Study on a green synthetic method of TRPPMCl (M = Fe, Mn, Co)

A green synthetic method using mixted solvents of di-methyl formamide (DMF) and acids instead of single DMF to synthesize metalloporphyrins (TRPPMCl) from TRPPH₂ and MCl₂ metallization was proposed in this paper. A series of TRPPMCl (M = Fe, Mn, Co) were synthesized through this innovative synthetic method, and these complexes were characterized with various spectroscopic techniques, including IR and UV-Vis spectroscopy. The results showed that the metallization time was markedly reduced from about 10 h to 0.5 h in contrast with the conventional synthetic methods.     

Ag-Zn_3(VO_4)_2催化剂的水热合成及其可见光催化活性

以Zn(NO_3)_2·6 H_2O、Ag NO_3和Na VO_3为原料,采用水热法合成Ag-Zn_3(VO_4)_2催化剂,并通过SEM、TEM和UV-Vis DRS等对催化剂进行表征分析。以甲基橙染料废水为探针污染物,考察Ag~+与Zn~(2+)物质的量比、水热温度和水热时间对Ag-Zn_3(VO_4)_2光催化剂催化活性和表面形貌的影响。结果表明,在Ag~+与Zn~(2+)物质的量比为0.15、水热温度160℃和水热时间16 h条件下,合成的Ag-Zn_3(VO_4)_2光催化剂光催化活性最好,光照5 h后,对甲基橙染料的脱色率达99.18%,较Zn_3(VO_4)_2催化剂(合成条件为p H=10和160℃水热反应16 h)提高43.99%。采用水热合成法制备的催化剂Ag-Zn_3(VO_4)_2具有较好的可见光活性。     

Zn/Cu单晶转换MOF材料的CO2/CH4分离性能研究

CO₂的捕获和分离具有重要的工业和环境意义。采用溶剂热法,以羧基和路易斯碱位点功能修饰的配体和锌离子构筑了阴离子型金属有机框架材料{[Zn₂(N)·(DMF)₃·(CH₃)₂NH₂]·(DMF)₂}_n (NEM-7-Zn)。为了提高骨架的稳定性,通过金属离子置换工艺,将NEM-7-Zn转化为高稳定性的铜基框架材料NEM-7-Cu。采用EA、PXRD、TGA及比表面积分析等技术对多孔材料进行综合表征,并测定了NEM-7-Cu对二氧化碳、乙炔和甲烷单组分气体的吸附等温线。实验结果表明,NEM-7-Cu不仅具有较高的CO₂ 吸附性能（74 cm³·g^-1）,更表现出优异的CO₂/CH₄（11.5）和C₂H₂/CH₄（7.1）吸附选择性。通过巨正则Monte Carlo方法（GCMC）计算得到CO₂在NEM-7-Cu中的主要吸附位点为功能基团羧基与路易斯碱位点附近以及Cu的金属团簇附近。     

DMF effect on the morphology and the luminescence properties of Y2O3:Eu red phosphor prepared by spray pyrolysis

N,N-Dimethylformamide (DMF) was used as a drying control chemical additive (DCCA) in spray pyrolysis in order to improve the luminous properties of Y₂O₃:Eu particles. It was found that the addition of DMF to the spray solution containing citric acid (CA) and ethylene glycol (EG) greatly enhances the photoluminescence intensity as well as the morphology of Y₂O₃:Eu particles. According to BET analysis, the surface area of Y₂O₃:Eu particles prepared from the solution containing only the organic additives was not reduced, whereas, the surface area of the Y₂O₃:Eu particles prepared from the solution containing both DMF and organic additives was decreased gradually as increasing the concentration of DMF. From these results, it was concluded that the adding of DMF to the spray solution containing the organic additives is a very effective way to reduce the porosity of phosphor particles, keeping the spherical morphology. As a result, the densification of porous structure led to greatly improve the photoluminescence intensity of Y₂O₃:Eu particles under ultraviolet (254 nm) excitation. Finally, the prepared Y₂O₃:Eu particles with dense structure showed about 208% improved photoluminescence intensity compared with the particles which have a spherical shape but porous structure.     

