Korean Journal of Chemical Engineering (v.26, #3)

Dynamics and stability of ethylene polymerization in multizone circulating reactors by Nayef Mohamed Ghasem; Wee Lee Ang; Mohamed Azlan Hussain (603-611).
Multizone circulating bed reactors (MZCR) have the exclusive characteristics of producing polymers of different molecular weights in a single particle. Traditional fluidized bed reactors, on the other hand, can produce only one kind of molecular weight with relatively narrow distribution. A dynamic model for the MZCR is used to illustrate the basic dynamic behavior of the new reactor design used for polyethylene production. The model is used to study the copolymerization of ethylene with butene. Several parameter sensitivity analyses are performed to show the computer-simulated time responses for reactor temperature, number-average molecular weight, weight-average molecular weight, catalyst feed rate and the monomer/comonomer concentration along the reactor length. At certain operating conditions dynamic instability is observed and the results for the effect of cooling water temperature, catalyst feed rate, monomer and comonomer initial feed concentration on the reactor temperature and polymer molecular weight reveal that the system is very sensitive to disturbances in the heat exchanger coolant temperature. Also, at some operating conditions, the reactor temperature oscillates above the polymer melting temperature. Temperature runaway above polymer softening point is a serious problem which may cause polymer melting and hence reactor shutdown. The oscillatory behavior of the reactor temperature necessitates a suitable temperature control scheme to be installed.
Keywords: Polyethylene; Multi Zone Circulating Reactor; Ethylene; Polymerization

A scenario-based robust framework for short-term and long-term operation planning problems by Hong-Rok Son; Jun-Hyung Ryu; Soon-Ki Heo; In-Beum Lee (612-621).
This paper discusses a scenario-based scheme to address process operation problems under variations. As an illustration, two typically encountered problems, a short-term operation planning problem and a long term supply chain planning problem, are investigated considering the effect of variations. Their mathematical programming models explicitly reflecting the variations in the form of multiple scenarios with their probabilities are presented to provide robust decisions in the face of variations. It is hoped that the proposed framework can be a reminder of the importance of the scenario-based approach in the current uncertain business circumstances.
Keywords: Scenarios; Robust; Variation; Scheduling; SCM (Supply Chain Management)

An analytical method for the design of a proportional-integral-derivative (PID) controller cascaded with a second-order lead-lag filter is proposed for various types of time-delay process. The proposed design method is based on the IMC-PID method to obtain a desired, closed-loop response. The process dead time is approximated by using the appropriate Pade expansion to convert the ideal feedback controller to the proposed PID·filter structure with little loss of accuracy. The resulting PID·filter controller efficiently compensates for the dominant process poles and zeros and significantly improves the closed-loop performance. The simulation results demonstrate the superior performance of the proposed PID·filter controller over the conventional PID controllers. A guideline for the closed-loop time constant, λ, is also suggested for the FOPDT and SOPDT models.
Keywords: PID Controller; Lead-lag Filter; IMC-PID Design; Robust Analysis; Lag Time Dominant Process

An approximate procedure for the estimation of operational variables in fully thermally coupled distillation columns (FTCDCs) using two pseudo-pinch points of the feed and side draw trays is proposed, and its performance is examined with two example processes. The estimates from the proposed procedure show some 20% error compared with the results of rigorous simulation using commercial design software, the HYSYS. In addition, the relation between vapor flow rate and composition at one stage above the feed tray-required in the estimation of operational variables of the FTCDC-is analyzed to give information for the selection of the feed tray composition. A preliminary evaluation of operational variables helps to screen unrealizable design obtained often from iterative trial procedures employing the mathematical programming.
Keywords: Distillation Column Design; Thermally Coupled Distillation; Pseudo-pinch Point; Operational Variable Estimation; Multi-component Distillation

Process systems engineering approaches to speed-up the auto-titrator operations by Jietae Lee; Tae Hun Lee; Seungjae Lee; Dae Ryook Yang (636-640).
Acid-base titration is widely used in the fields of chemical engineering, environmental engineering, agriculture, and medical science. The auto-titrator is a commercial apparatus that carries out the titration operation automatically and provides equivalence point data. For some test samples and operating conditions, titration operations require up to 5 minutes. Here, we propose a method to reduce this operation time. For this, process systems engineering approaches such as alternative dosing of titrating and sample solutions, reducing sensor time-constant with a lead-lag filter and parameter identification technique have been applied. Simulations and experimental results with test equipment for auto-titration show the performance of the proposed method.
Keywords: Auto-titrator; pH; Equivalence Point; Titration Curve

Simulation of DME synthesis from coal syngas by kinetics model by Hyun Min Shim; Seung Jong Lee; Young Don Yoo; Yong Seung Yun; Hyung Taek Kim (641-648).
DME (Dimethyl Ether) has emerged as a clean alternative fuel for diesel. There are largely two methods for DME synthesis. A direct method of DME synthesis has been recently developed that has a more compact process than the indirect method. However, the direct method of DME synthesis has not yet been optimized at the face of its performance: yield and production rate of DME. In this study it is developed a simulation model through a kinetics model of the ASPEN plus simulator, performed to detect operating characteristics of DME direct synthesis. An overall DME synthesis process is referenced by experimental data of 3 ton/day (TPD) coal gasification pilot plant located at IAE in Korea. Supplying condition of DME synthesis model is equivalently set to 80 N/m3 of syngas which is derived from a coal gasification plant. In the simulation it is assumed that the overall DME synthesis process proceeds with steadystate, vapor-solid reaction with DME catalyst. The physical properties of reactants are governed by Soave-Redlich-Kwong (SRK) EOS in this model. A reaction model of DME synthesis is considered that is applied with the LHHW (Langmuir-Hinshelwood Hougen Watson) equation as an adsorption-desorption model on the surface of the DME catalyst. After adjusting the kinetics of the DME synthesis reaction among reactants with experimental data, the kinetics of the governing reactions inner DME reactor are modified and coupled with the entire DME synthesis reaction. For validating simulation results of the DME synthesis model, the obtained simulation results are compared with experimental results: conversion ratio, DME yield and DME production rate. Then, a sensitivity analysis is performed by effects of operating variables such as pressure, temperature of the reactor, void fraction of catalyst and H2/CO ratio of supplied syngas with modified model. According to simulation results, optimum operating conditions of DME reactor are obtained in the range of 265–275 °C and 60 kg/cm2. And DME production rate has a maximum value in the range of 1–1.5 of H2/CO ratio in the syngas composition.
Keywords: DME Synthesis; Coal Syngas; Kinetics; ASPEN Plus

The effect of phase transition of methanol on the reaction rate in the alkylation of hydroquinone by Jung Je Park; Soo Chool Lee; Sang Sung Lee; Suk Yong Jung; Soo Jae Lee; Jae Chang Kim (649-653).
An O-alkylation reaction of hydroquinone with excess methanol was carried out by using alkaline metal ion-exchanged zeolite catalysts at various phases of methanol in a slurry type reactor. The amount of methanol, used as a methylating agent and also a solvent, significantly affected the reaction rate. When the amount of methanol was decreased from 2 mol to 0.6 mol, the reaction rate was increased more than nine times. These changes in the reaction rate could be explained by the pressure change and the phase transition of the reactant, methanol, depending on the temperature and the elimination of a diffusion limitation of reactants through the zeolite pores in a gas phase condition. Thus, higher than 89% selectivity to 4-methoxyphenol was obtained at 80% conversion of hydroquinone at a gas phase reaction condition using 1 mol of methanol for 2 hours.
Keywords: Alkylation; Hydroquinone; Methanol; Phase Transition

