全氟己酮抑制航空煤油燃烧实验及化学动力学研究

为了研究全氟己酮对航空煤油燃烧的抑制作用,将杯式燃烧器的燃烧方式由液面燃烧改为灯芯燃烧,解决了气体灭火剂灭火性能测试中较高闪点燃料难以点燃的问题。通过实验可知,随着空气中全氟己酮浓度的增加,航空煤油的燃烧经历了火焰先缓慢增高再迅速降低的过程,可见全氟己酮在不同浓度下对燃烧的作用存在由促进到抑制的转变。为深入探索这一转变的原因,基于化学动力学构建了1403个组分、7496个反应组成的全氟己酮抑制RP-3航空煤油燃烧机理并进行了验证。通过化学动力学分析可知全氟己酮在低温下对燃烧的抑制比在高温下的效果更好,全氟己酮在低浓度时温度升高导致抑制作用减弱主要是源于温度升高后,促进燃烧的反应提速幅度远大于其他反应;全氟己酮降低RP-3航煤燃烧温度的途径之一是通过热分解等吸热反应来实现的;随着全氟己酮浓度的增大,反应路径发生变化,使得H、O和OH自由基的生成量减少、消耗量大量增多,宏观上体现出全氟己酮作为燃料的促进燃烧的作用减弱、作为灭火剂抑制燃烧的作用增强。研究结果可为利用全氟己酮防控航空煤油火灾提供理论指导,为研制新型灭火剂提供参考。     

全氟己酮灭火剂的应用及展望

全氟己酮灭火剂是一种新型、环保的灭火剂，在消防领域应用越来越广泛，成为消防工程的重要组成部分。本文将从全氟己酮灭火系统的概况、应用场景、技术特点、存在问题以及未来展望等方面对其进行阐述。概述了全氟己酮灭火系统的基本概况，包括其组成和工作原理等；介绍了全氟己酮灭火剂在不同场景中的应用情况；阐述了全氟己酮灭火剂的技术特点以及存在的问题；展望了全氟己酮灭火剂的未来发展趋势。     

全氟三乙胺热解机理的实验与理论研究

氟胺类物质是最有希望作为哈龙替代品的含氮化合物之一,全氟三乙胺作为典型的氟胺类物质具有良好的灭火效果。为研究全氟三乙胺热解机理,在管式加热炉内对全氟三乙胺进行热分解,通过GC-MS分析全氟三乙胺在不同温度条件下的热解产物,并用Gaussian软件对其热解反应路径进行理论计算。结果表明：保持停留时间为10 s,全氟三乙胺的初始热解温度为600℃,750℃完全热解,热解产物有C₄F₉N、C₃F₇N、C₂F₆和C₃F₈,热解温度较低时C₄F₉N体积分数最大,热解温度较高时C₃F₇N体积分数最大。在全氟三乙胺热解反应路径计算中,全氟三乙胺分子中的C—C键断裂后存在1条反应路径,可生成实验产物中的C₃F₈;全氟三乙胺分子的C—N键断裂后存在3条反应路径,可生成实验产物中的C₃F₇N、 C₄F₉N和C₂F₆。全氟三乙胺热解后产生的CF₃自由基可与H、OH自由基发生反应,从而产生灭火作用。此外,其热解产物C₄F₉N和C₃F₇N具有CN双键,更容易与燃烧活泼自由基·OH、·H发生化学作用,对研究全氟三乙胺的灭火机理具有十分重要的意义。     

全氟三乙胺热解机理的实验与理论研究

氟胺类物质是最有希望作为哈龙替代品的含氮化合物之一,全氟三乙胺作为典型的氟胺类物质具有良好的灭火效果。为研究全氟三乙胺热解机理,在管式加热炉内对全氟三乙胺进行热分解,通过GC-MS分析全氟三乙胺在不同温度条件下的热解产物,并用Gaussian软件对其热解反应路径进行理论计算。结果表明：保持停留时间为10 s,全氟三乙胺的初始热解温度为600℃,750℃完全热解,热解产物有C₄F₉N、C₃F₇N、C₂F₆和C₃F₈,热解温度较低时C₄F₉N体积分数最大,热解温度较高时C₃F₇N体积分数最大。在全氟三乙胺热解反应路径计算中,全氟三乙胺分子中的C—C键断裂后存在1条反应路径,可生成实验产物中的C₃F₈;全氟三乙胺分子的C—N键断裂后存在3条反应路径,可生成实验产物中的C₃F₇N、 C₄F₉N和C₂F₆。全氟三乙胺热解后产生的CF₃自由基可与H、OH自由基发生反应,从而产生灭火作用。此外,其热解产物C₄F₉N和C₃F₇N具有CN双键,更容易与燃烧活泼自由基·OH、·H发生化学作用,对研究全氟三乙胺的灭火机理具有十分重要的意义。     

