Mechanism and Kinetics of Polychlorination of Long Chain n-Alkanes by Photo-Initiation

Based on the mechanism analysis of the polychlorination of long chain n-alkanes by photo-initiation, a kinetic model was developed. The model parameters were obtained by the method of non-linear fitting. The influences of luminous intensity and concentration of molecular chlorine on the rate of polychlorination are demonstrated by the model. If the luminous intensity is adequate, the polychlorination rate of n-alkane is only controlled by the flow rate of molecular chlorine in a wide range of temperature, and the changes of temperature and luminous intensity have less effect on the reaction rate. In addition, the predictions of chlorine content, of polychlorinated n-alkane calculated with the model agree very well with experimental results.     

Effect of chloralkanes on the phenyltrichlorosilane synthesis by gas phase condensation

To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis wa...     

光引发长链正构烷烃多氯代反应机理与动力学

Based on the mechanism analysis of the polychlorination of long chain n-alkanes by photo-initiation,a kinetic model was developed. The model parameters were obtained by the method of non-linear fitting. The influences of luminous intensity and concentration of molecular chlorine on the rate of polychlorination are demonstrated by the model. If the luminous intensity is adequate, the polychlorination rate of n-alkane is only controlled by the flow rate of molecular chlorine in a wide range of temperature, and the changes of temperature and luminous intensity have less effect on the reaction rate. In addition, the predictions of chlorine content of polychlorinated n-alkane calculated with the model agree very well with experimental results.     

Evaluation of an improved epichlorohydrin synthesis from dichloropropanol using a microchemical system

Synthesizing epichlorohydrin (ECH) from dichloropropanol (DCP) is a complicated reaction due to the partial decomposition of ECH under harsh conditions. A microchemical system can provide a feasible platform for improving this process by conducting a separation once full conversion has been achieved. In this work, referring to a common DCP feed used in industry, the reaction performance of mixed DCP isomers with NaOH in the microchemical system on various time scales was investigated. The operating window for achieving high conver-sion and selectivity was on a time scale of seconds, while the side reactions normal y occurred on a time scale of minutes. Plenty of Cl?ions together with a high temperature were proved to be critical factors for ECH hydrolysis. A kinetic study of alkaline mediated ECH hydrolysis was performed and the requirements for an improved ECH synthesis were proposed by combining quantitative analysis using a simplified reaction model with experimen-tal results on the time scale of minutes. Compared with the conventional distillation process, this new strategy for ECH synthesis exploited microchemical system and decoupled the reaction and separation with potentials of higher productivity and better reliability in scaling up.     

搅拌式有限氧补偿条件下乳状液中多不饱和脂肪酸氧化模型

The oxidation of polyunsaturated fatty acids （PUFA） in emulsion with stirring and limited oxygen compensation was studied. A mathematical model of diffusion-oxidation was developed considering the mass transfer resistance of a gas-liquid boundary, the resistance of the boundary layer from the emulsifier membrane, and the autocatalytic-type autoxidation reaction of PUFA. The dynamic mass transfer coefficient of the emulsifier membrane, k0, was introduced. The model was verified by comparing the predictions of the model with the experi- mental data. The results indicated that the model was in good agreement with the oxygen diffusion and linoleic acid oxidation in the emulsion, and showed good applicability in the prediction of the effect of the emulsifier type on the oxidation of PUFA in the emulsion. It indicated that the oxidation of PUFA in emulsions, with stirring and limited oxygen compensation from the atmosphere, was controlled mostly by mass transfer resistance from the emulsifier membrane.     

非均相羰基氧化一步合成碳酸二苯酯的研究(Ⅴ)筛选催化剂及优化合成条件

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the     

固定化金属离子亲和分配用的亚胺二乙酸-聚乙二醇偶联物的制备

The synthesis route was investigated and optimized for the preparation of iminodiacetic acid polyethylene glycol (IDA-PEG) for immobilized metal ion affinity partitioning in aqueous two-phaze systems. IDA PEG was synthesized from PEG in two steps by the reaction of iminodiacetic acid with a monosubetituted derivative of epichlorohydrin-activated PEG. The Cu2+ content combined with IDA-PEG was determined by atomic absorp tion spectrometry as 0.5 mol.mol-1 (PEG). Furthermore, the affinity partitioning behavior of lactate dehydrogenase in polyethylene glycol/hydroxypropyl starch aqueous two-phaze systems was studied to clarify the affinity effect of the Cu(Ⅱ)-IDA-PEG.     