Oxidation of cyclopentene catalyzed by tungsten-substituted molybdophosphoric acids by Jinjuan Xue; Hengbo Yin; Haixia Li; Dongzhi Zhang; Tingshun Jiang; Longbao Yu; Yutang Shen (654-659).
A series of Keggin type tungsten-substituted molybdophosphoric acids (H3PMo12−n W n O40·XH2O) were synthesized and characterized by ICP-AES, FT-IR, TG-DSC, and XRD. The tungsten substitution extent significantly affected their catalytic activity in the oxidation of cyclopentene and the selectivity of the resultant products. The tungsten-substituted molybdophosphoric acids with tungsten substitution numbers in a range of 3–6.8 exhibited high catalytic activity in the oxidation of cyclopentene. After reaction for 8 h, the conversion of cyclopentene was up to 97%; the oxidation products mainly consisted of glutaraldehyde, cis-1,2-cyclopentanediol and trans-1,2-cyclopentanediol with the yields of ca. 23%, 27%, and 45%, respectively.
Keywords: Tungsten-substituted Molybdophosphoric Acid; Cyclopentene; Glutaraldehyde; cis-1,2-Cyclopentanediol; trans-1,2-Cyclopentanediol

Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA-15 and polypyrrole as a templating agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site for the immobilization of [PMo10V2O40]5−. By taking advantage of the overall negative charge of [PMo10V2O40]5−, H5PMo10V2O40 (PMo10V2) catalyst was chemically immobilized on the N-MC support as a charge-matching component. Characterization results showed that nitrogen in the N-MC played an important role in forming a nitrogen-derived functional group (amine group), and PMo10V2 catalyst was finely and chemically immobilized on the nitrogen-derived functional group of N-MC support. In the vapor-phase selective conversion of methanol, the PMo10V2/N-MC catalyst showed a higher conversion of methanol than the bulk PMo10V2 catalyst. Furthermore, the PMo10V2/N-MC catalyst showed a higher selectivity for dimethoxymethane (a product formed by bifunctional oxidation-acid-acid catalysis) and a higher selectivity for methylformate (a product formed by bifunctional oxidation-acid-oxidation catalysis) than the PMo10V2 catalyst. Reaction pathway for selective conversion of methanol to dimethoxymethane over PMo10V2/N-MC catalyst could be controlled by changing the methanol feed rate.
Keywords: Heteropolyacid; Nitrogen-containing Mesoporous Carbon; Chemical Immobilization; Selective Conversion of Methanol; Dimethoxymethane

Reactivity of Brönsted acid ionic liquids as dual solvent and catalyst for Fischer esterifications by Zuojun Wei; Feijin Li; Huabin Xing; Shuguang Deng; Qilong Ren (666-672).
Several water-stable ionic liquids with different acidity and affinity were synthesized and applied as both solvents and acid catalysts for Fischer esterification of ethanol reacting with four aliphatic carboxylic acids (acetic acid, n-hexanoic acid, lauric acid, and stearic acid). Among the studied ionic liquids, [(n-bu-SO3H) MIM][HSO4] (3-butyl-1-(butyl-4-sulfonyl) imidazolium sulfate) and [(n-bu-SO3H) MIM][p-TSO] (3-butyl-1-(butyl-4-sulfonyl) imidazolium toluenesulfonate) show higher reactivity for the production of ethyl esters. The catalytic activities of these ionic liquids are strongly dependent on the acidity of their anions and cations, as well as their hydrophilicity and affinity with the reactants. Water refluxing through the condenser may be another important reason for obtaining high conversion of esterification, indicating a water-sequester process is still needed in order to obtain a higher yield of ester in the ionic liquid catalyzed esterification system. Kinetics studies show the conversions of the acids increase with reaction temperature and time, and reach equilibrium within about two hours. The apparent activation energies are 39.1±2.0, 49.7±2.5, 51.4±2.5 and 59.3±3.0 kJ·mol−1 for the formation of ethyl acetate, ethyl n-hexanoate, ethyl laurate and ethyl stearate, respectively.
Keywords: Brönsted Acid Catalyst; Ionic Liquid; Fischer Esterification; Reaction Kinetics; Water Content

The electrophotographic properties of a negatively charged double-layered photoconductor that consisted of y-type metal phthalocyanine (TiOPc) and x-type metal-free phthalocyanine (H2Pc) composites were studied. The undercoating layer (UCL) was fabricated by a dip-coating method with Al2O3 and polyamide, and the charge transport layer (CTL) was prepared from N,N′-Bis-(3-methylpenyl)-N,N″-bis-(phenyl)-benzidine (TPD), polycarbonate (PC), and polyester (PE). In the charge generation layer (CGL), the dispersion state becomes more homogeneous with increasing amounts of non-metal phthalocyanine (H2Pc). The electrophotographic properties of the photoconductor were obtained by using photo-induced discharge curves (PIDC) of charge acceptance, dark decay, photosensitivity, and photofatigue. It was found that the initial charge potential was not dependent on the compositional ratio of the charge generating material. However, the dark decaying rates and the photosensitivity were proportional to the content of TiOPc in the organic photoconductors.
Keywords: Photoconductor; Phthalocyanine; Dip-coating; Charge Generation Layer; Charge Transport Layer

Effects of curing condition of solution cast Nafion® membranes on PEMFC performance by Singaram Vengatesan; Eunae Cho; Hyoung-Juhn Kim; Tae-Hoon Lim (679-684).
To study the feasibility of applying solution-cast membranes to polymer electrolyte membrane fuel cells (PEMFCs), single cells prepared with solution-cast membranes were tested. The solution cast membranes were fabricated from a commercial Nafion solution under various conditions. Effects of annealing temperature on characteristics of the solution-cast membranes were investigated by measuring water uptake and ionic conductivity of the membranes. Performance of the single cells using the prepared solution cast membranes was evaluated in terms of i-V curves, Nyquist plots, and H2 crossover current density. Based on the results, solution-cast membranes were fabricated by being cured at 150 °C for different hours to examine effects of curing time on cell performance. Finally, durability of solution-cast membranes was investigated with operating the single cells for 1,000 hr.
Keywords: Solution-cast Membrane; Polymer Electrolyte Membrane Fuel Cell; Curing Temperature; Curing Time; Performance

