室温下介孔MnO_2降解低浓度甲醛的研究（英文）

以KMnO_4和P123为原料采用溶胶-凝胶法在不同条件下制备了介孔MnO_2,研究了反应物比和pH对催化剂结构和催化降解性能的影响。合成材料的结构和性能采用XRD、N_2吸脱附、FT-IR的测试方法表征。最后讨论了介孔MnO_2催化氧化HCHO的影响因素。结果表明,溶胶-凝胶法制备介孔MnO_2的最佳条件为:原料配比为10:1,pH值为7。P123和KMnO_4合成的介孔MnO_2具有较大的比表面积和孔径,且有良好的HCHO催化降解性能。在pH=7的情况下最有利于介孔MnO_2的活性稳定;在原料比为10:1情况下生成的介孔MnO_2比表面积较大,催化降解性能较强,在10 h内保持在对甲醛的降解率为95%以上。     

溶胶凝胶法制备含铁介孔催化剂用于二苯甲烷的合成

本文采用溶胶凝胶法以柠檬酸铁为铁源合成含Fe纳米介孔材料。室温下凝胶样品60 ℃真空干燥后得到的干凝胶采用热重分析(TG)。最终400 ℃焙烧3 h得到介孔Fe₂O₃/SiO₂纳米粒子。合成材料的结构和性能采用XRD、N₂吸脱附、TEM、FT-IF、及H₂-TPR测试方法表征,结果显示合成了尺寸约50 nm的带有30-45? 介孔孔道的球形的Fe₂O₃/SiO₂纳米粒子,并且成功引入了高分散的Fe₃₊物种。催化性能是通过傅克烷基化法合成二苯甲烷的反应测试的,实验结果表明该催化剂具有优异的催化性能,高达100 % 苄基氯的转化率和相对较高的二苯甲烷的选择性,并且能够重复利用。     

溶胶凝胶-离子交换法制备具有可见光活性介孔AgInO2光催化剂

具有可见光响应高效光催化剂的设计和制备是环境与能源光催化研究领域的前沿和热点之一。本文采用溶胶凝胶-离子交换法制备AgInO₂介孔纳米材料,利用热分析(TGA-DSC)、X-射线衍射(XRD)、场发射扫描电镜(FESEM)、N₂吸附脱附以及紫外-可见吸收光谱等测试手段,研究了制备条件对AgInO₂微观结构的影响因素,并以甲醛为目标降解物研究了AgInO₂在可见光条件下光催化性能。研究结果表明：制备的介孔AgInO₂具有铜铁矿结构的晶型,颗粒尺寸约200-500纳米,N₂吸附脱附非等温曲线呈IV型,吸收边位于500-600 nm可见光范围内,在可见光照射180 min 的条件下,介孔AgInO₂对甲醛的光催化降解率达93.97%。本研究为介孔AgInO₂光催化剂在净化室内空气的广泛应用奠定了实验基础。     

MgO气凝胶制备及结构研究

以甲醇镁为镁源,甲醇和去离子水为溶剂,采用溶胶-凝胶法结合乙醇超临界干燥工艺制备MgO气凝胶,考察去离子水、甲醇、丙三醇对MgO气凝胶凝胶时间及比表面积的影响,采用红外光谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸脱附测试仪等对其结构及形貌进行表征,并且利用同步辐射小角X射线散射(SAXS)对其进行了分形结构分析。结果表明：MgO气凝胶具有丰富的网络骨架结构、高的孔隙率(98%)、高的比表面积(904.9 m₂/g)、较低的密度(0.055 g/cm₃),平均孔径为19.6 nm,属典型的介孔材料,SAXS测试显示MgO气凝胶分形维数为2.32,表面粗糙且疏松,具有明显的孔分形结构。     

