Table of Content

20 December 2009, Volume 9 Issue 6

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流动与传递

Distributions of Catalyst Concentration and Particles Velocity in a Large-scale Fast Fluidized Bed Reactor

LI Guo-zhi DENG Hai-yan MA Yan-mei ZHANG Zhen-qian

. 2009, 9(6):  1041-1047. 

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The flow characteristics of FCC particles were studied in a fast fluidized bed reactor with 300 mm diameter. Flow behaviors of gas and solids in the system were measured by pressure cyclic detecting and optical fiber measuring instruments, respectively. The effects of operating conditions on catalyst concentration, particles velocity, screening distribution along the bed axle and radial direction were examined. The experimental results show that when the superficial gas velocity is enhanced in 2.0~2.6 m/s, the catalyst flux is increased to 60~160 kg/(m2×s) and the axial distribution of catalyst concentration can be maintained in 50~650 kg/m3. The radial distribution of catalyst concentration is lower in the central region and higher near the wall. In the axial direction, the radial local catalyst concentration gradually decreases in the particle accelerating region and tends to smooth in the fully developed region. The radial local catalyst concentration decreases with superficial gas velocity increasing or catalyst flux decreasing, radial homogenization is improved. And catalyst concentration appears to be close at the non-dimensional radial position r/R<0.7. The radial distribution of particle velocity is the parabola structure with higher particle velocity in the central region and lower near the wall. The radial local particle velocity increases with superficial gas velocity increasing or catalyst flux decreasing.

Back-mixing of Particles in a Gas-Solid Loop Reactor

YAN Chao-yu LU Chun-xi GUO Rong-mian

. 2009, 9(6):  1048-1054. 

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Under different operation conditions, by optical fiber measurement with suitable data processing, the local and cross-sectional particle back-mixing characteristics in the riser and annular sections of a large-scale compound fluidized bed combustor were investigated. The experimental results show that the radial distribution profiles of particle local back-mixing ratio (Rmix,L) is uniform in the annulus, but non-uniform in other three regions (draft tube, bottom and particle separation regions) of the loop reactor. The value of Rmix,L in the loop reactor varies from 0 to 0.9. And the value of the particle cross-sectional back-mixing ratio ranges from 0.1 to 0.6 in the whole region of the reactor.

Flow Characteristics in a High Temperature Fluidized Bed with Sound Assistance

ZHANG Jian GUO Qing-jie

. 2009, 9(6):  1055-1060. 

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The flow characteristics in a bubbling fluidized bed of 50 mm i.d. and 1000 mm in height under sound excitation at high temperatures were investigated. With Geldart A, B group particles as fluidized materials, the effects of bed temperature, acoustic frequency and the sound pressure level (SPL) on the minimum fluidization velocity were examined in detail. It is demonstrated that the minimum fluidization velocity decreases with increasing temperature. At a given temperature and sound frequency, the velocity decreases with increasing SPL. At the same SPL and temperature, there always exists an optimal frequency range. As the sound frequency increases, the velocity decreases firstly and then increases. Based on the statistical analysis of pressure fluctuation signals, the criterion of influence on the fluidization quality at high-temperature fluidized bed was presented. The experimental results indicate that the pressure standard deviation and the minimum fluidization velocity decreases when the SPL is beyond 110 dB and acoustic frequency between 100~200 Hz.

反应与分离

Extraction of Copper and Ammonia from Cu2+-NH3-Cl--H2O System with Mixture of LIX84 and TBP

LIU Chun-xuan HU Hui-ping HAN Xue-tao LIANG Qi-wen CHEN Qi-yuan

. 2009, 9(6):  1061-1067. 

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With Cu2+-NH3-Cl--H2O solution as ammoniacal solution, the copper extraction rate and ammonia extraction were investigated. The effects of concentration of Tributyl phosphate (TBP) in the organic phase, concentration of copper ion, total ammonia concentration and pH in the aqueous phase, phase ratio and concentration of LIX84 on copper extraction rate and ammonia extraction in the loaded organic phase were studied. The experimental results show that with the increase of TBP concentration in LIX84, copper extraction rate had little effect, while the ammonia extraction in the organic phase significantly decreased. When the copper concentration in the aqueous phase and total ammonia concentration were 25 g/L and 3 mol/L, respectively, the pH of aqueous phase was 9.1. The solvent extraction with 40%(j) LIX84 adding 0.1 mol/L TBP in the organic phase and a phase ratio of 1:1 in 30 min of contact resulted in 81% of copper extraction rate and 85 mg/L of ammonia extraction in the loaded oil phase, while the copper extraction rate and ammonia extraction in the loaded organic phase in the absence of TBP were 81% and 260 mg/L, respectively.

Permeation Property of Trace Water in the Chloromethanes through NaA Zeolite Membrane Simulated by Maxwell-Stefan Theory

YAN Shi-wei WANG Jin-qu ZHOU Zhi-hui YANG Jian-hua CHANG LI-feng; MIAO Qian;

. 2009, 9(6):  1068-1073. 

