煤制气再燃中NH2与NO反应的物化研究

对煤制气再燃低NOx燃烧过程进行分析,采用量子化学密度泛函理论(DFT)研究NH2自由基与NO的反应机理。全参数优化了各反应物、中间体、过渡态和产物的几何构型,并计算了它们的能量,通过振动频率分析证实中间体和过渡态的真实性。同时用内禀反应坐标(IRC)计算以进一步确定过渡态。为了得到更精确的能量信息,在QCISD(T)水平上计算了单点能。对NH2自由基与NO反应机理进行分析比较,并通过模拟NH2自由基与NO的反应,得出通道NH2+NO→IM1→TS1→IM3→N2+H2O的活化能最低(206.1kJ/mol),为最佳反应通道。揭示其微观机理,对进一步认识再燃脱氮的本质和主要过程提供了重要的理论依据和实践指导。     

对苯二甲酸与乙二醇反应机理的量子化学研究

用从头算理论的Hartree-Fock（HF）方法，在3～21g基组水平上研究了以盐酸为催化剂对苯二甲酸与乙二醇反应的微观机理，优化了反应物、中间体、过渡态和产物的几何构型，并分别计算了它们的能量。振动分析结果证实了中间体和过渡态的正确性，内禀反应坐标（IRC）计算结果进一步确认了反应路径。在3—21g基组水平上计算了它们的能量。反应机理研究结果显示，对苯二甲酸与乙二醇反应过程可分为以下步骤①1A＋HCl→TSl→M1＋CI^-②M1＋2B→TS2→M2→TS3→M3＋H2O③M3＋Cl^-→TS4→M＋HCl。反应活化能分别为0．85kJ／mol；105．91kJ／mol；202．64kJ／mol；85．91kJ／mol。通过比较各步反应的活化能可以看出，反应通道M2→TS3→M3＋H2O的活化能最高，因此对苯二甲酸与乙二醇反应的速率是由本控制步骤决定的，这与实验结果相吻合。     

烟气脱硫中CaS与SO_2的反应机理研究

为了研究固硫反应中Ca S与SO2的反应机理,采用密度泛函理论中的B3LYP方法,在6-311G++(d,p)水平上优化得到反应物、中间体、过渡态和产物的稳定构型和相应的能量值。结果表明:Ca S与SO2反应时,先络合生成具有链状的中间体IM1,随后经过S原子与O原子成键,生成过渡态TS;TS经过分子重排和能量重新排布生成中间体IM2、IM3、IM4,最后生成产物Ca SO4和硫单质;由中间体IM4到产物P1的过程能垒最大,说明该步骤是反应的速率控制步骤。     

先驱体制备典型陶瓷(C,SiC和B_xC)的化学反应机理研究

以C3H6(丙烯)+H2,MTS+H2,CH4+BCl3+H2,C3H6(丙烯)+BCl3+H2为先驱体,采用量子力学结合统计热力学、变分过渡态理论和反应动力学等方法,研究制备典型陶瓷(C,SiC和BxC)的化学反应机理。重点阐述用精确量子化学方法获取可能中间体、过渡态的结构与热化学数据、用化学势极小原理确定复杂体系化学平衡规律,以及确定化学反应通道、最佳反应途径、速率常数和反应动力学规律等。为这些陶瓷材料应用于层状碳、抗氧化SiC以及自愈合BxC陶瓷的成分控制和工艺优化提供科学基础的同时,本文也指出理论方法中的不足和改进方向。     

固态制冷剂的性能研究

对单组分无机盐溶质NH4SCN,NH4Cl及混合组分无机盐溶质KNO3+NH4NO3、KNO3+NH4Cl、KNO3+NH4SCN、NH4Cl+NH4NO3分别与结晶水合物Na2CO3.10H2O混合的冷效应进行了实验研究,得出最佳混合比和最大制冷温差,并将制冷效果与无机盐溶质与水混合时的最佳制冷效果进行对比。     