对全氟壬烯氧基苯磺酸钠的合成与表面活性

以全氟壬烯、苯酚和氯磺酸为主要原料,经醚化、磺化和中和反应制备对全氟壬烯氧基苯磺酸表面活性剂,用红外光谱和19FNMR,1HNMR对分子结构进行了表征。研究了醚化反应投料方式对全氟壬烯基苯酚醚收率的影响,氯磺酸和全氟壬烯基苯酚醚的配比以及反应时间对磺化反应收率的影响。结果显示,向苯酚、三乙胺和二甲基甲酰胺(DMF)的混合物中滴加全氟壬烯,比向全氟壬烯、苯酚和二甲基甲酰胺的混合物中滴加三乙胺,醚化反应收率高17%。氯磺酸和全氟壬烯基苯酚醚的摩尔比为3∶1,40℃反应2h,磺化反应收率67.6%。表面活性的测定结果表明,对全氟壬烯氧基苯磺酸钠表面活性剂的临界胶束浓度为1.28×10-3mol/L,γcmc为19.23mN/m(20℃)。对全氟壬烯氧基苯磺酸钠表面活性剂性能优良。     

高效液相色谱法测定废水中的全氟辛酸含量

研究了高效液相色谱法检测工业废水中全氟辛酸含量的分析方法。采用kromasil(250 mm×4.6 mm×5μm)ODS C-18色谱柱,以乙腈与水的体积比50:50、加高氯酸(HClO4,质量分数1%)、三乙胺调pH=3.0为流动相,在该条件下可使试样中各组分完全分离,全氟辛酸的质量浓度在0.05～5 mg/L内线性良好(R=0.999 7、n=7、相对标准偏差1.60%),回收率在95.92%～105.2%。方法准确、快速、简便,可用于工业废水中全氟辛酸的检测。     

全氟代壬烯氧基苯磺酸钠的合成、表征与应用

以六氟丙烯三聚体和对羟基苯磺酸钠为主要原料,合成了对全氟壬烯氧基苯磺酸钠。考察了反应温度、催化剂和投料方式对对全氟壬烯氧基苯磺酸钠收率的影响。通过正交实验确定了最佳工艺条件:反应温度66℃、反应时间4 h、催化剂三乙胺,投料方式为待对羟基苯磺酸钠在N,N-二甲基甲酰胺(DMF)中完全溶解后加入催化剂,再滴加六氟丙烯三聚体,产物收率达80.15%。经FTIR和19FNMR确证了产物结构,TG测出它的热分解温度为350～360℃;表面活性测定结果表明,产物临界胶束浓度为9.26×10-4mol/L,γCMC为18.95 mN/m(20℃)。橡胶脱模应用实验发现,当脱模剂中对全氟壬烯氧基苯磺酸钠的质量分数为4%时,脱模次数达43次。     

河流水源水中全氟类化合物的深度处理效能研究

河流水源水中全氟类化合物是常见的污染物,为探究深度处理工艺对河流原水中全氟类化合物(PFCs)的去除效果,研究检测了自来水厂臭氧和生物活性炭组合深度处理对17种全氟类化合物的去除效率,分析了深度处理工艺调整对去除效果的影响。结果表明:河流原水中检出14种PFCs,ΣPFCs的浓度范围是19.35~57.57ng/L,夏季最高,冬季最低;其中全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)所占的比例较高,达到47.6%~57.9%;臭氧和生物活性炭联合深度处理工艺对PFCs的去除率达到37.3%,砂滤后置工艺比常规臭氧-生物活性炭工艺去除效果更好。     