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High quality NaA zeolite membrane was prepared secondary hydrothermal synthesis using hot dip-coating seeding and studied for the removal of trace water from chloromethanes by vapor permeation. The NaA zeolite membrane showed an excellent separation selectivity of water over chloromethanes as high as 74831, the water content of product decreased from 0.2582%(w) to 0.005%(w). The observed water permeation dependencies of pressure and temperature were simulated by Maxwell-Stefan approach. There was good agreement between the simulated and observed results. It reveals that water vapor permeation is governed by surface diffusion, and the adsorption isotherm of water is Langmuir type, the adsorption water plays an important role in the water permeation flux. Furthermore the calculated adsorption enthalpy of water was -34.15 kJ/mol.

Preparation of Cationic Sawdust Cellulose and Its Adsorption to 2,4-Dichlorophenol in Aqueous Solution

QIAN Xiao-rong WANG Lian-jun SHAO Rong MAO Ai-rong

. 2009, 9(6):  1074-1079. 

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Sawdust cellulose was modified by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) as etherizing agent and the resulting products were characterized. The effects of amount of cation sawdust cellulose, pH, adsorption temperature and adsorption time on adsorption rate of 2,4-dichlorophenol (2,4-DCP) in aqueous solution were discussed. The results showed that the preparation conditions of cation sawdust cellulose were mass ratio of CTA/MC 2.0, reaction time 2.0 h, reaction temperature 30℃, and mass fraction of sodium hydroxide solution 30%. The optimum adsorption conditions for 2,4-DCP were pH 8.0, adsorption time 90 min, adsorption temperature 25℃. When 100 mL 2,4-DCP solution (50 mg/L) was treated at those optimum adsorption conditions, the adsorption rate could reach 88.92%, and the adsorption capacity 1.482 mg/g. After the sawdust cellulose was modified, the chemical adsorption existed in the adsorption process for 2,4-DCP in aqueous solution, and its adsorption capacity for 2,4-DCP in aqueous solutions was obviously improved.

Selective Oxidation Behavior of Chlorides Produced by Chlorination of Chalcopyrite Concentrate

FU Nian-xin Iwasaki Iwao Tamagawa Takeo Kobayashi Mikio

. 2009, 9(6):  1080-1084. 

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The selective oxidation behavior of chlorides produced by chlorination of chalcopyrite concentrate was studied using a fluidized bed reactor. Balance among reaction temperature, flow rate of the carrier gas N2, O2 concentration, feed rate and percent sulfur in the chlorides has to be adjusted for satisfactory fluidization. Although the particles of raw materials do not frit at higher temperatures (390~410℃), more chlorides are vaporized. The fritting of particles readily occurring at a lower temperature (350~360℃) can be avoided by employing the raw materials with lower sulfur content, and raising N2 flow rate and O2 concentration. The reason for that the particles are ready at fritting in the process of oxidation is the formation of a low-melting-point eutectic mixture due to its containing of few CuCl and FeCl3 in the raw materials. In order to overcome the fluidized bed fritting, it is critical to have the chlorinated products dispersed as soon as possible in the oxidizing particles and quickly oxidized to form an out layer of Fe2O3. Using the raw materials with lower sulfur content can avoid overheating and fritting of the fluidizing bed due to highly exothermic oxidation and chlorination reactions of more residual sulfides.

Hydroxylation of Benzene by Mimetic Enzyme of Iron Complexes

ZHOU Shi-lin ZOU Feng GU Ying-ying

. 2009, 9(6):  1085-1089. 

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The mimetic enzymes of iron complexes were found to be very good catalysts for one-step benzene hydroxylation to phenol. [FeIII(EDTA)]- performed the most excellent catalytic activity among the mimetic enzyme catalysts tested in this work. Molecular oxygen and ascorbic acid were used as oxidant and reductant, respectively, in this reaction. The phenol yield and selectivity were obtained as high as 15.8% and 100%, respectively. The effects of some reaction conditions, such as oxygen pressure, reaction temperature and time, on the benzene hydroxylation were investigated. And the kinetics and mechanism of benzene hydroxylation were also studied. In the presence of reducing agent, molecular oxygen could be activated to hydroxyl radical over [FeIII(EDTA)]-.

Adsorption of Phenol from Aqueous Solution with Carbonate Hydroxylapatite

TANG Wen-qing ZENG Rong-ying FENG Yong-lan LI Xiao-ming ZENG Guang-ming YU Run-lan

. 2009, 9(6):  1090-1094. 

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The adsorption of phenol from aqueous solution by carbonate hydroxylapatite (CHAP) synthesized using abandoned eggshell and urea was studied, and CHAP characterized by FT-IR, SEM and EDS. Influential factors of adsorption performance were investigated, such as pH value, adsorption period, phenol initial concentration and temperature from aqueous solution. The results showed that adsorption capacity for phenol was better at pH=3~5 and pH=9~10 from aqueous solution. The equilibrium adsorption data could be described by the Langmuir and Freundlich isotherm models. The first-order and pseudo-second-order kinetic models provided the better correlation of the used experimental data.