酸性氧化物和酸碱比对煤灰熔融行为的影响

为了研究酸性氧化物（SiO₂和Al₂O₃）的相对含量和酸碱比对煤灰熔融行为的影响,本文以准东煤灰化学组成为基础,利用分析纯试剂制备了28组合成灰样品,在马弗炉815℃灰化后利用灰熔融特性分析仪、扫描电子显微镜-能谱仪（SEM-EDS）和X射线衍射仪（XRD）对样品熔融特性、表观形貌和矿物组成进行表征。进而采用多元线性回归法建立了灰熔融温度预测模型,并对该模型的适用性进行了检验。结果表明：在相同酸碱比下,当SiO₂含量由9%上升至33.73%,而Al₂O₃含量由35.98%降至11.25%时,合成灰的变形温度（DT）、软化温度（ST）、半球温度（HT）和流动温度（FT）均呈单调下降趋势,这意味着SiO₂含量的增加可能促进了煤灰的熔融过程;在不同碱酸比下,合成灰的熔融温度随着酸碱比的增加呈先下降后升高的变化趋势,在酸碱比为1.25时合成灰的特征温度出现最小值,表明酸碱比对合成灰熔融温度的影响呈非线性关系。通过SEM-EDS和XRD表征发现,合成灰中CaO、Fe₂O₃、Ca₂MgSiO₇、Ca₂Fe₂O₅、SiO₂和Al₂O₃等耐熔矿物和CaSiO₃等助熔矿物的相对含量以及与钠相关的低温共熔反应是改变合成灰熔融温度的主要因素。本文所建立模型对文献中6组灰样4个特征温度的预测结果与其对应测量值之间最大残差绝对值均小于80℃,说明该模型在本文的合成灰化学组分范围内可用性较好,具有一定的应用价值。     

卤素负载锌-腺嘌呤骨架材料的构建及无助剂催化CO2环加成反应

富氮型金属有机骨架材料（MOFs）具有良好的CO₂捕集性能,但其CO₂催化性能常需添加带氢键或亲核基团的助催化剂。以硝酸锌-腺嘌呤-异烟酸［Zn（NO₃）₂-Ad-Int-DMF］构建稳健的骨架材料,发现其催化合成碳酸丙烯酯（PC）收率不足2%;尝试选型锌盐前体引入亲核卤素,在DMF溶剂中部分卤代锌盐不能络合结晶成MOFs,而形成的ZnI₂-Ad-Int-DMF收率提升至19.5%;溶剂由DMF调变为H₂O-DMF混合溶剂,H₂O的引入避免了卤素对金属和配体间络合的影响,使得以ZnCl₂、ZnBr₂和ZnI₂为前体均能晶化成MOFs,其热分解起始温度（Tonset,434℃）明显高于ZnI₂-Ad-Int-DMF（280℃）,而比表面积（<14 m²/g）明显小于后者（571 m²/g）,造成活性低于后者。通过CO₂吸附脉冲和UV-Vis漫反射推测I^-由于与Zn碱位的相互作用而均匀吸附于骨架上。进而,在无助剂、无溶剂工况下对CO₂环加成反应进行活性评价。温度升高显著提升PC产率,140℃下ZnI₂-Ad-Int-DMF催化产率可达98.5%,但由于吸附在骨架上的卤素在高温、溶剂环境下会脱落,造成重复性实验中活性下降,而该类MOFs在反应前后骨架保持稳定,未造成坍塌或明显孔堵塞现象。后续如能强化卤素的吸附或温和化反应条件,则具有良好的应用潜力。     

Facile preparation of polybenzoxazine-based carbon microspheres with nitrogen functionalities: effects of mixed solvents on pore structure and supercapacitive performance

