ODA合成反应热风险分析研究

在我国发生的重大火灾、爆炸等事故中大部分是由化学物质引起,避免类似事故发生的首要解决办法是对热失控问题进行风险分析研究。所以在化工领域探究化学反应过程、物料运输及储存的必要性越来越高。通过反应过程热危险性分析的方法学出发,运用反应量热仪(RC1)和差热扫描量热仪(DSC)测试了4,4'-二辛基二苯胺(ODA)合成反应过程中的热力学、动力学数据,放热事件或吸热事件的起始温度及能量总量,从而评估分析了该反应过程中的风险。

自蔓延高温合成反应热喷涂Al_2O_3基复相陶瓷涂层的性能

为了改善AZ31B镁合金的耐磨性,以Al2O3-13% TiO2为陶瓷骨料,在其中加入Al/CuO铝热剂,采用普通氧乙炔火焰自蔓延高温合成反应热喷涂技术在镁合金表面制备Al2O3基复相陶瓷涂层。通过X射线衍射分析了陶瓷涂层的组成。结果表明,所得复相陶瓷涂层具有良好的抗热震性,涂层内有Cu4MgO5,CuAlO2等新的物相产生。磨粒磨损试验、黏着干磨损试验和黏着油磨损试验表明:自蔓延反应热喷涂陶瓷涂层的耐磨性是AZ31B基体的6.48,3.32,6.04倍,普通热喷涂层的耐磨性是AZ31B基体的3.60,1.76,1.67倍,自蔓延反应热喷涂陶瓷涂层的耐磨性比普通热喷涂层有较大提高。

氯乙烯合成反应热水循环系统的改造

对氯乙烯合成产生的大量反应热需要强制循环水带走的常规生产工艺进行了改造,实现转化器热水自循环,不仅节省了动力电和纯水,而且提高了转化器的生产能力。

甲基咪唑及离子液体合成反应热的测定

运用大型量热仪,在典型条件下测定甲基咪唑和离子液体(AMIMCl)合成的反应热,测量结果不仅对设计甲基咪唑和离子液体的合成装置有价值,而且对合成生产工艺的优化有指导作用。

AZ31B镁合金表面SHS反应热喷涂复相陶瓷涂层的制备及性能

采用SHS反应火焰喷涂技术,把Al-TiO2-B2O3铝热反应剂引入喷涂材料中,采用机械球磨和聚乙烯醇(PVA)造粒制成喷涂复合粉末,在镁合金AZ31B表面制备Al2O3基复相陶瓷涂层。利用XRD和SEM分析了喷涂复合粉末和复合陶瓷涂层的组成及形貌,并对涂层的热震性能、致密性、显微硬度和耐磨性进行测试。结果表明:复合粉末经12 h球磨后发生铝热反应,粉末呈球形及少量片状,造粒后形成相互包覆的球形结构。涂层中生成TiB2、MgAl2O4等新相。该复合涂层熔化较充分,涂层与基体结合紧密,界面处Mg元素有扩散。复合涂层热震次数可达45次,清漆封孔后,孔隙率为0%,致密性很好,最大显微硬度值达1224 HV0.1,耐磨性比镁合金基体提高8倍以上。涂层热震性能、致密性、显微硬度和耐磨性明显优于普通热喷涂陶瓷涂层。

Hydrothermal synthesis of nanosized ZSM-22 and their use in the catalytic conversion of methanol

ZSM‐22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co‐solvent have important effects on the crystal size of ZSM‐22. The nanosized zeolite samples were characterized by X‐ray diffraction, X‐ray fluorescence, nitrogen adsorption, scanning electron microscopy, temperature‐programmed desorption of am‐monia and solid state nuclear magnetic resonance. The catalytic performance of nanosized ZSM‐22 was tested using the conversion of methanol. Compared to conventional ZSM‐22, the nanosized ZSM‐22 zeolite exhibited superior selectivity to ethylene and aromatics and lower selectivity to propylene. Stability against deactivation was clearly shown by the nanosized ZSM‐22 zeolite. A higher external surface area and smaller particle size make this nanosized ZSM‐22 zeolite attractive for catalytic applications.

