20 wt%）转化率达到89.3%,脱水产物丙烯醛和乙醛选择性分别达到53.4%和22.1%,液体冷凝产物碳平衡达到86%,且Cat400展现出较好的再生性。     

Role of Promoters on the Acrolein Ammoxidation Performances of BiMoOx

Ammoxidation of acrolein to acrylonitrile was studied using multicomponent (MC) BiMoOx catalysts in the presence of ammonia and oxygen. The MC catalysts containing bivalent and trivalent metal promoters were found to be highly active and selective to acrylonitrile. The corresponding MC catalysts were characterized by X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron spectroscopy, ICP‐MS and UV–visible diffuse reflectance spectroscopy. It was observed that, among the bivalent cations, the catalysts containing both Co–Ni showed superior performances due to the presence of the metastable β‐Co_xNi_1?xMoO₄ phase. The presence of a trivalent cation, and especially of iron, promoted the formation of both the γ‐Bi₂MoO₆ active phase and the active β‐phase of bivalent metal molybdate. Further, optimization of the reaction conditions enabled the achievement of a 59 % acrylonitrile yield.     

Gas-phase dehydration of glycerol over commercial Pt/γ-Al2O3 catalysts

Gas-phase dehydration of glycerol to produce acrolein was investigated over commercial catalysts based onγ-Al2O3, viz. A-64, A-56, I-62, AP-10, AP-56, AP-64 and KR-104. To understand the effect of Cl?anions, HCl-impregnated sup-ports have been investigated in the dehydration reaction of glycerol at 375 °C. For comparison, various H-zeolites were also examined. It was found that the glycerol conversion over the solid acid catalysts was strongly dependent on their acidity and surface area. And the relationship between the catalytic activity and the acidity of the catalysts was discussed. The outstanding properties of Pt/γ-Al2O3 catalyst systems for the dehydration of glycerol were revealed. Pt/γ-Al2O3 catalyst (AP-64) showed the highest catalytic activity after 50 h of reaction with an acrolein selectivity of 65%at a conversion of glycerol of 90%. Based on these results, catalysts based onγ-Al2O3 appear to be most promising for gas phase dehydration of glycerol.     

AgBiVMo oxide catalytic membrane for selective oxidation of propane to acrolein

A metal ions (Ag, Bi, V, Mo) modified sol–gel method was used to prepare a mesoporous Ag_0.01Bi_0.85V_0.54Mo_0.45O₄ catalytic membrane which was used in the selective oxidation of propane to acrolein. By optimizing the preparation parameters, a thin and perfect catalytically active membrane was successfully prepared. SEM results showed that the membrane thickness is 5 μm. XRD results revealed that Ag_0.01Bi_0.85V_0.54Mo_0.45O₄ with a Scheelite structure, which is catalytically active for the selective oxidation of propane to acrolein, was formed in the catalytic membrane only when AgBiVMoO concentrations were higher than 40%. Catalytic reaction results demonstrated that the selective oxidation of propane could be controlled to a certain degree, such as to acrolein, in the catalytic membrane reactor (CMR) compared to the fixed bed reactor (FBR). For example, a selectivity of 54.85% for acrolein in the liquid phase was obtained in the CMR, while only 8.31% was achieved in the FBR.     

高密度LiFePO4正极材料的合成与性能

以高温固相法制备了高密度的LiFePO4正极材料,利用XRD、SEM、粒度分析、交流阻抗以及充放电测试等方法研究了前驱体Li3PO4和FePO4的比例与LiFePO4的物理性能和电化学性能的关系。其中,在Li3PO4与FePO4物质的量比为3：2时,制备的LiFePO4正极材料振实密度高达1.4g／cm^3,以0.1C放充电时,其首次放电比容量为159.0mA·h／g,体积比容量为222.6A·h／L,循环25次后,容量保持率达94.0％。     

磷酸铁对砷吸附性能的研究

采用实验室自制磷酸铁,从溶液的p H值、砷初始浓度、温度、搅拌速度等方面探讨磷酸铁对砷的吸附作用。得到磷酸铁吸附砷的最佳工艺条件为：砷初始浓度为0.000 1 mol/L、p H=7、搅拌速度为600 r/min、反应体系温度为80℃和反应时间为1 h,该条件下磷酸铁对砷的吸附效率达到99.6%。为解决饮用水或土壤中砷污染的问题提供一定的参考意义。     

Selective formation of 2-methyl-2-butene and 2-methyl-1-butene: Operating conditions and kinetic analysis

The effect of linear gas velocity, catalyst particle size, reaction temperature, space time, etc. on the dehydration of amyl alcohols (from fusel oil) was studied, using as catalyst a pre-treated bentonite. The analysis of the kinetic data, using Hougen-Watson type models, gives as the best model one in which amyl alcohol is absorbed on two active sites, the reaction rate being determined by the surface reaction of absorbed species.     

Silica‐Supported Phosphotungstic Acid for Gas Phase Dehydration of Glycerol

Phosphotungstic acid (H₃PW₁₂O₄₀ 6H₂O) was immobilized within a hierarchically structured silica matrix by sol–gel inclusion using polyethylene oxide as a phase separation initiator (one‐pot synthesis). The macropore size of the SiO₂‐HPW composites was controlled by the polymer content. The hierarchically structured catalysts with different HPW loadings were tested against their counterparts with monomodal pore size distribution, applying the dehydration of glycerol as a test reaction. The catalysts with bimodal pore size distribution showed a significantly better long‐term stability. The improved performance was attributed to their balanced acidity, excellent leaching stability, and enhanced mass transfer within the hierarchically structured pore system.     