La2O3掺杂氧化铝气凝胶的制备与耐温性能研究

以仲丁醇铝为前驱体,采用溶胶-凝胶法结合丙酮-苯胺原位生成水技术,通过乙醇超临界干燥,制备出不同含量(1.5 mol%~12 mol%)La₂O₃掺杂的氧化铝气凝胶。采用电子扫描电镜(SEM)、透射电子显微镜(TEM)、X线衍射仪(XRD)、N₂吸附分析仪等仪器表征了La₂O₃掺杂对氧化铝气凝胶的微结构和耐温性能的影响。结果表明：La₂O₃的引入使氧化铝气凝胶的形貌由球状颗粒向大的片状结构转变。适量的La₂O₃掺杂能提高氧化铝气凝胶的比表面积,9 mol% La₂O₃掺杂的氧化铝气凝胶比表面积最大。通过La₂O₃掺杂,能够抑制氧化铝晶粒在高温下的生长和α-Al₂O₃的相变,提高氧化铝气凝胶的耐温性能。1200℃热处理后,La₂O₃掺杂的氧化铝气凝胶仍维持在θ-Al₂O₃,比表面积为86.5 m₂/g,高于未掺杂的氧化铝气凝胶(46 m₂/g)。     

PAN预氧丝复合RF气凝胶的性能研究

本文以间苯二酚(C6H4(OH)2)和甲醛(HCHO)为前驱体,碳酸钠(Na2CO3)为催化剂,采用溶胶-凝胶技术、超临界干燥工艺制备了间苯二酚-甲醛(RF)气凝胶。另外,通过添加聚丙烯腈(PAN)预氧丝改善了RF气凝胶的力学性能,制备了PAN预氧丝复合RF气凝胶。文中通过调节质量分数ω、间苯二酚与催化剂摩尔比(R/C值)这两个参数对微结构进行调控,其中选取质量分数ω为15%, R/C值为100和500的气凝胶进行比较,经过分析可知R/C值为100的气凝胶性能优良,复合后样品的比表面积变为618.6 m₂/g,孔体积为2.423 cm₃/g,平均孔径为15.1nm。PAN预氧丝复合后的气凝胶依然具有优异的热学性能,在常温下热导率为0.032W/(m.K)。力学性能有了很好的改善,压缩模量为1.499MPa,比纯RF气凝胶提高了0.6倍。     

Al掺杂TiO2介孔材料的合成、表征和光催化性能

以钛酸四丁酯为钛源、十八水硫酸铝为铝源、三乙醇胺为模板剂,采用研磨-溶胶技术合成了Al掺杂的TiO2介孔材料,并利用XRD、EDS、TEM、BET、UV-vis和IR等手段表征了材料的结构、形貌、比表面积、孔径分布及光学性能.结果表明:Al掺杂能够减小TiO2光催化剂的粒径,提高介孔TiO2的热稳定性;Al掺杂TiO2介孔材料的平均孔径为4.5 nm,比表面积达到110.2 m2/g;相比商用P25和介孔TiO2,Al掺杂介孔TiO2的吸收边发生红移,对初始浓度为20 mg/L的甲基橙进行催化降解1h后,其降解率达到92.5％.     

溶胶-凝胶法制备ErFeO3及其可见光催化性能研究

钙钛矿结构的ErFeO₃是一种新型的光催化材料。本文以Er(NO₃)₃.5H₂O、Fe(NO₃)₃×9H₂O、柠檬酸和尿素为主要原料,采用溶胶-凝胶法制备得到ErFeO₃的凝胶,将凝胶于80 ℃烘箱中48 h得到干凝胶,然后将干凝胶于700-1000 ℃煅烧制备ErFeO₃。通过热重-差示扫描量热法(TG-DSC)、X射线衍射谱(XRD)、扫描电镜(SEM)、傅立叶红外光谱(FT-IR)和漫反射谱(DRS)等对ErFeO₃进行表征。以甲基橙溶液为模拟污水,研究了ErFeO₃的可见光催化性能。结果表明：制备得到了钙钛矿结构的ErFeO₃,其平均晶粒粒径为80-100 nm左右,带隙宽度为2.0 eV。在可见光光照下, ErFeO₃对甲基橙表现出了优良的可见光催化活性。溶胶-凝胶法制备的ErFeO₃在光催化降解有机污染物领域具有实际应用前景。     