In this study, polybenzoxazine (PBZ)-based carbon microspheres were prepared via a facile method using a mixture of formaldehyde (F) and dimethylformamide (DMF) as the solvent. The PBZ microspheres were successfully obtained at the F/DMF weight ratios of 0.4 and 0.6. These microspheres exhibited high nitrogen contents after carbonization. The microstructures of all the samples showed an amorphous phase and a partial graphitic phase. The porous carbon with the F/DMF ratio of 0.4 showed significantly higher specific capacitance (275.1 F∙g^‒1) than the reference carbon (198.9 F∙g^‒1) at 0.05 A∙g^‒1. This can be attributed to the synergistic electrical double-layer capacitor and pseudo-capacitor behaviors of the porous carbon with the F/DMF ratio of 0.4. The presence of nitrogen/oxygen functionalities induced pseudo-capacitance in the microspheres, and hence increased their total specific capacitance. After activation with CO₂, the specific surface area of the carbon microspheres with the F/DMF ratio of 0.4 increased from 349 to 859 m²∙g^‒1 and the specific capacitance increased to 424.7 F∙g^‒1. This value is approximately two times higher than that of the reference carbon. The results indicated that the F/DMF ratio of 0.4 was suitable for preparing carbon microspheres with good supercapacitive performance. The nitrogen/oxygen functionalities and high specific surface area of the microspheres were responsible for their high capacitance.     

用于CO2/CH4分离的cPIM-1/ZIF-8混合基质膜的制备

自聚微孔聚合物（PIM-1）虽具有良好的CO₂渗透性能,但其气体选择性普遍较差,限制其在CO₂/CH₄分离领域的应用。本文以N,N-二甲基甲酰胺（DMF）为溶剂制备ZIF-8纳米粒子,将其引入到羧基化的PIM-1基质中,制备了cPIM-1/ZIF-8混合基质膜,用于CO₂/CH₄分离。结果表明：由于合成ZIF-8的溶剂也是cPIM-1的良溶剂,使得两者之间具有良好的界面相容性,从而使ZIF-8添加量高达质量分数45%。随着ZIF-8添加量的增加,膜的CO₂渗透速率持续增加,CO₂/CH₄选择性呈现先上升后下降的趋势。当ZIF-8添加量为质量分数25%时,膜的CO₂/CH₄分离性能最好,即CO₂渗透系数为3942 Barrer,CO₂/CH₄选择性为18.7,较cPIM-1纯膜分别提高了 84%和43%,成功地超越了Robeson分离上限。     

Catalytic reduction of sulfur dioxide using hydrogen or carbon monoxide over Ce1−xZrxO2 catalysts for the recovery of elemental sulfur

This study focuses on the direct sulfur recovery process (DSRP), in which SO₂ can be directly converted into elemental sulfur using a variety of reducing agents over Ce_1−xZr_xO₂ catalysts. Ce_1−xZr_xO₂ catalysts (where x = 0.2, 0.5, and 0.8) were prepared by a citric complexation method. The experimental conditions used for SO₂ reduction were as follow: the space velocity (GHSV) was 30,000 ml/g_-cat h and the ratio of [CO (or H₂, H₂ + CO)]/[SO₂] was 2.0. It was found that the catalyst and reducing agent providing the best performance were the Ce_0.5Zr_0.5O₂ catalyst and CO, respectively. In this case, the SO₂ conversion was about 92% and the sulfur yield was about 90% at 550 °C. Also, a higher efficiency of SO₂ removal and elemental sulfur recovery was achieved in the reduction of SO₂ with CO as a reducing agent than that with H₂. In the reduction of SO₂ by H₂ over the Ce_0.5Zr_0.5O₂ catalyst, SO₂ conversion and sulfur yield were about 92.7% and 73%, respectively, at 800 °C. Also, the reduction of SO₂ using synthetic gas with various [CO]/[H₂] molar ratios over the Ce_0.5Zr_0.5O₂ catalyst was performed, in order to investigate the possibility of using coal-derived gas as a reducing agent in the DSRP. It was found that the reactivity of the SO₂ reduction using the synthetic gas with various [CO]/[H₂] molar ratios was increased with increasing CO content of the synthetic gas. Therefore, it was found that the Ce_1−xZr_xO₂ catalysts are applicable to the DSRP using coal-derived gas, which contains a larger percentage of CO than H₂.     

