硅烷处理N2O氧化苯生产苯酚催化剂抑制结碳失活研究

The main cause to the deactivation of ZSM-5 catalyst, used for oxidation of benzene to phenol (BTOP) by nitrous oxide, is that the carbon deposition on the catalyst surface blocks the mouth of pores of the catalyst.In the experiments, ZSM-5 catalyst was modified by chemical surface deposition of silicon, and then the effect of modification condition on the catalyst activation was studied. The catalyst samples were characterized by XRF,EPS, XRD, TEM, N2 adsorption at low temperature, pyridine adsorption-infrared technique and etc. All the above results show that the uniform SiO2 membrane can be formed on ZSM-5 crystal surface. The SiO2 membrane covers the acid centers on ZSM-5 surface to inhibit surface coking, to avoid or decrease the possibility of ZSM-5 pore blockage so that the catalyst activity and stability can be improved efficiently. The optimum siliconiting conditions determined by the experiments are as follows: 4% load of silanizing agent, volume (ml)/mass (g) ratio of hexane/ZSM-5=15/1, and 16 h of modification time. Compared with the samples without siliconiting treatment,the samples treated under the above optimum condition can increase the productivity of phenol by 14% for 3 h reaction time and by 41% for 6 h reaction time respectively.     

基于魏格纳分布的鼓泡流化床中结焦早期诊断

An experimental verification is reported on the early predicting index of agglomeration in bubbling fluidized bed. Coarse quartz sand, which has the same density but larger diameter than the bed material, was used to simulate the initial agglomerated particle. Wigner distribution was used to analyze the pressure fuctuation of the tested bed, and the average amplitude of local domain frequency （LDF） and local peak weighted average frequency （LPWA） under different operating conditions were measured and compared. The results showed that the LDF is sensitive to the agglomeration phenomena and had quick response to the incipient agglomeration in fluidized beds. It can be concluded from the results that these two parameters could be taken as the characteristic indexes to the agglomeration in fuidized beds.     

用NRTL方程推算高压汽液平衡并同时描述过量焓

The non-random two liquids （NRTL） equation together with the Pitzer/Curl Virial equation of state are used to investigate the simultaneous representation of excess enthalpies （h^E） and vapour-liquid equilibria （VLE） and the VLE prediction from h^E data. The calculation strategy for properly determining NRTL parameters and the effect of their temperature dependence on the simultaneous correlation of h^E and VLE data and the VLE extrapolation are analysed in detail.     

颗粒尾涡增强湍流的大涡模拟以及气固两相流中湍流变动的数值模拟

The turbulence enhancement by particle wake effect is studied by large eddy simulation （LES） of turbulent gas flows passing a single particle. The predicted time-averaged and root-mean-square fluctuation velocities behind the particle are in agreement with the Reynolds-averaged Navier-Stokes modeling results and experimental results. A semi-empirical turbulence enhancement model is proposed by the present-authors based on the LES resuits. This model is incorporated into the second-order moment two-phase turbulence model for simulating vertical gas-particle pipe flows and horizontal gas-particle channel flows. The simulation results show that compared with the model not accounting for the particle wake effect, the present model gives simulation results for the gas turbulence modulation in much better agreement with the experimental results.     

一种用于计算机辅助产物设计中基于BP-NN优化问题的求解方法

Because of the powerful mapping ability, back propagation neural network (BP-NN) has been employed in computer-aided product design (CAPD) to establish the property prediction model. The backward problem in CAPD is to search for the appropriate structure or composition of the product with desired property, which is an optimization problem. In this paper, a global optimization method of using the a BB algorithm to solve the backward problem is presented. In particular, a convex lower bounding function is constructed for the objective function formulated with BP-NN model, and the calculation of the key parameter a is implemented by recurring to the interval Hessian matrix of the objective function. Two case studies involving the design of dopamine β-hydroxylase (DβH) inhibitors and linear low density polyethylene (LLDPE) nano composites are investigated using the proposed method.     

燃烧法制备二氧化钛催化剂的条件对其可见光催化性能的影响

Titania catalysts were synthesized by a solution combustion method （SCM）. Photodegradation of 4-chlorophenol （4-CP） using the synthesized catalysts was studied under both visible light （λ≥420nm） and sunlight irradiation. The effect of preparation conditions on photocatalytic activities of the synthesized catalysts was investigated. The optimal photocatalytic activity of the catalyst （denoted as A1 ） was obtained under the following synthesis conditions： ignition temperature of 350~C, fuel ratio （ φ） of 1 and calcination time of lh. The degradation and mineralization ratio of 4-CP were 78.2% and 53.7% respectively under visible light irradiation for 3h using catalyst A1. And the catalyst A1 also showed high photocatalytic activity under sunlight irradiation.     

