Polymer Chemistry
·
2019
·Vol. 10
·期 43
·5905-5912
·
IF 4.76
Chuanzhi Wei,Xinhui Kou,Shaofeng Liu,Zhibo Li
Ring-opening polymerization (ROP) is a powerful method used for converting cyclic monomers to polymers, but ethylene carbonate (EC), which has a five-membered ring, is an exception owing to the unfavorable thermodynamics of its ring-opening reaction unless the release of CO2. This behavior stems from the faster cyclization to form a stable five-membered ring in comparison to the direct ring-opening reaction. Hence, many attempts have been made to copolymerize EC with other cyclic monomers such as cyclic esters to overcome the thermodynamic barrier. In this context, the copolymerization of EC with various cyclic esters, including ε-caprolactone (CL), δ-valerolactone (VL) and L-lactide (LLA), has been successfully achieved using an organocatalytic phosphazene superbase, such as a cyclic trimeric phosphazene base (CTPB). The random copolymerizations proceeded fast with a turnover frequency (TOF) of 19 800 h−1 under mild polymerization conditions and afforded the corresponding copolymers without formation of the ether unit. Under all kinds of experimental conditions, no homopolymerization of EC occurred. The molecular structures of the obtained P(EC-co-CL) copolymers were characterized using 1H NMR and 13C NMR, which demonstrated that ca. 38 mol% EC can be incorporated within the copolymer chain depending on the different ratios of the EC and CL monomers. With the same catalytic system and under similar conditions, the amounts of EC incorporated into EC/VL (up to 26 mol%) and EC/LLA (ca. 4.8 mol%) copolymerizations were lower than that for the EC/CL copolymerization. 2D NMR (1H–1H correlated spectroscopy (COSY), 1H–13C heteronuclear single quantum coherence (HSQC) and 1H–13C heteronuclear multiple bond correlation (HMBC)) were performed to confirm the assignments in the 1H NMR and 13C NMR spectra of the copolymers and to better understand the chain structures of the copolymers. Therefore, polycarbonate/polyester copolymers with greater incorporation of EC were realized using a fast, selective and metal-free process.
研究领域:
高分子化学
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有机催化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2018
·
IF 1.712
Ying Qing,Houfang Lu,Yingying Liu,Changjun Liu,Bin Liang,Wei Jiang
The biodiesel production technology catalyzed by 1,8-diazabicycloundec-7-ene (DBU) is developed in this work. Crude glycerol containing DBU and DBU/glycerol/CO 2 (DGC) ionic compounds reacts directly with dimethyl carbonate (DMC) to produce high value-added glycerol carbonate (GC) catalyzed by DBU and DGC. The catalytic performance of DBU and DGC, as well as the kinetics of the reaction catalyzed by DBU, were investigated. The results show that DGC has a weak catalytic effect on the transesterification of glycerol and DMC. When the temperature is higher than 60 °C, DGC catalyzes the reaction jointly with DBU, which is produced from the decomposition of DGC. DBU has a good catalytic effect on the reaction between glycerol and DMC, with 90% conversion of glycerol and 84% selectivity to GC under the following conditions: DMC-to-glycerol molar ratio of 3:1, 4.0% DBU (based on glycerol mass), reaction time of 60 min, and reaction temperature of 40 °C. The apparent kinetics results show that the activation energies are 30.95 kJ·mol − 1 and 55.16 kJ·mol − 1 for the forward and reverse GC generation reactions, respectively, and the activation energy of the decomposition reaction of GC to glycidol (GD) is 26.58 kJ·mol − 1 .
