Fe2O3/Al2O3氧载体用于甲烷化学链燃烧：负载量与制备方法的影响

以不同方法制备了系列Fe₂O₃/Al₂O₃氧载体,采用XRD、H₂-TPR、CH₄-TPR、O₂-TPD和BET等分析技术对氧载体进行了表征。研究了不同Fe₂O₃负载量氧载体的甲烷化学链燃烧性能,考察了不同制备方法对Fe₂O₃/Al₂O₃氧载体结构、反应性和产物选择性的影响。结果表明,Fe₂O₃负载量对氧载体活性及产物中CO₂选择性的影响较大,负载量较低时氧载体活性较低且引起甲烷部分氧化产物CO含量增加。制备方法亦对氧载体与甲烷的反应活性有所影响,整体上共沉淀法制备的质量分数60％Fe₂O₃/Al₂O₃氧载体具有较高的氧化活性和化学链循环稳定性。其在反应温度850℃、反应时间15 min、30次循环后甲烷转化率及产物中CO₂选择性均未见明显降低。     

V2O5-Sb2O3-TiO2催化剂 低温NH3还原NO及其抗H2O和SO2毒化性能

浸渍法制备了催化剂V₂O₅-Sb₂O₃-TiO₂,考察了V₂O₅、Sb₂O₃负载量、pH值和焙烧温度对催化剂V₂O₅- Sb₂O₃-TiO₂低温氨选择性催化还原(SCR)NO活性的影响;同时,考察了催化剂V₂O₅-Sb₂O₃-TiO₂抗H₂O和SO₂毒化性能。结果表明,V₂O₅和Sb₂O₃负载量分别为5%和2%、焙烧温度为400℃、pH值为4时,催化剂SCR活性最好,反应温度220℃时,可达97%。Sb₂O₃的加入不仅能增强V₂O₅/TiO₂的催化活性,而且能明显提高催化剂的抗H₂O和SO₂毒化性能。SO₂、NO吸附暂态反应和TG-DTG测试表明,Sb₂O₃的促进机制主要是促进了催化剂在SO₂存在条件下对NO的吸附,同时,减弱了硫酸铵盐与催化剂之间的相互作用,硫酸铵盐更容易分解。     

尿素/H2O2溶液同时脱硫脱硝机理研究

在填料塔上对尿素/H₂O₂溶液同时脱硫脱硝进行了实验研究。结果表明,尿素溶液对SO₂具有很高的去除效率,但对NO_x的去除受到多种因素的影响。实验主要研究了H₂O₂浓度、吸收反应温度、溶液pH值等因素对脱硝效率的影响,并确定了最佳实验条件,在此条件下脱硫脱硝效率分别达到100%和52.6%。同时,采用化学分析法和气相色谱法对尿素溶液同时脱硫脱硝的反应产物进行分析,推导出尿素/H₂O₂溶液同时脱硫脱硝的反应机理和总化学反应方程式。该技术可用于对现有湿法脱硫技术的改造,使其同时具有脱硫脱硝功能。     

O2/CO2气氛下稻秆添加磷酸二氢铵对固钾及灰熔融特性的研究

研究了21%O₂/79%CO₂气氛下,磷酸二氢铵对稻秆不同温度下的固钾能力及对灰熔融性的影响。利用电感耦合等离子体发射光谱(ICP-AES)、X射线衍射(XRD)以及扫描电子显微镜(SEM)等检测手段,对稻秆燃烧灰中K元素含量、产物物相以及微观形貌进行分析。固定床燃烧固钾实验表明,添加NH₄H₂PO₄能够有效提高稻秆固钾率,900℃下稻秆自身固钾率为14.65%,添加NH₄H₂PO₄后固钾率为68.79%,可以有效抑制生物质燃烧过程中碱金属以气态形式析出,并缓解了灰结渣现象。700℃燃烧条件下NH₄H₂PO₄和钾反应的主要产物为KPO₃;900℃下反应的主要产物为高熔点物质K₂CaP₂O₇,从微观形貌可以看出NH₄H₂PO₄能够抑制灰颗粒的烧结,添加NH₄H₂PO₄能有效提升稻秆灰熔点。     

