EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2015
·Vol. 117
·期 8
·1171-1178
·
IF 1.812
Shangde Sun,Bingxue Hu,Fanfan Song,Yanlan Bi
Glyceryl ferulates (GMF + GDF, combination of glyceryl monoferulate and glyceryl diferulate), and feruloylated acylglycerols (FMAG + FDAG, combination of feruloylated monoacylglycerols, and feruloylated diacylglycerols) are hydrophilic and lipophilic derivatives of ferulic acid (FA), which can be used as antioxidants and UV absorbers in food and other fields. In this study, the effect of ionic liquids (ILs) and organic solvents on the enzymatic transesterification of ethyl ferulate (EF) with monostearin was investigated. The effects of reaction time, temperature, and enzyme load on EF conversion and reaction selectivity were also evaluated and optimized using response surface methodology. Among ILs tested, high EF conversion (98.4 ± 0.5%), and reaction selectivity for GMF + GDF (0.81) were obtained in [Emim]TF 2 N; and for organic solvents tested, EF conversion (72.7 ± 1.5%) and reaction selectivity (0.75) were achieved in n-hexane. Results also showed that, compared with n-hexane, [Emim]TF 2 N can improve the selective synthesis of GMF + GDF, and [Emim]TF 2 N also shows significant protection on the enzyme inactivation at high temperature (90°C). The activation energies (Ea) of hydrolysis to form GMF + GDF and transesterification to form FMAG + FDAG were 51.98 and 43.49 kJ/mol in [Emim]TF 2 N, 72.35, and 53.11 kJ/mol in n-hexane, respectively. , , and in [Emim]TF 2 N were 0.01, 0.19 mol/L, and 4.13 × 10 −4 mol/(L · min), respectively. Practical applications: In this work, FMAG + FDAG and GMF + GDF were prepared by enzymatic transesterification of EF with monostearin. During the reaction, the competitive reaction of the hydrolysis of monostearin to form hydrophilic GMF + GDF and the transesterification of monostearin and EF to form lipophilic FMAG + FDAG take place in parallel. The effect of ionic liquids (ILs) and organic solvents on the competitive reaction was investigated. Compared with organic solvent (n-hexane), IL ([Emim]TF 2 N) is apt to the formation of hydrophilic GMF + GDF; and [Emim]TF 2 N shows remarkably protective effect on the inactivation of enzyme at high temperature up to 90°C than that (65°C) of n-hexane. This study can give information about the influence of different reaction media on the enzymatic transesterification and reaction selectivity. Enzymatic transesterification of ethyl ferulate (EF) with monostearin to produce hydrophilic glyceryl monoferulate (GMF)+glyceryl diferulate (GDF) and lipophilic feruloylated monoacylglycerols (FMAG)+feruloylated diacylglycerols (FDAG) in ionic liquids or organic solvents.
研究领域:
食品科学
·
生物化学
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产品关联
DOI
高影响因子
POLYMER
·
2020
·
IF 4.231
Xiangli Li,Dongsheng Yang,Youbo Zhao,Xingyuan Diao,Hongwei Bai,Qin Zhang,Qiang Fu
Stereoblock copolymerization is regarded an appealing strategy to substantially enhance the melt stability (i.e., the survival ability of the intermolecular collaboration between poly( l -lactide) (PLLA) and poly( d -lactide) (PDLA) upon melting) of high-molecular-weight (high-MW) stereocomplex-type polylactide (SC-PLA), however it usually suffers from complicated synthetic procedures and even impaired sustainability. Herein, solid-state transesterification (SST) has been devised as a facile and robust route to prepare unique multi-stereoblock PLA copolymers with outstanding melt stability and unexpectedly strong crystallizability from commercial available linear high-MW PLLA/PDLA (50/50) blends. The SST was performed through low-temperature (i.e., 180 °C) melt-blending of PLLA and PDLA in the presence of trace amounts (0.03–0.035 wt%) of catalysts, where the enantiomeric PLA chains could rapidly co-crystallize into solid-state SC crystallites upon melting and subsequently the hetero-chain transesterification reaction occurs exclusively in the mobile amorphous phase of the pre-formed SC crystallites. As a result, multiblock-like PLLA- b -PDLLA- b -PDLA copolymers with long crystallizable PLLA and PDLA blocks are in-situ generated. The results show that high-content SC crystallites can be exclusively formed in the melt-crystallization of the copolymers even at high cooling rates (e.g., 40 °C/min) and low temperatures (e.g., 140 °C). More interestingly, the presence of the non-crystallizable PDLLA blocks not only does not disturb the SC crystallizability of the enantiomeric PLA blocks, as evidenced by the same high crystallinity and melting temperature as those of starting PLLA/PDLA blends, but also increase the crystallization rate by stabilizing the clusters of ordered PLLA/PDLA segments in the copolymer melt. Overall, these findings could open a new pathway to develop melt-processible all SC-PLA for engineering applications.
