Frontiers of Chemical Science and Engineering

ISSN 2095-0179

ISSN 2095-0187(Online)

CN 11-5981/TQ

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RESEARCH ARTICLE
Combustion characteristics and kinetics of bio-oil
Ruixia ZHANG, Zhaoping ZHONG, Yaji HUANG
Front Chem Eng Chin. 2009, 3 (2): 119-124.  
https://doi.org/10.1007/s11705-009-0068-x

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The combustion characteristics of bio-oils derived from rice husk and corn were studied by thermogravimetry analysis. According to the thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) curves of bio-oils in air and nitrogen atmosphere, we analyzed the combustion characteristics of different kinds of bio-oils in different atmospheres and worked out the combustion kinetics parameters of the bio-oil, providing reliable base data for the burning of bio-oil. The thermogravimetry indicated that the combustion process of bio-oil was divided into three stages. At the same time, the combustion process can be described by different order reaction models, and with the method of Coats-Redfern, the activation energy and frequency factor of different kinds of bio-oils were obtained.

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Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal phase: growth kinetics analysis
Motoi YAMASHITA
Front Chem Eng Chin. 2009, 3 (2): 125-134.  
https://doi.org/10.1007/s11705-009-0001-3

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The morphology and lateral growth rate of isotactic polybutene-1 (it-PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of it-PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.

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COMMUNICATION
Effect of counter current gas phase on liquid film
Shujuan LUO, Huaizhi LI, Weiyang FEI, Yundong WANG
Front Chem Eng Chin. 2009, 3 (2): 135-137.  
https://doi.org/10.1007/s11705-009-0129-1

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Liquid film flow is very important in many industrial applications. However, there are few reports about its characteristics on structured packings. Therefore, in this paper, liquid film phenomena were investigated experimentally to exploit new approaches for intensifying the performance of the structured packings. All experiments were performed at room temperature. Water and air were the working fluids. The effect of counter current gas phase on the liquid film was taken into consideration. A high speed camera, a non-intrusive measurement technique, was used. It is shown that both liquid and gas phases have strong effects on film characteristics. In the present work, liquid film width increased by 57% because of increasing liquid flow rate, while it decreased by 25% resulting from the counter current gas phase.

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RESEARCH ARTICLE
CFD based combustion model for sewage sludge gasification in a fluidized bed
Yiqun WANG, Lifeng YAN
Front Chem Eng Chin. 2009, 3 (2): 138-145.  
https://doi.org/10.1007/s11705-009-0050-7

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Gasification is one potential way to use sewage sludge as renewable energy and solve the environmental problems caused by the huge amount of sewage sludge. In this paper, a three-dimensional Computational Fluid Dynamics (CFD) model has been developed to simulate the sewage sludge gasification process in a fluidized bed. The model describes the complex physical and chemical phenomena in the gasifier including turbulent flow, heat and mass transfer, and chemical reactions. The model is based on the Eulerian-Lagrangian concept using the non-premixed combustion modeling approach. In terms of the CFD software FLUENT, which represents a powerful tool for gasifier analysis, the simulations provide detailed information on the gas products and temperature distribution in the gasifier. The model sensitivity is analyzed by performing the model in a laboratory-scale fluidized bed in the literature, and the model validation is carried out by comparing with experimental data from the literature. Results show that reasonably good agreement was achieved. Effects of temperature and Equivalence Ratio (ER) on the quality of product syngas (H2 + CO) are also studied.

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Removal of malachite green from aqueous solution by sorption on hydrilla verticillata biomass using response surface methodology
R. RAJESHKANNAN, N. RAJAMOHAN, M. RAJASIMMAN
Front Chem Eng Chin. 2009, 3 (2): 146-154.  
https://doi.org/10.1007/s11705-009-0007-x

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In the present study, the effect of adsorbent dose, pH, temperature, initial dye concentration and contact time on malachite green removal from an aqueous medium using hydrilla verticillata biomass has been investigated. The central composite face-centered experimental design (CFCD) in response surface methodology (RSM) was used for designing the experiments as well as for full response surface estimation. The optimum conditions for maximum removal of malachite green from an aqueous solution of 75.52 mg/L were as follows: adsorbent dose (11.14 g/L), pH (8.4), temperature (48.4°C) and contact time (194.5 min). This was evidenced by the higher value of coefficient of determination (R2=0.9158).

