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对在纤维素溶剂中具有广泛应用的N-甲基氧化吗啉(NMMO)热分解动力学进行研究。首先利用绝热加速量热仪(ARC)开展绝热分解实验,得到NMMO在绝热条件下的初始分解温度为119.87℃,通过动力学计算得到反应活化能为219.7 kJ·mol-1,为自分解一级反应。其次通过差示扫描量热仪(DSC)对NMMO进行非等温分解实验,并利用Friedman法、Flynn-Wall-Ozawa法和ASTM E698法3种动力学模型进行分解动力学计算。研究结果显示NMMO的初始分解温度为161.07~186.40℃,反应活化能分别为81~134、75.81~100.34和101.92 kJ·mol-1。最后利用风险矩阵法定量评估NMMO热分解危险等级为Ⅲ级。该研究结果为降低NMMO生产、储存和运输中发生分解反应的风险提供了理论依据。 相似文献
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采用热重分析法(DTA-TGA)研究了腐殖酸的热分解过程及其动力学,分析其DTA-TGA曲线可得:热分解反应发生在284.65~417.16℃;用红外光谱(FT-IR)、核磁氢谱(1H NMR)、核磁碳谱(13C NMR)对腐殖酸结构进行表征,用Flynn-Wall-Ozawa(F-W-O)法、Kissinger法及?atava-?esták法计算出腐殖酸热分解反应的表观活化能为210.83 kJ·mol-1,指前因子对数为17.55;确定了其热分解反应的级数和动力学参数,且热分解反应机理为二级反应;腐殖酸在氮气氛围下维持1min寿命的最高使用温度为278℃;同时,计算出腐殖酸样品热力学参数焓变、熵变及摩尔自由能变分别为67.99 kJ·mol-1、-164.83 J·(mol·K)-1和176.36 kJ·mol-1。 相似文献
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采用热重分析法(DTA-TGA)研究了腐殖酸的热分解过程及其动力学,分析其DTA-TGA曲线可得:热分解反应发生在284.65~417.16℃; 用红外光谱(FT-IR)、核磁氢谱(1H NMR)、核磁碳谱(13C NMR)对腐殖酸结构进行表征,用Flynn-Wall-Ozawa(F-W-O)法、Kissinger法及Šatava-Šesták法计算出腐殖酸热分解反应的表观活化能为210.83 kJ·mol-1,指前因子对数为17.55;确定了其热分解反应的级数和动力学参数,且热分解反应机理为二级反应;腐殖酸在氮气氛围下维持1min寿命的最高使用温度为278℃;同时,计算出腐殖酸样品热力学参数焓变、熵变及摩尔自由能变分别为67.99 kJ·mol-1、-164.83 J·(mol·K)-1 和176.36 kJ·mol-1。 相似文献
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双季戊四醇合成工艺研究进展 总被引:4,自引:0,他引:4
介绍了双季戊四醇(双季)合成工艺的研究现状。阐述了由单季戊四醇(单季)生产中副产双季,以单季为原料在酸催化下分子间脱水、或基于与尿素/碳酰胺反应、或经过单季偏酯、或采用3,3-二羟甲基氧杂环丁烷和赤藓(糖)醇为起始原料制取双季的工艺过程及新技术,指出在生产单季中副产双季是双季的主要获取途径,提高副产双季的收率及单、双季分离条件是今后的主要研究方向。 相似文献
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研究了一种改进的双季戊四醇重结晶工艺,使双季戊四醇的灰份从0.1%以上降至0.05%以下,纯度从80%提高到85%以上,收率比传统重结晶工艺提高10%左右,且成本下降,操作更简便。实验确定的优化工艺条件为:溶解水量1:5~6、溶解水温度60℃、结晶冷却时间6~8h、离心分离温度20℃。 相似文献
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CraigM. Tarver TriD. Tran RichardE. Whipple 《Propellants, Explosives, Pyrotechnics》2003,28(4):189-193
A chemical kinetic model for the thermal decomposition of the solid high explosive pentaerythritol tetranitrate (PETN) is developed for prediction of times to thermal explosion using the Chemical TOPAZ heat transfer computer code. The model is based on times to thermal explosion measured in a new One Dimensional Time to Explosion (ODTX) apparatus. ODTX experiments are reported for pure PETN and for Semtex 1A. The pure PETN results are accurately modeled using a four reaction decomposition process in which an autocatalytic process produces intermediate reaction product gases, which subsequently react in a second order gas phase process to produce the final reaction products. Semtex 1A exhibits longer times to explosion than PETN at low temperatures, indicating that its endothermic binder decomposition absorbs heat produced by PETN decomposition. This binder reaction is modeled as a first order endothermic process. Three experiments on 5.08 cm diameter unconfined cylinders of PETN ramp heated to explosion at different rates are reported. The PETN model accurately predicts the thermocouple records and explosion times for these unconfined experiments in which only intermediate gaseous products can form. 相似文献
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The crystal structures of two potentially useful cyanonitramines are reported. Bis(cyanomethyl)nitramine (BCMN), (NCCH2)2NNO2: monoclinic, C2, a = 10.247(1), b = 7.771(1), c = 12.230(2) [Å], β = 107.45 (2)°, Z = 6, Dcalc = 1.502 g.cm−3, RF = 2.8%, RwF = 3.1%. A syn (C2) and anti (Cs) isomers of BCMN crystallize together in a 2:1 ratio in the unit cell. Bis(cyanoethyl)nitramine (BCEN), (NCCH2CH2)NNO2: monoclinic, P21/c, a = 7.512(2), b = 10.840(3), c = 10.181(3) [Å], β = 97.39(2)°, Z = 4, Dcale = 1.357 g.cm−3, RF = 4.6%, RwF = 4.7%. Only one conformation of the BCEN molecule having no symmetry is present in the unit cell. The IR spectrum shows that BCEN forms an amorphous phase when the melt is cooled or when an acetone or acetonitrile solution is rapidly evaporated. The amorphous phase slowly crystallizes at room temperature. High-rate thermolysis of BCMN liberates NO2 as the predominant initial product. This difference is qualitatively predictable on the basis of the variation in the N-N bond distance in these two compounds. 相似文献