添加硫酸铵的氢氧化物先驱体制备Y2O3纳米粉热分解动力学

采用TG-DSC分析方法,研究了添加硫酸铵分散剂的氢氧化物先驱体制备Y2O3纳米粉热分解反应动力学.分别用Flynn-Wall-Ozawa法和Satava-Sestak法处理了不同升温速率下的TG-DSC曲线,两种方法得到的热分解反应动力学参数非常接近.先驱体的热分解过程为:Y2(OH)5NO3·nH2O→Y2(OH)5NO3→Y2O2(OH)NO3→Y2O3→脱出吸附的SO2-4,计算所得的活化能分别为13.42、57.90、132.08和137.56kJ/mol,并推断了各阶段的反应动力学模型和最可机理函数.研究表明热分解各阶段分别符合Mampel Power法则,Avrami-Erofee方程,Avrami-Erofee方程和Mampel Power法则,相对应的机理为随机成核和随后生长.     

BAMO-GAP三嵌段共聚物的热分解动力学及反应机理

用热重-红外-质谱(TG-IR-MS)联用技术对三嵌段共聚物的热分解产物进行了表征,利用Ozawa公式和Kissinger公式研究了聚3,3-双叠氮甲基氧杂丁环/叠氮缩水甘油醚(PBAMO/GAP)三嵌段共聚物的热分解动力学,得到其分解活化能为148.40 kJ/mol,指前因子lnA=33.5s-1,通过Grane公式计算得反应级数n=1。最后,对不同产物的红外和质谱特征峰进行了归属,实验结果证明,PBAMO/GAP三嵌段共聚物的分解产物主要有CH4/CH3+、N2O、NO2、N3/HN3、HCN+、CHO+和NH2+,其主要分解机理与一般烷基化合物相同,主要过程为CH2-N3分解为氮宾,氮宾经重排生成亚胺,随后有NH3生成。但其分解过程中存在经过-CH2N3进一步分解得到N3和HN3的特殊过程。     

沉淀法制备纳米AlO3过程中亚稳态相变温度的研究

采用沉淀法以Al(NO3)3·9H2O和NH3·H2O为原料制备了Al(OH)3干凝胶,经过高温煅烧合成纳米级的α-Al2O3粉末,研究了不同的Al(OH)3干凝胶样品的TG/DTA变化和煅烧过程中亚稳态Al2O3的相变过程.试验证明,Al(OH)3干凝胶中NH4NO3和α-Al2O3籽晶的存在使θ→α成核势垒降低,从而使得相变温度也降低.NH4NO3的存在使θ-Al2O3→α-Al2O3的相变温度降低了40℃;NH4NO3和2wt%α-Al2O3籽晶的双重作用则使θ→α的相变温度约降低220℃.制备出的α-Al2O3粉末,粒径分布均匀,无明显团聚,近似六方球形,平均粒径为70nm.     

沉淀法制备纳米Al_2O_3过程中亚稳态相变温度的研究

采用沉淀法以Al(NO3)3.9H2O和NH3.H2O为原料制备了Al(OH)3干凝胶,经过高温煅烧合成纳米级的α-Al2O3粉末,研究了不同的Al(OH)3干凝胶样品的TG/DTA变化和煅烧过程中亚稳态Al2O3的相变过程。试验证明,Al(OH)3干凝胶中NH4NO3和α-Al2O3籽晶的存在使θ→α成核势垒降低,从而使得相变温度也降低。NH4NO3的存在使θ-Al2O3→α-Al2O3的相变温度降低了40℃;NH4NO3和2wt%α-Al2O3籽晶的双重作用则使θ→α的相变温度约降低220℃。制备出的α-Al2O3粉末,粒径分布均匀,无明显团聚,近似六方球形,平均粒径为70nm。     

