活性炭深度脱灰的新方法

将活化后的活性炭置于密封的反应炉内,在高温还原气氛以及脱灰介质与催化剂的作用下,活性炭中的矿物质与脱灰介质发生反应,生成气态物排出炉外。利用该工艺可使活性炭的灰分降到１％～５％,脱灰率达８５％以上     

Mechanistic Study of Carbon Oxidation with NO2 and O2 in the Presence of a Ru/Na‐Y Catalyst

The oxidation of model soot by NO₂ and O₂ in the presence of a Ru/Na‐Y catalyst under conditions close to automotive exhaust gas after‐treatment systems is investigated. Isothermal oxidation experiments of a physical mixture of carbon black and catalyst were performed in a temperature range of 300–400 °C. A remarkable increase of the oxidation rate by NO₂ and O₂ in the presence of the Ru/Na‐Y catalyst was observed. An overall mechanism involving oxygen transfer from the Ru catalyst to the carbon surface leading to an increase of C(O) complexes is proposed. These C(O) complexes are destabilized in the presence of NO₂ increasing the carbon oxidation rate.     

超临界二氧化碳中的不饱和聚酯树脂固化反应

本文研究了超临界二氧化碳对不饱和聚酯树脂固化反应的影响。结果表明超临界二氧化碳能够使不饱和聚酯树脂体系的固体时间有明显的缩短,达到原来固体时间的53.8%。随着超临界二氧化碳的加入,双键反应率有明显降低,但是双键反应率并没有随着压力的升高继续减小。     

超临界条件下二氧化碳与甲醇直接合成碳酸二甲酯

二氧化碳与甲醇直接合成碳酸二甲酯是一条对化学工业和环境保护都具有吸引力的工艺路线。本文筛选了催化剂、测定了催化剂用量,粒度与反应条件对反应结果的影响,并定量研究了ｘｐ－Ｔ、ＴＤ－Ｐ的关系,反应中出现的临界反应现象,作出解释;并提出反应分三步进行,其中第二步为反应控制步骤,认为甲氧基镁为反应催化活性物质。     

二氧化铈硫化反应动力学

对二氧化铈的硫化反应动力学进行了系统研究，研究结果表明：二氧化铈的制备工艺对其硫化反应活性有明显影响，热解氢氧化物活性＞热解硝酸盐产物活性＞热解高氯酸盐产物活性＞热解草酸盐产物活性；硫化反应速率随时间的变化规律符合吸附－自催化机理；在硫化反应初期，二氧化硫浓度对反应速率的影响很大，而在硫化反应速率减缓区，则无明显影响；热解氢氧化物所得二氧化铈的硫化反应动力学方程为：Ｒ＝５７６．０．ｅｘｐ（－９０２９．０／Ｔ）．Ｃ０．３３６ｍｇ／（ｍｇ．ｍｉｎ）     

Rheological study of mixing in molten polymers: 2-mixing of reactive systems

Three reactive polymer systems have been examined with a new mixing device adapted on a classical rheometer in order to investigate reactive mixing situations encountered in polymer blends. After having characterized the bulk polymerization of ε-caprolactone (ε-CL), the polymerization of 40 wt% of ε-caprolactone into a copolymer of ethylene and vinyl acetate (EVA) was run into the rheo-mixer. The kinetics of the reaction in dispersed media was observed slightly different from that in bulk since the characteristic time of ε-caprolactone diffusion into EVA is much lower than its time of mixing. On the other hand, it was observed that the molecular weight distribution of the poly(ε-caprolactone) is broader in dispersed media (I_p=2.6) than in bulk (I_p=1.6). A broadening of the molecular weight distribution in dispersed media was pointed out due to the fact that ε-CL monomer is partitioned between the EVA and PCL phases leading to a non-homogeneous concentration of monomer in the reactive phase.The polycondensation of 40 wt% of a epoxy-amine system into a polystyrene matrix was also investigated and the morphology of the resulting material examined. A gradient of structure and conversion was detected in a blend obtained from the assembly of two initially non-reactive layers. The gradient reveals that the amine diffuses faster than the epoxy leading to non-stoichiometry of the reactive functions across the sample. When the blend was polymerized under shear, the kinetic of the reaction remained unchanged regardless the level of shear. However, the morphologies were significantly different, pointing out the importance of the coalescence and droplet deformation phenomena. Spherical droplets were observed at 0.15 s⁻¹, elongated droplets and fibers at 1.5 and 15 s⁻¹.     

