修饰后的硼氢化钠在有机合成中的应用

综述了硼氢化钠以及硼氢化钠复合体系在烯烃和炔烃、羧酸、氨基酸、脂类、酰胺、硝基、醛和酮、叠氮化物、肟和肟醚类、烷基卤代物还原中的应用.     

碳酸二乙酯黏度和密度的实验测量及数据关联

采用振动弦黏度/密度计对碳酸二乙酯的黏度与密度进行了实验研究,测量的温度范围为263～363 K,压力范围为0.1～20 MPa。实验系统黏度和密度测量的不确定度分别为±2.0%和±0.2%。利用得到的实验数据,分别拟合了碳酸二乙酯黏度和密度方程。黏度实验数据与方程的平均绝对偏差为0.54%,最大绝对偏差为1.98%;密度实验数据与方程的平均绝对偏差为0.042%,最大绝对偏差为0.12%。最后将实验数据与文献数据进行了比较。为碳酸二乙酯作为替代燃料等研究提供了基础数据。     

分子动力学模拟预测天然气密度和黏度的可行性研究

天然气作为相对清洁、低碳的能源,在我国的一次能源消费占比持续增长,其物性的精准预测对天然气集输利用过程分析至关重要。通过收集文献中天然气在不同温度和压力下的物性实测数据,对比分析了分子动力学模拟和常用经验模型计算天然气密度和黏度的预测精度,明确了不同组成天然气适用的最佳物性预测模型。结果表明,分子动力学模拟在预测天然气黏度方面具有较强的适用性,尤其是在高温高压条件下,当温度为444.4 K时,平均相对误差小于5%;天然气密度则采用现有相对成熟的经验模型更合适,而采用分子动力学模拟方法的几种力场模型预测其精度均不高;天然气密度和黏度预测模型的预测精度,不仅受温度和压力范围的影响,还与天然气组成有关。     

NOX在氢氧化钠溶液中吸收速率的研究

通过实验对氮稀释气体中的NO_2/N_2O_4和NO/NO_2/N_2O_3在25℃时、在0.5M和1.0M氢氧化钠溶液中的吸收进行了动力学研究。当NO_2的浓度>2×10~(-7)mol/cm~8时,从排出的气流中观察到氧化氮的存在。故液体中的表面可能有酸膜存在。在此浓度下,NO_2的吸收速率与NO_2气体浓度的平方成正比。由此可以证实N_2O_4是主要的吸收和反应成份。生成的NO的三倍量与被吸收的NO_2的线性关系图表明,由N_2O_4水解生成的亚硝酸(HNO_2)实际上被分解成一氧化氮和硝酸。这是吸收器中存在酸性液膜表面层的有力证据。实验发现,N_2O_4一次不可逆水解的吸收速率常数H(KD)~(1/2)在25℃时为0.136m/s。这一数值远大于研究人员过去观察到的数值。在25℃的温度下,N_2O_3的一次不可逆溶解和水解的吸收速率常数H(KD)~(1/2)为2.71m/s,而Komiyama在1982年报告中给出的在15℃时的数值为2.55m/s。     

纳米二硫化钼对冷冻机油密度和黏度的影响

采用聚乙烯吡咯烷酮（PVP-K30）对纳米二硫化钼（MoS2）进行表面化学修饰,配制了分散稳定性良好的环烷基纳米冷冻机油。利用旋转式黏度计和密度仪对5种配比的纳米冷冻机油（二硫化钼质量分数为0.25%、0.5%、0.75%、1%、1.25%、1.5%）在不同温度（288~333K）下的密度和黏度进行了测试,并对其数据进行了拟合关联。实验结果表明：经PVP修饰的纳米MoS2在低浓度情况下在冷冻机油中分散稳定性能良好,且在质量分数之比为1∶1时达到最佳分散效果;纳米冷冻机油的黏度随MoS2和PVP质量分数的增加而下降,在温度较低时更为明显;纳米冷冻机油的密度测量值和计算值基本吻合,其密度黏度关联式的计算值与90%的实验数据吻合较好。该结果为纳米冷冻机油在传热、流动和摩擦领域的应用提供了重要的基础数据。     

