Effect of metal oxide additives on the thermal decomposition of KMnO4

The study of the thermal decomposition of potassium permanganate in air has been studied using DTA, TG and isothermal decomposition between 150 and 400°C. Rate constants were evaluated and found to be affected by the presence of foreign ions. Oxides such as Fe₂O₃ and Cr₂O₃ resulted in a lowering of the decomposition temperature. The modified catalytic mechanisms were proposed by considering the electron transfer and the oxygen-abstraction models.     

Surface modification of HDPE, PP, and PET films with KMnO4/HCl solutions

Surface modification of high-density-polyethylene (HDPE), polypropylene (PP), and poly(ethylene terephthalate) (PET) films was promoted by potassium permanganate solutions in HCl acidic medium using eight conditions by varying time, temperature, and oxidative solution concentration. This oxidation system introduced different amounts of carbonyl-carboxyl and hydroxyl groups onto the polymer surfaces. Drop water contact angle, FTIR, TGA, and SEM were used to assess oxidation efficiency and the surface changes suffered by the polymer film. The hydrophilicity of films obtained by contact angle was analyzed using a 2³ factorial design in Design-Expert^® program to obtain the main effects, the variance, and the interaction between the effects in action in the oxidation process.     

Au/γ-MnO2催化剂催化无溶剂条件下甲苯氧化反应

采用氧化还原法制备了α, δ, γ-MnO₂载体, 采用原位还原法制备了Au负载量为0.5%-3.0%的Au/γ-MnO₂催化剂, 并采用X射线衍射、扫描电镜、透射电镜和N₂物理吸附等手段对其进行了表征. 透射电镜照片表明Au/γ-MnO₂催化剂中Au颗粒的大小约为10 nm. 采用无溶剂存在下的甲苯氧化反应测试所制备样品的催化活性. 结果表明, 甲苯转化率随着Au负载量的增加而增大. 这是由于Au颗粒数量增多, 尺寸减小的缘故. 同时, 负载Au颗粒对苯甲醛具有较高的选择性. Au/γ-MnO₂催化剂具有良好的重复使用性.     

Selective oxidation of toluene over layered structures of Bi2MoO6 and La2MoO6

The vapor phase catalytic aerial oxidation of toluene to benzaldehyde (B_zH) was carried out over La₂MoO₆ containing the same kind of layered structure as Bi₂MoO₆. The overall kinetic analysis indicated the oxidation of toluene to B_zH to be first order with a frequency factor of log 0.63 and activation energy (E_a) of 26.3 kJ mol^–1 and 34.0 kJ mol^–1, respectively, for Bi₂MoO₆ and La₂MoO₆ catalysts. A relation between the activity and activation energy of conduction (E) is shown.     

Oxidizing supported reagents, I. Nature of the supported KMnO4 on solids

The nature of supported KMnO₄ reagents on several solids (SiO₂ AlPO₄, BPO₄ and sepiolite) is discussed. The oxidation of PhCHO to PhCO₂H was the test reaction. The KMnO₄ supported reagent is shown to be a mixture of physisorbed KMnO₄ and Mn(IV). The influence of the nature of the solvent is discussed.

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, (SiO₂, AlPO₄, BPO₄ ). PhCHO PhCO₂H. KMnO₄ KMnO₄ Mn(IV). .

     

纳米片聚结Co3O4微球催化甲苯燃烧

采用乙二胺辅助的水热法制备了纳米片聚结的Co₃O₄微球. 利用多种分析技术表征了其物化性质,并评价了其对甲苯燃烧的催化活性. 结果表明,由添加1.0 ml乙二胺经140 ℃水热处理12 h后制得的Co₃O₄样品呈纳米片聚结的微球状表面形貌. Co₃O₄微球样品的比表面积约为66 m² g^-1. 与体相Co₃O₄样品相比,Co₃O₄微球样品具有较高的氧吸附物种浓度和较好的低温还原性. 当空速为20000 ml g^-1 h^-1时,在Co₃O₄微球样品上甲苯转化率达到50%和90%时的反应温度分别为230和254 ℃. 这与该样品具有较大的比表面积、较高的氧吸附物种浓度和较好的低温还原性相关.     

Valence states of 57Fe decayed from 57Mn implanted into KMnO4

In-beam Mössbauer spectra of ⁵⁷Fe, decayed from short-lived ⁵⁷Mn (T_1/2 = 1.45 min) implanted into potassium permanganate, KMnO₄, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional ⁵⁷Fe atoms for Mn-sites in tetrahedral [MnO₄]^– with an unusually high valence state of Fe⁸⁺.     