The effect of operating conditions on acylation of 2-methylnaphthalene in a microchannel reactor

Acylation of 2-methylnaphthalene(2-MN) is a very important reaction in organic synthesis,and the effiency of the continuous reactor is more than one of the batch reactor.Considering that the Friedel–Crafts acylation is a rapid exothermic reaction,in this study,we perform the acylation of 2-MN in a stainless steel microchannel flow reactor,which is characterized by high mass and heat transfer rates.The effect of reactant ratio,mixing temperature,reaction temperature,and reaction time on product yield and selectivity were investigated.Under the optimal conditions,2-methyl-6-propionylnaphthalene(2,6-MPN) was obtained in 85.8% yield with 87.5% selectivity.Compared with the conventional batch system,the continuous flow microchannel reactor provides a more efficient method for the synthesis of 2,6-MPN.     

铜基催化剂上甲醇合成的动态反应动力学

Adsorption, surface reaction and process dynamics on the surface of a commercial copper-based cata-lyst for methanol synthesis from CO/CO2/H2 were systematically studied by means of temperature programmed desorption (TPD), temperature programmed surface reaction (TPSR), in-situ Fourier transform-inferred spectroecopy(FTIR) and stimulus-response techniques. As a part of results, an elementary step sequence was suggested and a group of ordinary differential equations (ODEs) for describing transient conversations relevant to all species on the catalyst surface and in the gas phase in a micro-fixed-bed reactor was derived. The values of the parameters referred to dynamic kinetics were estimated by fitting the solution of the ODEs with the transient response data obtained by the stimulus-response technique with a FTIR analyzer as an on-line detector.     

内部部分润湿催化剂的动力学行为

The global reaction rate of benzene hydrogenation to cyclohexane accompanied by partial internal wetting of catalyst pellets was measured by a new method, which investigated both adsorption and chemical reaction. The adsorption investigation was used to establish a relationship between the extent of liquid filling of the catalyst and the bulk conditions while the chemical reaction investigation was to study the effect of partial internal wetting of the catalyst on the global reaction rate. It was shown that the extent of liquid filling in the catalyst interior showed a significant effect on the global rate, and the current state of the catalyst depended on the history, i.e. whether it was a liquid evaporation process or a vapor condensation process, and two steady states were found under certain circumstances. A mathematical model was developed, which took multicomponent diffusion, chemical reaction, pore size distribution of the catalyst and capillary condensation of condensable components in the catalyst pellet into consideration. The predicted values were in good agreement with the experimental data.     

氯代有机物结构性质对还原脱氯速率的影响

研究了氯代甲烷系列和氯代乙烷系列的多种氯代烷烃在铁、铜二相金属体系中的还原脱氯反应,分析了氯代有机物结构性质对还原脱氯反应的影响和规律性。结果表明氯代有机物的结构性质对还原脱氯速率有着明显影响,有机物氯化程度越高,脱氯速率越快,四氯化碳经过1h后脱氯率可达50.7%,而二氯甲烷脱氯则很慢,在氯代乙烷系列中脱氯速率最快的是1,1,1-三氯乙烷。电子直接转移是氯代烷烃还原脱氯的主要途径。     

Flame-retardant action of chlorine compounds and antimony trioxide on cellulose fabric

Chemical research on the flame-retardant action of halogen compounds and antimony trioxide on cellulose fabric was carried out by thermogravimetry, infrared spectrum analysis, and x-ray diffraction analysis. The following results and conclusion were drawn: (1) Independently of the type of chlorine atoms introduced, that is, whether chlorine atoms are chemically bonded with cellulose chains or not, the introduction of chlorine atoms alone has little flame-retardant effect, while combination of chlorine atoms with antimony trioxide is more effective. (2) Addition of only antimony trioxide to samples obtained from the dechlorination of chlordeoxycellulose is as effective as the combination of chlorine compounds and antimony trioxide, in spite of a trace of chlorine in the DCDC samples. (3) Introduction of chlorine compounds yielded the formation of carbonyl and double bond groups in the cellulose chains. The formation of the latter groups was accelerated by the combination of antimony trioxide; that of the former groups was inhibited. Most of the introduced chlorine atoms were missing in the condensed phase even at 300°C while a large portion of the initially added antimony trioxide remained in the condensed phase at least up to 400°C. One mode of flame-retardant action of the combination of chlorine compounds and antimony trioxide was assumed to be the catalytic effect on the dehydration of cellulose to yield a thermostable polyene structure in the cellulose chains.     

Effects of 6-anilino-1,3,5-triazine-2,4-dithiol,zinc stearate,and barium stearate on the thermal stabilization of PVC

Individual action and synergistic effect in the combination of 6-anilino-1,3,5-triazine-2,4-dithiol (AF), zinc stearate, and barium stearate on the color stabilization of PVC were investigated. In this system, AF selectively reacts with allylic chlorine atoms in PVC. Consequently, unstable allylic chlorine units were converted to thermally stable allylic structures, thus retarding the development of polyene sequences. Zinc stearate accelerated the reaction of AF with allylic chlorine atoms in PVC, forming the zinc salts of AF (AFZ_nSt, St?C₁–H₃₅COO? ) by reacting with AF. Barium stearate reacted with ZnCl₂ which is formed in the above reaction to give St₂Zn and BaCl₂. Consequently, barium stearate led to the selective reaction of AF with allylic chlorine atoms in PVC and the remarkable retarding effect of discoloration of PVC.     