Liquid phase catalytic dehydration of glycerol to acrolein over Brønsted acidic ionic liquid catalysts

Liquid phase dehydration of glycerol to acrolein catalyzed by Brønsted acidic ionic liquids (BAILs) using semi-batch reaction technique was investigated. For the BAILs catalysts, the acrolein yields were in an order of [Bmim]H₂PO₄ > [Bmim]HSO₄ > [BPy]HSO₄ > [PSPy]HSO₄ > [N₂₂₂₄]HSO₄ > [PSPy]H₂PO₄ > [BPy]H₂PO₄ > [N₂₂₂₄]H₂PO₄. When [Bmim]H₂PO₄ and [Bmim]HSO₄ were used as the catalysts at 270 °C with the molar ratio of catalyst to glycerol of 1:100, the acrolein yields were 57.4% and 50.8%, respectively, at complete conversion of glycerol. The BAILs with [Bmim] cation and moderate acidity favored the formation of acrolein in liquid phase glycerol dehydration.     

含铈固体超强酸SO42-/ZrO2-Ce2O3的制备及对环己醇催化脱水制环己烯的研究

在２５ ℃下,将０－５ ｍｏｌ／Ｌ的氨水滴加到不同配比的二氯氧锆和硝酸铈（ Ⅲ） 的混合溶液中,经过滤、洗涤,制备了不同质量分数的三氧化二铈和二氧化锆的混合物,再经０－５ ｍｏｌ／Ｌ的稀硫酸浸渍１ ｈ、过滤、１００ ℃干燥１ ｈ,最后分别在５５０、６５０ 和７００ ℃焙烧４ ｈ 制得了一系列的含铈固体超强酸ＳＯ４２－／ＺｒＯ２Ｃｅ２Ｏ３ 。发现加入质量分数为０－５％ ～２％ 的三氧化二铈可使其对环己醇脱水活性显著提高,过高的酸强度不利于环己烯的生成,其中以５５０ ℃时焙烧制得的固体超强酸ＳＯ４２－／ＺｒＯ２Ｃｅ２Ｏ３［ ｗ（Ｃｅ２Ｏ３）＝ １－５％ ］ 的催化活性及环己烯的选择性最好,在１４０ ℃下,环己醇的转化率为９５－３ ％ ,环己烯的选择性高达１００％ 。并分别用正己烷和吡啶做探针分子对其进行了差动热分析研究,结果表明加入质量分数为０－５％ ～２％ 的三氧化二铈使ＳＯ４２－／ＺｒＯ２Ｃｅ２Ｏ３ 超强酸酸强度和酸总量得到不同程度的提高。     

Environmentally friendly solid acid catalyst prepared by modifying TiO2 with cerium sulfate for the removal of volatile organic chemicals

An environmentally friendly solid acid catalyst, Ce(SO₄)₂/TiO₂ was prepared simply by modifying TiO₂ with Ce(SO₄)₂ for acid catalysis of volatile organic chemicals, 2-propanol and cumene. The characterization of prepared catalysts was performed using FTIR, XRD and DSC. The surface area of 7-Ce(SO₄)₂/TiO₂ calcined at 300 °C was very high (206.0 m²/g) compared to that of unmodified TiO₂ (115.2 m²/g) due to the interaction between Ce(SO₄)₂ and TiO₂. 7-Ce(SO₄)₂/TiO₂ containing 7 wt% Ce(SO₄)₂ and calcined at 300 °C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acid amounts of catalysts measured by an ammonia chemisorption method. The role of Ce results in an increase in the thermal stability of the surface sulfate species and consequently the acid amount of Ce(SO₄)₂/TiO₂ is increased. The asymmetric stretching frequency of the SO bonds for Ce(SO₄)₂/TiO₂ catalysts was related to the acidic properties and to the catalytic activity for acid catalysis to remove volatile organic chemicals, 2-propanol and cumene.     

控制结晶法制备球形磷酸铁的团聚尺寸模型

磷酸铁是制备锂离子电池正极材料磷酸铁锂的主要前躯体之一,磷酸铁的形貌和粒度大小对磷酸铁锂材料的电化学性能有较大影响.为了更好地实现磷酸铁的可控制备,有效改善磷酸铁锂的电化学性能,文中采用硝酸铁和磷酸反应合成磷酸铁的液相结晶控制工艺,研究了反应结晶釜中反应物浓度、温度、搅拌速度与沉淀物颗粒粒径之间的关系,结果表明:沉淀物...     

甘油水蒸汽重整制氢Ni、Co、Fe催化剂的研究

采用等体积浸渍法制备了催化剂,研究了Ni/Al2O3,Fe/Al2O3,CoMo/Al2O3和NiCo/Al2O3催化剂对甘油水蒸汽重整制氢反应的催化效果,对催化剂进行BET、TPR、XRD表征,以氢产率为实验指标对催化剂进行了评价。研究结果表明,CoMo/Al2O3催化剂在温度650℃氢产率6.02。NiCo/Al2O3催化剂在温度600℃、水醇比16、液空速0.12 h-1条件下的氢产率为6.08。催化剂活性次序为NiCo/Al2O3Co-Mo/Al2O3Ni/Al2O3Fe/Al2O3。