Carbon fiber growth kinetics and thermodynamics using temperature controlled LCVD

The chemical kinetics of carbon fiber deposition using Laser Chemical Vapor Deposition (LCVD) was studied. Using methane as the precursor at a total pressure of 78.4 kPa, the activation energy was 176 kJ/mol and the order of the reaction was 3.47. Using propylene as the primary reagent at a total pressure of 21.3 kPa, the activation energy was 286 kJ/mol and the order of the reaction was 1.90. The values are based on measured temperatures ranging from 1720 to 2170 °C. The cause of volcano shaped deposits was also explored through experimentation and thermodynamic modeling, and found to be an etching reaction induced by the elevated temperatures at the center of the laser spot.     

预烧法制备ZrO2—SiO2—V2O5绿色颜料

利用预烧法制备出了主反射波长在535nm的ZrO2-SiO2-V2O5绿色颜料，并用XRD和UV－V光谱对样品进行了表征。结果显示硅酸锆是所制备颜料的主晶相，其结晶越完整，颜料的色度越好；V2O5是该颜料生成反应的矿化剂，其加入极大的降低了硅酸锆的生成温度，原因在于该反应进行的主要途径是液相反应。     

Carbon particle type characterization of the carbon behaviour impacting on a commercial-scale Sasol-Lurgi FBDB gasifier

Char-form analysis, whilst not yet an ISO standard, is a relatively common characterization method applied to pulverized coal samples used by power utilities globally. Fixed-bed gasification coal feeds differ from pulverized fuel combustion feeds by nature of the initial particle size (+6 mm, −75 mm). Hence it is unlikely that combustion char morphological characterization schemes can be directly applied to fixed-bed gasifier chars. In this study, a unique carbon particle type analysis was developed to characterize the physical (and inferred chemical) changes occurring in the particles during gasification based on coal petrography and combustion char morphology. A range of samples sequentially sampled from a quenched commercial-scale Sasol-Lurgi fixed-bed dry-bottom (FBDB) Gasifier were thus analysed.It was determined that maceral type (specifically vitrinite and inertinite) plays a pivotal role in the changes experienced by carbon particles when exposed to increasing temperature within the gasifier. Whole vitrinite particles and vitrinite bands within particles devolatilized first, followed at higher temperatures by reactive inertinite types. By the end of the pyrolysis zone, all the coal particles were converted to char, becoming consumed in the oxidation/combustion zone as the charge further descended within the gasifier.The carbon particle type results showed that both the porous and carbominerite char types follow similar burn-out profiles. These char types formed in the slower pyrolysis region within the pyrolysis zone, increasing to around 10% by volume within the reduction zone, where 53% carbon conversion occurred. Both of these char forms were consumed by the time the charge reached the ash-grate at the base of the reactor, and therefore did not contribute to the carbon loss in the ash discharge. It would appear as if the dense char and intermediate char types are responsible for the few percent carbon loss that is consistently obtained at the gasification operations.The carbon particle type analysis developed for coarse coal to the gasification process was shown to provide a significant insight into the behaviour of the carbon particles during gasification, both as a stand alone analysis and in conjunction with the other chemical and physical analyses performed on the fixed-bed gasifier samples.     

Kinetics for Preparation of K2Ti2O5 Using TiO2 Microparticles and Nanoparticles as Precursors☆

The formation mechanism of K2Ti2O5 was investigated with TiO2 microparticles and nanoparticles as precursors by the thermogravimetric (TG) technique. A method of direct multivariate non-linear regressi...     