高温下硅酸锂吸收CO2的研究

以SiO₂和Li₂CO₃为反应原料，采用高温固相法于不同温度下合成了一系列可在高温500~750 ℃之间直接吸收CO₂的硅酸锂(Li₄SiO₄)材料。采用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)分别观察和评价了合成材料的表面形貌与结构特征，用热重分析仪(TG)研究了硅酸锂材料吸收CO₂的性能。实验结果表明，在750 ℃下煅烧6 h即可合成出吸收CO₂性能良好的硅酸锂材料，在CO₂气氛下，于700 ℃保持约15 min即可达到吸收平衡，其吸收量约达43%(wt)左右。与文献报道相比，材料的合成条件有所改善，材料吸收CO₂的容量也有较大提高。     

The resonance raman effects of VCl4 and SnI4

Raman spectra of VCl₄ and SnI₄ in solution are obtained using the exciting lines of a HeNe and an Ar⁺ laser. The spectra show a pre-resonance Raman effect with an enhancement of the stretching vibrations for shorter wavelengths of excitation. The features of the intensity variation are discussed quantitatively in terms of the frequency factors given by Albrecht and Hutley.     

High catalytic activity of V2O5-ZrO2 modified with H2SO4 for propene partial oxidation

For V₂O₅–ZrO₂ catalysts, up to 10 mol% the crystalline structure of V₂O₅ was not observed, indicating a good dispersity the surface of ZrO₂. V₂O₅–ZrO₂ catalyst modified with H₂SO₄ exhibited much on higher catalytic activity for propene partial oxidation than unmodified catalysts due to the increased acidity and acid strength of modified catalyst.     

Temperature behavior of the protonic conductor K4LiH3(SO4)4

The results of the X-ray structural study for the K₄LiH₃(SO₄)₄ single crystal are presented at a wide temperature range. The thermal expansion of the crystal using the X-ray dilatometry and the capacitance dilatometry from 8 to 500 K was carried out. The crystal structures data collection, solution and refinement at 125, 295, 443 and 480 K were performed. The K₄LiH₃(SO₄)₄ crystal has tetragonal symmetry with the P4₁ space group (Z=4) at room temperature as well as at the considered temperature range. The existence of a low-temperature, para-ferroelastic phase transition at about 120 K is excluded. The layered structure of the crystal reflects a cleavage plane parallel to (001) and an anisotropy of the protonic conductivity. The superionic high-temperature phase transition at T_S=425 K is isostructural. Nevertheless, taking into account an increase of the SO₄ tetrahedra libration above T_S, a mechanism of the Grotthus type could be applied for the proton transport explanation.     

Acidity and oxidation activity of MoO3?UO3/SiO2 catalysts

The effect of UO₃ on the acidity of MoO₃–UO₃/SiO₂ catalysts has been studied by means of infrared spectroscopy of adsorbed pyridine. The surface acidity exhibited a maximum for the same U/(U+Mo) atomic ratio (=0.11) that yielded a maximum in total conversion for isobutene oxidation. The catalytic properties for oxidation are discussed in terms of the acidic properties of the samples.

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UO₃ MoO₃–UO₃/SiO₂ . U/(U+Mo)=0,11, . , .

     

甲苯和一氧化碳氧化用介孔LaFeO3催化剂（英文）

以KIT-6和二氧化硅纳米球为硬模板制备了比表面积分别为138和65 m2/g的正交相蠕虫状介孔LaFeO3催化剂LFO-1和LFO-2.在空速为20000 mL/(g劒h)的条件下,LFO-1样品显示出最高的催化活性:对于CO氧化反应,T50%和T90%分别为155和180 oC;对于甲苯氧化反应,T50%和T90%分别为200和253 oC.该样品优异的催化性能与它具有较大的比表面积、较高的氧吸附物种浓度、较好的低温还原性以及良好的蠕虫状介孔结构有关.     

