球形硝基胍粒径对改性单基发射药热安定性和力学性能的影响

为了改善改性单基发射药的安定性和力学性能,制备了含3种不同粒径(50、80和110μm)球形硝基胍(NQ)的改性单基发射药,通过差示扫描量热法、真空安定性试验和甲基紫试验研究了其热分解过程和热安定性,并测试了其抗冲击和抗压缩强度,分析了NQ粒径变化对改性单基发射药热行为和力学性能的影响。结果表明,3种含球形NQ的改性单基发射药试样有两个热分解过程,第一个分解过程对应的是混合硝化棉的分解,第二个分解过程是RDX和NQ的分解,但是第二个分解过程不明显;随着NQ粒径从50μm增至110μm,发射药试样的热分解峰温从176.84℃提高至179.71℃;真空安定性试验中试样48h放气量从0.7558mL/g降至0.5964mL/g,甲基紫试纸变为橙色的时间从44min延长至54min,且加热5h后未发生爆炸;发射药试样的抗冲击强度从4.23kJ/m~2降至3.81kJ/m~2,抗压缩强度从56.93MPa降至53.85MPa。表明球形NQ粒径的增加有利于提高发射药的热安定性,但会降低其力学性能。     

浓硫酸磺化苯酚合成对羟基苯磺酸工艺研究

以均三甲苯为溶剂,苯酚和浓硫酸为原料,亚磷酸为催化剂合成对羟基苯磺酸,探究了温度、原料配比、老化时间、浓硫酸加入流量、溶剂用量、搅拌转速对对羟基苯磺酸收率和含量的影响。结果表明,当反应温度为100℃、原料配比n(H₂SO₄):n(C₆H₅OH)为1.1:1、老化时间为25 min、浓硫酸滴加速度为0.8 mL/min、溶剂配比n(C₆H₅OH):n(C₉H₁₂)为1:1.25、搅拌转速为2 kr/min时,对羟基苯磺酸收率达89.85%。该工艺具有操作简单和生产成本低等特点艺。     

低碳烷烃烯烃在超微孔柔性Cu(Qc)2上的吸附行为

采用实验研究与分子模拟相结合的方法研究了低碳烷烃烯烃在超微孔柔性Cu(Qc)₂上的吸附热力学、动力学和吸附分离机理。用常温合成方法制备了超微孔金属-有机骨架材料Cu(Qc)₂,测定了低碳烷烃烯烃（CH₄/C₂H₄/C₂H₆/C₃H₆/C₃H₈）在Cu(Qc)₂上的吸附相平衡和吸附动力学。使用Materials Studio中的Fortcite模块模拟低碳烷烃烯烃在超微孔柔性Cu(Qc)₂上的吸附机理以及材料的结构形变。结果表明Cu(Qc)₂具有优良的C₂H₆ /C₂H₄吸附选择性和吸附动力学,而对C₃H₈ /C₃H₆的吸附选择性很低。273 K和0.1 MPa下,C₂H₆/C₂H₄在Cu(Qc)₂上的IAST选择性达4.6。298 K和0.05 MPa下C₂H₆/C₂H₄在Cu(Qc)₂上的扩散时间常数分别达1.42×10^-3和1.48×10^-3_{s^-1,扩散活化能分别为16.62 和16.43 kJ/mol。应用装填Cu(Qc)2的固定床可在常温条件下实现C2H6 /C2H4二元混合气的完全分离。模拟结果显示Cu(Qc)2为二维堆叠结构,材料会由于吸附不同分子而发生不同程度的结构形变。甲烷易从变大的层间扩散脱附,导致其在材料上的吸附量很低;C2H6/C2H4两者都能稳定吸附在层中的孔道中,其分离推动力主要来源于两种气体在材料上明显的吸附热差异;C3H8/C3H6会分别吸附在两种不同的环境,吸附热差异小导致Cu(Qc)2对C3H8 /C3H6的吸附选择性低。}     