This study was conducted by combining fluorescence in situ hybridization (FISH) performed on 16S rRNA and polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) with 16S CTOs primers to characterize the nitrifying microbial communities in biofilm processes, which were tested to retrofit the S municipal wastewater treatment plant in Busan, Korea. Four aerophilic biofilm reactors were operated with hydraulic retention times of 2 to 8 h and biofilms were grown on ceramic media. The same low COD/ NH 4 + -N ratio (100 mg/L of COD over 40 mg/L of NH 4 + -N) with the S plant was used. The average relative population ratios of Nitrosomonas spp. to ammonia oxidizing bacteria (AOB) as measured by specific FISH probes (%/Nso190) were 75.0%, 80.0%, 73.0% and 73.5%, respectively, while those of Nitrosospira spp. to AOB were 21.0%, 14.7%, 24.6% and 24.1% after 180 days of operation. The microbial composition of Nitrobacter spp. detected by using a Nit3 probe was below 10% in each reactor. In contrast, Nitrospira genus detected with an Ntspa662 probe was around 20%. When CTOs primer was applied in PCR-DGGE analysis to define the nitrifying bacteria, the bands of group B in the R-1 reactor with the highest hydraulic retention time (HRT) had the strongest light intensity compared with two other reactors with lower HRTs after day 64. The bands of the groups were responsible for nitrification with the major dominant population in each reactor depending on the change of ammonia removal rate. These results would directly lead to an understanding of the reactor performance in relation to the ammonia removal, when conventional municipal wastewater treatment plants are retrofitted or upgraded to biological nitrogen removal processes using biofilm.
Keywords: Aerophilic Biofilm; Ammonia Oxidizing Bacteria; FISH; Nitrification; PCR-DGGE

Binary self-assembled monolayers (SAMs) have been much studied due to their high applicable potential as a model of biomimetic surfaces. However, the research about miscibility of binary SAMs has not much been investigated yet. In this work, we focused on analyzing the binary SAMs composed of mercaptohexadecanoic acid (MHA)-hexadecanthiol (HDT) on gold surfaces with Cassie equation, Israelachvili equation, and FTIR spectroscopy to confirm that the binary SAMs are well mixed. As a result, MHA-HDT binary SAMs are considered miscible because the result obtained from FTIR spectra is in good agreement with that calculated by Israelachvili equation for the case that two different molecules are well mixed on the surface. Also, the adsorption of cadmium ions on binary SAMs was confirmed by the appearance of carboxylate stretching bands.
Keywords: Self-assembled Monolayers; Binary Miscibility; FTIR Spectroscopy; Surface Wettability

We investigated the effect of organic or inorganic materials on membrane fouling in advanced drinking water treatment by hybrid module packed with granular activated carbon (GAC) outside a tubular ceramic microfiltration membrane. Instead of natural organic matters (NOM) and fine inorganic particles in the natural water source, synthetic water was prepared with humic acid and kaolin. Concentrations of kaolin or humic acid were changed to see effects of inorganic or organic matter. And periodic water-back-flushing using permeate water was performed during 10 sec per filtration of 10 min. As a result, both the resistance of membrane fouling (R f ) and permeate flux (J) were influenced higher by concentration of humic acid rather than kaolin. It was proved that NOM like humic acid could be a more important factor on membrane fouling in drinking water treatment than fine inorganic particles. Treatment efficiencies of turbidity and UV254 absorbance were very high above 97.4% and 92.0%, respectively.
Keywords: Hybrid Module; Ceramic Membrane; GAC; Microfiltration; Water Treatment

The effects of promoter type and moisture on the catalytic activity of fluorosulfonic acid (FSO3H) as a liquid catalyst for the synthesis of HFC-152a by the hydrofluorination of acetylene were investigated. The catalyst containing SnCl4 as a promoter had a long catalyst lifetime compared to that without any promoter. It was also found that the composition of HFC-152a can be maintained at 100% for a long time by the control of the moisture content.
Keywords: HFC-152a; Additives; Liquid FSO3H Catalyst; Acetylene; Hydrofluorination

Simultaneous absorption of CO2 and SO2 into aqueous AMP/NH3 solutions in binary composite absorption system by Won-Joon Choi; Jong-Beom Seo; Sang-Won Cho; Sang-Wook Park; Kwang-Joong Oh (705-710).
To enhance the absorption rate for CO2 and SO2, aqueous ammonia (NH3) solution was added to an aqueous 2-amino-2-methyl-1-propanol (AMP) solution. The simultaneous absorption rates of AMP and a blend of AMP+ NH3 for CO2 and SO2 were measured by using a stirred-cell reactor at 303 K. The process operating parameters of interest in this study were the solvent and concentration, and the partial pressures of CO2 and SO2. As a result, the addition of NH3 solution into aqueous AMP solution increased the reaction rate constants of CO2 and SO2 by 144 and 109%, respectively, compared to that of AMP solution alone. The simultaneous absorption rate of CO2/SO2 on the addition of 1 wt% NH3 into 10 wt% AMP at a p A1 of 15 kPa and p A2 of 1 kPa was 5.50×10−6 kmol m−2 s−1, with an increase of 15.5% compared to 10 wt% AMP alone. Consequently, the addition of NH3 solution into an aqueous AMP solution would be expected to be an excellent absorbent for the simultaneous removal of CO2/SO2 from the composition of flue gas emitted from thermoelectric power plants.
Keywords: Carbon Dioxide; Sulfur Dioxide; Simultaneous Absorption; 2-Amino-2-methyl-1-propanol; Ammonia

This study investigated the toxicity of Cu (1, 10, 15, and 25 mol%) loaded TiO2 and pure TiO2 nanometersized photocatalysts during the development of zebrafish embryogenesis. The hatch rate decreased in the Cu x TiO y nanoparticles exposed groups (10, 20 ppt) compared to pure TiO2 nano-particles (10, 20 ppt) exposed or control groups. These Cu x TiO y and TiO2 nanoparticles led to developing mutated embryos with abnormal notochord formation, no tail, damaged eyes and abnormal heart development. Exposure to Cu x TiO y and pure TiO2 nanoparticles led to glutathione increase, catalase activity increase, GST increase and GSR increase than control. Penetration of the Cu x TiO y and pure TiO2 nanoparticles to the embryo was also tested. It was observed that Cu x TiO y and pure TiO2 nanoparticles penetrated into cells. Moreover Cu x TiO y penetrated into the skin, nerve and yolk sac epithelium cells on the zebrafish larvae as aggregated particles, which may induce the direct interaction between nanoparticles and cell to cause adverse biological responses. As a result, the Cu-loaded TiO2 nanoparticles had the toxicity of zebrafish embryo and larvae in the water environment.
Keywords: Cu Loaded TiO2 (Cu x TiO y ); Nanoparticles; Oxidative Stress; Zebrafish Embryo

Application of full permeate recycling to very high gravity ethanol fermentation from corn by Zhongyang Ding; Liang Zhang; Yaye Fang; Ling Xu; Kechang Zhang; GuiYang Shi (719-723).
A ceramic membrane with pore size of 0.2 μm was used to percolate grain stillage of very high gravity (VHG) ethanol fermentation from corn, and the micro-filtration permeate was completely recycled for the cooking step in the next fermentation process. The concentrations of solids, sugars, total nitrogen and Na+ in the grain stillage and permeate reached a relative steady state after two or three batches of filtration and recycling process. There are no negative effects of by-products on VHG ethanol fermentation, and the final ethanol yield was above 15% (v/v). The conditions of filtration were examined to determine the optimum conditions for the process and included an initial flux of clean water above 550 L·m−2·h−1 (0.1 MPa), an operating differential pressure of 0.15 MPa, an operating temperature above 70 °C, and a permeation flux greater than 136 L·m−2·h−1. It could be concluded that full permeate recycling during ethanol production was an efficient process that resulted in less pollution and less energy consumption.
Keywords: Very High Gravity (VHG); Ethanol Fermentation; Ceramic Membrane; Full Permeate Recycling