Adsorption of Methylene Blue onto Activated Sepiolite

WANG Liang CHEN Meng-lin HE Xing-cun HUANG Zhi

. 2009, 9(6):  1095-1098. 

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Sepiolite was activated by sulfuric acid, heat and sulfuric acid-heat methods. The adsorption of methylene blue on the modified sepiolite samples was investigated. The pore size and volume of these samples were characterized. The results showed that the sulfuric acid-heat activation method has the best effect in three methods, the adsorptive capacity of modified sepiolite reached 41 mg/g, up by 47.8%. The Langmuir equation could be adaptable to the adsorption isotherm process. The pore size and pore volume of sepiolite activated by acid-heat method reached 9.74 nm and 7.064′10-2 cm3/g, up by 117% and 92.6% respectively. The adsorption mechanism of methylene blue was also studied.

Adsorption Mechanism of Heavy Rare Earth by Cyanex272 Impregnated Resin

JIAO Yun-fen LIAO Chun-fa NIE Hua-ping JIANG Ping-guo LIANG Yong

. 2009, 9(6):  1099-1102. 

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Through the methods of saturation, equivalent molarity and slope, the experimental results showed that the extraction ratio for Cyanex272 resin approached 3 and chlorine ions did not take part in the coordination reaction. The results by infrared spectroscopy also showed that Cyanex272 was single-polymer in extraction chromatography by which the amount of extractant was less than double-polymer in solvent extraction. The extracted compound was determined as REA3. The adsorption-extraction mechanism by Cyanex272 could be expressed as RE3+(a)+3HA(r)=REA3(r)+3H+(a).

过程与工艺

Preparation of Complex of L-Histidine Calcium with Cation Exchange Resin

GAN Lin-huo WENG Lian-jin　 CHEN Jin-he

. 2009, 9(6):  1103-1108. 

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The complex of L-histidine calcium was prepared with D151 and 110 cation exchange resins. The calcium exchange capacities and exchange kinetic curves at 26℃ with the resins were measured. And the effects of temperature, molar ratio of NaOH to L-histidine, concentration of L-histidine, and quantity of resin on calcium exchange process were determined. The results show that calcium exchange capacities of D151 and 110 resins were 1.12 and 2.59 mmol/g, the exchange process was quick, and calcium exchange process exothermic, so industrial process could be carried out at room temperature or low temperature. The proper molar ratio of NaOH to L-histidine was (1~1.25):1, the proper concentration and resin quantity of D151 cation exchange resin were 0.46 mol/L and 0.125 g/mL or so, and those of 110 resin were 0.4 mol/L and 0.15 g/mL or so.

Treatment of Arsenic-containing Wastewater by Potassium Ferrate

JIANG Guo-min WANG Yun-yan CHAI Li-yuan SHU Yu-de WANG Qing-wei CHEN Run-hua

. 2009, 9(6):  1109-1114. 

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Equilibrium equations and principle of thermodynamics were derived and investigated on oxidization of trivalent arsenic by ferrate. It was considered that the trivalent arsenic was oxidized by ferrate via the direct oxygen transfer from ferrate. Arsenic-containing wastewater (100.0 mg/L) was treated by oxidation-flocculation process with ferrate, and the effects of Fe/As mass ratio, pH value, temperature and reaction time on removal rate of arsenic were studied. The results show that the optimum conditions were Fe/As mass ratio of 3, pH value of 5~7, temperature of 25℃ and oxidation time of 30 min. The concentration of treated arsenic-containing wastewater was lower than 10 mg/L, which qualifies health standard for domestic drinking water (GB5749-2006).

Photocatalytic Degradation of Omethoate with Iron Doped Nanometer TiO2

FU Min WANG Jian-wei GAO Kun; WU Si-wei

. 2009, 9(6):  1115-1120. 

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Titanium dioxide sol was synthesized by sol-gel method with adulteration of Fe(NO3)3×9H2O. The samples were characterized by XRD, DTA-TG and UV-Vis. The results show that the diameter of particles is 17.5 nm and pure anatase. From the UV-Vis spectra the absorption edge of iron-doped titania has a red shift and the absorption intensities are increased. The degradation rate of omethoate reaches 85.23% when the dosage of photocatalyst is optimally 0.2 g/L, pH=8.6 and 2.5 h illumination with high-voltage mercury lamp. The photocatalytic degradation kinetics follows the pseudo-first order reaction.

Dissolution Kinetics of P and Mg in Phosphate Tailings with High Magnesium Content in Sulfuric Acid

HUANG Fang WANG Hua LI Jun-qi CHEN Yi WANG Zheng

. 2009, 9(6):  1121-1126. 