Reaction mechanism in mechanochemical synthesis of Cu2-xSe

This paper investigates the reaction mechanism in mechanochemical synthesis of Cu_2-xSe by vibrational milling of (Cu+Se) powder mixture. The effects of milling time, milling mode, ball-to-powder weight ratio (BPWR), and Cu/Se molar ratio in the starting composition on the phase assemblage of the products are investigated. It is found that, the synthesis of Cu_2-xSe is improved by increasing milling time, BPWR, and Cu/Se ratio. For a fixed total milling time, continuous milling is better than intermittent milling to facilitate the formation of Cu_2-xSe. By continuous milling for 20?min with BPWR?=?6 and Cu/Se?=?2, almost single-phase β-Cu_2-xSe is produced except for minor un-reacted Cu. A diffusion-controlled reaction mechanism is proposed for the mechanochemical synthesis of Cu_2-xSe, where intermediate phases such as CuSe and Cu₃Se₂ with lower Cu/Se ratios are produced at first and then gradually converted into Cu_2-xSe with the diffusion of Cu atoms.     

Thermal analysis and characterization of 2-allylphenoxyorganocyclotriphosphazene copolymers

The radical copolymerizations of I (2-allylphenoxyorganocyclotriphosphazene) with chloride, phenoxy, 2,2,2-trifluoroethoxy side group reacting with II (styrene, methyl methacrylate and vinylbenzyl chloride) using AIBN, n-BuLi and ultraviolet as initiator were investigated. The type of the copolymerization, reaction time, temperature were evaluated to obtain the optimum reaction condition. The incorporation of organophosphazene units into an organic polymer backbone decreased the glass transition temperature and increased the thermal stability of the copolymers. The weight conversion and the molecular weight had a maximum value at reaction temperature of around 70 °C. The order for both weight conversion of the copolymerization and the thermal stability of phosphazene polymer with the co-monomer was VBC > STY > MMA, and with the side group Cl-> C₆H₅O-> CF₃CH₂O-. The phosphazene copolymer is of conductivity and crystallization.     

Carbon/carbon composites based on a polyimide matrix with coal tar pitch

Blending of coal tar pitch with a polyimide precursor based on acetyl derivatives of aromatic diamines during its synthesis leads to a homogeneous, highly thermostable matrix for carbon fibre reinforced composites. If the weight content of the pitch in the polyimide matrix does not exceed 40%, the mechanical properties (flexural strength, shear modulus and fracture toughness) of these composites are comparable to those of similar composites based on a pure polyimide matrix. Carbonisation and graphitisation of the composites with a properly blended matrix precursor leads to carbon fibre reinforced carbon composites with lower open porosity and higher density, elastic modulus and flexural strength than those of composites based on a pure polyimide matrix.     

SrBi2Ta2O9(SBT)铁电陶瓷的制备及性能

用固相反应法合成了SrBi2Ta2O9(简称SBT)粉体，通过冷等静压成型、无压烧结的方法，制备出SBT铁电陶瓷。采用XRD、SEM、EPMA研究了材料的物相和微观组织结构，用阻抗分析仪测试了材料的介电和铁电性能。     

Dynamic Model of the Homopolymerization of Propylene with the Me2Si(2-Me-Ind)2ZrCl Catalyst: The Effect of Reaction Variables

The effect of four variables—temperature, propylene pressure, Al/Zr ratio, and catalyst concentration—on catalyst productivity and molecular weight of the polymer synthesized with Me₂Si(2-Me-Ind)₂ZrCl₂ was studied. A mathematical model was developed based on the method of the moments that fit the experimental data. A special effect was seen with respect to the co-catalyst (MAO) on productivity, and therefore it was necessary to add deactivation-reactivation mechanisms associated with MAO to the model. With respect of the molecular weight of the polymer, a bimolecular transfer reaction associated with the active center was added to fit the experimentally observed data.     