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2018
·
IF 2.631
Lin Mou,Yuying Chai,Guizeng Yang,Quan Xia,Qingshan Liu,Qige Zheng,Qingguo Zhang
Two hydrophobic ionic liquids (ILs) 1-alkyl-2, 3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C 2 mmim][NTf 2 ] and [C 4 mmim][NTf 2 ]) were synthesized. The binary mixtures of the two ILs were prepared with dimethyl carbonate (DMC) or diethyl carbonate (DEC) over the entire mole fraction range, respectively. The density and viscosity of the binary mixtures were investigated at temperature ranging from 293.15 to 328.15 K. The excess molar volumes and viscosity deviations were calculated for the four binary mixtures. The effects of the extension of the alkyl chain of the cation on the above properties are discussed. The Redlich-Kister equation was used for the fitting of the excess molar volumes and viscosity deviations versus mole fraction. The thermal expansion coefficients of the systems were obtained according to the density.
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2024
·
IF 9.3
Nan Hu,Lijuan Su,Hongyan Li,Ning Zhang,Yongqin Qi,Hongliang Wang,Xiaojing Cui,Xianglin Hou,Tiansheng Deng
Various excellent catalysts have been explored for the methanolysis of polycarbonate (PC), but it is still challenging to develop green and economical catalysts for solvent-free PC methanolysis to recover both bisphenol A (BPA) and dimethyl carbonate (DMC). Herein, green, efficient and solvent-free degradation of PC to BPA and DMC was achieved using urea as a cheap green catalyst. At 140 °C for 3 h, PC was completely degraded to BPA and DMC with yields of 93.4% and 74.7%, respectively. A possible catalytic degradation mechanism of PC was proposed by kinetic experiments and NMR, where urea, methanol and carbonate formed a six-membered ring in the reaction. It was found that the increase of urea concentration significantly reduced the activation energy, which was attributed to the fact that the increase of urea concentration made the six-membered ring easier to form and activated the carbonate bond. The degradation system can be reused directly up to 10 times and 100% degradation rate can be maintained. This work provides a simple, green and economical method for industrial PC recycling.
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2018
·
IF 3.849
Yuanfeng Wu,Xianghai Song,Jiahui Zhang,Shuai Li,Xinghui Yang,Huazheng Wang,Ruiping Wei,Lijing Gao,Jin Zhang,Guomin Xiao
A series of Ce 1- x Cd x O mixed oxide catalysts prepared by co-precipitation method were tested for synthesis of glycerol carbonate (GC) from glycerol and diethyl carbonate (DEC). The microstructural and physicochemical properties of the bimetal catalysts were characterized by XRD, SEM, TEM, XPS, CO 2 -TPD, N 2 -adsorption, TG-DSC and 1 H NMR. The results show that the spherical particles of CdO were uniformly dispersed on the surface of lamellar CeO 2 . Besides, a noticeable increase was observed in the moderate basic sites concentration, because more oxygen atoms were adsorbed on the bimetal sample surface which was attributed to Ce 4+ doped into CdO lattice. The Ce 0.7 Cd 0.3 O sample annealed at 500 °C was observed with the highest catalytic activity. 96.84% of glycerol conversion and 100% selectivity to GC were obtained over this catalyst under the optimized conditions (5 wt.% catalyst of glycerol, 90 °C, 180 min, glycerol/DEC molar ratio of 1:3). Besides, it was found that the conversion of glycerol carbonate was synergistically accelerated by the moderate and strong basic sites.