温度对MOF-74(Ni)吸附分离丙烯丙烷机理和选择性的影响

采用水热法成功制备了MOF-74(Ni),使用PXRD、孔径分析对材料进行了表征,测定了材料在不同温度下的C₃H₆和C₃H₈吸附等温线,应用程序升温脱附技术估算了脱附活化能,并使用IAST理论预测了材料对C₃H₆/C₃H₈二元体系的吸附选择性。讨论了温度对吸附机理和吸附选择性的影响。结果显示,MOF-74(Ni)的BET比表面积高达1306 m²·g^-1。在298 K下,C₃H₆的吸附量高达7.4 mmol·g^-1。随着温度升高,C₃H₈的吸附量大幅降低,而C₃H₆的吸附量下降程度较小,导致材料对C₃H₆/C₃H₈吸附选择性升高。当温度为328K时,MOF-74(Ni)对C₃H₆/C₃H₈二元气体混合物的吸附选择接近12。程序升温脱附的实验结果显示,C₃H₆在MOF-74(Ni)上的脱附活化能大于C₃H₈,分别为68.92 kJ·mol^-1和50.80 kJ·mol^-1。C₃H₆是通过与MOF-74(Ni)的不饱和金属位点Ni²⁺以p络合作用方式吸附,作用力较强,而C₃H₈与Ni²⁺之间的作用力较弱。根据吸附机理不同的特点,适当提高温度,将有助于提高MOF-74(Ni)吸附分离C₃H₆/C₃H₈混合物体系的吸附选择性。     

不同氧浓度下煤挥发分燃烧的化学动力学研究

燃煤有机污染物对人类健康和生态环境存在严重危害,而O₂对火焰中有机产物的形成具有明显的调控作用。鉴于煤挥发分燃烧是燃煤过程中至关重要的一环,本文以煤热解气为燃料,通过数值模拟研究了氧化剂侧O₂浓度对对冲扩散火焰中碳氢产物生成特性和机制的影响。结果表明,O₂浓度升高促进了O和OH的生成,进而提高H浓度,突显了含H和OH参与的反应的重要性。此外,乙炔(C₂H₂)、丙炔(PC₃H₄)、炔丙基(C₃H₃)、乙烯基乙炔(C₄H₄)、苯(C₆H₆)和萘(C₁₀H₈)的浓度均增大。增加O₂浓度促进了C₂H₂向PC₃H₄的转化,并使得C₃H₃更倾向于转化为丁二烯(C₄H₆),而富烯更倾向于通过苯基(C₆H₅)生成C₆H₆,因此C₆H₅作为C₆H₆前体的地位被加强。     

不同氧浓度下煤挥发分燃烧的化学动力学研究

燃煤有机污染物对人类健康和生态环境存在严重危害,而O₂对火焰中有机产物的形成具有明显的调控作用。鉴于煤挥发分燃烧是燃煤过程中至关重要的一环,本文以煤热解气为燃料,通过数值模拟研究了氧化剂侧O₂浓度对对冲扩散火焰中碳氢产物生成特性和机制的影响。结果表明,O₂浓度升高促进了O和OH的生成,进而提高H浓度,突显了含H和OH参与的反应的重要性。此外,乙炔(C₂H₂)、丙炔(PC₃H₄)、炔丙基(C₃H₃)、乙烯基乙炔(C₄H₄)、苯(C₆H₆)和萘(C₁₀H₈)的浓度均增大。增加O₂浓度促进了C₂H₂向PC₃H₄的转化,并使得C₃H₃更倾向于转化为丁二烯(C₄H₆),而富烯更倾向于通过苯基(C₆H₅)生成C₆H₆,因此C₆H₅作为C₆H₆前体的地位被加强。     

HPLC法测定复元胶囊中五味子醇甲的含量

建立复元胶囊中五味子醇甲的含量测定方法。采用高效液相色谱(HPLC)法对复元胶囊中五味子主要成分五味子醇甲(C₂₄H₃₂O₇)进行含量测定;流动相为甲醇-水(65∶35),检测波长为250 nm。五味子醇甲(C₂₄H₃₂O₇)在4.096～40.96μg/mL范围内溶液浓度与峰面积存在良好的线性关系,定量限为0.399μg/mL,检测限为0.120μg/mL,平均回收率为94.4%,RSD为0.6%(n=6);精密度试验、重复性试验、稳定性试验均良好。该方法灵敏度高、准确可靠,可以有效地控制复元胶囊的质量。     