Mg(BH4)2-NaNH2体系的加热放氢性能研究

采用机械球磨法制备了Mg(BH4)2-NaNH2复合储氢材料,研究了Mg(BH4)2和NaNH2之间的相互作用及其加热放氢性能。当物质的量比为1∶2时,Mg(BH4)2与NaNH2之间发生反应:Mg(BH4)2+2NaNH2→2NaBH4+Mg(NH2)2。当物质的量比为1∶1时,Mg(BH4)2与NaNH2之间发生反应:Mg(BH4)2+NaNH2→NaBH4+MgBNH6。加热到400℃,该样品分两步进行放氢反应,放氢峰温分别在190℃和369℃,可以放出4.7%(质量分数)氢气。第一步放氢反应为MgBNH6分解产生MgH2,即:MgBNH6→MgH2+BN+2H2。第二步放氢反应为MgH2的分解:MgH2→Mg+H2。     

汽车驾驶员反应特性与交通事故关系的分析研究

本文阐述了驾驶员反应特性的有关理论．作者采用反应时运动时测定仪对驾驶员的选择反应时间、动作时间、运动反应时等进行了抽样调查；运用统计学原理对其与交通事故的关系做了相关分析．从而探明了反应特性各项指标与交通事故的相关性．以及这些指标在各类驾驶员之间的差异性。     

气体同位素交换技术及其在冶金中的应用

气体同位素交换技术是研究气-固、气-液反应的有效工具。它利用气相质谱仪在线监测同位素交换反应过程中气体成分的变化,进而解析反应的动力学方程。气体同位素交换技术已经广泛应用于化学、生物、地质等领域的化学反应机理的研究。简要介绍气体同位素交换技术的原理,重点阐述其分类及动力学,并概述其在冶金领域中的研究进展。     

甲基苯基二氯硅烷与苯基三氯硅烷共水解缩聚研究

研究了甲基苯基二氯硅烷与苯基三氯硅烷的共水解缩合反应,探讨了甲基苯基二氯硅烷含量、反应温度、水的用量及反应时间对水解缩聚反应的影响,确定了最佳工艺.采用红外、核磁等手段对水解缩聚产物进行了结构表征.     

Rational Construction of Hollow Core‐Branch CoSe2 Nanoarrays for High‐Performance Asymmetric Supercapacitor and Efficient Oxygen Evolution

Metal selenides have great potential for electrochemical energy storage, but are relatively scarce investigated. Herein, a novel hollow core‐branch CoSe₂ nanoarray on carbon cloth is designed by a facile selenization reaction of predesigned CoO nanocones. And the electrochemical reaction mechanism of CoSe₂ in supercapacitor is studied in detail for the first time. Compared with CoO, the hollow core‐branch CoSe₂ has both larger specific surface area and higher electrical conductivity. When tested as a supercapacitor positive electrode, the CoSe₂ delivers a high specific capacitance of 759.5 F g^?1 at 1 mA cm^?2, which is much larger than that of CoO nanocones (319.5 F g^?1). In addition, the CoSe₂ electrode exhibits excellent cycling stability in that a capacitance retention of 94.5% can be maintained after 5000 charge–discharge cycles at 5 mA cm^?2. An asymmetric supercapacitor using the CoSe₂ as cathode and an N‐doped carbon nanowall as anode is further assembled, which show a high energy density of 32.2 Wh kg^?1 at a power density of 1914.7 W kg^?1, and maintains 24.9 Wh kg^?1 when power density increased to 7354.8 W kg^?1. Moreover, the CoSe₂ electrode also exhibits better oxygen evolution reaction activity than that of CoO.     

Development of a universal accelerated test for alkali-silica and alkali-carbonate reactivity of concrete aggregates