全氟碳涂料树脂胶乳的制备研究

全氟辛酸和SOCl2经酰基化反应，得全氟辛酰氯(Ⅰ)，(Ⅰ)再与乙醇胺在30℃下反应3h得到N-羟乙基全氟辛酰胺(Ⅱ)，产品以三氯甲烷重结晶，然后以二月桂酸二丁基锡为催化剂，在无水无氧的条件下先与2，4-甲苯二异氰酸醇(TDI)于65℃～70℃反应3h，然后再与甲基丙烯酸-β-羟乙醇于75℃-80℃反应4h，得N-羟乙基全氟辛酰胺丙烯酸醇单体(Ⅲ)。以十二烷基二苯醚二磺酸钠和OP—lO为乳化剂，叔丁基过氧化氢为引发剂，水为介质，上述单体与其他醇类单体进行乳液聚合得到树脂胶乳，该胶乳性能稳定，具有优良的耐水、耐溶剂及耐碱性能等，可用来制备性能优良的全氟碳涂料。     

泡沫分离法回收废水中的全氟辛酸铵的研究

本文研究了用泡沫分离法回收废水中的全氟辛酸铵，通过实验研究了气体流量、进料液流量、进料液浓度、泡沫层高度和清液层高度之比、进料液的pH值等因素对废水中全氟辛酸铵脱除率的影响，得到了最佳的操作条件，为工业设计提供了有用的参考价值。     

Iminium cations as intermediates in the hydrodenitrogenation of alkylamines over sulfided NiMo/γ-Al2O3

The mechanism of the hydrodenitrogenation of the mixed dialkyl- and trialkylamines C₁NHC₆ and C₁N(C₆)₂ was studied over sulfided NiMo/γ-Al₂O₃ at 280 °C and 3 MPa. C₁NHC₆ reacted by disproportionation to C₁N(C₆)₂ as well as C₆N(C₁)₂ and by substitution by H₂S to methylamine and hexanethiol as well as hexylamine and methanethiol. C₁N(C₆)₂ reacted by substitution with H₂S to C₁NHC₆ and C₆NHC₆ and methane- and hexanethiol. The probability of breaking the C₁N bond was only slightly smaller than of breaking the C₆N bond in C₁N(C₆)₂. In the reaction of an equimolar mixture of C₅NHC₅ and C₁N(C₆)₂ both C₁N(C₅)₂ and C₆N(C₅)₂ were formed. The transfer of the methyl group in these reactions cannot be explained by imine and enamine intermediates, only iminium cation intermediates can explain all the products in the hydrodenitrogenation of monoalkyl-, dialkyl- and trialkylamines.     

Time resolved powder neutron diffraction investigations of reactions of solids with water

The reactions of brownmillerite (C₄AF) with D₂O as well as those of a mixture of C₁₂A₇ and CaSO₄. 2D₂O with D₂O were investigated by on-line powder neutron diffraction. The crystalline reaction products in the hydrolysis of C₄AF are Ca₃Al₂(OD)₁₂ with Ca(OD)₂. For the sulphate containing system a precursor phase was observed before the formation of deuterated ettringite, Ca₆Al₂(OD)₁₂(SO₄)₃. 26D₂O.     

Hydration reactions in pastes C3S+C3A+CaSO4.2aq+H2O at 25°C.I

A characteristic retardation of the hydration of C₃A is found in pastes C₃S+C₃A+CaSO₄.2aq+H₂O of weight ratios 1:3:z:4 at certain values of z, when sulphate concentration becomes insufficient for monosulphate formation. This retardation is ascribed to precipitation of amorphous Al(OH)₃, when C₃A dissolves in a limited amount of the aqueous phase shielded from the rest by C₄AH₁₃ or C₄AH₁₉. Evidence for the conversion of C₃AH₆ into C₄AH_n in supersaturated Ca(OH)₂ solution is found.     