废轮胎热解炭黑的表面修饰及其在平版印刷油墨中的应用

Pyrolysis has the potential of transforming waste into valuable products. Pyrolytic carbon black （PCB） is one of the most important products resulting from the pyrolysis of used tires. One of the most significant applications of modified pyrolytic carbon black is its use as pigment for offset printing ink to obtain high added values. Inverse gas chromatography （IGC） results show that a large quantity of inorganic matters and carbonaceous deposit are removed by treating the pyrolytic carbon black with nitric acid solution. Plenty of active sites originally occupied by inorganic ash and coke are recovered. The surface energy of pyrolytic carbon black （TWPC） modified by titanate-coupling agent-especially the specific interaction γs^SP determined by the specific probe molecule, toluene-shows the strong interaction between the TWPC and the synthetic resins. The offset printing ink performance confirms the IGC prediction. And TWPC has the great potential of applications in printing ink industry as pigment.     

胞外高分子物质对基质在复合生物膜内传质速率影响的测定

A model, for evaluating the effect of porosity and volume fraction of extracellular polymeric substances (EPS) within multispecies biofilms on the effective diffusivity, is developed and experimentally validated, based on the extraction of EPS from intact biofilms. The amount of EPS in biofilms significantly affects the effective diffusivity. For biofilms with porosity of 77%—95% in the top layers and 54%—58% in the bottom layers, the value of De/Dw decreases from 0.52—0.83 in the top layers to 0.23—0.31 in the bottom layers. Generally, the effective diffusivity in the heterotrophic/autotrophic biofilms is slightly lower than that in the heterotrophic biofilms, due to the lower porosity in the heterotrophic/autotrophic biofilms.     

DCV-GCMD方法模拟近临界条件下乙烯、苯与乙苯在圆柱形孔道中苯烃化反应条件下的吸附和传递性质

Abstract A cylindrical pore model was used to represent approximately the pore of β-zeolite catalyst that had been used in the alkylation of benzene with ethylene and spherical Lennard-Jones molecules represented the components of the reaction system-ethylene, benzene and ethylbenzene. The dual control volume-grand canonical molecular dynamics (DCV-GCMD) method was used to simulate the adsorption and transport properties of three components under reaction in the cylindrical pore at 250℃and 270℃in the pressure range from 1 MPa to 8 MPa. The state map of the reactant mixture in the bulk phase could be divided into several different regions around its critical points. The simulated adsorption and transport properties in the pore were compared between the different near-critical regions. The thorough analysis suggested that the high pressure liquid region is the most suitable region for the alkylation reaction of benzene under the near-critical condition.     

约束优化控制的约束调整与目标协调及在重油分离器过程中的作用

In this paper, the feasibility and objectives coordination of real-time optimization (RTO) are systemically investigated under soft constraints. The reason for requiring soft constraints adjustment and objective relaxation simultaneously is that the result is not satisfactory when the feasible region is apart from the desired working point or the optimization problem is infeasible. The mixed logic method is introduced to describe the priority of the constraints and objectives, thereby the soft constraints adjustment and objectives coordination are solved together in RTO. A case study on the Shell heavy oil fractionators benchmark problem illustrating the method is finally presented.     

酚醛树脂改性煤焦油沥青中制得的中间相球体的结构特征

Mesocarbon microbeads （MCMB） were prepared from coal tar pitch modified by phenolic resin and from the same pitch modified by phenolic resin and hexamethylenetetramine at 440℃ for lh. By investigating the morphology of mesophase spheres and the structure of the MCMB carbonized at 1000℃ for lh using scanning electron microscope （SEM） and XRD, it was found that phenolic resin accelerated the formation and coalescence of mesophase spheres. Some of the obtained MCMB were hi- or tri-spheres with the distorted microtextural carbon layers. Hexamethylenetetramine in the pitch modified by phenolic resin accelerated the condensation of phenolic resin and consequently expedited the combination of mesophase spheres, which was proved by the formation of some tetra-spheres. Owing to the cross-linkage of the additives, MCMB with complex structure were obtained.     

杂合基因算法在酵母中间代谢途径代谢通量分析中的应用

A scheme of investigating the intracellular metabolic fluxes in central metabolism of Saccharomyces cerevisiae based on isotope model and tracer experiment was developed. The metabolic model applied in this study includes the Embden-Meyerhof-Parnas pathway, the pentose phosphate pathway, the tricarboxylic acid cycle, CO2 anaplerotic reactions, ethanol and acetate formation, and pathways involved in amino acid synthesis. The approach of hybridized genetic algorithm combined with the sequential simplex technique was used to optimize a quadratic error function without the requirement of the information on the partial derivatives. The impact of some key parameters on the algorithm was studied. This approach was proved to be rapid and numerically stable in the analysis of the central metabolism of S.cerevisiae.     

