Effect of pressures on decomposition reaction kinetics of double-base propellant catalyzed with cerium citrate

The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions. The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol⁻¹ under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction mechanism function under a pressure.     

Influence of the heating rate on the temperature profiles and on the conversion rate of powdery cellulose and pine sawdust

An experimental study of the thermal decomposition of powdered cellulose and pine sawdust has been performed. The influence of the heating rate on the temperature profiles in the sample and on the solid conversion rate has been studied. A mathematical model without adjustable parameters has been used to calculate the temperature at different points in the solid bed and the average total solid conversion. The experimental results have been compared with those calculated by the model. A good agreement has been obtained for sawdust. Some differences are observed for cellulose at high heating rates, and the influence of the thermal conductivity and the reaction heat on the results has been analysed.     

不同液化条件下生物质残渣的燃烧特性研究

对锯屑在不同液化条件（溶剂、气氛、温度、催化剂）下所得液化残渣在热天平上进行了燃烧特性研究,通过比较液化残渣燃烧的三个特征温度,着火点ti、燃烧峰温tp和燃烬温度tb,分析了液化条件对残渣燃烧特性的影响。同时通过热重曲线所得数据探讨了液化残渣燃烧过程的动力学,并计算了活化能和频率因子 。结果表明,不同溶剂下所得液化残渣的燃烧特性显著不同,以四氢萘为溶剂所得液化残渣具有较好的燃烧特性;不同气氛下所得残渣的燃烧特性没有明显的不同;350℃下所得液化残渣的燃烧特性要好于300℃下所得液化残渣的燃烧特性;由于催化剂的影响,加入1%Mo后降低了所得液化残渣的燃烧特性;液化残渣的燃烧反应符合两段一级反应动力学。     

温度对松木屑气化液体产物组成的影响

利用傅里叶变换红外光谱(FT-IR)和气质联用(GC/MS)技术,研究了松木屑在400~900℃气化液体产物的主要组成成分和液体产物主要化学组成的来源与转化随气化温度变化的规律。结果表明,松木屑低温气化液体产物主要为酮、呋喃和愈创木酚等含氧化合物。随气化温度升高,液体产物的组成发生显著变化,400~ 500℃主要发生愈创木酚向酚类化合物的转变,500~600℃主要发生酮、呋喃向酚类化合物的转变,600~700℃主要发生酚类向茚和PAHs (多环芳烃)的转变,700~900℃主要发生酚类化合物向PAHs的转变,900℃液体产物的组成为大分子量的PAHs。     

乙二醇醇解松木屑反应特征及机理分析

利用酸化的乙二醇作溶剂对松木屑进行醇解,探讨了温度和时间对醇解转化率的影响。利用热重分析、红外光谱分析、扫描电镜及X射线衍射考察了醇解残渣的性质。分别利用傅里叶变换红外光谱及色质联用分析了正己烷不溶物和可溶物中组分的分布及特征。结果表明,松木屑转化率在90 min、160℃达到最大值95.3%。松木屑中纤维素无定形区的组分和木质素发生了解离,醇解残渣的表面结构被破坏;正己烷不溶物是含有羟基、甲氧基及醚键等含氧官能团的化合物;正己烷可溶物主要由苯二甲酸酯、硬脂酸甲酯、2-甲基己酸丙酯、2-甲基丙酸、聚乙二醇及未反应的乙二醇组成。乙二醇与松木屑解离的羧酸发生酯化反应,对液相产物具有稳定作用,促进了松木屑的醇解反应;醇解过程中乙二醇自缩聚生成聚乙二醇,增大了乙二醇的消耗。     

Separation of cellulose/hemicellulose from lignin in white pine sawdust using boron trihalide reagents

A mild method for the separation of cellulose/hemicellulose from extractives free sawdust is described. Sequential treatments with an equimolar mixture of BCl₃ and BBr₃ remove polysaccharide components from a white pine sawdust sample. Spectroscopic analyses, including solution and solid-state NMR spectroscopy, confirm a reduction in the amount of aliphatic sugars in solid samples and show that extracted components consist only of polymeric sugars and are free of aromatics. Staining with fluorescent and colorimetric dyes confirm that the sawdust sample after boron trihalide treatment is primarily lignin, with no detectable polysaccharides.     