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The dissolution kinetics of phosphate tailings with high magnesium content in sulfuric acid was studied. The effects of reaction temperature and sulfuric acid concentration on acid digestion process of P and Mg were discussed. The Drozdov equation taking into account of the self-impeding effect was selected to simulate the dissolution kinetics of P2O5 and MgO. The results showed that reaction rate constant k changed with reaction temperature and sulfuric acid concentration, and retardancy coefficient b of MgO was higher than that of P2O5. Activation energy of P2O5 dissolution was 14.881 kJ/mol and that of MgO 11.908 kJ/mol, the effects of phase and morphology of solid film on dissolution of P and Mg were important, which indicated that the reactions of tailing dissolved by sulfuric acid were controlled by diffusion.

Reclamation of Wastewater Containing Phenol and Sodium Sulfate Generated by Sebacic Acid Production

ZHOU Quan XU Hang WANG Guang-run WANG Jin-fu

. 2009, 9(6):  1127-1131. 

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The wastewater containing phenol and sodium sulfate was treated by evaporation method. The results show that when the initial pH value is under 10, the evaporation rate of phenol reaches 34%, and phenol is not evaporated when the pH value in solution is above 13. The powder of Na2SO4 is yellow under alkali condition and the chromaticity is the deepest at pH 12.8. There are some technologies to eliminate the color of Na2SO4, e.g calcination in air circumstances or evaporation in N2 circumstances. Phenol evaporation process is insignificantly affected by solid sodium sulfate.

Precipitation Enhancement of Pseudoboehmite from Seeded Sodium Aluminate Solution under Subpressure Condition

HU Yu-zhen CAI Wei-quan ZHANG Jie YANG Wen-yong

. 2009, 9(6):  1132-1136. 

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Based on decomposition of seeded sodium aluminate solution under certain subpressure for preparing pseudoboehmite, the effects of hydrothermal time, caustic ratio (molar ratio of Na2O to Al2O3), seed ratio (mass ratio of seed to Al2O3 in sodium aluminate solution), precipitation cycle number and degree of subpressure on the precipitation yield of Al2O3, and crystal structure and textural properties were studied. The results showed that subpressure condition could remarkably intensify precipitation of pseudoboehmite from seeded sodium aluminate solution without changing its basic crystal structure. However, the obtained pseudoboehmite had lower pore volume and specific surface area than seed. Under the conditions of 120 g/L Al2O3, seed ratio of 1.0, caustic ratio of 1.3 and 125℃, about 46.0% precipitation yield of Al2O3 was obtained with hydrothermal time of 0.5 h by changing degree of subpressure from 0.01 to 0.09 MPa, while it was only about 33.4% under atmospheric pressure. Furthermore, the precipitation yield of Al2O3 ranged from 41.0% to 44.0% during the 1st to 3rd precipitation cycle, indicating that the precipitation activity of the seed was stable.

Thermodynamic Analysis and Experimental Study on Reduction of Mg from Magnesite with Ferrosilicon

GAO Feng FENG Nai-xiang REN Bao-yi; SUN Huai-yu

. 2009, 9(6):  1137-1141. 

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Based on thermodynamic analysis, the Gibbs free energy and critical temperature of deoxidization of MgO with ferrosilicon were calculated. The analysis showed that the slagging reaction and vacuum could make critical temperature decrease from 3846 K to 1358 K below. Corresponding experimental result showed that Mg metal reduction rate of 94.42% was achieved under the conditions of reduction temperature 1200℃, 10.13 Pa vacuum, and reaction time 1 h in the reactor with a molar ratio of CaO to MgO of 1.4, and pure metallic magnesium (98.36%) was prepared, the main compounds in the slag were Ca2SiO4 and SiO2.

Effect of pH Value on Growth of Desulphurization Gypsum Whiskers

DENG Zhi-yin YUAN Yi-yi SUN Jun SHI Pei-yang JIANG Mao-fa

. 2009, 9(6):  1142-1146. 

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Using desulphurization gypsum as raw material, hydrothermal method was applied to prepare calcium sulfate whiskers and using conductivity, SEM, XRD and high resolution microscope as analysis methods, the growth principle of calcium sulfate under different pH values was explored. The results reveal that with the increase of pH value, the aspect ratio of calcium sulfate whiskers firstly increased and then decreased. When the pH value was 5, the whisker diameter was 1~4 mm, the average length 218.67 mm and the aspect ratio reached the maximum value of 82.57. The change of pH value exerted a direct influence on the existence of impurities, with the increase of pH, SiO2 within the impurities gradually transformed into CaSiO3, and the equilibrium of ions in the solution changed and hence affected the growth tendency of the whiskers in a specific direction.

生化工程专栏

Microwave-assisted Aqueous Two-phase Extraction of Steroidal Saponins in Dioscorea zingiberensis

LIU Lin DONG Yue-sheng XIU Zhi-long

. 2009, 9(6):  1147-1152. 