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Sulfate digestion process for high purity TiO2 from titania slag
T. A. LASHEEN
Front Chem Eng Chin. 2009, 3 (2): 155-160.  
https://doi.org/10.1007/s11705-009-0005-z

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A titania slag product of Rosetta ilmenite assaying 72% TiO2 is treated by the sulfate process option of the pigmentary TiO2 manufacture. The relevant factors of acid concentration, particle size, slag/acid ratio besides the reaction temperature, and time have been studied. After dissolving the cured mass in dilute acid and clarification, the obtained solution was subjected to hydrolysis of its titanium content. The final product was bleached under reducing conditions to redissolve the residual coloring impurities before being dewatered and calcinated. The obtained results indicated that a leaching efficiency of about 92% was realized due to the presence of some refractory components in the working slag material, namely, rutile and magnesium iron titanate. The obtained white pigment assay attained up to 99.85% TiO2, while the analyzed impurities involve 77 ppm Mn and only 14 and 7 ppm of total iron and V, respectively.

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Research on combustion characteristics of bio-oil from sewage sludge
Rui LI, Baosheng JIN, Xiangru JIA, Zhaoping ZHONG, Gang XIAO, Xufeng FU
Front Chem Eng Chin. 2009, 3 (2): 161-166.  
https://doi.org/10.1007/s11705-009-0057-0

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Combustion characteristics of bio-oil from sewage sludge were investigated using thermogravimetry (TG) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. The combustion process could be divided into two weight loss stages. Light compounds volatilized and were oxidized in the first stage and the heterogeneous combustion between oxygen and heavy compounds happened in the second stage, which were confirmed by FT-IR technique. Most weight loss occurred in the first stage. The effect of heating rate was also studied and higher heating rates were found to facilitate the combustion process. The kinetic parameters of the two stages were calculated and the change of activation energy indicated higher heating rates benefited combustion.

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Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite
Jiangbo WANG, Zhong XIN
Front Chem Eng Chin. 2009, 3 (2): 167-171.  
https://doi.org/10.1007/s11705-009-0006-y

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The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

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Simulation studies on metastable phase equilibria in the aqueous ternary systems (NaCl-MgCl2-H2O) and (KCl-MgCl2-H2O) at 308.15 K
Tianlong DENG, Baojun ZHANG, Dongchan LI, Yafei GUO
Front Chem Eng Chin. 2009, 3 (2): 172-175.  
https://doi.org/10.1007/s11705-009-0048-1

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The solubilities and densities of the aqueous metastable ternary systems (NaCl-MgCl2-H2O) and (KCl-MgCl2-H2O) at 308.15 K were determined by the isothermal evaporation method. On the basis of the experimental results, the phase diagrams for those systems were plotted. It was found that the former system belongs to the hydrate-I type with one invariant point of (NaCl+ MgCl2?6H2O), two univariant curves, and two crystallization regions corresponding to halite (NaCl) and bischofite (MgCl2·6H2O); and the latter system belongs to the type of incongruent-double salts with two invariant points of (KCl+ KCl·MgCl2·6H2O) and (MgCl2·6H2O+ KCl·MgCl2·6H2O), three univariant curves, and three crystallization regions corresponding to potassium chloride (KCl), carnallite (KCl·MgCl2·6H2O) and bischofite (MgCl2·6H2O). No solid solutions were found in both systems.