TiO2/膨润土复合光催化材料的常温制备及性能研究

采用改进的溶胶-凝胶法,在以水为主要溶剂的反应体系中,控制钛酸四丁酯充分水解、缓慢聚合,在 常压、低温(70℃)的温和条件下制备出稳定的TiO₂纳米晶溶胶,并利用TiO₂纳米晶溶胶在膨润土表面负载,获得TiO₂/膨润土复合光催化材料。采用 X 射线衍射、扫描电镜、比表面积测定等研究手段对样品的结构形貌进行了表征,并考察了其光催化活性。结果表明：较高的水用量有利于TiO₂晶体形成,当去离子水:钛酸四丁酯摩尔比大于167:1时,在溶胶体系中出现了锐钛矿型TiO₂纳米晶体；TiO₂纳米晶主要负载于膨润土表面,并未嵌入到膨润土层间结构,但相对于单一膨润土,TiO₂负载显著提高了材料比表面积；当去离子水:钛酸四丁酯摩尔比=192:1时,在紫外光照射下,复合光催化材料表现出最高的光催化活性,对亚甲基蓝的降解率达到93.8%。     

溶胶凝胶法制备LaMn1-XVXO3及光催化氧化性能

以La(NO₃)₂、MnC₄H₆O₂、柠檬酸和乙二醇(EG)为主要原料,NH₄VO₃为掺杂试剂,采用溶胶凝胶法制备LaMnO₃和LaMn_1-XV_XO₃粉体。采用XRD进行晶体结构表征;采用甲基橙(MO)模拟污水,进行光催化降解实验。研究了煅烧温度、催化剂用量和掺杂量对光催化氧化降解率的影响,讨论MO降解的动力学规律。结果表明700-900 ℃煅烧温度不影响LaMnO₃晶体结构和光催化氧化降解率;掺杂量影响LaMn_1-XV_XO₃晶体结构,光催化氧化降解率随着掺杂量增加而呈下降趋势;光催化氧化实验中,LaMn_1-XV_XO₃粉体效果高于LaMnO₃,两者均符合一级动力学方程。     

Pd/TiO2/棉花纤维复合催化材料的制备与性能研究

先通过浸渍-提拉法将纳米TiO_2对棉花纤维表面进行修饰,再通过浸渍-NaBH4还原法将Pd纳米颗粒沉积在TiO_2/棉花纤维(TC)表面,制备得到Pd/TiO_2/棉花纤维复合催化材料(PTC)。所制备的复合催化材料用于室温氧化分解甲醛,研究了Pd负载量对催化性能的影响。结果表明,PTC催化材料具有远低于粉末状样品的气阻,此特点对催化材料的实际应用具有非常大的优势;该催化材料能有效室温分解甲醛成CO_2和H_2O。PTC催化材料的催化活性随Pd含量(0.25%～1.0%,质量分数)的增加而增加。鉴于PTC催化材料具有低气阻、轻质、使用灵活的属性和良好催化效率以及载体棉花原料来源广泛、成本低等优点,具有良好的实际应用于室内空气净化和相关催化过程的潜力。     

One-Step Synthesis of MnO2 Particles Distributed Polyaniline–Poly(styrene-sulfonic acid)

In this paper, polyaniline–poly(styrene-sulfonic acid)–manganese dioxide (PANI–PSS–MnO₂) composite was prepared by an interfacial reaction of potassium permanganate (KMnO₄) in PSS/ANI in chloroform. This method synthesizes MnO₂ particles incorporated in PANI–PSS by reduction of Mn⁷⁺ to Mn²⁺ and oxidation of Mn²⁺ to Mn⁴⁺ (MnO₂) with the simultaneous chemical oxidation polymerization of ANI. The immiscible liquid interface offers a unique microenvironment for confining the growth of PANI to form PANI–MnO₂ in the presence of PSS. The PANI–PSS–MnO₂ composite was verified through characterization by scanning microelectronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and FTIR spectroscopy. Cyclic voltammetric (CV) results showed that PANI–PSS–MnO₂ effectively catalyzed the oxidation of hydrogen peroxide (H₂O₂). The simple and inexpensive route for the preparation of PANI–PSS–MnO₂ composites can be used in the production of sensor electrodes in H₂O₂ and glucose detection.     