两例基于对氯苯乙酸配体构筑的铜(Ⅱ)配合物晶体结构及荧光性能测试

室温下,通过溶剂挥发法合成了对氯苯乙酸邻菲啰啉铜(Ⅱ)配合物(C₂₈H₂₀Cl₂CuN₂O₄)和对氯苯乙酸2,2′-联吡啶铜(Ⅱ)配合物(C₂₆H₂₂Cl₂CuN₂O₅)。用X-射线单晶衍射测定了配合物的晶体结构;结果显示配合物C₂₈H₂₀Cl₂CuN₂O₄属于三斜晶系,■空间群,每个不对称单元由1个铜(Ⅱ)离子、2个对氯苯乙酸配体及1个邻菲啰啉配体组成。配合物C₂₆H₂₂Cl₂CuN₂O₅属于单斜晶系,P2₁/n空间群;每个不对称单元由1个铜(Ⅱ)离子、2个对氯苯乙酸配体及1个2,2′-联吡啶配体组成。在荧光光谱上,配合物C     

富勒烯交联季铵化聚苯醚阴离子交换膜的制备

通过富勒烯C₆₀与乙二胺合成立体纳米分子C₆₀(EDA)₈,并以此为交联剂与三阳离子功能化聚苯醚制备了一系列交联型阴离子交换膜。C₆₀(EDA)₈中立体纳米结构有效地支撑了高分子链段,构建了更发达的离子通道,有效地提升了电导率。实验结果表明,随着C₆₀(EDA)₈加入量增加,交联膜的离子交换容量减小,而电导率却逐渐增加。当交联剂C₆₀(EDA)₈加入量为5%时,电导率提高了34%。此外,所制备的离子交换膜均表现出良好的抗溶胀能力、力学性能与耐碱性。     

双β-二酮钛系烯烃聚合催化剂的合成、表征及其催化乙烯聚合

合成了一种新型β-二酮钛配合物[(acac)₂Ti(C₆H₆)₂(3a)、(acac)₂Ti(C₆H₅OCH₃)₂(3b)、(acac)₂Ti(C₆H₅CF₃)₂(3c)],采用¹H NMR、¹³C NMR、元素分析等方法进行表征。用配合物作催化剂,以甲基铝氧烷(MAO)为助催化剂催化乙烯聚合,研究了聚合条件(如Al/Ti摩尔比、聚合温度和催化剂结构)对催化活性的影响。其中3a对乙烯聚合活性达6.26×10⁵ g·mol^-1·h^-1,聚合物最大的重均分子量M_w为13.47 kg·mol^-1,分子量分布PDI为2.0。     

Stable titanium metal-organic framework with strong binding affinity for ethane removal

Direct separation of high purity ethylene (C₂H₄) from an ethane (C₂H₆)/ethylene mixture is a critical and challenging task owing to the very similar molecular size and physical properties of the two components. While some studies have attempted this separation, there is a lack of excellent porous materials with strong binding affinity for C₂H₆-selective adsorption via an energy-efficient adsorptive separation process. Herein, we report a titanium metal-organic framework with strong binding affinity and excellent stability for the highly efficient removal of C₂H₆ from C₂H₆/C₂H₄ mixtures. Single component adsorption isotherms demonstrated a larger amount of adsorbed ethane (1.16 mmol·g^-1 under 1 kPa) and high C₂H₆/C₂H₄ selectivity (2.7) for equimolar C₂H₆/C₂H₄ mixtures, especially in the low-pressure range, which is further confirmed by the results of grand canonical Monte Carlo simulations for C₂H₆ adsorption in this framework. The experimental breakthrough curves showed that C₂H₄ with a high purity was collected directly from both 1:9 and 1:15 C₂H₆/C₂H₄ (volume ratio) mixtures at 298 K and 100 kPa. Moreover, the unchanged adsorption and separation performance after cycling experiments confirmed the promising applicability of this material in future.     

