气化氯装置运行小结

介绍了将“液氯钢瓶淋水气化的通氯方式”改为“气化氯装置的通氯方式”的改造及运行工作。论证了“气化氯装置的通氯方式”是使用高纯氯气生产氯下游产品的有效途径,安全节能效果显著。

一种液氯全气化工艺的设计

介绍一种液氯连续气化供氯的全气化工艺及干式气化器设备,该气化器改变了传统液氯不能用蒸汽直接加热的局限,且降低了能耗,工艺过程的控制延长了设备的使用寿命,并且提高了液氯在气化工艺上的本质安全性。从液氯气化工艺控制、气化器设备的技术参数及特点、材料选择、结构设计等方面进行了阐述。

气化液氯过程中三氯化氮的危害及预防措施

三氯化氮的危险性是很大的,现针对气化液氯过程中三氯化氮的危害提出相应的预防措施。

氯化石蜡差异化生产

介绍了氯化石蜡生产装置的技改以及使用不同的原料氯及蜡油进行差异化生产的情况。通过改造,可以灵活地使用不同的原料,并最大限度地生产优质的产品。

Effects of magnesium chloride-based multicomponent salts on atmospheric corrosion of aluminum alloy 2024

Atmospheric corrosion of aluminum alloy 2024 （AA2024） with salt lake water was simulated through a laboratory- accelerated test of cyclic wet-dry and electrochemical techniques. Effects of the soluble magnesium salt contained in the salt water were investigated by scanning electron microscope （SEM）, transmission electron microscope （TEM）, energy dispersive spectrometer （EDS）, electron probe micro analyzer （EPMA）, X-ray diffraction （XRD）, infrared transmission spectroscope （IR）, and atmospheric corrosion monitor （ACM）. The results showed that, with the deposition, atmospheric corrosion of AA2024 could occur when the relative humidity （RH） was lower than 30%. A main crystalline component of corrosion products, layered double hydroxides （LDH）, [Mg1-xAlx（OH）2]^x＋ Clx-·mH2O （LDH-C1）, was determined, which meant that magnesium ion played an important role in the corrosion process. It not only facilitated the corrosion as a result of deliquescence, but also was involved in the corrosion process as a reactant.

Kinetic and Microstructure of SiC Deposited from SiCl_4-CH_4-H_2

Silicon carbide was prepared from SiCl4-CH4-H2 gaseous precursors by isothermal, isobaric chemical vapor deposition (CVD) at atmospheric pressure and temperatures ranging from 900°C to 1100°C. Kinetic studies showed that carbosilane of SiH2Cl2, SiHCl3 and SiCl2 formed from decomposition of SiCl4 and CH4 contributed to the deposition of hexangular facet and granular pebble structured SiC. An average apparent activation energy of 152 kJ·mol-1 was determined. The overall CVD process was controlled not only by the surface reactions but also by complex gas phase reactions. The as-deposited thin film was characterized using scanning electron microscopy, X-ray diffraction and transmission electron microscopy, these analysis showed that the deposited thin film consisted of pure phase of the β-SiC, the growth morphology of β-SiC differs from hexangular facet to granular pebble struc-tures, which varied with substrate length and CVD temperature.

Preparation and characteristic research of anhydrous magnesium chloride with dehydrated ammonium carnallite

Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuously followed by filtration as raw materials with a molar ratio of 1∶1 of MgCl2 to NH4Cl, ammonium carnallite was synthesized. And then the ammonium carnallite was dehydrated to some extent at 160℃ for 4 h. Ammonium carnallite reacted with ammonia at 240℃ for 150 min and the ammonation ammonium carnallite was produced. Finally, the ammonation ammonium carnallite was calcined at 750℃ into anhydrous magnesium chloride containing only 0.1%（mass fraction） of MgO. On the other hand, dehydrated ammonium carnallite was mixed with the solid ammonium chloride at mass ratio 1∶4 at high temperature and with the differential pressure of NH3 above 30.5kPa. The dehydrated ammonium carnallite of mixture was dehydrated at 410℃, and then calcined at 700℃ into anhydrous magnesium chloride with only 0.087%（mass fraction） of MgO. X-ray diffraction and electron microscopy analysis results prove that anhydrous magnesium chloride obtained by both methods hasn’t mixed phases, the particle is large and even has good dispersion, which is suitable for preparation of metal magnesium in the electrolysis.

Smelting chlorination method applied to removal of copper from copper slags

In order to reasonably utilize the iron resources of copper slags, the smelting chlorination process was used to remove copper from copper slags. Higher holding temperature and O2 flow rate are beneficial to increasing copper removal rate. However,the Cu2O mode is formed by the reaction of surplus O2 and CuCl with O2 flow rate increasing over 0.4 L/min, causing CuCl volatilization rate and copper removal rate to decrease. The resulting copper removal rate of 84.34% is obtained under the optimum conditions of holding temperature of 1573 K, residence time of 10 min, Ca Cl2 addition amount of 0.1(mass ratio of CaCl2 and the copper slag) and oxygen flow rate of 0.4 L/min. The efficient removal of copper from copper slags through chlorination is feasible.