Charge-discharge process of MnO2 supercapacitor

Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn（CH3COO）2 in 1：1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current impedance. The charge-discharge process of MnO2 supercapacitor in 6 mol/L KOH was studied within 1.2 V at 200 mA/g, suggesting that it displays double-layer capacibility in low potential scope and pseudo-capacitance properties in high potential scope. It is found that Mn3O4, an electrochemical inert, mainly forms in the initial 40 charge-discharge cycles. During cycling, the pseudo-capacitance properties disappear and the discharge curves are close to ideal ones, indicating double-layer capability. The maximum capacitance of MnO2 electrode is as high as 416 F/g, and retains 240 F/g after 200 cycles. The equivalent series resistance increases from 17 to 41Ω.     

Synthesis of layered birnessite-type manganese oxide thin films on plastic substrates by chemical bath deposition for flexible transparent supercapacitors

Layered birnessite-type manganese oxide thin films are successfully fabricated on indium tin oxide coated polyethylene terephthalate substrates for flexible transparent supercapacitors by a facile, effective and inexpensive chemical bath deposition technology from an alkaline KMnO₄ aqueous solution at room temperature. The effects of deposition conditions, including KMnO₄ concentration, initial molar ratio of NH₃·H₂O and KMnO₄, bath temperature, and reaction time, on the electrochemical properties of MnO₂ thin films are investigated. Layered birnessite-type MnO₂ thin films deposited under optimum conditions display three-dimensional porous morphology, high hydrophilicity, and a transmittance of 77.4% at 550 nm. A special capacitance of 229.2 F g⁻¹ and a capacitance retention ratio of 83% are obtained from the films after 1000 cycles at 10 mV s⁻¹ in 1 M Na₂SO₄. Compressive and tensile bending tests show that as-prepared MnO₂ thin film electrodes possess excellent mechanical flexibility and electrochemical stability.     

Controllable synthesis and catalytic activity of SnO2 nanostructures at room temperature

SnO₂ hollow spheres and rod bundles were prepared using SnSO₄ as raw material and sodium dodecyl benzenesulfonate and poly(vinyl pyrrolidone) as templates at room temperature through oxidation-crystallization of colloidal spheres in different systems. The products were characterized with X-ray diffractometer, X-ray photoelectron spectrometer, transmission electron microscope and scanning electron microscope. Meanwhile, the catalytic performance of the SnO₂ hollow spheres and rod bundles toward CO oxidation was studied. The result indicates that SnO₂ hollow spheres with the uniform size exhibit a better catalytic activity toward CO oxidation, suggesting that the morphology of the materials has exerted a noticeable influence on the catalytic performance.     

Synthesis and structure screening of nanostructured chromium oxide powders

The evolution with calcinations of chromium oxide (Cr₂O₃) nanocrystals of catalytic interest, prepared from reduction of K₂Cr₂O₇ with maleic acid has been studied. The characterization of the materials was confirmed by X-ray diffraction (XRD), Fourier transformation infrared (FT-IR), transmission electron microscope (TEM), N₂ adsorption–desorption isotherms, and thermo-analytical methods. The influence of the operating variables such as molar ratio, pH, gelation time and specific surface area was investigated and discussed. The results showed that the K₂Cr₂O₇/maleic acid of 1:1.7 molar ratio at pH 7 and 15 days gelation time were considered to be the best conditions for producing Cr₂O₃ of the pore diameter distribution in the range of 2–6 nm and specific surface area of 123 m²/g. The particle size and phases of chromium oxide were affected by the ratio of K₂Cr₂O₇ to maleic acid, temperature, and time of calcination. The amorphous phase appeared at room temperature, whereas it turned to crystalline phase when the calcination temperature increased to about 400 °C.     