混合废塑料与煤共热解液体产物中氯的含量与赋存形态

采用离子色谱等方法测定了不同热解条件下液体产物（包括焦油和水）中氯的质量分数,讨论了影响煤与废塑料共热解过程中,热解温度、恒温时间、升温速率及气体流量等因素对液体产物中氯质量分数的影响。并通过红外光谱、离子色谱等手段分析了液体产物中氯的赋存形态。结果表明,煤热解过程中加入一定量的废塑料,并没有给焦油中带来大量的有机含氯化合物,但增加了焦油的产率,同时降低了水的产率。水中氯主要以无机盐（NH₄Cl）和有机胺类盐酸盐等含氯化合物的形式存在;焦油的红外光谱中没有明显的C-Cl吸收峰,说明焦油中有机氯的含量非常少。     

煤与混合废塑料共热解固体产物中氯的赋存形态及在燃烧时的释放特性

通过红外光谱、热重 质谱及燃烧 水解实验,研究了煤与废塑料共热解固体产物中氯的赋存形态及在燃烧过程中氯的释放特性。结果表明,温度低于600℃热解的半焦中存在有机氯化合物;600℃以上热解的半焦（或焦炭）中氯主要以无机盐类存在。燃烧过程中氯的释放率与燃烧温度,煤与废塑料共热解的温度以及共热解时废塑料的加入量有关。燃烧温度越高,氯的释放率越大,900℃燃烧时,氯的释放率都在94%以上;在同一温度燃烧时,热解温度越高,氯的释放率越低。400℃热解的半焦最高释放率达99.86%,而1000℃热解的焦炭的最高释放率为94.35%。     

Determination of dissolved sulphides in waste water samples by flow-through stripping chronopotentiometry with a macroporous mercury-film electrode

Sulphides in water samples were determined by stripping chronopotentiometry in a computer controlled flow system with a flow-through electrochemical cell. The working electrode was a porous glassy carbon electrode coated with Nafion and mercury. The sample was diluted with 0.1 mol L⁻¹ NaOH and analysed. Sulphides in the sample were collected in the porous electrode as mercury sulphide and then stripped by a current of −500 μA. The limit of detection was found to be 1.6 μg L⁻¹ and 0.5 μg L⁻¹ for 1 mL and 5 mL of preconcentrated sample, respectively. The linear range for 1 mL sample was found to be 5-400 μg L⁻¹. The repeatability and reproducibility was found to be 2.6% and 4.8%, respectively. The method was applied to analyses of waste water samples from a tannery.     

气相色谱直接进样法分析环己烷氧化废液中的有机酸

环己烷氧化废液经酸化、抽滤等预处理后 ,采用气相色谱直接进样法分离了样品中的 1 0种有机酸 ,并测定了其含量。测定废液中各有机酸的回收率在 95 %～ 1 0 5 %之间。气相色谱固定相为 5 %新戊二醇己二酸酯 +0 .2 %磷酸/1 0 1酸洗白色担体。     