研究领域:
材料科学
·
高分子化学
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DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2026
·
IF 5.1
Xiaoyan Chen,Yaxin Cai,Yiwei Lan,Changshen Ye,Ting Qiu,Jie Chen
Base-facilitated transesterification reactions hold a central position in the chemical industry, as they serve as crucial strategies for producing numerous chemicals, particularly for manufacturing ethyl methyl carbonate (EMC) electrolyte of lithium batteries from ethanol (EtOH) and dimethyl carbonate (DMC). However, reported catalysts face challenges including catalyst deactivation and environmental pollution. To tackle these challenges, we report functionalized quaternary ammonium ionic liquids with fine-tuned electronegativity and alkalinity via anion design and electron-withdrawing/donating substituents on the quaternary ammonium. N B222 Im achieves the fastest and highest catalytic performance to date; at an ultra-mild reaction time of 5 min and 58 ℃, its EMC yield reaches 55.61% with 91.57% product selectivity. We successfully correlate electrostatic attraction/electron delocalization ability of anions with the catalytic performance, visualizing the effective production of ethoxy group from EtOH, the selective cleavage of methoxy group from DMC, and their directional combination to form EMC by the nitrogen atoms in imidazole anions. Moreover, compared with the uncatalyzed system, DFT calculations on the proposed reaction mechanism demonstrate that N B222 Im can lower the reaction energy barrier for the conversion of DMC to EMC. This barrier is also lower than that of the EMC-to-DEC pathway, thus endowing this ionic liquid with high selectivity toward EMC formation. This work offers a viable strategy to overcome conventional catalyst drawbacks and new insights for efficient EMC synthesis catalyst design, and promotes electrode material development.
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2025
·
IF 3.9
Mei Meng,Min Xiao,Jintao Wang,Peiyuan Li,Xianli Wu,Yuezhong Meng
Carbon dioxide (CO2) has been utilized for synthesizing biodegradable polymers to promote sustainable energy conservation and mitigate emissions. Nonetheless, the low glass transition temperature of amorphous CO2-based polyester–polycarbonate (PPC-P) significantly impedes its practical application. Herein, semi-crystalline copolymers, PPC-P-co-PLA, were successfully synthesized via copolymerization of propylene oxide (PO), phthalic anhydride (PA), and CO2 in combination with PLA through transesterification catalysed by Lewis acid–base pairs in a one-pot/one-step method. Metal-free catalysts were utilized for the first time to catalyse both ring-opening copolymerization and transesterification reactions for copolymer synthesis. The mechanism study of PLA transesterification catalysed by triethyl borane (TEB)/Lewis bases revealed that effective depolymerization and transesterification of PLA hinge on α-H chemical shift alterations induced by the Lewis bases. Lewis acid–base pairs facilitate the formation of PPC-P-co-PLA multi-block copolymers by terminating one end of PPC-P with PLA segments via continuous transesterification reactions. Compared to PPC-P, the copolymers exhibit an increase in glass transition temperature by 5–7 °C and an elevation in thermal decomposition temperature by 18–45 °C. The optimal mechanical and rheological properties of PPC-P-co-PLA multi-block copolymers are achieved at a PLA concentration of 8 wt%. This study opens new avenues for the synthesis of semi-crystalline polyester–polycarbonate-based copolymers with high glass transition temperatures, thereby enriching the theoretical foundation for the synthesis of block copolymers.