高温高压下湿空气循环中增湿塔的计算研究

Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.     

超临界二氧化碳渗透聚丙烯成核剂的初步研究

Impregnation of isotactic polypropylene （iPP） with nucleating agent （NA21） using supercritical carbon dioxide as the swelling agent at different temperature and pressure and its non-isothermal crystallization kinetics were investigated. The results showed that NA21 was dispersed at a nanometer-scale in the PP matrix, resulting in the formation of different types .of crystal phases of iPP and the enhancement of its mechanical properties.     

气-液-固三相气升式环流反应器中牛顿型及非牛顿型流体局部液相传质模型

A small scale isotropic mass transfer model was developed for the local liquid side mass transfer coefficients in gas-liquid-solid three-phase flow airlift loop reactor for Newtonian and non-Newtonian fluids. It is based on Higbie‘s penetration theory and Kolmogoroff‘s theory of isotropic turbulence with kl=3√2D∈11/3/π(η1^-1/3-λf^-1/3)where e1 is local rate of energy dissipation, Af is the local microscale, r/l is the local Kolmogoroff scale and D is the diffusion coefficient. The capability of the proposed model is discussed in the light of experimental data obtained from 12 L gas-liquid-solid three-phase flow airlift loop reactor using Newtonian and non-Newtonian fluids. Good agreement with the experimental data was obtained over a wide range of conditions suggesting a general applicability of the proposed model.     

PSRK模型的修正混合规则及其应用于聚合物溶液汽液平衡的预测

To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑xiln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied [bij^1/2=1/2(bi1/2 bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters of i3 - 2- pure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.     

N-异丙基丙烯酰胺凝胶在NaCl水溶液中溶胀行为的预测研究

In this paper, a model is presented to correlate and predict the swelling behavior of hydrogels in aqueous solutions of electrolytes. The model is a combination of VERS-model, “phantom network“ theory and “free-volume“ contribution. The VERS-model is used to calculate Gibbs excess energy; “phantom network“ theory to describe the elastic properties of polymer network, and “free-volume“ contribution to account for additional difference in the size of the species. To test the model, a series of N-isopropylacrylamide based hydrogels are synthesized by free radical polymerization in oxygen-free, deionized water at 25~C under nitrogen atmosphere. Then, the degree of swelling of all investigated gels as well as the partition of the solute between the gel phase and the surrounding coexisting liquid phase are measured in aqueous solution of sodium chloride. The model test demonstrates that the swelling behavior correlated and predicted by the model agrees with the experimental data within the experimental uncertainty. The phase transition appeared in the experiment, and the influences of the total mass fraction of polymerizable materials ξgel as well as the mole fraction of the crosslinking agent YCR on the swelling behavior of IPAAm-gels can also be predicted correctly. All these show the potential of such model for correlation and prediction of the swelling behavior of hydrogels in aqueous solutions of electrolytes.     

设计过程工业多杂质用水网络的计算方法

This paper introduces a non-iterative algorithmic procedure to design water utilization networks with multiple contaminants in process plants. According to the water pinch analysis rules, the processes in water utilization systems were first divided into three groups, then water-supply priority algorithm was proposed. The results of case studies showed that the water networks designed by this method gave water consumption lower than that estimated by other approaches. In addition, the procedure was subiect to no limitation on the problem scale.     

基于双槽式孔板组合和神经网络技术的凝析天然气流量计开发

A slotted orifice has many superiorities over a standard orifice. For single-phase flow measurement, its flow coefficient is insensitive to the upstream velocity profile. For two phase flow measurement, various characteristics of its differential pressure （DP） are stable and closely correlated with the mass flow rate of gas and liquid. The complex relationships between the signal features and the two-phase flow rate are established through the use of a back propagation （BP） neural network. Experiments were carried out in the horizontal tubes with 50ram inner diameter, ooerated with water flow rate in the range of 0.2m^3·h^-1 to 4m3·h^-1, gas flow rate in the range of 100m^3·h^-1 to 1000m^3·h^-1, and pressure at 400kPa and 850kPa respectively, where the temperature is ambient temperature. This article includes the principle of wet gas meter development, the experimental matrix, the signal processing techniques and the achieved results. On the basis of the results it is suggested that the slotted orifice couple with a trained neural network may provide a simple but efficient solution to the wet gas meter development.     

一种新型含肉桂酸酯结构的螺吡喃光致变色染料的合成与性能研究

A novel bifunctional dye containing spirobenzopyran and cinnaznoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated.The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.