Kinetics of the Chlorination of Copper （I） Sulphide by Calcium Chloride in the Presence of Oxygen

The chemism of the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen has been determined based on the thermodynamic analysis in the Cu2S-CaCl2-O2 system as well as characterization of used raw materials and obtained products. The influence of temperature （from 473 to 773 K）, time （from 2 to 120 min）, oxygen flow （from 20 to 100 L/h） and calcium chloride quantity （from 5 to 40%） on the chlorination degree has been investigated. Kinetic analysis and the activation energy values of 20.89 kJ/mol showed that the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen is diffusion controlled.

High performance ORR electrocatalysts prepared via one-step pyrolysis of riboflavin

Efficient,cost‐effective electrocatalysts for an oxygen reduction reaction(ORR)are currently required for fuel cells.In the present work,riboflavin was used as a cheap,nontoxic carbon and nitrogen precursor to prepare Fe-N-C catalysts via one‐step pyrolysis in the presence of anhydrous iron chloride.Raman spectroscopy indicated that the catalyst containing nitrogen created a great quantity of defects in the carbon structures,while nitrogen adsorption‐desorption isotherms showed that the catalyst was mesoporous.Transmission electron microscopy demonstrated that the Fe-N-C catalyst was composed of very thin,curved and porous graphene layers together with some Fe2O3nanoparticles,and X‐ray diffraction patterns confirmed that the carbon in the catalyst was highly graphitized.X‐ray photoelectron spectroscopy indicated that the active sites for the ORR were primarily composed of graphitic nitrogen,although Fe sites also played an important role.The ORR activity of the Fe-N-C catalyst reached a maximum of4.16mA cm-2,and its chronoamperometric response was found to decrease by only3%after operating for3h at0.66V(vs RHE)in an O2‐saturated0.1mol L-1KOH solution.In contrast,a commercial40wt%Pt/C catalyst with a loading of0.2mgPt cm-2exhibited an activity of4.46mA cm-2and a40%loss of response.The electrochemical performance of this new Fe-N-C catalyst was therefore comparable to that of the Pt/C catalyst while showing significantly better stability.

Gas Phase Thermodynamic Properties of Polychlorinated Xanthones Predicted with DFT Method and Cl Substituted Position

The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G**level.It is found that the chlorine substitution pattern strongly influences the thermodynamic properties of the compounds.The thermodynamic properties of congeners with the same number of chlorines also depend on the chlorine substitution pattern,especially for ortho-substituted congeners.PCXT congeners with one phenyl ring fully chlorinated are found to be the least stable among the analogues.The effect of the chlorine substitution pattern is quantitatively studied by considering the number and position of Cl atom substitution(NPCS).The results show that the NPCS model may be used to predict the thermodynamic properties for all 135 PCXT congeners. In addition,the values of molar heat capacities at constant pressure(cp,m)from 200 to 1000 K for PCXT congeners are calculated,and the temperature dependence relation of this parameter is obtained using the least-squares method.

Dechlorination by combined electrochemical reduction and oxidation

Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electro- chemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.

New Method for Desalination of Seawater

The present study explores the possibility of appealing to the laws of inorganic chemistry, i.e., the rules of precipitation to desalinate seawater. Historically, the industry has been using these techniques for the preparation of some compounds. Based on these rules, using suitable salts will react with each other. The results are evident all unwanted salts including sodium chloride are removed. In fact, it is a selective precipitation as other salts which are not harmful are kept such as potassium. The other aim of the study is to reduce the current ratio desalination/power which is very high 60,000 to 80,000 cal/L for distillation （A. Payant. P. Chiliotti L. Sainte-Marie Physic Arm and Colin, Paris, France） or 4.5 kWh/m3 for RO （desalination and water reuse, California, USA） a cause of greenhouse gas except desalination using solar energy. Another aspect of this study, authors noticed rather than consume energy, regeneration or recycling of products provides energy. And in addition, the operation does not cause any pollution.

Effect of Boundary Layers on Polycrystalline Silicon Chemical Vapor Deposition in a Trichlorosilane and Hydrogen System

This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition （CVD） reactors. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane （TCS）-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCl gas so that HCl gas could be pushed away from the surface of the substrate immediately.

Reaction Kinetics of Ozonation of Trichloroethylene and Benzene in Gas and Liquid Phases

The kinetics of ozonation reactions of trichloroethylene (TCE) and benzene in gas and liquid phases at 101.3 kPa and 298 K was investigated in this paper. The ozonation of TCE is first order with respect to the ozone concentration and one and half order to TCE in the gas phase with the average rate constant 57.30 (mol·L-1)-1.5·s-1, and the TCE ozonation in aqueous medium is first order with respect to both ozone and trichloroethylene with the average rate constant 6.30 (mol·L-1)-1·-1. The ozonation of benzene in the gas phase is first order in ozone but independent of the benzene concentration with the average reaction rate constant 0.0011s-1. The overall kinetics of reaction between ozone and benzene in aqueous solution is found to be first order with one-half order in both ozone and bezene, with the average reaction rate constant 2.67s-1. It is found that the ozonation rate of pallutants is much quicker than that of self-decomposition of ozone in both gas and aqueous phase.