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FESEARCH ARTICLE
Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property
Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU
Front Chem Eng Chin. 2009, 3 (2): 176-181.  
https://doi.org/10.1007/s11705-009-0203-8

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A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the impact resistance property of PP/KT specimens (with similar interparticles distance, 1.8 μm) was studied by notched izod impact tests. It was found that the brittle-ductile transition (BDT) of the PP/KT microcomposites took place at the filler content of about 4%, and the impact strength attains the maximum at 5% (with filler particles size of 1.5 μm), which is about 2.5 times that of unfilled iPP specimens. The impact fracture morphology was investigated by scanning electron microscopy (SEM). For the PP/KT specimens and the high-density polyethylene/KT (HDPE/KT) specimens in ductile fracture mode, many microfibers could be found on the whole impact fracture surface. It was the filler particles that induced the plastic deformation of interparticles ligament and hence improved the capability of iPP matrix on absorbing impact energy dramatically. The determinants on the BDT were further discussed on the basis of stress concentration and debonding resistance. It can be concluded that aside from the interparticle distance, the filler particles size also plays an important role in semicrystalline polymer toughening.

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RESEARCH ARTICLE
Investigation of electrochemical degradation and application of e-paper dyes in organic solvents
Luhai LI, Ming WANG, Yi FANG, Shunan QIAO
Front Chem Eng Chin. 2009, 3 (2): 182-185.  
https://doi.org/10.1007/s11705-009-0062-3

Abstract   HTML   PDF (195KB)

To avoid environmental pollution due to organic dye solutions, the electrophoresis and degradation of dye in organic solvents such as alcohol were investigated. Many dyes were tested in the Indium tin oxide (ITO) electrode driving cell, and about 15 dyes moved under voltage driving. Both the curves of ultraviolet-visible (UV-Vis) and infrared (IR) spectra of the electrophoresis samples showed that the metal complexes Red 04 and Acid Black 1 were degradable in alcohol solution by electrochemical reaction. The cyclic volt-ampere curves of the samples from the electrochemical working station proved that electrochemical reactions took place. Based on the analysis of UV-Vis and IR spectra, the electrochemical degradation products of azo and metal complex azo dyes at lower voltage driving (1-5 V) in organic solvents are oxidized azobenzene, not hydrazine, which was found in the electrochemical degradation of dye water solutions. When the ITO electrode is modified by a polyimide (PI) film to a thickness less than 4 μm, the electrochemical degradation of the dye in alcohol solution will not appear in the cyclic volt-ampere curves. A dye electrophoresis in organic solution flexible prototype e-paper display was formed and the display picture is shown.

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Microwave-assisted synthesis and antimicrobial activities of 2-aryl-3-(naphthalene-1 or 2-yl)-1,3-thiazolidin-4-ones
Hua CHEN, Yanan LI, Jie BAI, Lian ZHAO, Xiangguo YUAN, Xiaoliu LI, Keqiang CAO
Front Chem Eng Chin. 2009, 3 (2): 186-191.  
https://doi.org/10.1007/s11705-009-0004-0

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2-aryl-3-(naphthalene-1 or 2-yl)-1,3-thiazolidin-4-ones 4 and 5 were synthesized in 41%-67% yield by using microwave-assisted one-pot protocol. The structures of the new compounds 4l, 4m, 5c, 5e, 5g, 5h, and 5j-5m were confirmed by IR, NMR, MS, and elemental analysis. The antimicrobial activities of the compounds against Pseudomonas syringae pv. lachrymans (Smith et Bryan) Young, Dye & Wilkie, Botrytis cinerea Pers., and Sphaerotheca fusca Blum. were examined. Some of the compounds showed good antifungical activity against Sphaerotheca fusca Blum.