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Microwave-assisted aqueous two-phase extraction of steroidal saponins in Dioscorea zingiberensis was studied by ethanol/ammonium sulphate system. The results showed that almost all the five main saponins were enriched in the top phase, and the maximum partition coefficients of Zingibernsis newsaponin, deltonin, Diosgenin-triglucoside, Diosgenin-diglucoside and trillin were 89, 91, 93, 117 and 153, respectively. The optimum mass ratio of material to ethanol was 1:21. The optimum system was composed of 25%(w) ethanol and 19%(w) (NH4)2SO4. Under the optimum condition, the yield of total saponins was 95.1%, and the yields of Zingibernsis newsaponin, deltonin, Diosgenin-triglucoside, Diosgenin-diglucoside and trillin were 99.8%, 97.4%, 97.3%, 86.6% and 63.2%, respectively.

Simultaneous Determination of Amino Acids and Inorganic Cations by Ion Chromatography with Direct Conductivity Detection

JIAO Yang YANG Peng-bo LI Chun CONG Wei

. 2009, 9(6):  1153-1158. 

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A simple, rapid and accurate method for simultaneous determination of six amino acids (glutamic acid, alanine, methionine, leucine, phenylalanine and lysine) and five inorganic cations (Na+, NH4+, K+, Ca2+ and Mg2+) was developed. The quantitative determination of these ions was accomplished by ion chromatography with direct conductivity detection based on their ionization in acidic medium without chemical suppression and derivatization. In a single chromatographic run, the five amino acids (glutamic acid, alanine, methionine, leucine and phenylalanine) and three inorganic cations (Na+, NH4+ and K+) were separated and determined within 12 min. The relative standard deviation (RSD, n=5) was less than 4.690%. The detection limits calculated were in the range from 0.27 to 10.34 mg/L. All the correlation coefficients (R2) of these ions were not less than 0.9984. The recovery rates of some amino acids in isoelectric supernant of monosodium glutamate were in the range from 88.7% to 107.2%.

Determination of Molecular Weight of Sodium Cellulose Sulfate by Low Angle Laser Light Scattering

WANG Ming-jun YAO Shan-jing

. 2009, 9(6):  1159-1163. 

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Molecular weight (Mw) of sodium cellulose sulfate (NaCS) was determined by using low angle laser light scattering in this work. The Mw values of three samples with the degree of substitution 0.28, 0.40 and 0.73 were 879.8, 593.5 and 226.9 kDa respectively. The effects of different salts and their concentrations on determination of Mw were also investigated. When the concentration of salts was in the range of 0.05~0.075 mol/L, the accuracy of determination was better. However, when the concentration was lower than 0.05 mol/L, accurate result was obtained hardly, and in this range, the molecules of NaCS were in expanded state and the viscosity of NaCS varied dramatically.

Separation and Immobilization of Protein on Macroporous Polystyrene Chromatography Microspheres

QU Rui-fang KONG Ying-jun QU Jian-bo MA Guang-hui; SU Zhi-guo SU Zhi-guo; LUO Jian;

. 2009, 9(6):  1164-1168. 

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Macroporous polystyrene microspheres with pore diameters between 300~500 nm were modified with hydrophilic agarose, and the hydrophilic surface was then immobilized with virus protein particles for protein purification experiments. The results showed that the modified macroporous polystyrene microspheres had excellent hydrodynamic characteristics, with a working flow rate as high as 1120 cm/h. The protein separation time was also greatly reduced compared with a commercially available agarose medium. The virus protein particle coupling capacity of 0.638 mg/g was about two times of commercially agarose medium. A recovery rate of 29.22% was achieved using RV-MPS medium, higher than 18.92% using commercially agarose medium.

Investigation on Site-specific PEGylation of Glucagon-like Peptide-1

ZHANG Lei ZHAI Yan-qin LEI Jian-du MA Guang-hui SU Zhi-guo

. 2009, 9(6):  1169-1173. 

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In order to obtain a more stable PEGylated glucagon-like peptide-1, and prolong its half life, glucagon-like peptide-1 was site-specifically modified with monomethoxy polyethylene glycol succinimidyl carbonate (mPEG-SC, 5000 kDa). It was found that the optimized reaction conditions for maximized bioactivity and the highest modification yield of mono PEGylated GLP-1 were as follows: in 50 mmol/L and pH 7.5 phosphate buffer, concentration of GLP-1 1.0 mg/mL, molar ratio of PEG to GLP-1 2:1, and reaction time 1 h at 4℃. Under the optimized conditions, the mono modification yield reached 50%. Reverse phase high performance liquid chromatography was used to separate and purify mono PEGylated GLP-1 from the reaction mixture. The purity of mono PEGylated glucagon-like peptide-1 was higher than 98%, characterized by gelfiltration chromatography, the bioactivity of mono PEGylated glucagon-like peptide-1 was 86% of the native GLP-1, while its half life in Sprague-Dawley rats was much longer than that of native GLP-1. The mono PEGylated glucagon-like peptide-1 was also stable in aqueous solution.

Optimization of Cofermentation of Glucose and Xylose for Sythesis of 2,3-Butanediol

ZHANG Gen-lin DENG Hui LU Jian-jiang SUN Shou-ling LI Chun

. 2009, 9(6):  1174-1177. 

