纳米金属粉对高氯酸铵热分解特性的影响

催化性能;纳米金属粉对高氯酸铵热分解特性的影响     

铝粉粒度对高氯酸铵热分解动力学的影响

采用热重-差示扫描量热(TG-DSC)联合技术研究了10.7 μm, 2.6 μm和40 nm铝粉对高氯酸铵(AP)热分解的影响. 结果表明, 铝粉的加入对AP的低温放热峰有抑制作用, 对高温放热分解反应有促进作用, 并且随铝含量的增加和铝粒径的减小这种作用更强烈. 采用多元非线性拟合技术对不同升温速率下TG-DSC实验数据进行拟合, 结果表明, 质量分数为40%的不同粒径铝粉的加入对AP的热分解三阶段(A→B→C→D)反应模型无影响, 但反应机理函数发生了改变. 纯AP, AP/Al(10.7 μm), AP/Al(2.6 μm)及AP/Al(40 nm)的反应机理函数组合分别为C1/D1/D1, C1/D1/D3, C1/D1/D4和C1/D1/F2.     

纳米铜粉对高氯酸铵热分解的影响

The decomposition behaviour of ammonium perchlorate (AP) has been investigated in the presence of Cu nanopowder by DTA. The results show that nanometer Cu powder decreased the first and second thermal decomposition temperature of AP by 35.1 ℃ and 130.2 ℃, respectively, and the DTA heat release of AP in the presence of Cu nanopowders increased to 1.20 kJ·g^-1, showing good catalytic effect on the thermal decomposition of AP. The catalytic effect of Cu micron-size powder on the thermal decomposition of AP was less than that of Cu nanopowder. With the increase in content, Cu nanopowder enhanced its catalytic effect on the high temperature decomposition of AP, however, it weakened its catalytic effect on the low temperature decomposition of AP. The mechanism of catalysis for the thermal decomposition of AP is as follows: (1) metal oxider acts as the intermedium in the process of election tranfer, (2) Cu nanopowder reacts with the decomposed product of AP, (3) Cu nanopowder has special surface effect.     

纳米Fe2O3的制备及其对高氯酸铵热分解的催化性能

 用两相体系方法制备了纳米Fe2O3，并用X射线衍射、红外光谱和粒度分析对其结构进行了表征．结果表明，当有机溶胶的pH＝6，油酸与Fe3＋的摩尔比为1∶3．5时，Fe（OH）3在油相中的萃取率可高达90％，将有机溶胶在120℃回流8h后可得到非晶态、窄粒度分布的纳米Fe2O3粒子，其粒径在12nm左右．分别采用恒容燃烧热和差热分析研究了纳米Fe2O3对高氯酸铵热分解的催化性能．结果表明，在模拟固体推进剂中分别加入4．7％微米Fe2O3和4．7％纳米Fe2O3后，恒容燃烧热分别提高了2350．84和5095．70J／g．在高氯酸铵中加入5％微米Fe2O3可使高氯酸铵两个放热峰的出现分别提前1．10和62．25℃，而加入5％纳米Fe2O3时分别提前61．89和118．82℃，这说明纳米Fe2O3的催化活性优于微米Fe2O3．     

纳米Cu2O的制备及其对高氯酸铵热分解的催化性能

 以Cu(NO3)2和NaOH为原料,以水合肼为还原剂,通过沉淀法在室温下制备了纳米Cu2O. 采用X射线衍射、透射电镜和X射线光电子能谱等手段对产物进行了表征,并用热分析法考察了不同形貌的纳米Cu2O对高氯酸铵热分解的催化作用. 结果表明,通过改变NaOH溶液的加入量可分别得到长针形和多边形的纳米Cu2O. 通过调节反应物浓度可以将纳米Cu2O粒径控制在19～68 nm. 不同形貌的纳米Cu2O均能强烈催化高氯酸铵的热分解,其中分散性良好的多边形纳米Cu2O的催化活性较高,添加2%的多边形纳米Cu2O可使高氯酸铵的高温分解温度降低103 ℃,分解放热量由590 J/g增至1350 J/g.     