Synthesis of yttrium barium copper oxide-0.325Ag superconductors via intermediate precursor with overall composition Y:Ba:Cu:0=l:2:3:Y, Y>7 produced by high-energy attrition milling

A highly homogeneous composite precursor containing nano-scale particles was synthesized from the highenergy attrition milling of a mixture of metallic Y, metallic Cu and barium nitrate (Ba(N0₃)₂) containing 5 wt.% silver. The particle size of the 20 hour attrition-milled precursor was in the range of 30~80 nm as estimated by the XRD technique and direct TEM observation. With the heat treatment of the attrition-milled precursor, an intermediate precursor with the overall composition Y:Ba:Cu:O=l:2:3:y, y>7 was synthesized. The analyzed Y:Ba:Cu:Ag:O molar ratio of the intermediate precursor by AES/AAS and iodimetric titration was 1:1.972:3.022:0.323:7.41, which was very close to the estimated composition: 0.5Y₂O₃+2BaCuO_2.5+CuO +0.325Ag. Y123-Ag superconductors in powder or bulk forms were prepared using heat treatment or thermomechanical processing of the intermediate precursor containing BaCu0_2.5. The high oxygen orthorhombic Y123-Ag phase (y>7) was obtained in quenched samples which were held for 30 min or less at 950°C in ambient air. As the holding time extended to 40 min, the sample was still orthorhombic Y123-Ag (6.7<y <7). The transport critical current density (J_c) at 77 K and zero magnetic field for the quenched sample which was held for 40 min at 950°C was ~1.3xl0³ A/cm².     

Adsorption of Cd2+ in aqueous solutions using KMnO4-modified activated carbon derived from Astragalus residue

Activated carbon obtained from Astragalus residue was chemically activated by KOH and modified with KMnO₄. The samples were characterized by N₂ adsorption, Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and Boehm titration. Accordingly, the original and modified carbon materials were used for the removal of Cd²⁺ from aqueous solution by batch adsorption experiments. Results showed that the contents of oxygen-containing functional groups increased, and MnO₂ was nearly uniformly deposited on the surface of activated carbon after modification by KMnO₄. The adsorption kinetics was described by pseudo-second order model. Langmuir model fitted the adsorption-isotherm experimental data of Cd²⁺ better than the Freundlich model. The maximum adsorption capacities of the activated carbon before and after modification for Cd²⁺ were 116.96 and 217.00 mg/g, respectively. KMnO₄ considerably changed the physicochemical properties and surface texture of activated carbon and enhanced the adsorption capacity of activated carbon for Cd²⁺.     

Designing for the cerium-based conversion coating with excellent corrosion resistance on Mg–4Y–2Al magnesium alloy

The cerium salt chemical conversion baths containing KMnO₄ are applied to prepare protective coatings on the WA42 alloy surface, and the effect of the concentration of KMnO₄ on the microstructure and corrosion properties of the coatings is investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests. The results indicate that with the addition of KMnO₄ to the conversion bath, the microstructure of the coating is more uniform and denser, and the coating with the KMnO₄ concentration of 4 g/L (4M coating) has the most uniform microstructure with the least microcracks. The 4M coating exhibits a two-layered structure, and it is mainly composed of MgO, Mg(OH)₂, CeO₂, Ce₂O₃, Ce(OH)₃, MnO, and MnO₂. In addition, as the KMnO₄ concentration increases from 0 to 6 g/L, the I_corr of the coatings in 3.5% NaCl solution decreases first and then increases, and the 4M coating shows the best corrosion resistance, which should attribute to the uniform and dense microstructure.     

载体中ZrO2/Al2O3比对Pt/ZrO2-Al2O3催化剂性能的影响

相比汽油车而言,柴油车具有高效、低油耗的优势已得到广泛应用。本实验以ZrO₂作为改性剂,探究了ZrO₂与Al₂O₃的质量比对催化剂的影响。研究结果表明：随着ZrO₂的加入,Pt粒子先减小后增大;Pt粒子与载体的交互作用先增大后减小。活性实验数据分析表明,ZrO₂的最佳添加量为40 wt%,CO和C₃H₆完全氧化温度分别降低20 _oC 、25 _oC。贵金属在催化剂的分散度以及贵金属与载体的相互作用随着ZrO₂与Al₂O₃质量比的变化而变化。Pt粒子越小,其与载体的交互作用越强,这表明催化剂性能越强。