研究领域:
催化化学
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材料科学
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绿色化学
✓ 已验证
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2018
·Vol. 34
·期 4
·578-583
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IF 1.248
Song Menglu,Yang Xiangui,Wang Gongying
Polycarbonate diols(PCDLs) with a number average molecular weight( M n ) of 2800 and a narrow polydispersity index(PDI=1.33) were synthesized from dimethyl carbonate(DMC) and 1,4-butanediol(BD) via a two-step process. The influences of the molar ratios of DMC to BD in the feedstock, polycondensation temperature and polycondensation time on the PCDLs preparation were studied. CH 3 COONa showed the best catalytic performance among the catalysts studied. The highest BD conversion of 73.8% and PCDLs yield of 64.7% were achieved under its optimum reaction conditions. Furthermore, based on the results of 1 H NMR, the relationships between the ratio of end groups (—OCH 3 /—OH) of oligomers, the M n and chainend constitute of resultant polycarbonates were also investigated. The results indicate that PCDLs can be synthesized when the oligomers mostly bear hydroxyl end groups. In contrast, it was impossible to prepare PCDLs when the oligomers were enriched with methyl carbonate end groups.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
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2019
·
IF 3.621
Bingkun Yan,Bingyu Liang,Jiaqian Hou,Chao Wei,Yan Xiao,Meidong Lang,Farong Huang
Ring-opening polymerization (ROP) of macrocyclic carbonates (≥12 ring) is still challenging due to the associated low ring-strain. Although organometallic and enzyme based catalysts have been studied, disadvantages such as organometallic residue and enzymic nature limit their applications. After screening commercially available organocatalysts, we report the use of organocatalysts for ROP of disulfide-containing macrocyclic carbonates (MSS, 16 ring). It was found that organocatalysts (TBD) presented high active and living ROP of MSS, as evidenced by kinetic studies, yielding main chain disulfide-containing polycarbonates with tailor-made structures and predictable molecular weights with low molecular weight distribution. Copolymerizations with trimethylene carbonate (TMC) generated random copolymers with controlled components, regulating the density of disulfide functional groups. By comparing with the behaviors of enzyme catalysis in kinetic studies and (co-)polymerization, it is observed that organic catalyzed ROP showed more efficient (~ ten times faster), milder condition and more controlled behaviors than enzyme catalyzed ROP (N-435). Therefore, we believe this organic catalyzed strategy will provide an alternative to the current enzymatic and organometallic catalyst for ROP of macrocyclic carbonates.
研究领域:
高分子化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
FLUID PHASE EQUILIBRIA
·
2022
·
IF 2.745
Jingjun Liu,Dandan Pan,Qing Zhang,Yulei Guan,Bolun Yang
Glycerol carbonate is a value-added glycerol derivative, which can be obtained by transesterification with dimethyl carbonate. Phase splitting and merging exist in the transesterification due to the low solubilities of glycerol with dimethyl carbonate. The isobaric liquid-liquid equilibrium data for two ternary systems (glycerol – dimethyl carbonate – glycerol carbonate/methanol) and one quaternary system (glycerol – dimethyl carbonate – glycerol carbonate – methanol) involved in the glycerol transesterification were measured at reaction relevant temperatures (333.2, 353.2, 373.2, and 393.2 K) and 1.5 MPa. The equilibrium data were correlated using the NRTL model to calculate activity coefficients, with temperature-dependent interaction parameters, which were estimated through data regression and validated by checking the consistency of the Gibbs free energy. The NRTL model with the regressed parameters could reproduce the phase equilibrium trends of all the studied systems.
研究领域:
化学工程
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热力学
✓ 已验证
产品关联
DOI
高影响因子
ChemistrySelect
·
2023
·Vol. 8
·期 8
·e202203952
·
IF 2.1
Pinmei Yan,Xin Zhang,Yuanyuan Huang,Gengwei Liu,Peng Liu,Chenjie Li,Pengbin Pan,Yuangen Yao
Graphical After desilication, the catalyst structure remained unchanged, the pore size increased, the number of mesoporous pores increased, the specific surface area increased, the alkalinity increases, and the strong acid site disappears. After oxides loading, medium strong alkalinity and medium strong acidity increased further. The higher the base strength, the higher the negative charge on EtO δ− , to facilitate the reaction. Ethyl methyl carbonate (EMC) is the product of the partial transesterification of dimethyl carbonate (DMC) with ethanol (EtOH). How to modulate the catalyst with suitable acidity and alkalinity is of key importance for achieving both high activity and selectivity toward EMC. Herein, an Mg−Zn−P/AT-ZSM-5 catalyst with moderate basicity and moderate acidity was intelligently designed by the co-doping of Mg−Zn−P after the desilication of ZSM-5. Under the optimized reaction conditions, the EtOH conversion can reach 99.1 % with a high EMC selectivity of 96.3 %. Based on the results of multiple characterizations, the enhanced EtOH conversion and high EMC selectivity should be attributed to the well dispersed supported metal species, and enhanced metal-support interactions, especially the suitable surface acidity and alkalinity property of the catalyst. Such work provides a more reasonable design strategy for the preparation of a catalyst used for the transesterification reaction of DMC and EtOH to selectively produce high-valued EMC.