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Synthesis, spectroscopic, and electrochemical properties of two dyads consisted of tetrathiafulvalene and carbazole
Guoqiao LAI, Yibo LIU, Meijiang LI, Yongjia SHEN
Front Chem Eng Chin. 2009, 3 (2): 192-195.  
https://doi.org/10.1007/s11705-009-0015-x

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Two donor-σ-acceptor molecules containing tetrathiafulvalene (TTF) and carbazole moieties were synthesized by the reaction of 9-(4-bromo-butyl)-carbazole (1) with 2,6-bis(hexylthio)-3-(2-cyanoethylthio)-7-(methylthio)-tetrathiafulvalene (2) or 2,6-bis(2-cyanoethylthio)-3,7-bis(methylthio)tetrathiafulvalene (3) in the presence of CsOH·H2O, respectively. The structures of the molecules were characterized by 1H NMR, 13C NMR, MS, and elemental analyses. They showed negligible intramolecular charge-transfer interaction in their ground states as indicated by their UV-Vis spectroscopics and cyclic voltammetry results. Compared with carbazole, their fluorescence was strongly quenched, which implied that a photo induced electron transfer (PET) interaction between TTF and carbazole moieties occurred.

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β-Cyclodextrin promoted oxidation of primary amines to nitriles in water
Dongpo SHI, Hongbing JI, Zhong LI
Front Chem Eng Chin. 2009, 3 (2): 196-200.  
https://doi.org/10.1007/s11705-009-0051-6

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A facile, efficient and substrate-selective oxidation of the primary amines with NaClO as oxidant catalyzed by β-cyclodextrin (β-CD) has been developed in water for the first time, and the behavior of β-cyclodextrin that catalyzed the primary amines to nitriles in water was investigated. It was found that the primary amines which could form host-guest complexes with β-cyclodextrin were oxidized to nitriles with excellent yields at ambient temperature. The results show that β-cyclodextrin worked not only as a solubilizing agent but also as a catalyst in these reactions.

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One-pot three-component Mannich reaction catalyzed by sucrose char sulfonic acid
Qiong XU, Zhigao YANG, Dulin YIN, Jihui WANG
Front Chem Eng Chin. 2009, 3 (2): 201-205.  
https://doi.org/10.1007/s11705-009-0052-5

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Sucrose char sulfonic acid efficiently catalyzed the one-pot three-component Mannich reaction of ketones, aromatic aldehydes and amines in ethanol to afford the corresponding b-amino carbonyl compounds in good to excellent yields. A series of heteroaromatic b-amino carbonyl compounds can be obtained when using 2-acetylpyrazine as substrate. This reaction can be performed under mild reaction conditions with clean reaction profiles and a simple workup procedure.

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Photocatalytic degradation of omethoate using NaY zeolite-supported TiO2
Dishun ZHAO, Jialei WANG, Zhigang ZHANG, Juan ZHANG
Front Chem Eng Chin. 2009, 3 (2): 206-210.  
https://doi.org/10.1007/s11705-009-0053-4

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The degradation of omethoate was conducted using H2O2 as oxidant, TiO2 supported on NaY zeolite as photocatalyst and a 300 W lamp as light source. The effect of the calcination temperature of the photocatalyst, the amount of TiO2 loaded on NaY zeolite, the photocatalyst amount, the pH value and the radiation time on the degradation ratio of omethoate were investigated. The results show that TiO2/NaY zeolite photocatalyst prepared by sol-gel method had good photocatalysis. The photocatalytic optimum oxidation conditions of omethoate are as follows: the calcination temperature of the photocatalyst is 550°C,the amount of TiO2 loaded on NaY zeolite is 35.2 wt-%, the amount of photocatalyst is 5 g/L, pH=8 and the radiation time is 180 min. Under these conditions, the removal ratio of omethoate is up to 93%.

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Ionic liquid mediated esterification of alcohol with acetic acid
Beilei ZHOU, Yanxiong FANG, Hao GU, Saidan ZHANG, Baohua HUANG, Kun ZHANG
Front Chem Eng Chin. 2009, 3 (2): 211-214.  
https://doi.org/10.1007/s11705-009-0054-3

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Highly efficient esterification of alcohols with acetic acid by using a Br?nsted acidic ionic liquid, i.e., 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4), as catalyst has been realized. The turnover numbers (TON) were able to reach up to 11000 and turnover frequency (TOF) was 846. The catalytic system is suitable for the esterification of long chain aliphatic alcohols, benzyl alcohol and cyclohexanol with good yields of esters. The procedure of separating the product and catalyst is simple, and the catalyst could be reused. [Hnmp]HSO4 had much weaker corrosiveness than H2SO4. The corrosive rate of H2SO4 was 400 times more than that of [Hnmp]HSO4 to stainless steel.