丁二酸二乙酯与乙醇混合液密度和黏度的测定及关联

在常压下采用U形振动管密度计和乌氏黏度计分别测定了丁二酸二乙酯与乙醇的混合液在298.15～343.15K下的密度和黏度,并由密度数据和黏度数据分别计算出了不同温度和组成下的超额体积VE和超额黏度Δη;VE为正值,Δη为负值,同时分别将不同温度下的超额体积、超额黏度与组成的关系用Redlich-Kister方程进行了关联。     

振动丝法测定常压和加压下液体的黏度和密度

介绍了自行研制的高温高压振动丝黏度密度仪的构造和测定原理,并以正戊烷作为实验流体对仪器的可靠性和准确性进行了测试.测定了环己烷在323.15～413.15 K温度范围内、正辛烷在313.15～393.15 K温度范围内、苯在303.15～445.15 K温度范围内压力分别为常压和6.10 MPa、正庚烷和异辛烷在298.15～403.15 K温度范围内压力分别为常压和5.10 MPa下的黏度与密度,并分别对不同压力下的黏度、密度数据进行了关联.     

三聚氰酸在氢氧化钠溶液中催化水解反应特性

三聚氰酸水解是三聚氰胺废渣降解生成氨和二氧化碳的关键步骤。在一间歇水解反应器中系统地研究了溶液酸碱性、三聚氰酸初始浓度、反应温度、反应时间对三聚氰酸降解率的影响,由结果可知:硫酸对三聚氰酸的水解无明显催化作用,而氢氧化钠的催化作用明显,且溶液中氢氧化钠浓度越高,催化效果越明显。在实验范围内,较优的工艺条件为:反应体系氢氧化钠浓度为0.18 mol/L、温度170℃、反应时间50 min,此时三聚氰酸的降解率达到94.10%。氢氧化钠作用下的三聚氰酸水解动力学研究结果表明:反应对三聚氰酸浓度为1级,对OH-浓度为0.284级,反应的活化能为70.1 k J/mol,指前因子为1.98×107L0.284/(mol0.284·min)。     

氢氧化钠在环氧树脂生产中的应用

论述了氢氧化钠在环氧树脂生产中的应用及其质量、浓度、用量等因素对环氧树脂产品质量的影响。     

高黏度合成油在小黏度液压油中的应用

介绍以高黏度合成油替代传统黏度指数改进剂的改进方案,分析这两类黏度指数改进剂调和后产品的黏温特性、低温流动性、剪切安定性、热氧化安定性等关键性能,并进行抗氧剂的复配,筛选出符合协议标准的小黏度液压油方案,使其在减少设备磨损、提高设备使用寿命、延长换油周期以及节能环保方面发挥显著的作用.     

NaBH4溶液催化制氢的阴离子效应研究

研究了Cl-和NO3-阴离子对NaBH4溶液现场制氢反应的影响,发现在制氢反应过程中存在着生成金属硼化物和生成金属氢氧化物的竞争反应.当溶液中阴离子为Cl-时,金属离子在催化NaBH4溶液制氢反应时将与硼结合,促使其活化为高活性金属硼化物,能有效促进制氢反应;当溶液中的阴离子为NO3-时,将诱导金属离子生成没有催化活性的金属氢氧化物,抑制制氢反应.     

Direct rotating ring-disk measurement of the sodium borohydride diffusion coefficient in sodium hydroxide solutions