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The production conditions of 2,3-butanediol by Klebsiella pneumoniae XJ-Li from glucose and xylose were optimized, and the regulation methods for 2,3-butanediol fermentation were also determined based on the metabolic features of hexose and pentose. The results displayed that suitable culture conditions were defined as glucose of 60 g/L, xylose of 40 g/L, ammonium dihydrogen phosphate of 5.75 g/L and pH of 5.5, and the concentration of 2,3-butanediol reached 19.24 g/L under the conditions when the strain was cultured at 38℃. The yield of 2,3-butanediol was increased by 16.4% after maintaining the pH about 5.5 in the fermentation process. And 60 mg/L of vitamin C was added into medium to regulate the redox state of system, which made the yield of 2,3-butanediol improved by 44.3% of 2,3-butanediol fermentation. 33.47 g/L of 2,3-butanediol was obtained in batch fermentation for 48 h under optimum culture conditions.

材料工程专栏

Preparation and Performance of Supported Iron-based Catalysts for Conversion of Synthesis Gas to Light Olefins

SHEN Xing WANG Lei ZHANG Yong-feng LI Zeng ZHANG Xiang-ping ZHANG Suo-jiang

. 2009, 9(6):  1178-1185. 

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The supported iron-based catalysts for the conversion of synthesis gas to light olefins were prepared by impregnation method and the effects of parameters, such as carrier, promoter, calcination temperature, reaction temperature, reaction pressure and space velocity, on the reaction were investigated in a fixed-bed reactor. The catalysts were characterized by XRD, N2 physisorption, thermo gravimetric analysis and Raman spectroscopy. The results indicated that FeK/ZSM-5 catalyst prepared by calcination at 500℃ after 3 h had the best catalytic activity. Increasing reaction pressure and decreasing space velocity, the activity of catalyst was all obviously improved. Using ZSM-5 as the carrier, the comparable catalytic performance of adding K and Mn promoters were studied. The results showed that FeMnK/ZSM-5 catalyst improved the CO conversion rate from 18.7% to 63.8%, and C2=~C3= selectivity from 4.8% to 14.1% contrast to Fe/ZSM-5 catalyst under the conditions of volume ratio of H2 to CO2, reaction temperature 380℃, reaction pressure 1.0 MPa and space velocity 4400 h-1.

Preparation of Nano-sized Gold-doped TiO2 Catalyst and Its Performance for Selective Oxidation of Cyclohexane at Low Temperature

WANG Ya-qing ZHOU Ji-cheng YANG Xiao-feng

. 2009, 9(6):  1186-1191. 

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Nano-sized Au clusters were deposited into the inner or outer surface of titania-modified MCM-41 by photodeposition method. The prepared samples were characterized by XRD, N2 adsorption isotherm, TEM and EDS. Their catalytic performance for oxidation of cyclohexane was investigated under mild conditions. The results showed that all the MCM-41support of prepared catalyst samples had high crystallinity and the size of gold particles was about 10 nm. The complex nano-sized gold catalysts exhibited high catalytic activity at low-temperature，due to the synergistic effect of nano-sized gold and photocatalysis for oxidation of cyclohexane. The catalytic performance of the prepared samples for the selective oxidation of cyclohexane under mild conditions using molecular oxygen in a solvent-free system was investigated. The conversion rate of cyclohexane was 3.9% and the total selectivity of purposed products 90.2% under the conditions of 100℃, 1.0 MPa and illumination by 250 W UV-lamp for 8 h.

Low-temperature Selective Catalytic Reduction of NO with NH3 over Mn-Fe-Ce/TiO2

GUO Feng YU Jian ZHU Jian-hong LIU Yun-yi XU Guang-wen

. 2009, 9(6):  1192-1197. 

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Manganese-iron-cerium-titania oxide (MnO2-Fe2O3-CeO2/TiO2) catalysts were prepared with impregnation method and tested for selective catalytic reduction of NO with ammonia at about 200℃. The catalysts were characterized by XRD, FT-IR, TGA and FE-SEM. The denitration activity and inhibition effect of steam were studied at varied contents of Mn, Fe, Ce and calcination temperatures. The results demonstrated that their low temperature activity was subject to an order of MnO2-Fe2O3-CeO2/TiO2> MnO2-Fe2O3/TiO2>MnO2/TiO2. The achieved best performance was over a catalyst of MnO2(10)-Fe2O3(5)-CeO2(5)/TiO2 calcined at 350℃. The realized NO conversion rate was over 95% at 200℃ at GHSV=24000 h-1, NH3/NO=0.8(j) and with 3%(j) O2. NO conversion rate was reduced to 87% with 10%(j) steam in the flue gas and to 55% when 100′10-6 SO2 was further included into the gas.

Preparation and Characterization of Pt/C Catalysts Stabilized by Ethylene Glycol

WU Feng LIU Yan-hong WU Chuan

. 2009, 9(6):  1198-1203. 