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Synthesis of magnetic Pb/Fe3O4/SiO2 and its catalytic activity for propylene carbonate synthesis via urea and 1,2-propylene glycol
Hualiang AN, Xinqiang ZHAO, Zhiguang JIA, Changcheng WU, Yanji WANG
Front Chem Eng Chin. 2009, 3 (2): 215-218.  
https://doi.org/10.1007/s11705-009-0055-2

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To facilitate the recovery of Pb/SiO2 catalyst, magnetic Pb/Fe3O4/SiO2 samples were prepared separately by emulsification, sol-gel and incipient impregnation methods. The catalyst samples were characterized by means of X-ray diffraction and N2 adsorption-desorption, and their catalytic activity was investigated in the reaction for synthesizing propylene carbonate from urea and 1,2-propylene glycol. When the gelatin was applied in the preparation of Fe3O4 at 60°C and the pH value was controlled at 4 in the preparation of Fe3O4/SiO2, the Pb/Fe3O4/SiO2 sample shows good catalytic activity and magnetism. Under the reaction conditions of a reaction temperature of 180°C, reaction time of 2 h, catalyst percentage of 1.7 wt-% and a molar ratio of urea to PG of 1∶4, the yield of propylene carbonate attained was 87.7%.

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Study on a green synthesis of μ-oxo-bis[tetraarylphenylporphyrinatoiron]
Aixin WANG, Yuanbin SHE, Jing FAN
Front Chem Eng Chin. 2009, 3 (2): 219-221.  
https://doi.org/10.1007/s11705-009-0058-z

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A novel method for the synthesis of μ-oxo-bis[tetraarylporphyrinatoiron] ([TRPPFe]2O) based on the reaction between tetraarylporphyrinironchloride (TRPPFeCl) and H2O in toluene was investigated in this paper. Three kinds of [TRPPFe]2O were synthesized by this novel synthetic method, and their structures were characterized by elemental analysis, IR spectra and UV-Vis spectroscopy.

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Study on a green synthetic method of TRPPMCl (M= Fe, Mn, Co)
Jing FAN, Yuanbin SHE, Aixin WANG
Front Chem Eng Chin. 2009, 3 (2): 222-223.  
https://doi.org/10.1007/s11705-009-0059-y

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A green synthetic method using mixted solvents of di-methyl formamide(DMF) and acids instead of single DMF to synthesize metalloporphyrins(TRPPMCl) from TRPPH2 and MCl2 metallization was proposed in this paper. A series of TRPPMCl (M= Fe, Mn, Co) were synthesized through this innovative synthetic method, and these complexes were characterized with various spectroscopic techniques, including IR and UV-Vis spectroscopy. The results showed that the metallization time was markedly reduced from about 10 h to 0.5 h in contrast with the conventional synthetic methods.

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REVIEW ARTICLE
Methodologies for chemical utilization of CO2 to valuable compounds through molecular activation by efficient catalysts
Liangnian HE, Ya Du, Chengxia MIAO, Jinquan WANG, Xiaoyong DOU, Ying WU
Front Chem Eng Chin. 2009, 3 (2): 224-228.  
https://doi.org/10.1007/s11705-009-0067-y

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The reactions of CO2 with oxirane to produce cyclic carbonate, and with aziridine to afford oxazolidine have been of interest as a useful method for its fixation by a chemical process. Highly efficient processesemploying recyclable CO2-phlilic homogeneous catalyst were devised for environmentally benign synthesis of cyclic carbonates and oxazolidinones under supercritical CO2 without any organic solvent. These processes represent pathways for greener chemical fixations of CO2 to afford industrial useful materials such as organic carbonates and oxazolidinones with great potential applications.

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21 articles