Na4Ca(SO4)3复盐高温合成及温度对晶体形貌的影响

用高温合成法制备出硫酸钙复盐Na₄Ca(SO₄)₃，利用差热分析、X射线衍射、扫描电子显微分析等现代测试仪器研究了该复盐的反应历程。研究结果表明，其反应过程按CaSO₄+Na₂SO₄→(Na_0.8Ca_0.1)₂SO₄→Na₄Ca(SO₄)₃进行。Na₄Ca(SO₄)₃为高温稳定相，其最佳合成温度为800 ℃～1 100 ℃。育晶温度及时间对复盐形貌有明显影响，在1 000 ℃保温2 h后转到945 ℃育晶5 h,晶体生长较好。     

KMnO4溶液改性半焦对烟气中气态Hg0的吸附性能研究

在小型固定床实验台上利用半焦及其KMnO₄溶液改性样品进行气态Hg⁰吸附实验。结果表明,在低温时原料半焦对气态Hg⁰具有良好的吸附性能,升温则使其吸附性能迅速降低;经高锰酸钾溶液浸渍处理后,改性半焦在高温140 ℃时吸附性能明显提高,对浸渍样品在250 ℃进行热处理可使其吸附性能进一步提高。BET结果表明,原料半焦具有较发达的微孔结构,改性处理使微孔比例下降,孔隙结构发达程度降低;XPS测试表明,改性半焦表面的汞主要以氧化态(Hg²⁺)形式存在,高价锰化合物(KMnO₄、K₂MnO₄、MnO₂)是主要的氧化活性物质。     

焙烧与预处理条件对 Co3O4 催化氧化 CO 性能的影响

采用沉淀法制备了 Co₃O₄, 考察了焙烧和预处理条件对其结构、低温催化氧化 CO 性能的影响. 热重分析表明, 未经焙烧的样品以 Co(OH)₂CO₃ 的形式存在, 150~400 ^oC 空气气氛中焙烧后, 样品以立方相 Co₃O₄ 的形式存在. N2 吸附-脱附法、X 射线衍射、透射电镜及活性测试结果表明, 以纳米颗粒物存在的 Co₃O₄ 的比表面积、颗粒尺寸、催化氧化 CO 活性与焙烧温度密切相关. 正电子湮没寿命谱、O₂-程序升温脱附与定温条件下 CO 氧化测试结果表明, 合适温度 (150~250 ^oC) 下 N₂ 预处理有利于 Co₃O₄ 表面氧空穴团的形成, 它在吸附活化分子氧以及 CO 催化氧化反应中起到关键作用. 同时讨论了预处理作用下Co₃O₄表面氧空穴的再构机制.     

测定汽油中铅的KMnO4—Luminol化学发光体系

研究了KMnO4氧化鲁米诺(luminol)的化学发光反应过程,探讨了铅(Ⅱ)后续催化该化学发光反应的反应历程,建立了在最佳反应条件下利用该后续发光反应定量测试微量铅的方法;采用流动注射化学发光方法测定了汽油中铅含量,方法检出限达0.01mg/L,检测线性范围在1.0×10-7～5.0×10-4mol/L,对大量阴阳离子进行了干扰试验,结果表明方法有良好的选择性.     

BiVO4/ZnFe2O4同型异质结光阳极的构筑及其光电催化分解水性能

光生电子-空穴对的复合被认为是限制BiVO₄材料光电催化转换效率的重要原因之一。基于此,通过简单的水热-煅烧方法构筑了 BiVO₄/ZnFe₂O₄同型异质结光阳极,BiVO₄/ZnFe₂O₄复合光阳极在 1.23 V(vs RHE)下的光电流密度为 3.33 mA·cm^-2,较纯BiVO₄提升了2倍 (1.20 mA·cm^-2)。相关的结构及性能测试表明,BiVO₄和ZnFe₂O₄形成了带隙错开的n-n异质结,使得光生载流子得到有效分离,更有效地参与水氧化过程,进而提高了BiVO₄的光电催化水分解性能。     

Simple method for selective oxidation of 1,2-diols in water with KBrO3/KHSO4

Readily available off-the-shelf KBrO₃ and KHSO₄ have been used to selectively oxidize 1,2-diols in water as a solvent. Various cyclic 1,2-diols have been tolerated affording their corresponding α-hydroxy ketones in good yields.     

BiVO4/ZnFe2O4同型异质结光阳极的构筑及其光电催化分解水性能

光生电子-空穴对的复合被认为是限制BiVO₄材料光电催化转换效率的重要原因之一。基于此,通过简单的水热-煅烧方法构筑了BiVO₄/ZnFe₂O₄同型异质结光阳极,BiVO₄/ZnFe₂O₄复合光阳极在1.23 V(vs RHE)下的光电流密度为3.33 mA·cm^-2,较纯BiVO₄提升了2倍(1.20 mA·cm^-2)。相关的结构及性能测试表明,BiVO₄和ZnFe₂O₄形成了带隙错开的n-n异质结,使得光生载流子得到有效分离,更有效地参与水氧化过程,进而提高了BiVO₄的光电催化水分解性能。