Cl–改性对Ag/Al2O3催化剂结构及其催化C3H6-SCR和H2/C3H6-SCR反应性能的影响

以烯烃为还原剂的NOx选择性催化还原(HC-SCR)是重要的环境催化反应之一.Ag/Al2O3催化剂(SA)因在HC-SCR反应中表现高活性、高N2选择性及中等H2O和SO2耐受性等优点,而被广泛研究.SA催化剂中存在不同的Ag物种,包括孤立Ag+离子,带部分正电荷Agnδ+团簇和金属态Agn0团簇.文献研究结果表明,SA催化剂中Agnδ+团簇是催化HC-SCR反应的活性Ag物种,而Ag物种类型与Ag的负载量密切相关.因此文献中研究SA催化HC-SCR反应的结构-性能关系主要是通过改变Ag负载量来开展的,最优Ag负载量约为1％～2％.本文以Cl–改性的γ-Al2O3作为载体,采用传统的浸渍法制备了Ag/Al2O3-Cl催化剂(SA-Cl),通过XRD、TEM、H2-TPR、UV-Vis DRS以及XPS对催化剂进行了结构表征,并结合C3H6-SCR和H2/C3H6-SCR活性测试,建立催化剂结构-催化性能关系;同时利用原位傅里叶变换红外光谱(DRIFTS)和在线同步辐射单光子电离质谱(SVUV-PIMS)研究了SA催化HC-SCR的反应机理.结构表征结果表明,在SA催化剂中,Ag负载量的提高主要是增加了Agn0物种,而在SA-Cl催化剂中,Ag负载量的提高主要是增加了Agnδ+物种,因此Cl?改性能促进SA催化剂中Agnδ+物种的形成.活性测试结果表明,在相同Ag负载量下,SA-Cl催化剂表现出比SA催化剂更好的HC-SCR催化性能.Cl?改性对SA催化剂中Ag物种的调控作用和HC-SCR催化性能的促进作用随Ag负载量的增加变得更为明显.原位DRIFTS结果表明,γ-Al2O3载体(Al位点)是NO氧化形成硝酸盐物种的主要活性位点;Agnδ+物种催化丙烯适度氧化主要生成乙酸盐类物种,可以还原表面硝酸盐物种;而Agn0催化丙烯过度氧化主要生成羧酸盐类物种,进而生成CO2,不能还原表面硝酸盐物种.由此可见,Agnδ+是催化HC-SCR反应的活性Ag物种,而Agn0是催化烃类完全氧化反应的活性Ag物种;Cl–改性能有效促进Agnδ+的形成,进而提高HC-SCR催化反应活性.在线SVUV-PIMS结果检测到H2/C3H6-SCR反应中存在气态中间物种丙烯腈(CH2=CHCN).–CN和–NCO物种被认为是HC-SCR反应的关键中间物种,能够直接与气相NO+O2反应生成N2.因此,CH2=CHCN的存在说明HC-SCR反应涉及到气相反应机理.基于SA和SA-Cl催化剂,进一步研究了H2对C3H6-SCR低温活性的促进作用.结果表明,H2的促进作用是通过作用于Agnδ+物种,而不是通过Agn0物种来实现的;H2的引入有利于低温下强吸附硝酸盐物种的脱附或分解以及中间体向–NCO和–CN物种的转化,从而提高HC-SCR低温催化活性.综上,基于Cl–改性的Ag/Al2O3-Cl催化剂,本文成功证实了Agnδ+物种是催化HC-SCR反应的活性Ag物种,并结合原位DRIFTS在线SVUV-PIMS谱分别鉴定了催化反应表面中间物种和气相中间物种.这些结果加深了对SA催化HC-SCR反应构-效关系和反应机理的基础理解.     

Synthesis of an efficient bio-based plasticizer derived from waste cooking oil and its performance testing in PVC

In order to develop an efficient and sustainable plasticizer, the waste cooking oil and malic acid were used as the main raw materials in this study to synthesize a bio-based plasticizer (acetylated-fatty acid methyl ester-malic acid ester, AC-FAME-MAE) by environment-friendly methods, and the structure was characterized by FTIR and ¹H NMR. The properties of the poly (vinyl chloride) (PVC) with AC-FAME-MAE were tested and compared with those of the PVC plasticized with DOP (di-2-ethylhexyl phthalate) and EFAME (epoxy fatty acid methyl ester), respectively. The results of tensile test, TGA and leaching test showed that the mechanical properties, thermal stability and overall solvent resistance of PVC films with AC-FAME-MAE were significantly better than those of PVC films plasticized by DOP or EFAME. From the results of DMA, the plasticized efficiency of AC-FAME-MAE was as good as DOP. The application of AC-FAME-MAE has higher safety in the food industry based on the results of food simulation fluids experiment.     