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Pt/C catalysts with narrow size distribution and high dispersion were prepared by NaBH4 and ethylene glycol (EG) reduction methods, separately, using EG as both the solvent and stabilizing agent. Their morphology, composition, structure and electrochemically active specific surface area (ECSA) were characterized and compared. Electrocatalytic activities of the two catalysts for oxidation of methanol or ethanol were tested. The two catalysts present narrow size distribution, high dispersion, face centred cubic structure of Pt, and comparative Pt-mass based activities for electro-oxidation of methanol and ethanol. The Pt/C catalyst prepared by NaBH4 reduction method has more metallic Pt (Pt0) and more crystal face Pt (220), its Pt electrochemical surface area (Pt ECAS) based anodic peak current densities for methanol and ethanol oxidations are 0.68 and 0.67 mA/cm2, 1.2 times higher than those of the Pt/C catalyst prepared by EG reduction method, respectively. Their electrocatalytic activities for methanol and ethanol are comparable with those of commercial E-TEK catalysts.

Synthesis and Dispersive Properties of the Acrylic Acid-based Copolymer Dispersant

CHEN Jun REN Tian-rui YU Song-rui SUN Jin-feng WANG Li-dong WU Ya-kun

. 2009, 9(6):  1204-1209. 

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The copolymer dispersants were synthesized with acrylic acid, styrene sulfonic sodium and 3-hydroxypropyl acrylate as monomers through the orthogonal experiments. The molecular weights of dispersants were determined, and the best dispersant was chosen out based on the suspension rates of the granules. The influences of temperature, pH, NaCl concentration and dispersant concentration on the suspension rate of BaSO4 granules were studied with the best dispersant. Sedimentation speed of BaSO4 particles was determined as well as the dispersant adsorption. The adsorption increased with increasing copolymer concentration in a Langmuirian mode and reached a plateau at the concentration of 4 g/L. Size distribution of the particles was analyzed. The average particle size in the presence of the polymer was less than that in the absence of the polymer. Using synthesized dispersant, well-dispersed suspension of BaSO4 could be achieved. The suspension rate of BaSO4 granules was 99.18% with 0.4 g dispersant when pH and temperature were 7 and 20℃ respectively. At the same condition, the average diameter of BaSO4 particles was about 350 nm and the clear liquid volume above was only 2% after 6 h standing.

Preparation and Properties of Magnetic Zeolite

YUAN Ming-liang TAN Mei-yi YAN Guan-jie TAO Jia-hua

. 2009, 9(6):  1210-1215. 

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Magnetic zeolite was hydrothermally synthesized with a hydrothermal method by adding magnetic core in the zeolite synthesis system. The products were examined with X-ray diffractometer, transmission electron microscope, vibrating sample magnetometer, N2 adsorption apparatus, thermogravimetric and differential thermogravimetric instruments. The results show that the magnetic zeolite has an X-type zeolite structure. The product has good magnetic property and adsorption property. The saturation magnetization is about 3.7 emu/g. Magnetic zeolite can be separated from mother liquid by a magnet within 30 min. The BET specific surface area is about 517.5 m2/g and the adsorption capacity of Pb2+ about 196.8 mg/g.

Preparation and Corrosion-resistant Property of Mesoporous ZrO2 Membrane

QI Hong; JIANG Xiao-luo; HAN Jing; FAN Yi-qun XING Wei-hong

. 2009, 9(6):  1216-1221. 

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Preparation and characterization of mesoporous ZrO2 membrane with the pore sizes less than 10 nm were studied. A stable ZrO2 sol with a mean particle size about 100 nm was successfully synthesized with zirconium n-propoxide as precursor through a colloidal sol-gel route. PVA was selected as the drying chemical controlling additive to modulate the viscosity of sol suitable for membrane formation. Y(NO3)3×6H2O was used as a Y-precursor to form Y-stabilized ZrO2. Defect-free mesoporous ZrO2 membrane superimposed on a-Al2O3 support disk with a mean pore size of 70 nm was fabricated via dip-coating and subsequently calcined in the temperature range of 450~650℃. The effect of calcination temperature on the properties of unsupported ZrO2 membrane (powder) as well as the supported ZrO2 membranes was studied in detail. The molecular weight cut off (MWCO) and mean pore size of mesoporous ZrO2 membrane were in the range of 19500~62600 and 7.3~13 nm, respectively. The optimized membrane with an average pore size of 7.3 nm showed a MWCO value of 19500 after heat treatment at 450℃. The corrosion resistance of ZrO2 membrane showed a relative high stability, as proved by the variation of MWCO of PEG after the membrane was treated with HNO3 and NaOH.

Influence of Methylhydrosiloxane on Ammonium Dihydrogen Phosphate Fire-extinguishing Powder in Spray-drying Process

ZHANG Xiao-jing SHEN Zhi-gang FU Xian-hui CAI Chu-jiang ZHENG Yan-hong

. 2009, 9(6):  1222-1226. 