纳米NdCoO3催化高氯酸铵热分解的DSC/TG-MS研究

采用微乳液法制备了立方晶系的NdCoO3纳米晶.利用DSC/TG-MS研究了NdCoO3对AP热分解的催化作用.结果表明,在NdCoO3的催化作用下,AP的热分解反应峰值温度下降了113℃,表观分解反应热从655 J·g-1增加到1 363 J·g-1,分解的气相产物主要有NH3,H2O,O2,HCl,N2O,NO,NO2和Cl2.在金属氧化物表面吸附生成超氧化离子(O2-)和氧离子(O-,O2-),这是加速AP分解反应的主要原因.加入NdCoO3催化AP热分解,由于对氨的氧化深度不同而导致分解放热量的增加.     

铜/纳米金刚石复合物的结构及其对高氯酸铵热分解的催化作用

Nano-Copper and Cu/UDD (ultradispersed diamond) nanocomposites were separately prepared by reduction of CuCl₂ aqueous solution and that doped with 0.7%(weight percent) of ultra-dispersed diamond. The as prepared nano-crystals were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance techniques (EPR). It was found that homogeneous nucleation dominated the aqueous reduction reaction at high concentration and the diameter of nano-copper decreased as the reaction time shortened, yet at lower concentration heterogeneous nucleation predominated and the doped UDD functioned as heterogeneous nucleation. Otherwise large number of free-radicals existed in the nano-composites. Both of nano-copper and Cu/UDD nanocomposites were strong catalysts for AP decomposition, with Cu/UDD being a more effective one. The higher decomposition temperature for AP was 119 ℃ lower than that without catalyst. And the exothermic quantity of decomposition was from 590 J·g^-1 to 1 400 J·g^-1 by mix 2% of the Cu/UDD nanocomposites.     

纳米Co-B非晶态合金对高氯酸铵分解的催化性能

 利用化学还原法制备了纳米 Co-B 非晶态合金,并用透射电镜、X射线衍射、差示扫描量热和N2吸附表面积测试等技术对样品进行了表征. 运用差热分析研究了纳米 Co-B 非晶态合金对高氯酸铵(AP)分解的催化性能. 结果表明,加入 Co-B 非晶态合金后AP的高低温放热峰相连,合并成一个高而大的放热峰,且峰温有很大程度的降低, 这说明纳米 Co-B 非晶态合金对AP热分解有很好的催化活性. 同时, Co-B 非晶态合金能使AP的表观分解热显著增大.     

多孔纳米CoFe2O4的制备及其对高氯酸铵的热分解催化性能

采用胶晶模板法制备出具有三维多孔结构的纳米CoFe₂O₄。利用X射线衍射仪(XRD)、傅里叶变换红外(FT-IR)光谱仪、扫描电镜(SEM)、透射电镜(TEM)和N₂吸附-脱附对样品的晶型和形貌结构等进行表征,采用差示扫描量热法(DSC)对比研究多孔纳米CoFe₂O₄和球形纳米CoFe₂O₄对高氯酸铵(AP)的热分解性能的影响,并考察这两种催化剂对AP催化热分解的动力学参数。结果显示,制备出的多孔纳米CoFe₂O₄样品具有典型的尖晶石结构,孔径约200 nm;比表面积明显高于40 nm球形CoFe₂O₄,达到55.646 m²·g^-1。DSC测试结果表明：多孔纳米CoFe₂O₄的加入促进了AP的热分解,最高使AP的高温分解峰温降低91.46℃,能量释放最高达1120.88 J·g^-1,是纯AP分解放热量的2.3倍;多孔纳米CoFe₂O₄具有较高的比表面积,能提高催化反应的接触面积,使AP的高温分解峰温度更低,反应活化能较小,从而表现出比球形纳米CoFe₂O₄更高的催化活性。此外,对多孔纳米CoFe₂O₄催化AP的热分解机理进行初步探索,纳米多孔催化剂对气态中间产物的作用促进了AP的热分解。     