This paper presents the experimental determination of the diffusion coefficient of borohydride anion and solution kinematic viscosity for a large panel of NaOH + NaBH₄ electrolytic solutions relevant for use as anolyte in Direct Borohydride Fuel Cells (DBFC). The diffusion coefficients have been measured by the transit-time technique on gold rotating ring-disk electrodes, and verified using other classical techniques reported in the literature, namely the Levich method and Electrochemical Impedance Spectroscopy on a gold RDE, or chronoamperometry at a gold microdisk. The agreement between these methods is generally good. The diffusion coefficients measured from the RRDE technique are however ca. twice larger than those previously reported in the literature (e.g. ca. 3 × 10⁻⁵ cm² s⁻¹ in 1 M NaOH + 0.01 M NaBH₄ at 25 °C in the present study vs. ca. 1.6 × 10⁻⁵ cm² s⁻¹ in 1 M NaOH + 0.02 M NaBH₄ at 30 °C in the literature, as measured by chronoamperometry at a gold microsphere), which is thoroughly discussed. Our measurements using chronoamperometry at a gold microdisk showed that such technique can yield diffusion coefficient values below what expected. The origin of such finding is explained in the frame of the formation of both a film of boron-oxide(s) at the surface of the (static) gold microdisk and the generation of H₂ bubbles at the electrode surface (as a result of the heterogeneous hydrolysis at Au), which alter the access to the electrode surface and thus prevents efficient measurements. Such film formation and H₂ bubbles generation is not so much of an issue for rotating electrodes thanks to the convection of electrolyte which sweeps the electrode surface. In addition, should such film be present, the transit-time determination technique on a RRDE displays the advantage of not being very sensible to its presence: the parameter measured is the time taken by a perturbation generated the disk to reach the ring trough a distance several orders of magnitude bigger than the film thickness, thus minimizing its effect.     

Kinetics of sodium borohydride direct oxidation and oxygen reduction in sodium hydroxide electrolyte: Part II. O2 reduction

In order to mimic the operation of the air-cathode in a direct borohydride alkaline fuel cell, we studied the oxygen reduction reaction (ORR) in sodium hydroxide solution containing traces of borohydride. The activity of several ORR electrocatalysts, namely carbon-supported platinum, gold, silver and manganese oxide, has been investigated using slow-scan linear voltammetry. Whereas platinum is one of the best electrocatalyst in pure sodium hydroxide, none of the classical electrocatalysts: gold, silver and platinum, exhibit sufficient selectivity towards the ORR. When BH₄⁻ is present in solution, the potential taken by electrodes using such materials is a mixed potential, following the competition between the ORR and the NaBH₄ hydrolysis and/or oxidation. Conversely, manganese oxide-based electrocatalysts exhibit very interesting behaviour towards the ORR in alkaline medium; while their intrinsic ORR activity in pure sodium hydroxide is quite as good as that for platinum, they still display a remarkable selectivity for this reaction when the electrolyte contains traces of sodium borohydride.As a result, carbon-supported manganese oxide-based nanoparticles seem very interesting materials to be used in direct borohydride fuel cell.     

氢氧化钠溶液中氯酸钠含量测定方法探究

对GB/T11200.1-89与GB/T11200.1-2006测定氢氧化钠溶液中氯酸钠含量的方法进行了分析,对GB/T11200.1-89测定氢氧化钠溶液中氯酸钠含量分析方法进行了实验研究,并提出了修改建议。     

十二烷基硫酸钠对聚乙烯吡咯烷酮水溶液黏度特性的影响

利用乌氏黏度计在(30±0.05)℃条件下研究了不同聚乙烯吡咯烷酮(PVP)质量浓度与不同十二烷基硫酸钠(SDS)浓度组合的复合溶液的黏度,观察到PVP-SDS溶液黏度曲线上存在双临界浓度c1和c2,表明在c1和c2之间SDS以束缚胶束形式簇集在PVP高分子链上;研究了不同"比簇集量"的PVP-SDS团簇溶液的比浓黏度特性,发现比浓黏度随PVP质量浓度降低反而显著增大,偏离了单纯PVP溶液而与典型的聚电解质聚丙烯酸钠(Na PAA)溶液相似;计算了PVP-SDS团簇中高分子链的均方末端距r2及其与单纯PVP类比的链相对扩张量k值,发现随着比簇集量[Г]增加k值增大。根据实验结果,将上述现象解释为由于带电的SDS束缚胶束簇集在PVP高分子链上,产生了"聚电解质效应",从而导致高分子链扩张。     

用氢氧化钠溶液吸收硫化氢制取硫化钠工业技术

详细阐述了在氯化钡生产过程中,将产生的硫化氢用氢氧化钠溶液吸收并制取硫化钠的生产工艺,分别从技术和经济的角度讨论其可行性：用380~420 g/L氢氧化钠溶液在填料塔中吸收硫化氢,反应终点控制硫化钠质量浓度为330~350 g/L,硫化氢吸收率达95%~98%。该工艺不仅可有效保护环境,而且可为企业创造效益。     