Combustion synthesis of FeAl−Al2O3 composites with TiB2 and TiC additions via metallothermic reduction of Fe2O3 and TiO2

Combustion synthesis involving metallothermic reduction of Fe2O3 and TiO2 was conducted in the mode of self-propagating high-temperature synthesis(SHS)to fabricate FeAl-based composites with dual ceramic phases,TiB2/Al2O3 and TiC/Al2O3.The reactant mixture included thermite reagents of 0.6Fe2O3+0.6TiO2+2Al,and elemental Fe,Al,boron,and carbon powders.The formation of xFeAl−0.6TiB2−Al2O3 composites with x=2.0−3.6 and yFeAl−0.6TiC−Al2O3 composites with y=1.8−2.75 was studied.The increase of FeAl causes a decrease in the reaction exothermicity,thus resulting in the existence of flammability limits of x=3.6 and y=2.75 for the SHS reactions.Based on combustion wave kinetics,the activation energies of Ea=97.1 and 101.1 kJ/mol are deduced for the metallothermic SHS reactions.XRD analyses confirm in situ formation of FeAl/TiB2/Al2O3 and FeAl/TiC/Al2O3 composites.SEM micrographs exhibit that FeAl is formed with a dense polycrystalline structure,and the ceramic phases,TiB2,TiC,and Al2O3,are micro-sized discrete particles.The synthesized FeAl−TiB2−Al2O3 and FeAl−TiC−Al2O3 composites exhibit the hardness ranging from 12.8 to 16.6 GPa and fracture toughness from 7.93 to 9.84 MPa·m1/2.

Zirconium Diboride Powders Synthesized by Boro/Carbothermal Reaction Using Sol-Gel Technology

A single phase of zirconium diboride （ZrB2） powder was successfully synthesized by sol-gel method in Zr-B-C-O system, using zirconium oxychloride （ZrOC12 ~ 8H20）, nano-scale boron and suerose（C12H22011）as the starting materials and propylene oxide （PO） as complexing agent at a low temperature. Simultaneously, the experimen- tal and theoretical studies of ZrB2 synthesized by boro/carbothermal reduction from novel sol-gel technology were discussed. The results indicated that the pure rod-like ZrB2 powder without residual ZrO2 phase could be obtained with a B/Zr molar ratio of 3.5 at 1 400~C in argon atmosphere. Besides, in this study, a kinetic model for the Zr-B-C-O sys- tem producing ZrB2 by boro/carbothermal reaction was established based on thermodynamic analysis. It was also ob- served that, with the increase of reaction temperature, the reaction which produced ZrB2 powders changed from the borothermal reaction to boro/carbothermal reaction in the Zr-B-C-O system.

One-pot synthesis of 5-hydroxymethylfurfural from glucose over zirconium doped mesoporous KIT-6

Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method.Various characterization techniques confirm that highly distributed ZrO_2 nanoparticles and multicoordinated Zr^(4+) species are incorporated in the mesoporous composites.One-pot synthesis of 5-hydroxymethylfurfura(HMF) from glucose was examined in the presence of Zr-KIT-6(20) the molar ratio of Si to Zr is 20 under aqueous system.The effects of temperature,reaction time,catalyst dosage and biphasic solvent system on the conversion of glucose and the HMF yield were investigated.It was found that the glucose conversion and the HMF yield have been improved from 54.8% to 79.0% and from 19.5% to 34.5% in the biphasic MIBK-water system,respectively.Both the acidity of Zr-KIT-6(20) and the biphasic MIBK-water system are responsible for the improved performance of glucose dehydration to HMF.

Study on flow mode of combined converter for methanol synthesis from coal-based syngas

The mathematic model of combined converter with two different flow modes of gas-cooled reactor was established. The effects of gas flow mode in gas-cooled reactor on combined converter was investigated with the yield of methanol was 1 400 kt/a. The results show that if the flow mode of the cooling pipe gas and the catalytic bed gas change from countercurrent to concurrent, the catalytic bed temperature distribution does not fit the most optimum temperature curve of reversible exothermic reaction and the heat duty of heat changer in whole process increased seriously, which means that there is much more equipment investment and more operating cost. The gas flow mode of gas-cooled reactor affects the methanol yield slightly. There- fore, the countercurrent gas flow mode of gas-cooled reactor is more lucrative in the combined converter process.