Chlorocarboxylation of polyethylene. II. Reaction mechanism of the process

Chlorocarboxylated polyethylene (CCPE) is produced by simultaneous reaction of chlorine and maleic anhydride (MA) with polyethylene (PE). Hydrogen atoms on the PE chain are substituted either by chlorine atoms or by maleic anhydride moieties. The reaction mechanism involves creation of an active site, i.e. a radical on the PE chain. There is competition between chlorine and MA molecules for the reaction with this macroradical. Chlorine reacts to give chlorinated polyethylene (CPE) type segments, while MA reacts as a single unit (as chloro derivative) without forming any graft copolymer. There is a marked reduction in the rate of chlorination of PE due to the presence of MA. This is probably due to the competitive nature of the process and the radical scavenging action of MA.     

关于氯代烷烃稳定剂的探讨

简要介绍了氯代烷烃的生产方法及其原理，分析了影响氯代烷烃产品热稳定性的主要原因及其反应原理，探讨性提出作为氯代烷烃稳定剂所应具备的基本条件，指出采用复合型稳定剂是保证氯代烷烃产品性能稳定的较好方法。     

Synthesis of nitrogen-doped multilayer graphene from milk powder with melamine and their application to fuel cells

We reported on the facile synthesis of N-doped multilayer graphene (N-MLG) from milk powder that uses melamine as a nitrogen-doping source with Fe²⁺ ions as catalytic growth agents. We showed that milk powder could be used as a precursor for large-scale N-MLG synthesis through heat treatment at 1000 °C under N₂ atmosphere for 45–120 min. In addition, heating time has a remarkable effect on N content and type in N-MLG. The resulting N-MLG exhibited higher catalytic activity than undoped graphene and carbon nanotubes (CNTs), as well as comparable catalytic activity to commercial Pt/C catalyst toward oxygen reduction reaction (ORR). Furthermore, the catalytic activity was sensitive to N content and type, particularly the ratio of pyridinic-N to total N atoms. Results showed that Fe atoms in N-MLG were found to function not as synergetic catalysts for ORR but as catalytic growth agents for N-MLG formation, thereby promoting and stabilizing N atoms. The present method could lead to the synthesis of bulk amounts of N-MLG, which is promising for applications in electrochemical energy devices, such as fuel cells and metal–air batteries.     

3，5-二氯吡啶的合成工艺研究

3,5-二氯吡啶是生产各种农用和医用产品的重要中间体。在农用方面,3,5-二氯吡啶可用来制备各种高效、低毒、低残留的杀虫剂和除草剂：在医用方面,3,5-二氯吡啶可用来合成各种消炎药、抑制剂、抗生素、镇静剂等,如制备螺环酰胺类化合物,该类药物可用来治疗心理、记忆上的缺陷,认识混乱,如帕金森症和精神分裂症等。     

Kinetic analysis of catalytic hydrodechlorination process of polychlorinated biphenyls (PCBs)

Catalytic hydrodechlorination (HDCl) of 2,4,4′,6-tetrachlorobiphenyl and 2,3,4,5-tetrachlorobiphenyl has been studied in the presence of a sulphided Ni–Mo/γ-Al₂O₃ catalyst. The reaction runs were carried out at constant temperature and pressure in a stirred batch reactor using hexadecane as the reaction medium. Temperature levels of T=250°C and T=300°C at a hydrogen pressure of P_H2=20 bar were tested. The results demonstrate that the HDCl process proceeds via an irreversible stepwise pattern. The kinetic constants of all observed intermediate HDCl steps were evaluated. The selectivity of HDCl reactions has been interpreted on the basis of electrophilic aromatic substitution mechanism. It shows that the HDCl rate is slower when carbon atoms adjacent to a substituted chlorine atom are bonded to other chlorine atoms. This depends on the inductive effect of chlorine atoms. It also shows that ortho-substitution is slower than meta- and para-substitution. In this case, both steric and electronic effects are probably relevant.     

Potassium promotion of the ammonia synthesis reaction: A combined UHV-high pressure investigation

The ammonia synthesis rate has been measured as a function of the potassium coverage of a polycrystalline iron foil. The results clearly demonstrate a promoting effect of the potassium in agreement with the work of Ertl et al. on the dissociative dinitrogen adsorption at iron single crystal surfaces. However, the results also imply a marked difference between the state of the surface under ammonia synthesis conditions and during the dinitrogen adsorption experiments in ultra-high vacuum. It is suggested that in the former case the potassium atoms are surrounded by several strongly adsorbed atoms effectively blocking the corresponding sites for dinitrogen dissociation.