研究领域:
化学工程
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 38
·16836-16843
·
IF 2.7
Qingyun Ge,Baihu Dong,Yunqi Chen,Xinqiang Wang,Xiang Wang,Chaogang Fan,Chuhua Chen,Shaohui Lin,Qinmin Pan,Flora T. T. Ng
The polymerization and degradation behaviors of polypropylene carbonate (PPC) of different molecular weights were explored in the presence of catalyst Salen–Co(III)–Cl. The degradation of low-molecular-weight PPC (Mn = 2500 g mol−1, Đ = 1.01) was studied in detail, which was a second-order reaction related to the molar concentrations of PPC and the catalyst. Catalyzed by salen–cobalt, the degradation reaction proceeded spontaneously and could be completed at room temperature and atmospheric pressure, which provided a green and economical method for chemical degradation recycling of CO2-based polycarbonate plastics. On the basis of the degradation investigation, a method for the synthesis of cyclic propylene carbonate from propylene oxide and CO2 at room temperature and atmospheric pressure was developed.
研究领域:
材料科学
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化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Song Wang,Pengfei Hao,Sanxi Li,Ailing Zhang,Yinyan Guan,Linnan Zhang
Several anhydrous silicates were prepared by calcination at 400 °C and utilized as solid base catalyst for synthesizing glycerol carbonate (GC) by transesterification of glycerol with dimethyl carbonate (DMC). Among them, calcined sodium silicate showed the best catalytic activity with glycerol conversion of 97.7%. Then, a series of sodium silicates calcined at different temperatures were characterized using TGA, Hammett indicator method, BET, XRD, FT-IR and FESEM. Effect of calcination temperature on their catalytic ability was carefully investigated, followed by a reaction optimization study. The basicity of sodium silicates calcined at different temperatures highly depended on calcination temperature; their catalytic ability was affected by their total basicity rather than by their BET surface area; and the increased amount of strong basic sites resulted in the formation of by-product which decreased the GC yield and GC selectivity. Sodium silicate calcined at 200 °C (Na 2 SiO 3 -200), which had the intermediate total basicity and relative low amount of strong basic sites, incurred the highest GC yield. The highest catalytic performance of Na 2 SiO 3 -200 was achieved under the condition that the 4:1 molar ratio of DMC to glycerol was reacted at 75 °C for 2.5 h. This catalyst could be reused five times without noticeable drop in catalytic activity.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2018
·
IF 4.521
Yali Wan,Yizhu Lei,Guosong Lan,Dingfu Liu,Guangxing Li,Rongxian Bai
A large surplus of glycerol from the rapidly growing biodiesel industry has led to the conversion of glycerol into higher value-added products being of great industrial importance. In this paper, a promising route for the synthesis of glycerol carbonate from glycerol and dimethyl carbonate is described using DABCO (1,4-diazabicyclo[2.2.2]octane) embedded porous organic polymer as an efficient and robust catalyst. The porous catalyst with base sites and hydrophilic units (monoquaternized DABCO) was facilely synthesized through a one-pot radical copolymerization of divinylbenzene and vinyl functionalized DABCO monomer . By simply varying the mass ratio between divinylbenzene/DABCO monomer, the surface area, pore volume and surface wettability of the catalyst can be easily adjusted. Results of activity evaluations indicated that the catalyst with high surface area and excellent amphiphilicity exhibits much higher activity than other samples due to the enhanced accessibility of catalytic sites and mass transfer efficiency. Under the optimum reaction conditions, a 0.75 mol% catalyst loading is sufficient for excellent yield of glycerol carbonate in 60 min. Moreover, the optimized catalyst also shows excellent reusability and could be reused up to 13 consecutive recycles without obvious deactivation in activity.
研究领域:
化学工程
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催化材料
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绿色化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）