Comparison of granular activated carbon bio-sorption and advanced oxidation processes in the treatment of leachate effluent by Javeed Mohammed Abdul; Saravanamuthu Vigneswaran; Ho Kyong Shon; Areerachakul Nathaporn; Jaya Kandasamy (724-730).
Landfill leachate is a toxic effluent of a decomposing landfill that is produced when rainwater percolates through the landfill leaching out contaminants and pollutants. Untreated leachate is a potential source for the contamination of soil, surface and ground water. In this study, the treatment processes such as granular activated carbon (GAC) adsorption/bio-sorption (batch), and advanced oxidation processes (AOP) viz. photocatalysis and Fenton’s process were evaluated and compared by using synthetic landfill leachate (SLL) as a contaminant. TiO2 was used as a catalyst in photocatalysis, and Fenton’s reagent (H2O2/Fe+2) was used in Fenton’s process. The degradation of SLL effluent by the three above-mentioned processes was characterized by the % TOC removal. The % TOC removed by photocatalysis, Fenton oxidation and bio-sorption (which includes adsorption and biodegradation) was 30, 60 and 85%, respectively. The bio-sorption increased with the increasing GAC dose. The optimum dose of Fenton’s reagent in advanced oxidation was 15 and 400 milli moles of Fe+2 and H2O2, respectively. The Fenton’s process showed faster degradation kinetics compared to biodegradation and photocatalysis.
Keywords: Landfill Leachate; Bio-sorption; Advanced Oxidation; Photocatalysis

Effects of moderate pressure on premeability and viability of Saccharomyces cerevisiae cells by Shi-Ru Jia; Na-Chen; Yu-Jie Dai; Chang-Sheng Qiao; Jian-Dong Cui; Bo-Ning Liu (731-735).
With CO2 and N2 as the pressure media, the effects of the moderate pressure (0.1–1.0MPa) and the holding time on the conductivities of the cell suspension of Saccharomyces cerevisiae CICC1447 and Saccharomyces cerevisiae CICC1339, as well as the absorbances of the supernatant (after centrifuged) at 280 nm (A280) and 260 nm (A260) were determined. The membrane permeability of Saccharomyces cerevisiae CICC1447 increased significantly and the cell leakage was aggravated with the pressure increase. For Saccharomyces cerevisiae CICC1339, the conductivity of the cell suspension, A280 and A260 of the supernatant fluctuated with the pressure increase; as a whole, they increased with pressure. Different from high pressure, a moderate pressure not only remarkably improved the permeability of the yeast cell membrane, but also kept yeast cell viability; moreover, the integrity of the yeast cell membrane could be maintained.
Keywords: Moderate Pressure; Saccharomyces cerevisiae ; Permeability; Viability

Effect of Ni2+, V4+ and Mo6+ concentration on iron oxidation by Acidithiobacillus ferrooxidans by Debabrata Pradhan; Jong-Gwan Ahn; Dong-Jin Kim; Seoung-Won Lee (736-741).
The ferrous oxidation ability of Acidithiobacillus ferrooxidans was studied in the presence of Ni2+, V4+ and Mo6+ in 9 K media in order to implement the culture in the bioleaching of spent catalyst. The rate of iron oxidation decreased with increasing concentration of metal ions, but the rate of inhibition was metal-ion dependent. The tolerance limit was critical at a concentration of 25 g/L Ni2+, 5 g/L V4+ and 0.03 g/L Mo6+. The growth rate of microorganisms was negligible at concentrations of 6 g/L V4+ and 0.04 g/L Mo6+. Levels and degree of toxicity of these ions have been quantified in terms of a toxicity index (TI). The toxicity order of metal ions was found to be Mo6+>V4+>Ni2+. The significance and relevance of multi-metal ion tolerance in Acidithiobacillus ferrooxidans has been highlighted with respect to bioleaching of spent refinery catalyst.
Keywords: Iron Oxidation Rate; Acidithiobacillus ferrooxidans ; Adaptation; Tolerance; Toxicity Index; Bioleaching

Effect of pH on phase separation of globular protein by Sang Gon Kim; Young Chan Bae; Jae-Jun Kim (742-747).
A molecular-thermodynamic framework is proposed to describe protein precipitation by inorganic salt. The equation of state consists of a hard-sphere reference contribution and a perturbation term. The reference term is derived based on the modified Chiew’s model to describe the pre-aggregation effect of protein at various solution pH. In this study, we discuss protein-protein effective two-body potentials. The distribution and magnitude of charges on the surface of a protein vary significantly with pH. It changes the magnitude of charge-charge repulsion, charge-dipole attraction, dipole-dipole attraction, and induced dipole-induced dipole attraction forces between protein pairs in solution. The distribution of the charge fluctuation is slightly effective in solution pH. To investigate the effect of pH, modified charge fluctuation distribution model is proposed. Using the proposed model, we successfully describe the pH dependence of the protein precipitation.
Keywords: pH Dependence; Protein Precipitation; Interaction Potentials; Pre-aggregation

Increased generation of electricity in a microbial fuel cell using Geobacter sulfurreducens by Ngoc Trung Trinh; Jong Hyeok Park; Byung-Woo Kim (748-753).
The microbial fuel cell (MFC) has attracted research attention as a biotechnology capable of converting hydrocarbon into electricity production by using metal reducing bacteria as a biocatalyst. Electricity generation using a microbial fuel cell (MFC) was investigated with acetate as the fuel and Geobacter sulfurreducens as the biocatalyst on the anode electrode. Stable current production of 0.20–0.24 mA was obtained at 30–32 °C. The maximum power density of 418–470 mW/m2, obtained at an external resistor of 1,000 Ω, was increased over 2-fold (from 418 to 866 mW/m2) as the Pt loading on the cathode electrode was increased from 0.5 to 3.0 mg Pt/cm2. The optimal batch mode temperature was between 30 and 32 °C with a maximum power density of 418–470 mW/m2. The optimal temperature and Pt loading for MFC were determined in this study. Our results demonstrate that the cathode reaction related through the Pt loading on the cathode electrode is a bottleneck for the MFC’s performance.
Keywords: Microbial Fuel Cell; Geobacter sulfurreducens ; Electricity Generation

The medium compositions of Bacillus species (three strains) were optimized sequentially through two statistical experimental designs, Plackett-Burman and the Box-Behnken, which were determined by representative three-factor response-surface methodology. pH and DO control was found to enhance the viable cell number of Bacilli. Most strains grew well in the optimum condition and reached nearly up to of 5×109 CFU/mL. Additionally, when three of the Bacilli were cultivated in the optimized medium with pH and DO control, the viable cell number increased 3.6 times in B. subtilis, 64.1 times in B. licheniformis and 8.3 times in B. coagulans, respectively, in comparison with the original industrial medium.
Keywords: Optimization of Media; Bacillus Species; Plackett-Burman Design; Box-Behnken Design; Response Surface Method