增容剂对聚丙烯/粘土纳米复合材料热分解动力学的影响

采用三单体固相接枝聚丙烯作为增容剂制备了聚丙烯粘土纳米复合材料.通过XRD和TEM表征了其纳米结构.利用动态TGA方法研究了聚丙烯和纳米复合材料的热稳定性.分别采用Flynn Wall Ozawa和Kissinger法研究了聚丙烯及其纳米复合材料的热分解动力学.结果都表明,蒙脱土的加入明显提高了聚丙烯的起始热分解温度,纳米复合材料热失重10%时的温度比聚丙烯提高40K左右;纳米复合材料的热分解温度区间明显比聚丙烯的窄;纳米复合材料热分解表观活化能明显增大,与聚丙烯相比提高50%以上.     

Effects of Aluminum on Thermal Decomposition of Hexogen/Ammonium Perchlorate

Thermogravimetry-differential scanning calorimetry-mass spectrometry-Fourier transform infrared spectrometry（TG-DSC-MS-FTIR） simultaneous analysis was used to study the effects of 10.7 μm and 40 nm Al on the thermal decomposition of the Hexogen/ammonium perchlorate（RDX/AP,1/2,mass ratio） mixture.TG-DSC results show that there are two mass loss processes for the thermal decomposition of RDX/AP/Al.The first one is mainly ascribed to the thermal decomposition of RDX.The reaction rate of RDX/AP/10.7 μm Al is so fast that the apparent activation energy,calculated by model-free Friedman method,is negative,which is the same as that of RDX/AP.30％（mass fraction） 40 nm Al added in RDX/AP change the activation energy from negative to positive value.The second mass loss process of the RDX/AP/A1 mixture is ascribed to the thermal decomposition of AP.This process can be divided into three stages for RDX/AP with and without Al.The kinetics model is not changed in the presence of micro-sized Al,while it is changed from CnB/D1/D1 to CnB/D1/D4 after the addition of 40 nm Al to RDX/AP.The reaction rate constant of the first stage and the end temperature of the second stage decrease,while the end temperatures of the third stage increase in the presence of 40 nm Al.The MS-FTIR results show there is a competition between the formation reactions of HNCO,N2O and NO2 during the second mass loss process.     

Mg2NiH4对高氯酸铵热分解过程的影响

采用置换-扩散法制备了储氢材料Mg2NiH4, 用XRD, ICP和DSC-TG方法对其结构进行了表征. 用热分析法(DSC)研究了Mg2NiH4对高氯酸铵(AP)热分解过程的影响. 研究结果表明, Mg2NiH4对AP热分解过程有较大影响. Mg2NiH4可以显著促进AP的低温热分解过程, 降低高温热分解温度, 使DSC表观分解热明显增大. 随着加入量的增加, Mg2NiH4对AP热分解的催化促进作用增强, 当Mg2NiH4加入的质量分数为30％时, DSC表观分解热最大. 吸氢量越大, 储氢材料对AP的催化促进作用越强. Mg2NiH4催化促进AP分解过程的作用机理为: Mg2NiH4分解释放的H2及Mg和Ni与AP分解产物发生反应.     

干燥方式对高氯酸铵/石墨烯复合材料的结构和热分解行为的影响

通过溶胶-凝胶法制备了石墨烯水凝胶, 并将其与高氯酸铵(AP)复合, 然后分别采用自然干燥、冷冻干燥和超临界CO₂干燥三种干燥方式制备了AP/石墨烯复合材料, 并通过扫描电镜(SEM)、元素分析、X射线衍射(XRD)、差示扫描量热仪(DSC)和热重-红外联用技术(TG-FTIR)研究了不同干燥方式对其结构和热分解行为的影响. 结果表明, 干燥方式对AP/石墨烯复合材料的形貌具有明显影响, 其中通过超临界CO₂干燥制备的AP/石墨烯复合材料基本能保持与石墨烯气凝胶相似的外观和多孔结构. 通过自然干燥、冷冻干燥和超临界CO₂干燥制备的AP/石墨烯复合材料中AP的质量分数分别为89.97%、92.41%和94.40%, 其中通过超临界CO₂干燥制备的复合材料中AP的粒径尺寸为69 nm. DSC测试结果表明, 石墨烯对AP的热分解过程具有明显的促进作用, 能使AP的低温分解过程大大减弱, 高温分解峰温明显降低. 三种干燥方式相比, 通过超临界CO₂干燥制备的AP/石墨烯复合材料中石墨烯的促进作用最明显. 与纯AP相比, 其高温分解峰温降低了83.7℃, 表观分解热提高到2110 J·g^-1. TG-FTIR分析结果表明, AP/石墨烯复合材料的热分解过程中, AP分解产生的氧化性产物与石墨烯发生了氧化反应, 生成了CO₂.     