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Hiroshi Yamawaki Hiroshi Fujihisa Kunihiko Wakabayashi Kazumasa Honda Yoshito Gotoh 《Propellants, Explosives, Pyrotechnics》2013,38(3):394-398
The decomposition reaction of pentaerythritol tetranitrate (PETN), C(CH2ONO2)4, under static high pressure was examined by conducting observations and infrared measurements up to 5 GPa at around 500 K. The thermal decomposition of PETN proceeded rapidly at around 500 K and formed a fluid consisting of N2O, CO2, and H2O. The rate of the decomposition reaction at 423 K increased as the pressure increased, indicating a negative activation volume. The initial step of the decomposition reaction of PETN under static pressure was presumed to be the elimination of HNO3. 相似文献
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用热分析法研究了阻燃剂聚丙烯酸五溴苄基酯在空气和氮气气氛中的热分解动力学。该阻燃剂在空气气氛中为两步分解,在氮气气氛中为一步分解,利用Friedman法求出聚丙烯五溴苄基酯的第一步分解反应的活化能变化趋势,同时利用Satava-Sestak法研究了其热分解机理。结果表明,在0.10至0.90的转化率范围内,聚丙烯酸五溴苄基酯在空气气氛下的活化能为167.35kJ/mol,在氮气气氛下的活化能为171.94kJ/mol,热分解机理均为Avrami-Erofeev方程,随机成核和随后生长,反应级数分别为n=23和n=12。动力学方程分别为G(a)=[-ln(1-a)]23和G(a)=[-ln(1-a)]12。 相似文献
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亚磷酸酯类抗氧剂626的合成与表征 总被引:4,自引:0,他引:4
以季戊四醇、三氯化磷和2,4-二叔丁基苯酚为原料,在实验室合成了双(2,4-二叔丁基苯基)季戊四醇二亚磷酸酯。采用正交试验考察了反应温度、反应时间、催化剂及物料配比对产品收率的影响。试验结果表明,整个工艺过程适宜的工艺条件为:2,4-二叔丁基苯酚、三氯化磷和季戊四醇的摩尔比为2.00∶2.05∶1.00,催化剂B的用量为季戊四醇质量的2.2%,第一步反应温度为130℃,时间为2.5 h;第二步反应温度为120℃,时间3.0 h。产品元素分析及红外光谱与目的产物相一致。 相似文献
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WILLIAM D. CALLISTER JR. IVAN B. CUTLER RONALD S. GORDON 《Journal of the American Ceramic Society》1966,49(8):419-422
The decomposition of boehmite, or alpha alumina monohydrate, was studied in water vapor and nitrogen atmospheres between 430° and 500°C. Powder samples used consisted of agglomerates of very small boehmite crystallites. The rate of decomposition was determined with a transducer which measured the loss of sample weight due to the liberation of gaseous water. A linear rate law is obeyed by the decomposition of boehmite and, because of the characteristics of the fractional weight loss-time curve, an interface model was suggested as the mechanism of decomposition. The activation energy was 70 kcal/mole. The effect of water vapor on the rate of decomposition was investigated. A simple forward-back reaction mechanism did not satisfactorily explain the data. Two models, either of which could be valid, were proposed to describe the relation between decomposition rate and water vapor pressure: (1) An adsorption-desorption process of water on the boehmite was assumed, and (2) an intermediate species of Al2 O3 entering into the decomposition reaction was assumed. 相似文献
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氧氟沙星的热稳定性及其热分解动力学 总被引:4,自引:0,他引:4
测定了在氮气气氛中第三代氟喹诺酮类药物氧氟沙星(OFLX)的热稳定性。用差示扫描量热法(DSC)、热重法(TG)和微分热重法(DTG),研究了药物氧氟沙星的热分解动力学。计算了动力学参数E、n、A,并结合量子有机化学计算的键长、原子静电荷参数研究了热分解机理,推断了热分解机理及药品贮存期。用热分析研究固体药物的热分解过程方法简便,结果可行。 相似文献
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利用热重(TG)分析法,对不同粒度菱镁矿的热分解过程进行研究.根据Flynn-Wall-Ozawa法,拟合计算得到不同粒度菱镁矿热分解的活化能和指前因子.采用Thermo-kinetics软件对可能性最大的5种动力学机理函数进行拟合,根据相关系数最大的原则确定最佳分解机理.研究结果表明:菱镁矿热分解的活化能随菱镁矿粒度的增大而减小,当菱镁矿的粒度由小增大时,控制其热分解过程的机理由化学反应逐渐向颗粒内部的传热和CO2的扩散传质转变;其热分解过程的最可几机理函数为R3模型,即三级相边界扩散反应,函数方程为G(α)=1-(1-α)1/3. 相似文献