Thermal Decomposition Behavior and Non-isothermal Decomposition Reaction of Copper（ll） Salt of 4-Hydroxy-3,5-dinitropyridine Oxide and Its Application in Solid Rocket Propellant

The thermal decomposition behavior and kinetic parameters of the exothermic decomposition reactions of the title compound in a temperature‐programmed mode have been investigated by means of DSC, TG‐DTG and lower rate Thermolysis/FTIR. The possible reaction mechanism was proposed. The critical temperature of thermal explosion was calculated. The influence of the title compound on the combustion characteristic of composite modified double base propellant containing RDX has been explored with the strand burner. The results show that the kinetic model function in differential form, apparent activation energy E_a and pre‐exponential factor A of the major exothermic decomposition reaction are 1‐a,207.98 kJ*mol^?1 and 10^15.64 s^?1, respectively. The critical temperature of thermal explosion of the compound is 312.87 C. The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as: dα/dT=10^16.42 (1–α)e‐2.502×10⁴/T As an auxiliary catalyst, the title compound can help the main catalyst lead salt of 4‐hydroxy‐3,5dinitropyridine oxide to enhance the burning rate and reduce the pressure exponent of RDX‐CMDB propellant.     

Concentration and purification of malate ion from a beverage industry waste water using electrodialysis with homopolar membranes

Recovery of l-malate from a by-product of fermentation industry was investigated in order to decrease its polluting content as well as to ensure a better valorisation. Environmental-friendly process could consist in a first homopolar electrodialysis step to purify and concentrate malate and a subsequent electrodialysis step involving bipolar membranes in order to recover malic acid. The feasibility of the first step was assessed. Purification experiments on a two-compartment pilot device operated batch-wise with different homopolar membranes showed that the non-ionised impurities (sugars, alcohols) were retained better than 96% in the diluate stream and that the colour of the purified stream changed from dark brown to very pale yellow. More than 84% malate could be recovered with current efficiencies better than 90%. An additional purification effect was observed with the retention of a part of citrate, calcium and magnesium ions. The best flux conditions observed (316 g h⁻¹ m⁻²) corresponded to the Neosepta CMX-Sb/AXE 01 arrangement. Moreover, membrane arrangement using a monoselective cation-exchange membrane (Neosepta CMX-S) proved very efficient in removing divalent cations from the purified stream. Concentration was undertaken through a series of ten consecutive batches, allowing a malate concentration of 130 g L⁻¹ (i.e. approximately 2 equiv. L⁻¹) to be reached which complies with criteria for a subsequent bipolar electrodialysis step. According to these results, it was shown that a malate concentration as high as 300 g L⁻¹ could be expected in industrial operating conditions.     

Kinetics and Mechanism of Catalytic Reduction of U(VI) with Hydrazine on Platinum Catalysts in Nitric Acid Media

The kinetics of U(IV) produced by hydrazine reduction of U(VI) with platinum as a catalyst in nitric acid media was studied to reveal the reaction mechanism and optimize the reaction process. Electron spin resonance (ESR) was used to determine the influence of nitric acid oxidation. The effects of nitric acid, hydrazine, U(VI) concentration, catalyst dosage and temperature on the reaction rate were also studied. In addition, the simulation of the reaction process was performed using density functional theory. The results show that the influence of oxidation on the main reaction is limited when the concentration of nitric acid is below 0.5 mol/L. The reaction kinetics equation below the concentration of 0.5 mol/L is found as: -dc(UO₂²⁺)/dt)=kc^0.5323(UO₂²⁺)c^0.2074(N₂H₅⁺)c^-0.2009(H⁺). When the temperature is 50 ℃, and the solid/liquid ratio r is 0.0667 g/mL, the reaction kinetics constant is k=0.00199 (mol/L)^0.4712/min. Between 20 ℃ and 80 ℃, the reaction rate gradually increases with the increase of temperature, and changes from chemically controlled to diffusion-controlled. The simulations of density functional theory give further insight into the influence of various factors on the reaction process, with which the reaction mechanisms are determined according to the reaction kinetics and the simulation results.     