双核茂铁四氮唑的合成及对高氯酸铵热分解的催化作用

首先以二茂铁为原料合成丙基桥联的双聚二茂铁(DFP), 经甲酰化得到丙基桥联的双聚二茂铁甲醛(DFP-CHO, 1), 再与NH₂OH·5HCl进行缩合反应得到双核二茂铁肟(2), 然后脱水得到丙基桥联双聚二茂铁甲腈(3), 最后在(n-C₄H₉)₃SnCl 的催化作用下与NaN₃进行[2+3]环加成反应, 生成目标产物丙基桥联双聚二茂铁四唑(4); 通过¹H NMR, FTIR和ESI-MS对目标产物的结构进行了表征. 利用差示扫描量热分析(DSC)和热重(TG)分析研究了这2个双聚二茂铁氮杂衍生物的燃速催化性能, 结果表明, 通过添加质量分数为5%的丙基桥联双聚二茂铁氮杂化合物3和4均使高氯酸铵(AP)的热分解温度降至100℃左右.     

溶剂热合成Cu2O微球及其对高氯酸铵热分解的催化作用

以聚乙烯吡咯烷酮(PVP)为添加剂,利用溶剂热法合成了Cu2O微球.考察了PVP用量以及反应温度对产物形貌的影响,并在反应时间为2.5与4.5h时分别合成了直径为100-200nm和1μm的Cu2O微球.同时,利用差热分析(DTA)技术考察了不同直径的Cu2O微球对高氯酸铵(AP)热分解的催化效果,结果表明:添加2%(w)的直径为100-200nm和1μm的Cu2O微球使得AP的高温分解温度分别降低了116和118°C,AP在低温阶段的分解量也明显提高.     

A Comparison of Catalytic Effect of Nano‐Mn3O4 derived from MnC2O4.2H2O and Mn(acac)3 on Thermal Decomposition of Ammonium Perchlorate

The formation and catalytic effect of Mn₃O₄ spinel nanoparticles on thermal decomposition of ammonium perchlorate (AP) were investigated and compared to two manganese precursors of MnC₂O₄ · 2H₂O and Mn(acac)₃. The catalytic effects of two coated precursors on AP thermal decomposition were measured by differential scanning calorimetric (DSC) and thermogravimetric analysis (TG). The MnC₂O₄ · 2H₂O@AP composite showed a decrease in the decomposition temperature of AP from 428.35 to 310.93 °C in one step, whereas for the Mn(acac)₃@AP composite, the thermal decomposition was seen in two steps at 288.04 and 323.875 °C. The kinetic triplet of activation energy (E_a), frequency factor (log A) and model of mechanism function [f(α)] of thermal decomposition for pure ammonium perchlorate,MnC₂O₄ · 2H₂O@AP and Mn(acac)₃@AP were investigated via two model‐free (FWO, KAS and Starink) and model‐fitting (Starink) methods at different conversions of α (α = 0.05–0.95). Also, the thermodynamic parameters were obtained via activation energy and frequency factor for different concentrations of catalysts.     

钼酸铵热分解过程动力学研究

有关多相钥酸钦在加热过程中的热分解行为，我们已用热重、差热及高温X一射线衍射等测试方法进行了系统研究以．如物相！fi．rsro为例4．50％（质量分数，下同）（NH4kM070。。·4H。0＋44．85％（NH小M05017＋50．65％（（NH4）2M04013十几（NH4）2M04013）的用酸按混合物消记