Processing and Microstructure of Mullite-Zirconia Composites Prepared from Sol-Gel Powders

A high-purity stoichiometric mullite precursor was obtained by hydrolysis of the alkoxides Al(OC₃H₇)₃ and Si(OC₂H₂)₄. Fully sintered mullite ceramics can be prepared from sol-gel powders by sintering them at 1600°C for 4 h in air with the addition of 15 to 20 Vol% ZrO₂ or 1 to 3 mol% Y₂O₃ or both. Introduction of 1 to 3 mol% Y₂O₃ aids the retention of tetragonal ZrO₂; the volume fraction of t -ZrO₂ retained increases with increasing Y₂O₃ content. The maximum t -ZrO₂ retained reaches 34% in a matrix of synthetic mullite with 3 mol% Y₂O₃, but most of this t -ZrO₂ does not undergo stress-induced transformation during grinding.     

WO_3/BiOBr复合催化剂的制备及可见光催化降解甲基橙

以Bi(NO_3)5·5H_2O、Na Br、H_2WO_4为原料,采用一步水热合成法合成不同n(W)∶n(Br)的WO_3/BiOBr复合催化剂,并通过SEM和TEM对催化剂进行表征分析。以甲基橙为探针污染物,考察前驱液pH、水热温度、水热时间和n(W)∶n(Br)对WO_3/BiOBr复合催化剂活性的影响。结果表明,在pH为10.2、100℃水热时间6 h合成n(W)∶n(Br)为0.02的WO_3/BiOBr复合催化剂活性最好,光照120 min后,对目标污染物的降解率达99.39%,较BiOBr催化剂(合成条件为原始pH值,100℃水热反应6 h)提高了30.85%。采用水热合成法制备的WO_3/BiOBr复合催化剂具有良好的可见光活性。     

Solid-State Synthesis of 70 nm Li4Ti5O12 Particles by Mechanically Activating Intermediates with Amino Acids

A novel synthetic method of fine particles of highly pure Li₄Ti₅O₁₂ with the smallest possible particle size was proposed. A stoichiometric mixture of CH₃COOLi·2H₂O and anatase fine particles of ca. 50 nm was calcined at 773 K to obtain an intermediate, comprising Li₂TiO₃ and unreacted titania. The intermediate was then intensively milled by a planetary ball mill for 1 h. After adding an amino acid, glycine, alanine (ALA), or l -phenylalanine (PHE), the mixture was further milled under a milder condition for another 3 h and subjected to a second calcination at 973 K for 1 h to obtain Li₄Ti₅O₁₂ with a phase purity above 97%. When we used ALA or PHE as an additive, the microscopically determined average particle size of Li₄Ti₅O₁₂ was 70±10 nm. The mechanisms and significance of the present two-step calcination with mechanical activation and addition of an amino acid to the intermediate were discussed in terms of the topotactic nature of transformation between the two layer-structured species: Li₂TiO₃ and Li₄Ti₅O₁₂.     

Desolvation step preceding electroreduction and the electrochemical reactions of the Ni(II)/Ni(Hg) system in dimethylformamide (DMF) and its mixtures with water

The kinetics of the electrode reaction of the Ni(II)/Ni(Hg) system in DMF and its mixtures with water at different concentrations of several background electrolytes has been studied.

Similarly to aqueous solutions, at higher background electrolyte concentrations the charge transfer step is preceded by a chemical reaction. It was deduced that this proceeding reaction is due to slow dissociation of the solvent molecule in the S¹_N process.

The change of a solvent from water to 70 vol.% of DMF decreases the standard rate constant (k_s) for about one order of magnitude. At larger DMF content k_s is virtually independent of the solvent composition. The change of k_s with the DMF content was explained by assuming the resolvation of Ni(II) ions at the electrode surface in proportion to the surface coverage of the electrode molecules of both solvents.     