Determination of sulphur in liquids obtained by thermal cracking of waste polymers and commercial fuels with different analytical methods

Low sulphur concentration in hydrocarbon products as fuels or lubricants is an important requirement for the high quality standards of refineries. A non-polarised energy dispersive X-ray fluorescence spectroscopy (EDXRFS) and sample combustion technique (ASTM D6428-99) was compared. A new application of energy dispersive X-ray spectrometry as analytical method for the determination of sulphur in fuels and fuel-like fractions was investigated. Low sulphur containing fuels and hydrocarbon mixtures obtained by thermal cracking of waste polymers were measured and the influence of C/H ratio on accuracy was studied. The concentration of sulphur in samples was measured with calibration graphs of different hydrocarbon matrices (commercial gasoline, diesel oil and white oil were used). Good correlation was observed between the different methods, but the correlation was depending on the characteristics of the matrices. Detection limits of 1.0 ppm, 1.1 ppm and 0.9 ppm were obtained for S in gasoline, diesel oil and white oil, respectively.     

高效液相色谱研究丝素亲核基团与一氯均三嗪型活性染料反应动力学

以异丙胺、对甲酚和甲醇分别模拟蚕丝丝素的氨基、酚羟基和醇羟基,应用高效液相色谱分析一氯均三嗪型活性染料与蚕丝丝素的不同亲核基团的反应速率.结果表明:在pH=8～10、70～95 ℃的条件下,染料的酚解总反应速率远大于染料的氨解总反应速率和醇解总反应速率.其中C.I.活性红24 和C.I.活性橙2在pH=9,95 ℃条件下的酚解总速率分别约为其氨解总反应速率的8.5倍和12.5倍,为其醇解总反应速率的23倍和50倍;该两染料的酚解效率分别为47.4和96.3,氨解效率分别为4.6和6.9,醇解效率仅为1左右.通过异丙胺-对甲酚-甲醇混合溶液(1∶ 10∶ 100,V/V)模拟蚕丝与染料的反应,研究一氯均三嗪型活性染料与丝素上亲核基团的反应选择性,推断出一氯均三嗪型活性染料染蚕丝的最适宜条件为pH=8～9,温度85 ℃左右.在此条件下,酚羟基在蚕丝的一氯均三嗪型活性染料染色中起主要作用,氨基起次要作用,而醇羟基的作用甚微.     

Ni-Catalyzed Cross Coupling of Aryl Grignard Reagents with Aryl Halides in a Nonpolar Solvent and an Efficient Synthesis of Biaryls Under Neat Conditions

This study details Ni-catalyzed cross coupling of aryl Grignard reagents with aryl halides in toluene, a nonpolar solvent with a high boiling point. The reaction was applied for the synthesis of various biaryls in good yields without the introduction of a large steric ligand. The Kumada-Tamao-Corriu(KTC) reaction in toluene was then successfully modified to proceed under neat conditions for the efficient syntheses of symmetrical biaryls, particularly in large-scale preparations. Unactivated aryl chlorides show higher reactivity than aryl bromides, particularly under neat conditions. Mechanistic investigations suggest a radical procedure for the catalytic cycle, and the origin of the radical intermediates being aryl halides.     