UV enhanced gas–solid synthesis of chlorinated poly vinyl chloride characterized by a UV–Vis online analysis method

Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as soon as UV light was affiliated, which demonstrated the intensified effect of UV radiation on PVC chlorination directly.Different affiliation methods of UV light were then studied, proving that continuous UV radiation could enhance the chlorination process significantly while intermittent UV radiation was able to initiate the chlorination reaction once it was conducted. Besides, experiments were carried out to study the influences of parameters on the chlorination process such as UV wavelength, chlorination temperature, partial pressure of chlorine gas and PVC raw materials. Among all the parameters, chlorination temperature and partial pressure of chlorine gas were testified as two key factors to determine the chlorination performance. Thermal analysis of CPVC products showed that their corresponding properties such as the glass transition temperature(Tg) and the homogeneity of chlorine distribution in polymer phase were improved with the increase of chlorine content.

Vapor Pressure Measurement and Correlation of 2-Methyl-Butanol Acetate Containing Calcium Chloride

The CaCl2 solubility in 2-methyl-butanol acetate and the vapor pressure of 2-methyl-butanol acetate containing CaCl2 were measured in the range of 90-135°C and from very low salt concentration to saturation.The experimental data were correlated with two equations,a modified Antoine equation with the dissolved salt taken into account and a nonrandom two liquid-electrolyte（e-NRTL）model.Both models are in good agreement with the experimental data.This study provides essential physical data for further investigation of vapor-liquid equilibrium system containing salt.

Chemical vapor deposition of SiC at different molar ratios of hydrogen to methyltrichlorosilane

Chemical vapor deposition(CVD) of SiC from methyltrichlorosilane(MTS) was studied at two different molar ratios of H2 to MTS(n(H2) /n(MTS) ) . The total pressure was kept as 100 kPa and the temperature was varied from 850 to 1 100 ℃ at a total residence time of 1 s. Steady-state deposition rates as functions of reactor length and of temperature,investigated at different n(H2) /n(MTS) values,show that hydrogen exhibits strongly influences on the deposition rate. Especially,the deposition of Si co-deposit can be obtained in broader substrate length and at higher temperatures with increasing hydrogen partial pressure. Influence of hydrogen on the deposition process was also studied using gas phase composition and deposit composition analysis at various n(H2) /n(MTS) . SEM micrographs directly show the variation of surface morphologies at various n(H2) /n(MTS) . It can be found that the crystal grain of the deposit at 1 100 ℃ is better developed and the crystallization is also improved with increasing n(H2) /n(MTS) .

Ceria in halogen chemistry

Halogen chemistry constitutes an essential part in the industrial production of polymers and gains increasing attention as an attractive strategy to activate light alkanes that constitute natural gas. CeO2-based catalysts offer an exciting potential for advances in hydrogen halide recovery that enables a high efficiency of halogen-based processes for activation of small molecules. This review provides an overview of recently developed ceria-based catalysts in the context of polymer industry(polyvinyl chloride, polyurethanes, and polycarbonates) and activation of light hydrocarbons for natural gas upgrading. In addition, mechanistic insight and the challenges of ceria catalysts are provided, aiding the design of future catalytic materials and applications.

Thermodynamic behaviors of SiCl_2 in silicon deposition by gas phase zinc reduction of silicon tetrachloride

The modified Siemens process,which is the major process of producing polycrystalline silicon through current technologies,is a high temperature,slow,semi-batch process and the product is expensive primarily due to the large energy consumption.Therefore,the zinc reduction process,which can produce solar-grade silicon in a cost effective manner,should be redeveloped for these conditions.The SiCl2 generation ratio,which stands for the degree of the side reactions,can be decomposed to SiCl4 and ZnCl2 in gas phase zinc atmosphere in the exit where the temperature is very low.Therefore,the lower SiCl2 generation ratio is profitable with lower power consumption.Based on the thermodynamic data for the related pure substances,the relations of the SiCl2 generation ratio and pressure,temperature and the feed molar ratio（n（Zn）/n（SiCl4） are investigated and the graphs thereof are plotted.And the diagrams of Kpθ-T at standard atmosphere pressure have been plotted to account for the influence of temperature on the SiCl2 generation ratio.Furthermore,the diagram of Kpθ-T at different pressures have also been plotted to give an interpretation of the influence of pressure on the SiCl2 generation ratio.The results show that SiCl2 generation ratio increases with increasing temperature,and the higher pressure and excess gas phase zinc can restrict SiCl2 generation ratio.Finally,suitable operational conditions in the practical process of polycrystalline silicon manufacture by gas phase zinc reduction of SiCl4 have been established with 1200 K,0.2 MPa and the feed molar ratio（n（Zn） /n（SiCl4）） of 4 at the entrance.Under these conditions,SiCl2 generation ratio is very low,which indicates that the side reactions can be restricted and the energy consumption is reasonable.