We have successfully synthesized palladium (Pd) nanoparticles (NPs) protected by dialkylmorpholinium ionic liquids (ILs) via chemical reduction. ATR-FTIR, UV, and NMR spectroscopies and transmission electron microscopy (TEM) were employed for characterization of the Pd NPs. The ILs effectively stabilized the Pd NPs, and the particle sizes were precisely controlled by the alkyl chain length of the cation in the ILs. The produced particles had a highly crystalline structure with a face-centered cubic (fcc) lattice. Broadening of the (111) plane in the X-ray diffraction (XRD) patterns was observed and the particle sizes calculated by Scherrer’s equation were in good agreement with the TEM results. Additionally, UV, IR, and NMR spectra indicated that nano-sized particles were produced and ILs were bound to the surface of the NPs, thereby protecting the particles from aggregation.
Keywords: Ionic Liquid; Morpholinium Salt; Palladium Nanoparticles; Size Control

Reduction of concentration polarization at feeding interphase of a hollow fiber supported liquid membrane by using periodic operation by Prakorn Ramakul; Natchanun Leepipatpiboon; Chamaiporn Yamoum; Uthen Thubsuang; Sirapop Bunnak; Ura Pancharoen (765-769).
An experimental investigation was carried out to reduce the concentration polarization at feeding interphase between feed solution and liquid membrane imposing flow instabilities. The periodic operation of the hollow fiber supported liquid membrane for separation of lanthanide metal by using D2EHPA as extractant dissolved in kerosene. The operating flow rate of the feed solution was varied according to a symmetric square wave function around time-average values of 200, 300 and 400 ml/min. Time periods ranging from 18 to 3 minutes and amplitudes of 50 and 100 ml/min were investigated. The results of these periodic tests were compared with results obtained from the conventional steadystate mode of operation. It has been found that the periodic operation leads to higher stripping concentration or higher ion flux than that obtained from the corresponding steady state operating conditions. This is because periodic operation disturbs concentration polarization in the boundary layer between the feed solution and liquid membrane. It has also been found that the ion flux increases with increasing amplitudes and decreasing time periods of the forcing function. However, when the period is less than 3 minutes the flux decreases because the liquid membrane is peeled out from the pores of hollow fiber.
Keywords: Liquid Membrane; Hollow Fiber; Instabilities Flow; Periodic Operation; Concentration Polarization

Two well known room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and 1-butyl-3-methylimidazolium iodide ([BMIm][I]), were synthesized. Their physical properties such as reflective indices, densities, viscosities, heat capacities, and heats of dilution were measured. The overall properties of [BMIm][BF4] obtained after two-step reactions were superior to those of the IL with a halide anion. The incorporation of lithium ions using lithium tetrafluoroborate (LiBF4) in each IL was carried out and ionic conductivities as a function of temperature and Li ion concentration were investigated. The isothermal conductivity graph showed a parabolic curve shape suggesting that the maximum values exist at a specific concentration condition while they continuously increased as the temperature increased. The conductivities reached as high as 10−3 S·cm−1.
Keywords: Physical Properties; Electrochemical Properties; Ionic Liquid; Li-doped Ionic Liquids

Absorption of carbon dioxide into aqueous colloidal silica solution with different sizes of silica particles containing monoethanolamine by Byung-Jin Hwang; Sang-Wook Park; Dae-Won Park; Kwang-Joong Oh; Seong-Soo Kim (775-782).
Carbon dioxide was absorbed into an aqueous nanometer-sized colloidal silica solution in a flat-stirred vessel at 25 °C and 101.3 kPa to measure the absorption rate of CO2. The concentrations of silica were in the range of 0–31 wt% and the sizes were 7, 60, and 111 nm. The solution contained monoethanolamine (MEA) of 0–2.0 kmol/m3. The volumetric liquid-side mass transfer coefficient (k L a) of CO2 was correlated with the empirical formula representing the rheological property of silica solution. The use of the aqueous colloidal silica solution resulted in a reduction of the absorption rate of CO2 compared with Newtonian liquid based on the same viscosity of the solution. The chemical absorption rate of CO2 was estimated by film theory using k L a and physicochemical properties of CO2 and MEA.
Keywords: Absorption; Carbon Dioxide; Silica; Viscoelastic Liquid; Monoethanolamine

An ionic liquid (TEA-MS41), triethylamine-immobilized on chloropropyl-functionalized MCM-41, was synthesized by a grafting technique through a co-condensation method and used as a catalyst in the reaction of carbon dioxide with glycidyl methacrylate (GMA). CO2 was absorbed into the heterogeneous system of the GMA solution and dispersed with solid particles of the catalyst in a batch stirred tank with a plane gas-liquid interface at 101.3 kPa. The absorption of CO2 was analyzed by using mass transfer accompanied by chemical reactions based on film theory. The proposed model fits the measured data of the enhancement factor to obtain the reaction rate constants. Solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, and dimethyl sulfoxide influenced the reaction rate constants.
Keywords: Absorption; Carbon Dioxide; Glycidyl Methacrylate; MCM-41

The selective extraction of Cr(VI) from waste pickling solution of the stainless steel-cold rolled plate process by hydrophobic hollow fiber supported liquid membrane (HFSLM) was investigated. The effects of various parameters— types of organic extractants, i.e., metyl trioctylammonium chloride (Aliquat 336), tri-n-octylamine (TOA), tri-n-butyl phosphate (TBP) and the mixture of Aliquat 336 and TBP, concentration of the selected extractant, types of stripping solutions (NaCl and NaOH), pH and concentration of the selected stripping solution, and the operating temperature—were studied. The feed and stripping solutions flowed countercurrently. The results showed that the coexisting contamination in spent pickling solution of Fe(II) and Ni(II) ions had no significant effect on Cr(VI) extraction. Among the extractants used in this study, Aliquat 336 was a specific carrier to attain the highest percentage of Cr(VI) extraction. About 70% extraction was achieved by using 0.11 M Aliquat 336 and 0.5 M NaCl at pH 7. The percentage of stripping slightly increased when the concentration of NaCl increased. In addition, it was found that the operating temperature of 20, 30, 40, and 50 °C had almost no influence on the percentages of extraction and stripping of Cr(VI). The calculated diffusion energy of Cr(VI) extraction was 15.14 kJ/mol.
Keywords: Extraction; Cr(VI); Hollow Fiber; Metyl Trioctylammonium Chloride; Pickling

Nanofiltration (NF) membranes have recently been employed as pretreatment unit operations in seawater desalination processes and as partial demineralization to seawater. The present paper investigates the performance of selected commercial NF membranes to reject salts of high concentrations at salinity levels representative of brackish and sea water. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in detail to study their performance in filtering aqueous solutions containing different salt mixtures in a cross-flow NF membrane process within the pressure range from 4 to 9 bar. Spiegler-Kedem model (SKM) was used to fit the experimental data of rejection with the permeate flux. The results showed that NF90 membrane was shown to have a distinct ability to reject both monovalent and divalent ions of all investigated mixtures with very reasonable values but with relatively low flux. This will make NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values, but at very high permeate flux. The SKM model only fitted well the experimental data of divalent ions in salt mixture. Based on the evaluation of the overall performance of NF90 and NF270 membranes, their distinct ability to reject salts at high salinity from seawater is considered an advantage in the field of pretreatment of seawater feed to desalination units.
Keywords: Membrane; Nanofiltration; Salt Rejection; Pretreatment; Spiegler-Kedem Model