V2O5-WO3/TiO2-ZrO2脱硝催化剂中 ZrO2和 WO3的促进作用：催化性能、形态及反应机理

商业选择性催化还原(SCR)催化剂成分主要有 V2O5, WO3和 TiO2,但适用温度窗口较窄(300?400℃),使得实际操作过程中活性较低.目前,过渡金属广泛应用于催化剂制备中以提高其催化活性.相比于纯 TiO2和 ZrO2载体, TiO2-ZrO2具有较高的热稳定性以及较多的酸位,虽然有关 TiO2-ZrO2为载体的催化剂研究较多,但未与商业催化剂进行对比研究.而针对 NH3-SCR脱硝机理的实验研究也存在一些争议,主要原因归为以下两方面：(1)多数催化剂不同会直接导致催化剂的活性酸位不同;(2)不同 NH3-SCR脱硝催化剂的起活温度不同.同时, NH3和 NO在反应温度的吸附情况仍需要进一步研究.因此,有必要深入探究 NH3-SCR脱硝机理,以解决现行研究中存在的问题.本文首先采用共沉淀法制备摩尔比为1：1的 TiO2-ZrO2固溶体,并分步浸渍不同质量比的 WO3和1%V2O5,最终得到一系列1%V2O5-x%WO3/TiO2-ZrO2.然后通过 X射线衍射(XRD)和比表面积测试(BET)、程序升温还原(TPR)、原位漫反射红外光谱(in situ DRIFTS)研究了 WO3和 ZrO2对催化性能的影响以及 V2O5-WO3/TiO2-ZrO2催化剂的反应机理. N2物理吸附结果表明, WO3的添加使得催化剂孔结构的热稳定性有所提高,同时随着 WO3含量增加催化剂的比表面积逐渐减小,但仍高于 V2O5/TiO2-ZrO2催化剂; ZrO2对催化剂比表面积增大效果比较明显.结合 XRD结果表明, WO3能促进金属氧化物在载体上的分散;相比于 V2O5-WO3/TiO2催化剂, ZrO2有利于活性组分的分散负载.比较系列 V2O5-x%WO3/TiO2-ZrO2的氨吸附情况,发现 WO3的添加增加了 Br?nsted酸的稳定性,其中以9%WO3的效果最显著.催化剂氨吸附中间物种(–NH2)的发现,证实了 WO3添加促进了 NH3的活化,有利于脱硝反应的进行. SCR反应结果显示, V2O5-9%WO3/TiO2-ZrO2催化剂在300–450oC时 NOx转化效率最优,并发现 O2的存在促进了 NOx的转化.采用in situ DRIFTS研究了 V2O5-x%WO3/TiO2-ZrO2催化剂脱硝机理,300和350oC时 NH3, NO, NO + O2吸附情况表明,在真实的反应温度下,脱硝过程中的活性中心为 Lewis酸中心, Br?nsted酸中心的 NH4+极易从催化剂表面脱附,无法吸附在催化剂表面,且与 NH3相比, NO只能以 NO2的形式弱吸附在催化剂表面.因此,该催化剂遵循 Eley-Ridel脱硝机理.而 V2O5-9%WO3/TiO2-ZrO2催化剂具有相对较高的脱硝效率,因此用来着重研究 NH3-SCR机理.在 NH3吸附过程中, NH3(1204,1602,3156,3264,3347 cm?1)和活性中产物 NH2(1550 cm?1)在催化剂表面的吸附(恒温300oC)是稳定的;随后通入 NO + O2时, NH3吸附过程中的所有吸收峰(包括 NH2)均逐渐减小(NH3吸附态与 NO结合后分解为 N2和 H2O),同时出现 H2O的振动峰,这证明了 V2O5-x%WO3/TiO2-ZrO2催化剂的脱硝反应过程.各类气体吸附情况表明, NO在商业催化剂的吸附状态与 V2O5-x%WO3/TiO2-ZrO2催化剂相同;但 NH3吸附结果表明, Br?nsted酸中心和 Lewis酸中心都是催化剂的活性中心; NO + O2的通入使得催化剂表面的 NH3和 NH4+都逐渐消失.这两种催化剂脱硝反应过程差异主要在于催化剂表面活性中心的不同,导致了不同的 NOx脱除路径.通过in situ DRIFTS比较 O2的存在对脱硝反应产生的不同影响来确定 O2的作用.两类催化剂上 O2均参与了 H2O的形成,促进了催化反应的完成;当 O2不存在时, NO的还原受到了极大地抑制,同时也未出现 H2O;两者的脱硝效率大大降低. H2-TPR和 NH3-TPR结果进一步证实 O2的作用主要是氧化 NO及参与催化过程 H2O的形成.