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Superfine spherical fire-extinguishing powder, ammonium dihydrogen phosphate, was prepared using spray-drying, and modified in situ with silicon oil emulsion and fluorocarbon surfactant FK-510. The influences of methylhydrosiloxane dosage on activation index, surface element, surface morphology, dispersion and particle size distribution of ammonium dihydrogen phosphate were studied. The results indicate that methylhydrosiloxane and FK-510 congregates on the particle surface, with FK-510 outermost and methylhydrosiloxane second outer, which improves particle hydrophobicity and bring fine dispersion. When methylhydrosiloxane dosage is 3%(w) of ammonium dihydrogen phosphate, powder activation index reaches 93.7%, and powder gets nicer hydrophobicity, dispersion and sphericity, so it is the optimal dosage of surfactant.

Synthesis of Ni-Zn Ferrite by Sol-Gel Method and Its Electromagnetic Loss Property

LIU Shu-xin WANG Hai-bin LUO Juan HUO Ji-chuan YAO Xiao-xia

. 2009, 9(6):  1227-1231. 

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NixZn1-xFe2O4 ferrite was synthesized by sol-gel method with Zn(NO3)2×6H2O, Ni(NO3)2×6H2O and Fe(NO3)3×9H2O and C6H8O7·H2O as raw materials. The product was characterized and analyzed. The results indicated that all the products were single phase of cubic crystal system spinel structure ferrite and all the crystals were crystallized with good integrality. The size of particles was about 100 nm. Electromagnetic loss property of the sample was tested. The results indicated that Ni0.7Zn0.3Fe2O4 and Ni0.5Zn0.5Fe2O4 had a better magnetic loss property than Zn2Fe2O4 and Ni0.3Zn0.7Fe2O4 in 0.2~1.8 GHz. The tgd of Ni0.7Zn0.3Fe2O4 was 0.67~1.59, and that of Ni0.5Zn0.5Fe2O4 0.37~1.51. The electromagnetic loss of Ni-Zn ferrite increased with the increase of Ni content.

Hydrogenation Performance of Lauronitrile over Ni-Cu Supported g-Al2O3 Catalyst

YU Qing-yue WU Wen-liang ZENG Chong-yu

. 2009, 9(6):  1232-1236. 

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A series of Ni-Cu/g-Al2O3 catalysts were prepared by impregnation method. After modification by Na and Cr, the catalysts were characterized by TPD technology using H2 and CO2 as probe molecules to test their hydrogen adsorption abilities and alkali properties. And their catalytic performances were measured in hydrogenation of lauronitrile. The results show that hydrogen adsorption amount of catalyst was enhanced and the alkali nature adjusted observably, while the sample Ni-Cu-Cr-Na/g-Al2O3 owned the most hydrogen adsorption amount as well as the most low temperature alkali scalar. The catalyst Ni-Cu-Cr-Na/g-Al2O3 was provided with the best catalytic abilities of hydrogenation, with conversion rate of lauronitrile 98% and selectivity of primary dodecylamine 99.2% under the optimal reaction conditions of hydrogen fractional pressure 2.0 MPa, reaction temperature 70℃, reaction time 30 min，and stirring speed 600 r/min. The stability tests show that the result reacting for 10 times was conversion rate of lauronitrile 94.8% and selectivity of primary amine kept highly above 98.0%.

Mechanical and Rheological Properties of PC Composite Filled with Modified SiO2 Nanoparticles

WANGPing ZHAO Jian-qing JIANG　Zhi-jie LIU　Yun-chun LIU Shu-mei

. 2009, 9(6):  1237-1241. 

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Modified SiO2 nanoparticles were filled into polycarbonate (PC) by two different methods. In order to enable the inorganic nanoparticles dispersed evenly in the PC matrix, the silane coupling agent KH-550 was used to modify the surface of SiO2 nanoparticles by wet treatment. The relationships between mechanical and processing properties of PC/SiO2 composite and silica content were examined, and product performance characterized. The characteristics of rigid modified inorganic nanoparticles filled on a typical engineering plastic PC were also studied to explore the mechanism of its strength enhancement and the rheological properties of PC/SiO2 composite. The results show that the modified SiO2 spheres had uniform dispersion in PC matrix and PC/SiO2 composite had good tensile strength and rheological effect.

综述

A Review of Microalgae Recovery Technology

LIN Zhe KUANG Ya-li GUO Jin WANG Zhang-guo

. 2009, 9(6):  1242-1248. 

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Base on the characteristics of microalgae culture, different methods for pretreatment and dewatering in microalgae recovery technology have been reviewed, including pre-oxidation, chemical flocculation, physical pretreatment, sedimentation, filtration, centrifugation, foam flotation and air flotation. The results show that the cells release extra organic matters after pre-oxidation which is beneficial to flocculation sedimentation, but excess dosage of oxidant can damage the cells and even make extinction. The efficiency of successor dewatering can be greatly improved after chemical flocculation and physical pretreatment. Due to low concentration of culture and fine particles of microalgae, the problems of low efficiency and high cost may occur while using traditional methods of sedimentation, filtration, centrifugation and so on. However, air flotation is suitable for dewatering of low-concentration suspension system, and it is quite a feasible technology for microalgae recovery.