The excess molar volumes V m E and excess molar enthalpies H m E at T=298.15 K and atmospheric pressure for the binary systems {x1CH3CHClCH2Cl+x2CH3(CH2) n−1OH} (n=1 to 4) have been determined from density measurements by using a digital vibrating-tube densimeter and an isothermal calorimeter with flow-mixing cell, respectively. The 1-alkanols are methanol, ethanol, 1-propanol and 1-butanol. The V m E values of the binary mixtures increase with chain length of the 1-alkanols, resulting in entire negative V m E values for methanol, ‘S-shaped’ for ethanol, being nega- tive at low and positive at high mole fraction of 1,2-dichloropropane, and entire positive V m E values for both 1-propanol and 1- butanol. The H m E values for all systems show an endothermic effect (positive values), which exhibits a regular increase in magnitude when the number of -CH2- group in 1-alkanols is progressively increased and maximum values of H m E varying from 741 J·mol−1 (methanol) to 1,249 J·mol−1 (1-butanol) around x1=0.63−0.72. The experimental results of both H m E and V m E were fitted to Redlich-Kister equation to correlate the composition dependence. The experimental H m E data were also used to test the suitability of the Wilson, NRTL, and UNIQUAC models. The correlation of excess enthalpy data in these binary systems using UNIQUAC model provides the most appropriate results except for the system containing methanol.
Keywords: Excess Molar Properties; Redlich-Kister Equation; Thermodynamic Models; 1,2-Dichloropropane; 1-Alkanols

Linear solvation energy relationships (LSERs) are used to investigate the fundamental chemical interactions governing the retention of nine aromatic compounds on a C18 column. The mobile phases studied involve ionic liquids 1-Methyl-3-octylimidazolium tetrafluoroborate ([OMIm][BF4]) (0.003–0.009M), with 5 to 20% acetonitrile in water as mobile phase modifiers. The ability of the LSERs to account for the chemical interactions underlying solute retention is shown. A comparison of predicted and experimental retention factors suggests that LSER formalism is able to reproduce adequately the experimental retention factors of the solutes studied in the different experimental conditions investigated.
Keywords: Linear Solvation Energy Relationships; Chromatographic Retention; Ionic Liquid; [OMIm][BF4]; Modifier

A comparative study has been performed to compare the 30 wt% of 2-amino-2-methyl-1-propanol (AMP) aqueous solution and 30 wt% of methyldiethanol amine (MDEA) aqueous solution to capture carbon dioxide contained in the flue gas stream. The equilibrium constants for each electrolyte reactions have been used to estimate the carbon dioxide absorption process. Henry’s constants for each binary pairs between solute gases and solvent have been used to estimate solubility of the gas components.
Keywords: Carbon Dioxide Capture; Electrolytes; 2-Amino-2-methyl-1-propanol; Methyldiethanol Amine

Film properties of nitrogen-doped polycrystalline silicon for advanced gate material by Sang Ho Woo; Yil Wook Kim; Pyung Yong Um; Hae-Min Lee; Chang-Koo Kim (824-827).
Deposition of N-doped poly-Si films from SiH4 and NH3 using a single wafer type low pressure chemical vapor deposition (LPCVD) system was investigated to improve the grain size reduction and the grain size distribution. The deposition rate and surface roughness of N-doped Si were greatly affected by the NH3/SiH4 ratio such that they decreased with increasing NH3/SiH4 ratio. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements revealed that with increasing NH3/SiH4 ratio, the size of the grains was decreased and the grains size distribution became uniform. Finally, we successfully obtained N-doped poly-Si films having uniform grain size of approximately 6 nm.
Keywords: N-doped Si; Low Pressure Chemical Vapor Deposition; Grain Size; Surface Roughness

Molten salt oxidation process is one of the most promising alternatives to incineration that can be used to effectively destroy the organic components of mixed and hazardous wastes. To detect the flow characteristics of the molten salt oxidation process (air-molten carbonate salt two-phase flow), differential pressure fluctuation signals from a molten salt oxidation process have been analyzed by adopting the stochastic methods. Effects of the input air flow rate (0.05–0.22 m/sec) and the molten salt temperature (870–970 °C) on the phase holdup and flow characteristics are studied. The gas holdup increases with an increasing molten salt temperature due to the decrease of the viscosity and surface tension of the molten carbonate salt. It is found that a stochastic analysis of the differential pressure signals enables us to obtain the flow characteristics in the molten salt oxidation process. The experimentally obtained gas holdup data in the molten salt reactor were well described and characterized by means of the drift-flux model.
Keywords: Molten Salt Reactor; Gas Holdup; Stochastic Analysis; Flow Characteristics

Analysis on thermal stress deformation of rotary air-preheater in a thermal power plant by Hongyue Wang; Lingling Zhao; Zhigao Xu; Hyungtaek Kim (833-839).
Thermal stress deformation is a disadvantage of the rotary air preheater, which results in leakages of fluids and decrease of efficiency of the thermal system. To evaluate the results of deformation during its operation, the temperature distribution of storage materials is calculated by solving a simplified model. In this developed method, the effect of dimensionless parameters on the temperature distribution of rotary air preheater was investigated and compared with the results of modified heat transfer coefficient method. By solving coordination, structural and geometrical equations, and boundary condition in thermal-elastic theory, the thermal stress distributions in rotary air preheater are obtained in an analytical method. Experimental results are obtained by employing factorial design values of rotary air preheater for the validation of the calculation data. Good agreement has been yielded by comparing the analytical data and experimental data. Therefore, some conclusions necessary to undertake an adequate adjustment of thermal stress deformation have also been formulated, and online monitoring of the clearance of radial seals is proposed.
Keywords: Rotary Air-preheater; Thermal Stress Deformation; Non-dimensional; Temperature Distribution

Kinetic modeling of non-hydrocarbon/nitric oxide interactions in a flow reactor above 1,400K by Shaozeng Sun; Huali Cao; Zhiqiang Wang; Lin Qian; Yukun Qin (840-844).
The reduction of nitric oxide by reaction with non-hydrocarbon fuels under reducing conditions at comparatively higher temperature has been studied with a detailed chemical kinetic model. The reaction mechanism consists of 337 elementary reactions between 65 chemical species based on the newest rate coefficients. The experimental data were adopted from previous work. Analyses by comparing existing experimental data with the modeling predictions of this kinetic mechanism indicate that, at comparatively high temperature, apart from the reaction path NO→HNO→NH→N2, NO+N→N2 is also prominent. In the presence of CO, NO is partly converted to N by reaction with CO. Based on present model, the reduction of NO at high temperature, which was usually underestimated by previous work, can be improved to some extent.
Keywords: Nitric Oxide; Rate Coefficient; Non-hydrocarbon; Reburn; Reaction Mechanism