Synthesis, Characterization, and Consolidation of Si3N4 Obtained from Ammonolysis of SiCl4

Thermal decomposition of silicon diimide, Si(NH)₂, in vacuum resulted in very-high-purity, fine-particle-size, amorphous Si₃N₄ powders. The amorphous powder was isothermally aged at 50° to 100° intervals from 1000° to 1500°C for phase identification. Examination of ir spectra and X-ray diffraction patterns indicated a slow and gradual transition from an amorphous material to a crystalline α-phase occurring at 1200°C for >4 h and/or 1300° to 1400°C for 2 h. As the temperature was increased to ≥1450°C for 2 h, the crystalline β-phase was observed. Phase nucleation and crystallite morphology in this system were studied by electron microscopy and electron diffraction combined with TG as functions of temperature for the inorganic polymer starting materials. Powders prepared in this manner with 4 wt% Mg₃N₂ added as a sintering aid were hot-pressed to high-density fine-grained bodies with uniform microstructures. The optimum hot-pressing condition was 1650°C for 1 h. Silicon concentration steadily increased as the hot-pressing temperature or time was increased. A method for chemical etching for high-density fine-grained Si₃N₄ is described. Electrical measurements between room temperature and ∼500°C indicated dielectric constant and tan δ values of 8.3±0.03 and 0.65±0.05×10⁻², respectively.     

碱性氧化物对煤灰熔融特征行为的影响

利用分析纯试剂制备了酸碱比为0.82,但Na₂O、CaO、MgO和Fe₂O₃含量不同的合成灰,并在815℃下在马弗炉中进行灼烧后,对其熔融温度进行测定。同时利用扫描电子显微镜-能谱仪（SEM-EDS）和X射线衍射仪（XRD）对样品微观形貌和矿物组成进行表征。结果表明：随着Na₂O质量分数从4%升高到12%,合成灰变形温度（DT）、软化温度（ST）、半球温度（HT）和流动温度（FT）分别从1225℃、1233℃、1255℃和1297℃下降为1162℃、1174℃、1181℃和1189℃,意味着Na₂O对合成灰具有较强的助熔效果;随着CaO和MgO含量在合成灰中分别增加,DT、ST和HT均单调上升,而FT则呈先下降后上升趋势,说明二者含量变化与合成灰熔融温度呈非线性关系;随着Fe₂O₃质量分数由5%增加至30%,FT由1215℃上升至1308℃,而其他3个熔融特征温度并无显著变化。通过SEM-EDS和XRD表征发现,合成灰中耐熔矿物（SiO₂和CaAl₂Si₂O₈等）和助熔矿物（CaMgSi₂O₆和NaAlSiO₄等）的比例变化和含钠矿物、含钙矿物之间低温共熔反应程度是影响其熔融温度的主要原因。综合对比所有合成煤灰熔融特征温度和化学组成发现,对于具有相同酸碱比的煤灰,DT主要与样品中Na₂O含量和碱土金属总量（CaO+MgO）密切相关影响,而FT主要受Na₂O和Fe₂O₃含量影响。     

羧酸改性HKUST-1提高甲烷吸附容量

为提高吸附材料对甲烷的吸附容量,采用溶剂热法合成了金属有机骨架材料HKUST-1,并进行了改性研究。HKUST-1的优化合成工艺条件为：原料摩尔比n（Cu（NO₃）₂·3H₂O）：n（H₃BTC）：n（DMF）：n（C₂H₅OH）：n（H₂O）=1.7：1：46：60：100,晶化温度为80℃,晶化时间24 h。合成HKUST-1在25℃、3.5 MPa下的甲烷吸附容量为11.9 mmol/g。乙酸改性HKUST-1可以提高甲烷吸附容量,当反应母液中V_HAc/V_solvent=5.8%时,合成HAc-HK-1（5.8%）的甲烷吸附容量达到12.6 mmol/g。分子模拟结果表明,加入乙酸可以调控HKUST-1晶体孔道结构,增大比表面积和孔容,提高甲烷吸附容量。     