CeO2/γ-Al2O3复合材料制备及其光催化性能研究

以Ce(NO₃)₃·6H₂O及Al(NO₃)₃·9H₂O为原料,NH₄HCO₃为造孔剂,以沉淀法制备了具有介孔结构的CeO₂/γ-Al₂O₃光催化材料。研究了不同NH₄∶Al及Ce∶Al摩尔比等条件下制备CeO₂/γ-Al₂O₃样品的光催化性能。结果表明,所制备CeO₂/γ-Al₂O₃复合材料具有优异的光催化性能,最佳NH₄∶Al及Ce∶Al摩尔比分别为1及0.2,该条件下制备的样品BET比表面积为94.4642 m²·g^-1,孔径为5.8565 nm,对亚甲基蓝(MB)的光催化降解率可达93.59%,动力学常数k为0.0218 m...     

SO2对钙基CO2吸收剂循环煅烧/碳酸化反应的影响

在循环煅烧/碳酸化反应系统中,研究了SO₂对钙基吸收剂CaCO₃捕集CO₂的影响,获得了SO₂对钙基吸收剂碳酸化特性、煅烧特性以及循环稳定性的影响规律,并结合SEM分析结果,从循环煅烧/碳酸化反应角度,分析了可能存在的原因。结果表明,钙基吸收剂吸收CO₂的能力随着循环反应次数的增加逐渐发生衰减,在SO₂影响下,这种衰减会进一步加剧,且衰减程度随着SO₂浓度的增加而增大,经过十次循环后,碳酸化转化率分别为25.5%(0%SO₂)、16.9%(0.1%SO₂)和5.2%(0.2%SO₂)。造成这种衰减加剧的主要原因是反应产生较厚的硫酸化产物层,硫酸化产物层使颗粒表面孔隙发生堵塞,阻碍了CO₂在吸收剂内部的扩散,降低了碳酸化转化率。     

流化床O2/CO2气氛下添加石灰石对燃煤PM2.5的控制

采用小型流化床研究了在O₂/CO₂气氛下添加石灰石对PM_2.5(空气动力学直径小于2.5 μm的颗粒物)的控制.实验采用荷电低压撞击器(ELPI)采集和分析燃烧后的PM_2.5.结果表明,添加石灰石是燃烧过程中影响PM_2.5生成的重要因素.添加石灰石后,生成PM_1.0的数量浓度均降低,而PM_1.0~2.5的数量浓度均略有增加;PM_2.5质量粒径分布均呈双峰分布,峰值分别出现在0.2和2.0 μm左右.随着Ca/S物质的量比的增加,PM_2.5中Si、Na、K、S和Cu的含量呈减少的趋势;随着颗粒粒径的减小,S、Cu、K和Na的含量有增大的趋势,而Si的含量有减少的趋势.     

低阶煤半焦利用热重在O2/CO2、O2/N2和O2/Ar气氛下燃烧特性研究

利用热重研究了两种中国西北典型低阶煤半焦的燃烧特性。探究了不同气氛（O₂/CO₂、O₂/N₂和O₂/Ar）和不同氧气浓度对其燃烧特性的影响。实验结果表明,无论是反应气氛还是氧气浓度都会对低阶煤半焦的燃烧产生影响。相比于N₂和Ar,CO₂明显有利于燃烧反应进行：当反应气氛由O₂/CO₂变为O₂/Ar时,两种不同低阶煤半焦的燃尽温度分别升高了63.7和68.8℃;而当反应气氛由O₂/CO₂变为O₂/N₂时,两种不同低阶煤半焦的燃尽温度分别升高了135.9和129.6℃。在研究范围内,氧气浓度的提高也能明显提高半焦的燃烧性能。与此同时,半焦燃烧特性的动力学分析表明,随着氧气浓度提高,两种半焦燃烧反应的表观活化能E和指前因子A均呈增大趋势。通过对E和A两者关系的分析结果表明,半焦富氧燃烧的活化能和指前因子存在动力学补偿效应。     