硼氢化钠水解制氢技术研究进展

随着石化能源的日益枯竭,氢能成为解决当前能源危机的一种新能源。制氢的方式多种多样,由于金属氢化物在储氢容量上具有其他材料无法比拟的优势,因此,金属氢化物制氢技术得到了迅速发展。硼氢化钠就是一种典型的金属氢化物,硼氢化钠水解制氢技术作为一种安全、方便的新型制氢技术,已成为当前燃料电池氢源研究中的热点之一。介绍了硼氢化钠制氢原理;综述了硼氢化钠水解制氢技术的优点、影响产氢速率的因素;对硼氢化钠制氢技术的装置进行了举例说明;指出了目前此技术所存在的问题;概述了此技术的应用与发展前景。     

Kinetics of the dissolution of silica in aqueous sodium hydroxide solutions at high pressure and temperature

The kinetic of the reaction of sand with aqueous NaOH corresponding to the ratio SiO₂/Na₂O = 2 was studied in a pressure vessel at 220°C and 2.7 MPa. Since the kinetic curves could not be obtained directly from the experimental data, a new method is proposed to plot the entire kinetic graph from experimental data. An analytical expression of the type α = A [1 -exp(-Bt)] describes the system perfectly. The constants A and B were calculated for a silica sample having a narrow granulometric distribution (range i.e. 300–315 μm). The value of A is found to be almost constant, between 0.95 to 0.99 and B ranges from 0.03 to 0.14 when [OH-] increases from 0.5 to 12.5 mol/L. The kinetic order with respect to OH^? is equal to 0.470 + 0.013 and the kinetic constant at 220°C is 3.933 × 10^?6 g/m².s.     

Stability of PVDF hollow fibre membranes in sodium hydroxide aqueous solution

The stability of PVDF hollow fibre membranes in sodium hydroxide (NaOH) aqueous solutions were investigated in this study. PVDF hollow fibre membranes were prepared from each of the three commercial raw PVDF materials (Kynar 761, Solef 1015 and Solef 6010) from two major suppliers (Atofina Chemicals Inc., USA and Solvay, Belgium) for comparison purposes. The effect of NaOH concentration, treatment time and temperature on mechanical properties, thermal properties and crystalline structure of the PVDF hollow fibre membranes were investigated through mechanical strength measurement, surface area analysis, XRD, FTIR and DSC analyses. The obtained results indicate that the reaction between PVDF and NaOH was initiated even at low concentrations of NaOH and was aggravated with the extended treatment time, resulting in the decrease in mechanical strength and crystallinity of PVDF hollow fibre membranes. The reaction was accelerated and intensified by increasing the concentration of NaOH and/or treatment temperature. At 70 °C, the mechanical integrity of the PVDF membranes was completely destroyed in 4 wt% NaOH solution within 24 h or in 10 wt% NaOH solution within 8 h. The deterioration of stability in NaOH solutions is considered universal for all PVDF employed in this study, irrespective of the raw materials or the corresponding hollow fibre membranes.     

钴-硼/二氧化锆催化剂催化硼氢化钠水解制氢研究

采用浸渍负载-还原法制备了钴-硼/二氧化锆催化剂,研究了催化剂在催化硼氢化钠水解制氢中的性能。研究了催化剂的制备条件（钴与二氧化锆物质的量比、钴与硼氢化钠物质的量比）对其催化性能的影响,并考察了催化剂用量、反应温度、搅拌转速对硼氢化钠水解制氢的影响。结果表明,在钴与二氧化锆物质的量比为0.16:1、钴与硼氢化钠物质的量比为1:5条件下制备的钴-硼/二氧化锆催化剂催化硼氢化钠水解制氢的速率最快。硼氢化钠水解制氢速率随催化剂用量的增加和反应温度的升高而增大,随搅拌转速的增加呈现先增大后减小的趋势。反应动力学计算出钴-硼/二氧化锆催化剂催化硼氢化钠水解对硼氢化钠的浓度属于零级反应。钴-硼/二氧化锆催化剂的硼氢化钠水解反应活化能为43.97 kJ/mol。