C2H6/C3H8影响CH4爆炸极限参数及动力学特性研究

为研究C₂H₆/C₃H₈对甲烷爆炸极限参数及动力学特性的影响,采用标准的可燃气体爆炸极限测定装置测定了不同配比的C₂H₆/C₃H₈混合气体对甲烷爆炸极限的影响规律,同时得出了氮气惰化条件下甲烷爆炸临界参数的变化规律。此外,利用Chemkin软件模拟了C₂H₆/C₃H₈混合气体对甲烷爆炸过程中中间产物浓度的影响情况,并进行了敏感性分析。结果表明,C₂H₆/C₃H₈的存在降低了甲烷的爆炸上下限,增大了甲烷的爆炸危险度;在氮气惰化过程中甲烷的爆炸上限下降,爆炸下限上升,最终爆炸上下限重合,重合点处甲烷浓度和氮气临界浓度均随C₂H₆/C₃H₈的添加而逐渐减小;此外,C₂H₆/C₃H₈混合气体使甲烷爆炸过程中CO和·H的生成量逐渐增大,而CO₂、·O和·OH的生成量则有下降趋势,通过对爆炸过程中甲烷体积的敏感性分析,发现C₂H₆/C₃H₈的存在在某种程度上促进了甲烷爆炸。对比不同配比的C₂H₆/C₃H₈混合气体,发现C₃H₈含量越高,其对甲烷爆炸过程中相关参数的影响越大,这可为工矿企业的安全生产提供一定的理论依据。     

Preparation of CexZr1−xO2 (x = 0.75, 0.62) solid solution and its application in Pd-only three-way catalysts

Nanoparticles of Ce_xZr_1−xO₂ (x = 0.75, 0.62) were prepared by the oxidation-coprecipitation method using H₂O₂ as an oxidant, and characterized by N₂ adsorption, XRD and H₂-TPR. Ce_xZr_1−xO₂ prepared had single fluorite cubic structure, good thermal stability and reduction property. With the increasing of Ce/Zr ratio, the surface area of Ce_xZr_1−xO₂ increased, but thermal stability of Ce_xZr_1−xO₂ decreased. The surface area of Ce_0.62Zr_0.38O₂ was 41.2 m²/g after calcination in air at 900 °C for 6 h. TPR results showed the formation of solid solution promoted the reduction of CeO₂, and the reduction properties of Ce_xZr_1−xO₂ were enhanced by the cycle of TPR-reoxidation. The Pd-only three-way catalysts (TWC) were prepared by the impregnation method, in which Ce_0.75Zr_0.25O₂ was used as the active washcoat and Pd loading was 0.7 g/L. In the test of Air/Fuel, the conversion of C₃H₈ was close to 100% and NO was completely converted at λ < 1.025. The high conversion of C₃H₈ was induced by the steam reform and dissociation adsorption reaction of C₃H₈. Pd-only catalyst using Ce_0.75Zr_0.25O₂ as active washcoat showed high light off activity, the reaction temperatures (T₅₀) of 50% conversion of CO, C₃H₈ and NO were 180, 200 and 205 °C, respectively. However, the conversions of C₃H₈ and NO showed oscillation with continuously increasing the reaction temperature. The presence of La₂O₃ in washcoat decreased the light off activity and suppressed the oscillation of C₃H₈ and NO conversion. After being aged at 900 °C for 4 h, the operation windows of catalysts shifted slightly to rich burn. The presence of La₂O₃ in active washcoat can enhance the thermal stability of catalyst significantly.     

Synthesis of an active quaternary phosphonium salt and its application to the Wittig reaction: Kinetic study

The synthesis of liquid crystal methyl [4-(nonyloxy) styryl] benzoate was achieved in four stages. First, toluic acid [1] was brominated with N-bromosuccinimide in refluxing CCl₄ to form 4-bromotoluic acid [2] (BTA); second, BTA was esterified with methanol in SOCl₂/CH₂Cl₂ to afford methyl (4-bromomethyl) benzoate [3] (BME); third, BME was condensed with triphenylphosphine (PPh₃) in CH₂Cl₂ to produce the active Wittig reagent methyl (4-methylbenzoate) triphenylphosphonium bromide [4] (MBPB) and fourth, MBPB reacted with 4-nonyloxybenzaldehyde to produce MNSB in high yield. Each of these four reactions was carried out in a separate homogeneous organic solution and the effects of the reaction conditions in each reaction as well as a kinetic model for each individual reaction were studied. Furthermore, the active reagent was applied to the reaction of 4-nonyloxybenzaldehyde (n-C₉H₁₉O(C₆H₄)CHO) to synthesise cis-(E) and trans-(Z)methyl[4-(nonyloxy)styryl]benzoate (n-C₉H₁₉(C₆H₄)CHCH(C₆H₄)COOCH₃) from a two-phase medium alkaline solution of NaOH/organic solvent. High conversion and high selectivity were obtained via this reaction.     