SiO2改性的V2O5-MoO3/ TiO2催化剂抗碱中毒性能研究

以陶瓷为骨架,用溶胶凝胶法和浸渍法制备了V₂O₅-MoO₃/ TiO₂催化剂,并用SiO₂进行改性。采用浸渍法模拟碱K中毒,研究了SiO₂改性前后催化剂中毒脱硝效率的变化,并通过BET、H₂-TPR、NH₃-TPD等技术手段对催化剂进行了表征。结果表明,加入SiO₂后,催化剂的比表面积明显提高。SiO₂改性后新鲜催化剂还原温度向低温方向迁移10 ℃左右,氧化还原能力得到了提高,其表面酸强度和酸量也得到较大的提高。反应评价结果表明,SiO₂改性可以提高催化剂抗碱中毒的性能。     

实验参数对磁性AgI-BiOI/CoFe2 O4光催化剂湿法脱除Hg0的影响

采用水热-共沉淀法制备了一种新型的磁性AgI-BiOI/CoFe₂O₄复合材料光催化剂,考察了荧光灯辐照下光催化剂脱除模拟烟气中单质汞（Hg⁰）的性能,研究了实验参数对脱汞性能的影响及反应产物。结果表明,AgI-BiOI/CoFe₂O₄光催化剂的热稳定性较差,当煅烧温度超过400 ℃时该光催化剂的化学成分会发生变化;随着催化剂用量、反应溶液pH值、反应溶液温度和烟气中O₂浓度的增加,脱汞效率先增加后不变或下降;反应溶液中存在的CO₃^2-和SO₄^2-对脱汞效率有一定的抑制作用;当通入SO₂时,脱汞效率急剧下降;而NO对脱汞效率的抑制作用相对较小。反应产物分析表明,SO₂、NO和Hg⁰的最终氧化产物分别是SO₄^2-、NO₃^-和Hg²⁺     

KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems

phase diagrams of KCl-KBO₂-K₂CO₃, K₂MoO₄-KBO₂-K₂CO₃, and K₂WO₄-KBO₂-K₂CO₃ ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates of ternary eutectics were determined to be E ₁: 622°C, 8.5 mol % KBO₂, 56.5 mol % KCl, and 35 mol % K₂CO₃; E ₂: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂MoO₄; E ₃: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂WO₄. The specific heats of melting of the eutectics were determined.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

The preparation of NbH5(Me2PCH2CH2Me2)2 and NbHL2(Me2PCH2CH2PMe2)2 (L = CO or C2H4)

MMe₅(dmpe) (M = Nb or Ta, dmpe = Me₂PCH₂CH₂PMe₂) reacts with H₂ (500 atm) and dmpe in THF at 60°C to give MH₅(dmpe)_2? NbH₅(dmpe)₂ readily reacts with two mol of CO or ethylene (L) to give NbHL₂(dmpe)₂. The exchange of the hydride ligand with the ethylene protons in NbH(C₂H₄)₂(dmpe)₂ is not rapid on the ¹H NMR time scale (60 MHz) at 95°C.     

Li2SO4-Na2SO4-H2O和Li2SO4- K2SO4-H2O溶液的体积性质

本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li₂SO₄ + Na₂SO₄ + H₂O和 Li₂SO₄ + K₂SO₄ + H₂O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg_–1,混合溶液中Na₂SO₄和K₂SO₄的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θ_V和 ψ_V,模型的计算值与实验值的偏差在±0.002 g.cm_–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。     

NaBO2-NaCl-Na2CO3, NaBO2- Na2CO3-NaMoO4, NaBO2- Na2CO3-NaWO4, and NaBO2-NaCl-Na2WO4 ternary systems

The phase diagrams of the NaBO₂-NaCl-Na₂CO₃, NaBO₂-Na₂CO₃-Na₂MoO₄, NaBO₂- Na₂CO₃-Na₂WO₄, and NaBO₂-NaCl-Na₂WO₄ ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E ₁: 612°C, 16 mol % NaBO₂, 42 mol % NaCl, and 42 mol % Na₂CO₃; E ₂: 568°C, 12 mol % NaBO₂, 28 mol % Na₂CO₃, and 60 mol % Na₂MoO₄; E ₃: 575°C, 12 mol % NaBO₂, 32 mol % Na₂CO₃, and 56 mol % Na₂WO₄; E ₄: 628°C, 8 mol % NaBO₂, 20 mol % NaCl, and 72 mol % Na₂WO₄; and E ₅: 655°C, 9 mol % NaBO₂, 53 mol % NaCl, and 38 mol % Na₂WO₄.     