Additive effects of trialkylaluminum on propene polymerization with (t-BuNSiMe2Flu)TiMe2-based catalysts

Propene polymerization was conducted by [η³:η¹-tert-butyl(dimethylfluorenylsilyl)amido]dimethyltitanium combined with B(C₆F₅)₃ or methylaluminoxane (MAO) as a cocatalyst in the presence or absence of various trialkylaluminums: Me₃Al, Et₃Al, ⁱBu₃Al (triisobutylaluminum) and Oct₃Al (trioctylaluminum). In the case of living polymerization with B(C₆F₅)₃ at −50°C, addition of Oct₃Al and Et₃Al increased the propagation rate. Et₃Al also acted as a chain transfer reagent and selectively gave Al-terminated polymers, while Oct₃Al induced chain transfer reaction only in high concentration. Little polymer was obtained in the presence of Me₃Al or ⁱBu₃Al. When MAO was used as a cocatalyst, polymerization did not proceed at −50°C. The MAO system, however, showed high activity at 40°C and selectively gave low molecular weight polymers terminated with Al–C bonds. Contrary to the low temperature polymerization with B(C₆F₅)₃ at −50°C, the polymer yield was enhanced by the addition of Me₃Al and ⁱBu₃Al, while the molecular weight was reduced by Me₃Al and enlarged by ⁱBu₃Al. On the other hand, Et₃Al and Oct₃Al significantly decreased both the polymer yield and the molecular weight under these conditions. It was found that additive effects of trialkylaluminums were strongly dependent on polymerization temperature as well as on the structure of the alkyl group.     

Phase transitions in R2 SnCl6-type crystals (R = NH3 C2H3, NH3C2H5 and N(CH3)4)

The thermal dilatation in (NH₃ ·CH₃) SnCl₆, (NH₃ · C₂H₅) SnCl₆ and [N(CH₃)] SnCl₆ was measured, and as the results it has turned out that (NH₃ ⁶·C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnCl₆ undergo the first order transitions at 128 K and 158 K, respectively. The low temperature phases of (NH · C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnC1₆ are found to be monoclinic and tetragonal, respectively, No phase transition was observed in (NH₃ ·CH₃)₂ SnCl₆ down to 77 K.     

高弹性自愈水凝胶(C3H5O)1CB[7]/PAA的制备及性能

用丙烯氧基七元瓜环（（C₃H₅O）₁CB[7]）替代传统的交联剂N,N-亚甲基双丙烯酰胺（BIS）制备了新型丙烯氧基七元瓜环/聚丙烯酸凝胶（（C₃H₅O）₁CB[7]/PAA gel）,该凝胶具有高弹性和自愈性。采用IR和¹H NMR技术对其结构进行表征,研究了该水凝胶的溶胀、力学性能,宏观观察了其自愈性能。结果表明：（C₃H₅O）₁CB[7]/PAA gel的网络形成作用力主要是多重氢键;在丙烯酸（AA）17.2%,水82.1%,（C₃H₅O）₁CB[7]0.33%,过硫酸钾（KPS）0.33%时该水凝胶具有良好的自愈性及力学性能,其最大伸长量为105.6 cm,为原长的86倍,弹性模量0.39 kPa,平衡溶胀率是600%。该水凝胶有望成为一种潜在的生物组织工程材料。     

Structural response of organically modified layered niobate K4Nb6O17 to the adsorption of 2,4-dichlorophenol

We investigated structural alteration of organically modified layered hexaniobate K₄Nb₆O₁₇ upon adsorption of 2,4-dichlorophenol. Two adsorbents examined were hexaniobate intercalated with dodecylammonium (C₁₂N) or dioctadecyldimethylammonium (2C₁₈2MeN) ions. The adsorbent modified with the C₁₂N ions was structurally durable for the adsorption of 2,4-dichlorophenol from 0.4 to 10 mmol dm⁻³ aqueous solutions. The adsorbate molecules were accommodated among the pre-intercalated C₁₂N moieties. In contrast, the adsorbent intercalated with the 2C₁₈2MeN ions suffered from structural collapse with the uptake of adsorbate molecules from relatively concentrated solutions (10 mmol dm⁻³), although this sample adsorbed larger amount of 2,4-dichlorophenol than the niobate modified with C₁₂N ions. X-ray diffraction and IR spectroscopy showed that the 2C₁₈2MeN ions were deintercalated with the adsorption. However, liquid chromatography and total organic carbon analysis indicated that the deintercalated organic moiety stayed on the external surface of niobate to form an effective adsorption site of 2,4-dichlorophenol. The “deintercalative adsorption” was ascribed based on UV spectroscopy to a specific interaction between the adsorbate and 2C₁₈2MeN molecules. Such drastic structural response had not been reported for other organically modified layered adsorbents.