研究领域:
材料科学
·
高分子化学
·
绿色化学
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产品关联
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Tongxin Qu,Shengli Niu,Xiangyu Zhang,Kuihua Han,Chunmei Lu
The calcium modified Zn-Ce/Al 2 O 3 heterogeneous base catalysts are synthesized by the hydrothermal method, impregnation method and co-precipitation method, respectively. Further, they are applied to catalyze transesterification of palm oil with methanol for the biodiesel production. The hydrothermal method with the Ca: Zn: Ce: Al molar ratio of 5: 4: 1: 1 is preferred to synthesize the catalyst due to the best catalytic performance. The catalyst shows strong reusability, where the biodiesel yield of 87.37% is obtained for the fifth reused cycle and the weakened catalytic capability is mainly ascribed to the leaching out of the active sites. The response surface methodology with the central composite design (RSM-CCD) is employed to optimize the transesterification parameters and predict the biodiesel yield. The predicted maximum biodiesel yield of 99.44% is achieved at the reaction temperature of 66.12 °C, methanol to oil molar ratio of 18.53 and catalyst amount of 8.19 wt. % with 3 h, which is consistent with the experimental result of 99.41%. Also, the physical properties of the produced biodiesel meet the ASTM D 6751 standard. This study reveals the Ca-Ce-Zn/Al 2 O 3 catalyst gains a good application prospect in the biodiesel production and the response surface methodology is effective in optimizing the transesterification parameters and predicting the optimal values.
研究领域:
化学工程
·
可再生能源
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2019
·Vol. 94
·期 11
·3538-3547
·
IF 2.659
Lijuan Yang,Siyu Wang,Hong Yuan,Hai Liu
BACKGROUND Mesoporous double-layer carbon microspheres (DCSs) were synthesized using hollow tin(IV) oxide (SnO 2 ) microspheres as hard template and sucrose as carbon precursor via the hydrothermal method. Sulfonic acid groups (-SO 3 H) were introduced onto the surfaces of DCS by sulfuric acid heating and sulfanilic acid diazonium coupling, respectively, to form two solid acids (DCS-SS and DCS-DS, respectively). RESULTS The transmission electron microscopy images showed that the carbon microspheres possessed a hollow double-layer structure with diameters of about 200 to 300 nm and shell thickness of about 30 to 50 nm. Furthermore, the sulfonate treatments caused no changes in the morphology of carbon microspheres. The nitrogen (N 2 )-Brunauer–Emmett–Teller (BET) results indicate that DCS, DCS-SS, and DCS-DS featured mesopores with an average pore size of 4.5 to 4.8 nm and BET surface areas of 75 m 2 /g, 57 m 2 /g, and 53 m 2 /g, respectively. The X-ray photoelectron spectroscopy and Fourier-transform infrared results confirmed that the DCS-SS and DCS-DS contained a -SO 3 H group and their surface acid densities are 4.5 and 4.1 mmol/g, respectively. CONCLUSION DCS-SS and DCS-DS were used to catalyze the transesterification of waste frying oil, and the highest yields of fatty acid methyl esters, that is, 85% and 80%, respectively, could be obtained. © 2019 Society of Chemical Industry
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Junyao Shen,Xinyi Gao,Zhen Liu,Ling Zhao,Zhenhao Xi,Weikang Yuan
A deep insight into the reaction mechanism is essential to control the polymerization process with the desired macromolecular structure for high-performance thermotropic liquid crystalline polymer. In this work, density functional theory (DFT) was used to investigate the catalytic polymerization mechanism for the synthesis of thermotropic liquid crystalline polymer catalyzed by zinc(II) carboxylate. The polymerization of 4-acetoxybenzoic acid was studied as a typical reaction. Based on DFT calculations, the rate-limiting step is located in the transesterification between phenol and anhydride acid. The energetically favored pathway was found with the free energy barrier of 51.84 kcal/mol in the presence of zinc acetate, which is significantly lower than the energy barrier without a catalyst. In addition, the effects of the carboxylate group of zinc(II) carboxylate on the catalytic efficiency were revealed by DFT calculations and experiments. Compared with zinc acetate, zinc pivalate has a higher catalytic activity with the rate constant of 1.69 × 10 -2 min −1 ∙M −1 fitted with a second-order reaction model. The HOMO-LUMO gap of zinc pivalate was the smallest among the chosen catalyst, indicating that the chemical activity was strengthened by the methyl substituted. Furthermore, due to the enhanced orbital interactions and the decreased distortion energy in the transition state using zinc pivalate, the energy barrier of the rate-limiting step decreased to 51.36 kcal/mol. These results provide valuable guidance for modeling the catalytic mechanism in aromatic polyester systems.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 12