Polymorphism in the Sc2Si2O7-Y2Si2O7 system

This paper examines the structural changes with temperature and composition in the Sc₂Si₂O₇-Y₂Si₂O₇ system; members of this system are expected to form in the intergranular region of Si₃N₄ and SiC structural ceramics when sintered with the aid of Y₂O₃ and Sc₂O₃ mixtures. A set of different compositions have been synthesized using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1750 °C during different times. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β-RE₂Si₂O₇ polymorph, with γ-RE₂Si₂O₇ and δ-RE₂Si₂O₇ showing very reduced stability fields. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of the components. Although, the XRD data show a complete solid solubility of β-Sc₂Si₂O₇ in β-Y₂Si₂O₇ at 1300 °C, the ²⁹Si MAS-NMR spectra indicate a local structural change at x ca. 1.15 (Sc_2−xY_xSi₂O₇) related to the configuration of the Si tetrahedron, which does not affect the long-range order of the β-RE₂Si₂O₇ structure. Finally, it is interesting to note that, although Sc₂Si₂O₇ shows a unique stable polymorph (β), Sc³⁺ is able to replace Y³⁺ in γ-Y₂Si₂O₇ in the compositional range 1.86?x?2 (where x is Sc_2−xY_xSi₂O₇) as well as in δ-Y₂Si₂O₇ for compositions much closer to the pure Y₂Si₂O₇.     

Synthesis and characterization of inorganic solid electrolytes of Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 systems

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li₂O-SiO₂-P₂O₅ and Li₂O-TiO₂-SiO₂-P₂O₅ were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10⁻⁴ S/cm in the Li₂O-TiO₂-SiO₂-P₂O₅ system. Original Russian Text ? W. Li, M. Wang, Z.H. Li, X.F. Shang, H. Wang, Y.W. Wang, Y.B. Xu, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 11, pp. 1341–1345.     

(H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8: A new,templated one-dimensional ternary semiconductor stabilized by mixed organic cations

The novel, 1D semiconductor (H₂NC₄H₈NCH₂CH₂NH₂)(HNCH₂CH₂NH₂)₃Zn₂Ge₂Se₈ has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn₂Ge₂Se₈]⁴⁻ chains made of alternating edge-shared [ZnSe₄] and [GeSe₄] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV.     

Ag2Se-Tl2Se-Bi2Se3 quasi-ternary system

The Ag₂Se-Tl₂Se-Bi₂Se₃ quasi-ternary system (system A) was studied using DTA, X-ray powder diffraction, microstructure examination, and microhardness measurements. TlBiSe₂-AgBiSe₂, AgTlSe-AgBiSe₂, AgTlSe-Bi₂Se₃, and Tl₂Se-AgBiSe₂ polytherms, isothermal sections at 500 and 800 K, and liquidus surface projection of system A were constructed. System A is congruently triangulated into the following subordinate triangles: Tl₂Se-AgTlSe-Tl₉BiSe₆ (I), AgTlSe-Tl₉BiSe₆-TlBiSe₂ (II), Ag₂Se-AgTlSe-TlBiSe₂ (III), Ag₂Se-AgBiSe₂-TlBiSe₂ (IV), and AgBiSe₂-TlBiSe₂-Bi₂Se₃ (V). Subsystems I, III, and V are ternary systems with three-phase eutectic equilibrium; system II has a three-phase eutectic, and system IV is characterized by several invariant and monovariant peritectic and eutectic equilibria. Primary crystallization and homogeneity fields were outlined, and the types and coordinates of invariant and monovariant equilibria in system A were determined. A characteristic feature of the title system is an extensive field of solid solutions between high-temperature cubic AgBiSe₂ and TlBiSe₂ phases; this field lies as a continuous belt along the AgBiSe₂-TlBiSe₂ quasibinary section and covers about one-fourth of the surface area of the triangular diagram of system A.