Effects of microreactor wall heat conduction on the reforming process of methane

In this paper, the effect of wall conduction of an autothermal tubular methane microreformer is investigated numerically. It is found that the axial wall conduction can strongly influence the performance of the microreactor and should not be neglected without a careful a priori investigation of its impact. By increasing the wall thermal conductivity, the maximum wall surface temperature is decreased. Due to the complex exothermic–endothermic nature of the chemistry of reforming, the axial variation of the wall temperature is not monotonic. Methane conversion and hydrogen yield are strongly dependent on the wall inner surface temperature, hence the heat conduction through the channel wall. The equivalence ratio and the wall thickness also significantly affect the reforming effectiveness and must be carefully considered in reactor optimization. Furthermore, it is found that exothermic oxidation reaction mechanisms, especially partial oxidation, are responsible for syngas (hydrogen and carbon monoxide) production near the inlet. Farther downstream, in the oxygen deficient region, endothermic steam reforming is the main hydrogen producing mechanism. By increasing the thermal conductivity, steam reforming becomes stronger and partial oxidation becomes weaker. For all investigated inlet conditions, the highest hydrogen yield is obtained for no or very low conductive walls.     

1-乙基-3-甲基咪唑四氟硼酸盐离子液体结构性质的模拟计算

离子液体以其独特的性质广受关注,被称为"绿色设计者溶剂",人们对其潜在的应用价值做了大量的研究.实验采用HyperChem软件构建了1-乙基-3-甲基咪唑四氟硼酸盐([EMIM][BF4])离子液体分子结构的3D模型,并用PM3法进行预优化,然后应用Gaussian 03w程序分别在RHF/6.31G(d)和BLYP/6-31G(d)计算水平上进行量子化学计算,并经振动频率和强度分析得到理论红外谱图.结果表明,[EMIM][BF4]离子液体的阴阳离子存在着氢键等弱相互作用.     

2-巯基苯并咪唑缓蚀剂对Q235钢的缓蚀性能研究

采用静态失重法研究了2-巯基苯并咪唑缓蚀剂在盐酸溶液中对Q235钢的缓蚀性能。结果表明,2-巯基苯并咪唑缓蚀剂具有良好的缓蚀性能,缓蚀效率可达94.0%以上;随温度的升高,缓蚀剂的缓蚀效率显著降低。为了进一步研究缓蚀剂的作用机理,运用量子化学方法计算了缓蚀剂的EHOMO、ELUMO、电荷分布、Fukui指数等表征分子活性的参数,结果显示,2-巯基苯并咪唑在水溶剂环境中以质子化形式存在,质子化后的分子具有更好的全局反应活性和局部反应活性,可在金属表面形成多中心的吸附,从而提高了缓蚀效率。     

几种常用捕收剂与红柱石作用机理的量子化学研究

运用量子化学中RHF（Hartree-Fock-Roothaan）方法,利用STO-3G基组,研究红柱石晶体中各离子电荷分布及4种捕收剂与红柱石作用的键级与能量变化。经对红柱石与捕收剂成键机理分析表明,十二烷基磺酸钠为化学吸附,十二胺为物理吸附,油酸钠和羟肟酸为物理吸附与化学吸附共存。4种捕收剂按捕收能力从强到弱的排序为：十二烷基磺酸钠〉十二胺〉羟肟酸〉油酸钠。该排序结果与浮选试验结果一致。     

4种喹诺酮类药物分子荧光光谱的量子化学研究

喹诺酮类药物是目前广泛用于治疗各种感染性疾病的化学合成药物。文章采用量子化学B3LYP方法,在6-31g基组水平下对4种喹诺酮类药物进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用CIS方法计算了4种化合物的荧光光谱,所得计算值与实验值基本相符。     

压水堆一回路系统水化学控制的探讨

通过对压水堆核电厂一回路系统主要材料和腐蚀类型的分析,结合一回路水化学特性,探讨压水堆普遍采用的水化学控制措施,如硼-锂协调pH控制、一回路冷却剂水质控制、堆芯外辐射场控制等,寻求优化一回路水化学控制方法,维护反应堆的安全运行,提高核电站的叮利用率.     

化工课程教学中渗透审美教育

为了提高化工课程教学中的审美教育成分,从化工课程教学的不同角度分析了蕴含于专业知识中的统一美、辩证美和对称美,这对于改变传统教育观念,重视培养理工科学生感知美、欣赏美、创造美的能力有重要作用。     

Soil effects due to sewage sludge application in agriculture

Field trials show that increased nutrients (mainly P) and heavy metals in soil due to agricultural use of sewage sludge have mainly to be expected when sludge is applied in too high amounts. The biological effects of heavy metals on plants are determined by their solubility which is increased by pH decrease and degradation of organic matter. Normally, it should be expected that the microbial activity in soil would increase with the application of organic matter in sewage sludge. But, also negative effects on the microflora by simultaneous enrichment of organic matter or inorganic and organic pollutants were found. The most important deleterious effects on soil microorganisms are the reduction in size of the total biomass, a reduced nitrogen fixing activity and changes in the composition of microbial populations of the soil. At what stage heavy metal toxicity to soil microorganisms or to microbial processes in soil is likely to become evident is unfortunately still uncertain. Again, the soluble fraction of heavy metals (also of organic pollutants) is a determing factor. To minimize the shown environmental risks an adequate sludge management is proposed.     

3-溴甲基-3-甲基氧杂环丁烷的合成

以2,2-二溴甲基丙醇（BBMP）为初始原料,通过与碱发生关环反应生成3-溴甲基-3-甲基氧杂环丁烷（BrMMO）。讨论了碱的种类和用量对BBMP关环产率的影响以及反应体系中碱的浓度、反应温度和反应时间对合成BrMMO产率的影响。通过实验确定的最佳工艺条件为：BBMP与NaOH摩尔比为1.0∶1.1,NaOH醇溶液的质量分数为12%,反应温度为78℃,反应时间为4h时,BrMMO产率为65%。最终产品经元素分析、IR和1HNMR检测确定为BrMMO。该试验工艺简单,原料易得,且溶剂便于回收、污染小。     

超细六硝基芪的热分解性能

为了解超细六硝基芪（HNS）的热分解性能，通过DSC—TG实验研究HNS—IV的热分解过程，用Kissinger法和Ozawa法计算了HNS-Ⅳ热分解反应动力学参数。结果表明，HNS-Ⅳ的热稳定性与HNS-Ⅱ相当。Kissinger法和Ozawa法得到的HNS-Ⅳ分解表观活化能分别为221．4kJ／mol和220．3kJ／mol，比静态气氛下HNS-Ⅱ热分解反应的表观活化能减小27kJ／mol。