A universal accelerated test for both alkali-silica and alkali-carbonate reactivity was proposed based on extensive comparative studies on existed Accelerated Mortar Bar Test (AMBT), (e.g., ASTM C1260, CSA A23. 2–25A, RILEM TC191-ARP-AAR02) and Chinese accelerated procedures. A single size fraction of 2.5–5.0 mm aggregate particles is used in the test instead of five-graded requirements in the AMBT, and 0.15–0.80 mm fine particles for ASR, 5–10 mm particles for ACR in existed Chinese accelerated tests. Three short-fat bars, 40 × 40 × 160 mm, made at fixed cement-aggregate ratio of 1:1, and water-cement ratio of 0.33 are used and the length change of the bars is monitored till 28 days in 1 M NaOH solution at 80°C after being soaked in 80°C water for 24 h. Over 40 kinds of aggregates from various origins, which include both ASR and ACR aggregates and show a broad range of reactivity levels in the concrete prism test (CPT), were used to evaluate the reliability of the new test in this study. Experimental results indicate that, for ASR aggregates, the new test gives a better indication than the AMBT does of both the reactive/nonreactive characteristic and reactive levels of almost all tested aggregates based on an acceptance criteria of 0.093% at 14 days, although some very highly reactive aggregates show low expansions relative to the CPT. The “abnormal” low expansion of some highly reactive aggregate in the test is mainly due to the rapid formation and loss of fair amount of low viscosity ASR product into the soaking alkali solution. The results on some typical ACR aggregates usually undetected by the AMBT show that the new test gives the same outcome as using 5–10 mm particles in the Chinese Accelerated Concrete Microbar Test for ACR aggregates and is in agreement with the CPT, which suggests that it has good potentials to be used for ACR aggregate when an expansion criteria of 0.1% after 28 days is used.     

Boron nitride-based electrocatalysts for HER,OER, and ORR: A mini-review

A reliable and efficient solution to the current energy crisis and its associated environmental issues is provided by fuel cells, metal–air batteries and overall water splitting. The heart reactions for these technologies are oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Different supporters such as graphene, carbon nanotube, and graphitic carbon nitride have been used to avoid agglomeration of active materials and provide maximum active surface for these reactions. Among all the supporters, boron nitride (BN) gains extensive research attention due to its analogue with graphene and excellent stability with good oxidation and chemical inertness. In this mini-review, the well-known strategies (exfoliation, annealing, and CVD) used in the synthesis of BN with different morphologies for HER, OER and ORR applications have been briefly debated and summarized. The comparative analysis determines that the performance and stability of state-of-the-art electrocatalysts can be further boosted if they are deposited on BN. It is revealed that BN-based catalysts for HER, OER and ORR are rarely studied yet especially with non-noble transition metals, and this research direction should be studied deeply in future for practical applications.     

反应烧结碳化硅的研究与进展

反应烧结碳化硅以其适中的机械性能、抗氧化性能和相对较低的造价而日益受到重视.本文对反应烧结碳化硅的类型、当前研究热点及反应烧结机理进行了综合评述.     

歧化反应及置换反应制备Cu/纳米SiC复合粉体

为了实现Cu对纳米SiC的表面包覆改性,分别采用歧化反应和置换反应两种方法制备了Cu/纳米SiC复合粉体.利用扫描电子显微镜、透射电子显微镜和能谱仪研究了Cu/纳米SiC复合粉体的微观形貌、聚集状态、粒径以及Cu和纳米SiC的质量分数.实验结果表明:单个复合粒子的粒径约为100 nm;针对随机选择的两种方法制备的复合粉体的两个不同区域进行的分析表明,歧化反应条件下Cu的质量分数分别为37%和35%,成分均匀;置换反应条件下Cu的质量分数分别为79%和25%,成分差异大.歧化反应法比置换反应法的包覆效果好,实现了Cu对纳米SiC的均匀性包覆.     

氨基膦酸螯合纤维的制备及性能研究

氨基膦酸螯合纤维是以聚丙烯接枝苯乙烯氯甲基化纤维为原料,经过胺化反应和膦酸化反应后制得的。研究了胺化温度和胺化时间对纤维增重率的影响,运用正交实验优化了氨基膦酸纤维制备工艺。结果表明,氨基膦酸纤维对Cu2+的最大饱和螯合吸附容量为77.6mg/g,在相同质量浓度的Cu2+和Ni 2+的混合溶液中能把两种离子完全分开。运用元素分析(EA)、IR、SEM和TG等测试手段对自制纤维的性能进行了系统研究。