Oxygen-enriched carbon dioxide stream with oxygen concentration higher than 20 vol% was produced continuously by using a Co-based oxygen carrier packed in two parallel fixed-bed reactors operated in a cyclic manner. Oxygen was absorbed by the oxygen carrier with air being fed. An oxygen-enriched carbon dioxide stream was obtained when the fixed-bed was regenerated with carbon dioxide as a purge gas. Multiple absorption and desorption cycles indicated that the Co-based oxygen carrier had high cyclic stability. XRD analysis determined the absorbed and desorbed products were Co3O4 and CoO, respectively. The TGA results indicated that Co-based oxygen carrier did not react with NO or SO2 during the desorption stage. This Co-based oxygen carrier offers potential for applications in the O2-CO2 production for the oxy-fuel coal combustion process.
Keywords: Oxy-fuel Combustion; Oxygen Production/Separation; Co-based Oxygen Carrier

Characterization, activity and selectivity of ethylenediamine modified Co/SiO2 FT catalyst prepared by sol-gel method by Yuelun Wang; Bo Hou; Jiangang Chen; Litao Jia; Debao Li; Yuhan Sun (850-855).
Co/SiO2 catalysts were prepared by sol-gel method with varied en (ethylenediamine)/Co molar ratios under the same pH. Their physical-chemical properties were compared with those prepared with similar en/Co molar ratios at natural pH or without adding ethylenediamine. Regardless of pH, the catalysts prepared using ethylenediamine possessed high microporosity, which led to a better selectivity to C5–18 hydrocarbons, versus the catalyst possessing higher mesoporosity which showed slightly higher C18+ selectivity. As enough positions in the coordination sphere were blocked by ethanediamine ligands, the formation of cobalt silicate disfavored for (en/Co=2) catalysts, which resulted in the higher activity in FT reaction. Whereas the catalysts prepared with lower or higher en/Co molar ratio both showed lower activity due to the formation of [(SiO)Co(en)(EtOH)3] species or the electronic adsorption of cobalt complexes in the negatively charged silica surface, respectively. However, for the catalyst without using ethylenediamine, the lowest activity and the highest CH4 selectivity obtained due to its much lower reducibility.
Keywords: Cobalt Catalyst; Fischer-Tropsch Synthesis; Ethylenediamine; Sol-gel Method

Thermogravimetric analysis and pyrolysis of waste mixtures of paint and tar slag by Ling Tao; Guang-Bo Zhao; Juan Qian; Yu-Kun Qin (856-861).
We describe thermogravimetric analyses and pyrolysis kinetic studies carried out on hazardous waste mixtures of tar slag, paint slag, paper, sodium sulfate and calcium oxide. Both thermogravimetric (TG) and differential thermogravimetric (DTG) profiles were measured by a thermogravimetric analyzer at different final temperatures, particle sizes and heating rates. Pyrolysis kinetic parameters were calculated by the Coats-Redfern method. Influences of particle size, heating rate and final temperature on pyrolysis yields and kinetic parameters are also discussed. The results show that final temperature and particle size have a great effect on pyrolysis yields. We find that with increasing temperature the activation energy initially increases to a maximum value and then decreases.
Keywords: Thermogravimetric Analysis; Hazardous Waste; Pyrolysis Kinetics; Paint Slag; Tar Slag

Experimental studies were conducted to investigate the flame stability and the thermal/fuel NOx formation characteristics of the low calorific value (LCV) coal derived gas fuel. Synthetic LCV fuel gas was produced by mixing carbon monoxide, hydrogen and ammonia on the basis that the thermal input of the syngas fuel into a burner is identical to that of natural gas. The syngas mixture was fed to and burnt on flat flame burner. With the variation of the equivalence ratio for specific syngas fuel, flame behaviors were observed to identify the flame instability due to blow-off or flash-back and to define stable combustion range. Measurements of NOx content in exhaust gas were made to compare the thermal and the fuel NOx emissions from the LCV syngas combustion with those of the natural gas. In addition, the nitrogen dilution of the LCV syngas was attempted as an NOx reduction technique, and its effects on NOx emission and flame stability were investigated.
Keywords: Coal Derived Gas; Flame Stability; NOx Emission; Nitrogen Dilution

Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were performed in an experimental test facility with the conveying pressure up to 4MPa and the solid-gas ratio up to 500 kg/m3. The influences of the total conveying differential pressure, the moisture content, the superficial velocity and the pressure on the mass flow rate and the solid-gas ratio were investigated. Shannon entropy analysis of pressure fluctuation time series was developed to reveal the flow characteristics. Based on the distribution of the Shannon entropy in the different conditions, the flow stability and the evolutional tendency of Shannon entropy in different regimes and the regime transition processes were obtained. The results indicate that the solid gas ratio and Shannon entropy rise with increase in the total conveying differential pressure. A phase diagram and Shannon entropy reveal preferable regularity with superficial velocity. Shannon entropy is different for the different flow regimes, and it can be used to identify the flow regimes. As the moisture content increases, the mass flow rate, the pressure drop and Shannon entropy decrease. Shannon entropy rises with increase in pressure drop.
Keywords: Pneumatic Conveying; High Pressure; Solid-gas Ratio; Shannon Entropy

Effect of bed height on the carbon dioxide capture by carbonation/regeneration cyclic operations using dry potassium-based sorbents by Young Cheol Park; Sung-Ho Jo; Keun-Woo Park; Yeong Seong Park; Chang-Keun Yi (874-878).
The effect of bed height on CO2 capture was investigated by carbonation/regeneration cyclic operations using a bubbling fluidized bed reactor. We used a potassium-based solid sorbent, SorbKX35T5 which was manufactured by the Korea Electric Power Research Institute. The sorbent consists of 35% K2CO3 for absorption and 65% supporters for mechanical strength. We used a fluidized bed reactor with an inner diameter of 0.05 m and a height of 0.8 m which was made of quartz and placed inside of a furnace. The operating temperatures were fixed at 70 °C and 150 °C for carbonation and regeneration, respectively. The carbonation/regeneration cyclic operations were performed three times at four different L/D (length vs diameter) ratios such as one, two, three, and four. The amount of CO2 captured was the most when L/D ratio was one, while the period of maintaining 100% CO2 removal was the longest as 6 minutes when L/D ratio was three. At each cycle, CO2 sorption capacity (g CO2/g sorbent) was decreased as L/D ratio was increased. The results obtained in this study can be applied to design and operate a large scale CO2 capture process composed of two fluidized bed reactors.
Keywords: Solid Sorbent; Fluidized Bed Reactor; CO2 Capture; Carbonation/Regeneration; Bed Height

Numerical simulation of gas-solid flow in the axisymmetric inlets square separator by Yong-Fa Diao; Xun Li; Ping-Dao Gu; Hao Li (879-883).
Numerical simulation was used to research the two-phase flow in the axisymmetric inlet square separator, including the basic flow characteristics, separation efficiency and comparing the difference between single-inlet and double-inlet separator. The effect of the reflecting cone’s geometrical sizes on pressure loss and efficiency was discussed. And the wall erosion condition because of solid particle impingement was calculated and analyzed. The tangential inlet diffuse square separator using RSM modeling that considers anisotropic situation was researched. The distribution of axial, tangential and radial velocity and the pressure loss calculated were analyzed. The results show that there is the typical double deck flow structure in the separator, the square section influences the tangential velocity in the corner, the pressure distribution divides in the inlet on the reflecting cone, and the pressure loss increases with the increase of inlet velocity.
Keywords: Axisymmetric Inlets; Diffuse Square Separator; RSM; Reflecting Cone; Numerical Simulation