·5540-5550
·
IF 3.591
Qiang Wei,Gang Zhang,Jie Yao,Xuejun Chen,Gongying Wang,Xiangui Yang
Dimethyl carbonate (DMC) is well known as an extremely industrially valuable substance. The demand for high-efficiency synthesis of DMC has greatly driven the exploration of novel catalysts and their low-cost preparation methods. Herein, a novel method for the rapid batch preparation of CaO/carbon catalysts using calcium citrate (CaCi) was provided, and these catalysts were used to catalyze the transesterification reaction of methanol and ethylene carbonate (EC) to synthesize DMC and ethylene glycol (EG). Accordingly, the structure and properties of the catalysts were characterized using XRD, FTIR, N2 adsorption–desorption, TG, TG-IR, CO2-TPD, XPS, SEM, TEM and ICP-OES techniques. Meanwhile, the effect of various process conditions such as carbonization temperature, reaction temperature, reaction time and catalyst amount has been extensively evaluated. Under the optimal process parameters, the conversion of EC and the selectivity of DMC and EG were 81.2, 99.3 and 99.5%, while the turnover number (TON) and turnover frequency (TOF) were 54.1 and 162 h−1, respectively. Furthermore, kinetic analysis was carried out, and the value of k (reaction rate constant) was ≈0.159 mol L−1 min−1. The reusability was also investigated.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
RENEWABLE ENERGY
·
2024
·
IF 9
Wenlei Xie,Xiangxiang Wang,Lihong Guo
Improving the reactant mass transfer on the catalyst surface is a feasible approach to fabricate a robust solid catalyst for efficiently promoting the biomass macromolecules-involving reactions, specifically for biodiesel production by using non-edible acidic oils as feedstocks. In this premise, to reduce the mass transfer resistance, the hierarchical porous SOM-ZIF-8 was firstly synthesized using polystyrene spheres (PS) as templates and then employed as catalyst supports for loading of Keplerate-type polyoxomolybdates {Mo 132 } to prepare a novel {Mo 132 }@SOM-ZIF-8 solid acid catalyst. The catalyst characterization results revealed that the active species of {Mo 132 } clusters were well-dispersed on the SOM-ZIF-8 support and the primary framework of the SOM-ZIF-8 support remained nearly unaltered after the preparation processes. This prepared catalyst featured three-dimensional ordered hierarchical porous structure and dual Bronsted-Lewis acid sites, with a large surface area of 736.26 m 2 /g and high acidity of 903 μmol/g, presenting high activities for concurrent triglyceride transesterification and free fatty acids (FFAs) esterification. With the acidic soybean oils as feedstocks, 93.9 % of oil conversion and full FFA conversion to biodiesel were achieved over this solid catalyst at 130 °C for 8 h with a catalyst loading of 2 wt%, thus imparting the great potential for a one-pot efficient biodiesel manufacture from the acidic oils to comply with the demand of green and clean production. The synergy between the hierarchical porous structure and the strong acidity emerged, thus boosting the catalytic performance of this solid catalyst for the heterogeneous biodiesel production. The good FFA and moisture-resistance capacity was shown for this catalyst even in the case of moisture content of 3 % and FFA content of 25 %. Further, this catalyst showed excellent reusability without significantly losing its catalytic performance even after five runs, providing a deeper insight into constructing efficient solid catalysts with hierarchical porous structure that are utilized for cost-effective production of biodiesel from the non-edible acidic oils.
研究领域:
化学工程
·
可再生能源
·
催化材料
✓ 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）