Syngas Production from Crude Glycerol Using Pyrolysis

Glycerol pyrolysis is carried out in a fixed bed reactor filled with alumina oxide. The packing material diameter was examined according to each one, but in general it was varied between 0.1-5.0 mm. The reaction temperature was varied in the range of 700-900 ℃, the reaction time from 10 to 50 min and flow rate of carrier gas from 0 to 60 mL/min. The process parameters listed above （factors） were used to evaluate the syngas production yield （response）. Also, syngas properties such as composition and heat value were evaluated. The experiments were carried out according to a 23 factorial design plus three central points. At last, a technical-economical analysis is carried out to examine the feasibility of syngas production from glycerol pyrolysis considering not only feedstock, catalyst and energy required costs but also conventional procedures used nowadays to produce syngas such as water electrolysis and natural gas catalytic reform.

Low-temperature Synthesis of Belite Cement from Reactive Mixtures Based on Coal Fly Ash

This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of various waste kinds from fluidized brown coal combustion in Slovakian power plant and CaO addition. Based on XRD diffraction patterns and infrared spectra ofpre-treatment products, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment as well as metastables calcium silicates and aluminosilicates in mechanosynthesized products was confirmed. Calcination of hydrothermally treated products led to transformation of CSH phases to wollastonite （CS）, belite and gehlenite phase, whereas creation oft^- and I^-C2S or wollastonite in milled reactive mixture took place. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its mechanochemical or hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.

Preparation of Magnesium Oxide Whisker by MgSO4·5Mg（OH）2·2H2O Whisker ＂Pseudomorph＂ Technique

To promote the scale-up production and industrial application of magnesium oxide （MgO） whiskers, MgO whiskers were prepared by the calcination method of the precursor. The precursor MgSO4·5Mg（OH）2·2H2O （152 MOS） single component was prepared by hydrothermal synthesis reaction in MgSO4 solution and NaOH solution. MgO whisker was prepared by heating treatment of the precursor at low heating speed to keep the structure of the precursor not be destroyed. The composition, the morphology and the structure of these whiskers were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indicate that the MgO whisker was about 0.5-1.2 μm in diameter and 20-80 μm in length, with an aspect ratio no less than 100.

Preparation and properties of nano-composite ceramic coating by thermo chemical reaction method

Nano-composite ceramic coating was fabricated on Q235 steel through thermo chemical reaction method. Structure of the coating was analyzed and the properties were tested. The results show that a few of new ceramic phases, such as MgAI2O4, ZnAI2O4, AI2SiO5, Ni3Fe and Fe3AI, are formed on the coating during the process of solidifying at 600 ℃. The ceramic coating is dense and the high bonding strength is obtained. The average bonding strength between the coating and matrix could be 14.22 MPa. The acid resistance of the coating increase by 8.8 times, the alkali resistance by 4.1 times, the salt resistance bv 10.3 times, and the wear resistance bv 2.39 times.

Torrefied Pellets as Fuel for Two-Stage Technology of Biomass Conversion into Synthesis Gas

One of the most important properties of the torrefied pellets, along with high calorific value, is their hydrophobicity. Inability to absorb moisture and self-destruct under its influence determine possibility of using of pellets in the pyrolysis reactor. For the technology of two-stage thermal processing of biomass, developed at the Joint Institute for High Temperatures, the amount of synthesis gas which can be obtained from one kilogram of torrefied pellets is also important. A construction of the pilot torrefaction reactor powered by flue gas is shown. The results of experimental investigations of hydrophobicity of torrefied pellets produced by the reactor and quantity of synthesis gas which can be obtained by two-stage thermal processing of the pellets are presented. It is shown that torrefaction allows simplifying the process of conversion of pellets into synthesis gas without significant reduction in the volume of the gas.

Influence of Hydrothermal Pre-Treatment of Coal Fly on the Synthesis of Belite Phase

In this paper, the results of an extensive investigation of hydrothermal pre-treatment for synthesizing belite phase from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of one waste kinds （bottom ash-BA or fly ash-FA） from fluidised brown coal combustion in Slovakian power plant and CaO （analytical grade reagent） addition are summarized. Changes in structure and phase composition of hydrothermally synthesized belite precursors and subsequent calcinated products were compared with those of starting mixtures. Based on XRD diffraction patterns, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment was confirmed. Calcination of hydrotermally treated products at 900℃ led to transformation of CSH phases to wollastonite, belite and gehlenite phase. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.