Effects of preparation methods for V2O5-TiO2 aerogel catalysts on the selective catalytic reduction of NO with NH3 by Min Kang; Jinsoon Choi; Yong Tae Kim; Eun Duck Park; Chee Burm Shin; Dong Jin Suh; Jae Eui Yie (884-889).
A series of V2O5-TiO2 aerogel catalysts were prepared by the sol-gel method with subsequent supercritical drying with CO2. The main variables in the sol-gel method were the amounts of V2O5 and when the vanadium precursor was introduced. V2O5-TiO2 xerogel and V2O5/TiO2 (P-25) were also prepared for comparison. The V2O5-TiO2 aerogel catalysts showed much higher surface areas and total pore volumes than V2O5-TiO2 xerogel and impregnated V2O5/TiO2 (P-25) catalysts. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), FT-Raman spectroscopy, temperature-programmed reduction with H2 (H2-TPR), and temperature-programmed desorption of ammonia (NH3-TPD). The selective catalytic reduction of NOx with ammonia in the presence of excess O2 was studied over these catalysts. Among various V2O5-TiO2 catalysts, V2O5 supported on aerogel TiO2 showed a wide temperature window exhibiting high NOx conversions. This superior catalytic activity is closely related to the large amounts of strong acidic sites as well as the surface vanadium species with characteristics such as easy reducibility and monomeric and polymeric vanadia surface species.
Keywords: Selective Catalytic Reduction; NOx; V2O5-TiO2 ; NH3 ; Aerogel; Catalyst

Carbon dispersed iron-manganese catalyst for light olefin synthesis from CO hydrogenation by Jianli Zhang; Kegong Fang; Kan Zhang; Wenhuai Li; Yuhan Sun (890-894).
High performance iron-manganese catalysts dispersed with carbon to produce light olefins from CO hydrogenation were prepared by sol-gel method using citric acid as precursor. The effects of carbon content on the bulk structure, the water gas shift reaction, the chain propagation ability and the activity and selectivity of the catalysts were investigated. The results showed that the catalysts were gradually reduced during the decomposition of the precursor when calcined under pure N2. The formation of iron-manganese mixed crystallites was favored and stabilized because of the enhanced interaction of iron and manganese with increasing carbon content. During the subsequent CO hydrogenation reaction, all the catalysts showed high activity and olefin selectivity. With increasing carbon content, the water gas shift (WGS) reaction was restrained and the chain propagation ability was inhibited. Catalysts with higher carbon content showed much lighter hydrocarbon products; however, the selectivity of CH4 was almost unchanged.
Keywords: CO Hydrogenation; Fe-Mn Catalyst; Light Olefin; Selectivity; Chain Propagation Ability

A phenol-formaldehyde resin (PFR) and a bituminous coal (SH) were pyrolyzed at various temperatures. The structure and the char-NO reactivity were analyzed in order to examine the effect of pyrolysis temperature on the micro-structure of the resulting char and further on the reactivity towards NO. Micro-structure of the char samples was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy. It was indicated that the micro-structure of PFR char and coal char experienced remarkable changes during pyrolysis, which resulted in the decrease of phenolic OH, aromatic hydrogen and more ordered structure. The pyrolysis temperature showed a weak impact on the reactivity of PFR char but comparatively remarkable impact on that of coal char at lower reaction temperature. Mineral matter in coal char presented a weak effect on the reactivity.
Keywords: Pyrolysis; Char; Micro-structure; C-NO Reactivity

Methanol selective oxidation to dimethoxymethane on H3PMo12O40/SBA-15 supported catalysts by Heqin Guo; Debao Li; Haicheng Xiao; Jianli Zhang; Wenhuai Li; Yuhan Sun (902-906).
A series of SBA-15 supported H3PMo12O40 catalysts were prepared for the one-step oxidation of methanol to dimethoxymethane (DMM). The evaluation and characterization revealed that higher DMM selectivity obtained on the incipient wetness impregnation (IM) catalyst was related to the instability of H3PMo12O40 on it. Raman spectra showed that 12-molybdophosphoric acid was more stable on the direct synthesis (DS) catalyst than on the IM catalyst and the existence of SBA-15 support enhanced the stability of H3PMo12O40. Moreover, higher H3PMo12O40 loading resulted in more acid sites and low DMM selectivity, furthermore the thermal pretreatment on H3PMo12O40 influenced its structure and thus affected DMM selectivity.
Keywords: 12-Molybdophosphoric Acid; SBA-15 Mesoporous Sieve; Methanol; Selective Oxidation; Dimethoxymethane

Agglomeration of particles during coal combustion in multistage spouted fluidized tower by Jia-Xun Liu; Ji-Hui Gao; Jian-Min Gao; Xiao-Feng Wang; Shao-Hua Wu (907-912).
An experimental platform of spray agglomeration has been designed and built for removing small fly ash particles (PM10) from coal combustion. Systematic experiments were conducted in a multistage spouted tower using kinds of agglomerant solutions. The particle concentration increases greatly from the first stage to the second stage of the tower. With the increase of flue gas flow rate the oscillation of impulse signal response curves increases and the internal circulation of the tower intensifies. The influencing factors such as the surfactant, PH value, flow rate of the agglomerant solutions and inlet flue gas temperature were analyzed. SEM was used to analyze the microstructure of the particles. Final results indicate that the special shape of a multistage spouted fluidized tower has significant influences on the effect of agglomeration. The findings from this work will be helpful to form the basis, and provide guidance for, further studies on the control of fine particles such as PM2.5 or even smaller.
Keywords: Coal Combustion; Deep De-dust; Submicron Particles; Spray Agglomeration; Multistage Spouted

Catalytic dry oxidation of aniline, benzene, and pyridine adsorbed on a CuO doped activated carbon by Bingzheng Li; Zhenyu Liu; Zhiping Lei; Zhanggen Huang (913-918).
Adsorption of aniline, benzene and pyridine from water on a copper oxide doped activated carbon (CuO/AC) at 30 °C and oxidation behavior of the adsorbed pollutants over CuO/AC in a temperature range up to 500 °C are investigated in TG and tubular-reactor/MS systems. Results show that the AC has little activity towards oxidation of the pollutants and CuO is the active oxidation site. Oxidation of aniline occurs at 231–349 °C and yields mainly CO2, H2O and N2. Oxidation of pyridine occurs at a narrower temperature range, 255–309 °C, after a significant amount of desorption starting at 150 °C. Benzene desorbs at temperatures as low as 105 °C and shows no sign of oxidation. The result suggests that adsorption-catalytic dry oxidation is suitable only for the strongly adsorbed pollutants. Oxidation temperatures of CuO/AC for organic pollutants are higher than 200 °C and pollutants desorbing easily at temperatures below 200 °C cannot be treated by the method.
Keywords: Catalytic Dry Oxidation; CuO Doped Catalyst; Aniline; Benzene; Pyridine; Desorption