Microstructural Characterization of Cofired Tungsten-Metallized High-Alumina Electronic Substrates

Microstructural characterization of a high-Al₂O₃ substrate containing cofired thick-film tungsten metallization, with particular emphasis on the metal/ceramic interface, was conducted. The substrate contained tabular Al₂O₃ grains surrounded by a continuous calcium magnesium aluminum silicate glass containing particles of monoclinic ZrO₂ and reduced rutile (TiO_{2- x} ). The metal/ceramic adhesion was caused by mechanical interlocking between the W and Al₂O₃ grains by the glass phase which penetrated the porous W layers during sintering; there was no interfacial reaction or diffusion zone. The mechanical properties of the W metallization did not limit interfacial strength. Heat treatments of the substrate at 1400 K in air and under vacuum resulted in the devitrification of the intergranular glass. The most abundant devitrification product was anorthite (CaAl₂Si₂O₈), accompanied by magnesium aluminate titanate, magnesium aluminate spinel, α-cristobalite (SiO₂), and α-cordierite (Mg₂Al₄Si₅O₁₈). In addition, small rutile particles precipitated within the Al₂O₃ grains.     

Preparation of Aragonite Whiskers

A simple synthetic method for preparing aragonite whiskers has been developed. A suspension of CaCl₂-MgCl₂-Mg(OH)₂ with pH ∼9 has been prepared by adding Ca(OH)₂ to MgCl₂ aqueous solution. CaCO₃ whiskers (aragonite phase) have been prepared easily by blowing CO₂-containing gas into the suspension. The whiskers have high aspect ratios ranging from 20 to 80 with diameters of 0.5–1 μm .     

Effects of Rice Straw on the Color and Microstructure of Bizen, a Traditional Japanese Stoneware, as a Function of Oxygen Partial Pressure

The effects of oxygen partial pressure during thermal treatment on the color and microstructure of Bizen, a traditional Japanese stoneware, were studied through model experiments using clay pellets covered lightly with rice straw as a coloring assistant. When heated in flowing nitrogen, the model pellet turned blackish owing to the formation of α-Fe particles coated with graphite. However, schreibersite (Fe₃P), which is also blackish, was formed specifically on the pellet surface in direct contact with the straw. The rice straw seems to have generated a strongly reducing atmosphere, strong enough for the metallization to α-Fe, and also to have provided phosphorus through contact. When oxygen content in the surrounding gas atmosphere was raised to N₂/O₂=99/1, the pellet surface turned yellowish brown because the main coloring material was Fe³⁺-containing mullite. At oxygen contents of N₂/O₂=98/2 or more, the formation of hematite (α-Fe₂O₃) pushed the color to deep red.     

Damage Tolerance of Silicon Carbide- and Alumina-Matrix Surface Composites

A method for the fabrication of a ceramic-matrix composite (CMC) layer on the surface of a monolithic substrate via chemical vapor infiltration (CVI) is described. Preforms consisted of tows of fibers wound onto the surface of monolithic cylindrical tubes. Nicalon fibers were wound onto mullite substrates and infiltrated with β-SiC from CH₃SiCl₃/H₂ gas mixtures in a cylindrical cold-wall reactor. Similarly, Nextel fibers were wound onto A1₂O₃ substrates and infiltrated with α-Al₂O₃ from AlCl₃/H₂/CO₂/N₂ gas mixtures. Composites with densities as high as 88% of the theoretical value were fabricated in 8 h. The effective fracture strength of the SiC- and Al₂O₃-matrix surface composites, as determined from diametral compression tests of C-ring specimens, was found to be insensitive to damage caused to the outer diameter by a Vickers indentation. The tolerance of the SiC-matrix surface composites to surface damage was retained in specimens subjected to oxidation at 1000°C for 6 h.