One-step synthesis of fluorescent hydroxyls-coated carbon dots with hydrothermal reaction and its application to optical sensing of metal ions

Carbon dots (CDs) with average diameter of 3.1 ± 0.5 nm were facilely synthesized with candle soot through hydrothermal reaction in sodium hydroxide aqueous solution. The as-prepared CDs were covered with a lot of hydroxyls, possessed properties of good water-solubility, anti-photobleaching, salt tolerance, and low cytotoxicity, and had a fluorescence quantum yield (QY) of about 5.5%. The fluorescence of the hydroxyls-coated CDs could be selectively quenched by metal ions such as Cr3+, Al3+ and Fe3+, which is because these metals can easily combine with the hydroxyl groups on the surface of CDs and induce aggregation of hydroxyls-coated CDs. Experiments showed that the quenching of Cr3+ had a Sterm-Volmer constant of 1.03 × 107 M-1 with a liner range of 1.0-25.0 μM and detection limit of 60 nM (3σ).

A new insight into electrochemical detection of eugenol by hierarchical sheaf-like mesoporous NiCo2O4

NiCo2O4 nanosheets with sheaf-like nanostructure morphologies have been synthesized by a facile one-step hydrothermal reaction followed by annealing treatment. Impressively, the NiCo2O4 nanosheets exhibit rapid detection of eugenol. The linear range of detection is from 1-500μM, and the limit of detection is 5.4 μM. The NiCo2O4 modified electrode demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability （7% decrease in response over 30 days）. Based on this work, an electrochemical reaction mechanism for eugenol oxidation was proposed, and in addition, the NiCo2O4 modified electrode was successfully employed for the analysis of eugenol in medicative balm samples. Recovery values for eugenol in medicative balm samples were in the range 98.7%-105.5%.

Shaped Pt-Ni nanocrystals with an ultrathin Pt-enriched shell derived from one-pot hydrothermal synthesis as active electrocatalysts for oxygen reduction

Alloy nanocrystals （NCs） of Pt with 3d transition metals, especially Ni, are excellent catalysts for the oxygen reduction reaction （ORR）. In this work, we, for the first time, demonstrated the water phase colloidal synthesis of Pt-M （M = Ni, Co and Fe） alloy NCs with tunable composition and morphology through a facile hydrothermal method. Pt-Ni alloy NCs synthesized with this method presented better ORR activity than commercial Pt/C catalysts. The X-ray energy dispersive spectra （EDS） mapping technique revealed that Pt-enriched shells existed on the as-synthesized Pt-Ni alloy NCs. About two atom thick layered Pt-enriched shells formed on Pts0Nis0 NCs and the thickness of the Pt-enriched shells increased as the Ni content increased. Furthermore, X-ray photoelectron spectroscopy analysis revealed that the oxidation level of the surface Pt atoms on the Pt-Ni alloy NCs decreased compared with monometallic Pt NCs, implying a decrease in the oxophilicity of the surface Pt atoms. Pt-Ni alloy NCs with lower oxophilicity of the surface Pt atoms give higher ORR activity. The most active alloy sample showed 13 times higher specific activity and six times higher mass activity at 0.9 V vs. a reversible hydrogen electrode when compared with commercial Pt/C. Pt-Ni alloy NCs also showed better durability than commercial Pt/C in long term ORR tests.

A facile hydrothermal preparation and photoluminescence study of ZnO micro/nanostructures on Zn foils

ZnO micro/nanostructures with various morphologies were grown via hydrothermal etching of Zn foil.Controlling the reaction temperature and time,rod-like,pencil-like,tube-like and flowerlike ZnO micro/nanostructures could be prepared directly on the Zn foil surface at temperatures 100-180℃ with excellent reproducibility.X-ray diffraction patterns indicated that these ZnO micro/nanostructures were hexagonal.Possible mechanisms for the variation of morphology are discussed.Moreover,photoluminescence spectra of the as-grown samples revealed that all of them consist of UV emission band at around 392 nm.