A_2-B_4型超支化聚酯上活性端羧基与环氧氯丙烷的反应动力学

以季戊四醇和己二酸合成了具有活性端羧基的 A2 -B4型超支化聚酯 ,并进一步研究了该 A2 -B4型超支化聚酯活性端羧基与环氧氯丙烷的反应。讨论了浓度、温度以及搅拌速率对其反应动力学的影响。结果表明 ,该反应的动力学方程偏离了经典的一级方程。我们利用反常扩散控制理论对此结果进行了相应的微观解释 ,并给出了描述这一反应体系的唯象动力学方程。     

Pure perovskite BiFeO3–BaTiO3 ceramics prepared by reaction flash sintering of Bi2O3–Fe2O3–BaTiO3 mixed powders

In this work, the 0.67BiFeO₃-0.33BaTiO₃ ferroelectric ceramic was prepared by Reaction Flash Sintering (RFS). This preparation technique combines synthesis and sintering in a single Flash experiment. The starting oxides reacted during the flash to produce a stoichiometric well-sintered solid solution at a temperature of 858 °C by applying a modest field of 35 V cm⁻¹. The process takes place in a matter of seconds, which allows obtaining a pure perovskite structure without secondary phases. X-ray diffraction (XRD) results show the mixture of rhombohedral and pseudocubic phases expected for a composition that lies within a morphotropic phase boundary (MPB) region, since a significant splitting is observed in the reflections at 2θ values of 39° and 56.5°. The microstructure exhibit a peculiar bimodal grain size distribution that determines the electrical properties. As compared with previous results, flash-prepared 0.67BiFeO₃-0.33BaTiO₃ evidences smaller grain size, as well as slightly lower remanent polarization (P_r) and smaller coercive field (E_c) under similar electric fields. It is also demonstrated that the preparation by RFS provides benefits regarding electrical energy consumption.     

Ruthenium Supported on Nitrogen‐Doped Carbon Nanotubes for the Oxygen Reduction Reaction in Alkaline Media

Nitrogen‐doped carbon nanotubes (N‐CNTs) prepared via thermal chemical vapor deposition (CVD), were used to support ruthenium (Ru) nanoparticles made using a microwave assisted reduction technique. The amount of Ru deposited on N‐CNTs was varied between 0 and 10 wt.%. The activity of the prepared nanocatalysts toward the oxygen reduction reaction (ORR) was characterized using the rotating disk electrode and voltammetry techniques. The ORR activity was higher at lower concentrations of Ru on N‐CNTs. The four electron pathway of ORR is more favorable on 2Ru/N‐CNTs and 5Ru/N‐CNTs than 10Ru/N‐CNTs.     

反应烧结Al_2O_3-SiC制品的性能和结构研究

研究了SiC和添加剂对Al2 O3-SiC制品性能的影响。结果表明 :加入的SiC(10 %～ 15% )能在基质中形成紧密的网络结构 ;利用添加剂与碳素材料的反应 ,促进了制品的烧结 ,从而改善了制品的结构与强度。该结果为制取性能优良的烧成Al2 O3-SiC复合材料提供了依据     

Dynamic Model of the Copolymerization of Propylene and 1-Hexene with the Me2Si(2-Me-Ind)2ZrCl2 Catalytic System: Effect of 1-Hexene Concentration

The effect of the concentration of 1-hexene on catalytic productivity, copolymer molecular weight, and comonomer incorporation was studied and modeled for the synthesis of isotactic polypropylene copolymers by using the Me₂Si(2-Me-Ind)₂ZrCl₂/MAO catalytic system. The method of moments was employed to simulate the system and to quantify the corresponding catalytic behavior. An increase in the catalytic yield, associated with the “comonomer effect,” together with a decrease in the copolymer average molecular weight, was found when the comonomer concentration was increased. In the range studied, a linear relation between comonomer incorporation and its concentration in the reactor was found. All these behaviors were simulated with a good fit between experimental and predicted values. An important change appears at the highest comonomer concentration studied, associated with modifications in the catalytic behavior, and the model presented here aids in quantifying this performance.