Efficient separation of C4 olefins using tantalum pentafluor oxide anion-pillared hybrid microporous material

With the increasing demand for synthetic rubber, the purification of 1,3-butadiene (C₄H₆) is of great industrial significance. Herein, the successful removal of n-butene (n-C₄H₈) and iso-butene (iso-C₄H₈) from 1,3-butadiene (C₄H₆) was realized by synthesizing a novel TaOF₅^2- anion-pillared ultramicroporous material TaOFFIVE-3-Ni (also referred to as ZU-96, TaOFFIVE=TaOF₅^2-, 3=pyrazine). Single-component adsorption isotherms show that TaOFFIVE-3-Ni can achieve the exclusion of n-C₄H₈ and iso-C₄H₈ in the low pressure region (0-30 kPa), and uptake C₄H₆ with a high capacity of 92.78 cm³·cm^-3 (298 K and 100 kPa). The uptake ratio of C₄H₆/iso-C₄H₈ on TaOFFIVE-3-Ni was 20.83 (298 K and 100 kPa), which was the highest among the state-of-the-art adsorbents reported so far. With the rotation of anion and pyrazine ring, the pore size changes continuously, which makes smaller-size C₄H₆ enter the channel while larger-size n-C₄H₈ and iso-C₄H₈ are completely blocked. The excellent breakthrough performance of TaOFFIVE-3-Ni shows great potential in industrial separation of C₄ olefins. The specific adsorption binding sites within ZU-96 was further revealed through the modeling calculation.     

Highly selective separation of propylene/propane mixture on cost-effectively four-carbon linkers based metal-organic frameworks

The separation of propylene and propane is an important but challenging process, primarily achieved through energy-intensive distillation technology in the petrochemical industry. Here, we reported two natural C₄ linkers based metal–organic frameworks (MIP-202 and MIP-203) for C₃H₆/C₃H₈ separation. Adsorption isotherms and selectivity calculations were performed to study the adsorption performance for C₃H₆/C₃H₈ separation. Results show that C₃H₆/C₃H₈ uptake ratios (298 K, 100 kPa) for MIP-202 and MIP-203 are 2.34 and 7.4, respectively. C₃H₆/C₃H₈ uptake ratio (303 K, 100 kPa) for MIP-203 is up to 50.0. The mechanism for enhanced separation performance of C₃H₆/C₃H₈ on MIP-203 at higher temperature (303 K) was revealed by the in situ PXRD characterization. The adsorption selectivities of C₃H₆/C₃H₈ on MIP-202 and MIP-203 (298 K, 100 kPa) are 8.8 and 551.4, respectively. The mechanism for the preferential adsorption of C₃H₆ over C₃H₈ in MIP-202 and MIP-203 was revealed by the Monte Carlo simulation. The cost of organic ligands for MIP-202 and MIP-203 was lower than that of organic ligands for those top-performance MOFs. Our work sets a new benchmark for C₃H₆ sorbents with high adsorption selectivities.     

Silicone/non-silicone grafted blend composite membranes for air/vapor separation

Four types of new silicon-based graft blended polymers were developed and drawn to thin film composite membranes on high flux microporous polyetherimide support. The membranes and a 1 μm PDMS membrane as a standard were tested for the flux of the gases N₂, O₂, Ar, CH₄, CO₂, CH₃Cl, C₂H₅Cl, C₂H₆, and n-C₄H₁₀ and the vapors methanol (MeOH), t-butyl methyl ether (MTBE), 1, 1, 1-trichloroethane (Cl₃Eth), 1, 1, 2-trichlorofluoroethane (Cl₃F₃Eth), and n-hexane (n-C₆H₁₄). Methanol/argon mixtures were used to check the validity of the calculated selectivities. The results show higher performance for the newly developed membranes.