CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2021
·Vol. 100
·期 12
·3717-3726
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IF 2.007
Piao Cao,Lin Zheng,Weizhen Sun,Ling Zhao
Four typical Brønsted acidic ionic liquids (BILs) and concentrated sulphuric acid (H 2 SO 4 ) were used to catalyze the transesterification of fish oil with ethanol to produce fatty acid ethyl ester (FAEE) in this work. The experimental results show that the imidazole BILs lead to fewer side reactions and higher product quality than H 2 SO 4 . Molecular dynamics (MD) simulations indicate that [PSMim][HSO 4 ] molecules can be enriched at the interface and enhance the contact of eicosapentaenoic acid triglyceride (EPATG, a typical component of fish oil) and ethanol. And ester groups of EPATG tend to expose more to ethanol in the BILs system, which facilitates the occurrence of transesterification. However, H 2 SO 4 has no positive effect on the distribution of the two reactants. For the transesterification, the interfacial property affects the catalytic activity a lot, instead of catalyst acidity. Also, the reaction rate is accelerated, obviously, by ultrasound-led liquid–liquid phase emulsification.
研究领域:
生物化学
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催化化学
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产品关联
DOI
高影响因子
Processes
·
2023
·Vol. 11
·期 6
·1810
·
IF 3.5
Jichao Sun,Hewei Yu,Peisen Zhang,Gaoyu Qi,Xiuxiu Chen,Xiaohui Liang,Hongyu Si
For further resource utilization of solid waste steel slag and the reduction in biodiesel production costs, this study used steel slag as a carrier to synthesize a CaO-CeO2/slag solid base catalyst for the effective transesterification of palm oil into fatty acid methyl esters (FAMEs). The synthesis involved a two-step impregnation of steel slag with nitrate of calcium and cerium and thermal activation at 800 °C for 180 min. Then, the catalysts’ textural, chemical, and CO2temperature-programmed desorption properties were characterized. The catalytic activity depended highly on the ratio of Ca-Ce to steel slag mass; the CaO-CeO2/slag-0.8 catalyst showed outstanding performance. Characterization showed that the surface area and total basicity of the Ca-Ce/slag-0.8 catalyst were 3.66 m2/g and 1.289 mmol/g, respectively. The reactivity results showed that FAMEs obtained using 7 wt.% catalyst, 9:1 of methanol-to-palm-oil molar ratio, 180 min reaction duration, and 70 °C reaction temperature was optimum (i.e., 95.3% yield). In addition, the CaO-CeO2/slag-0.8 catalyst could be reused for at least three cycles, retaining 91.2% of FAMEs yield after n-hexane washing. Hence, the catalyst exhibits an excellent potential for cost-effective and environmentally friendly biodiesel production.Keywords:steel slag;calcium oxide;cerium oxide;transesterification;biodiesel
研究领域:
化学工程
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环境科学
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产品关联
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2022
·Vol. 16
·期 9
·1399-1406
·
IF 4.803
Feng Xing,Du Meiqing,Wei Hongbei,Ruan Xiaoxiao,Fu Tao,Zhang Jie,Sun Xiaolong
The degradation of polymeric materials is recognized as one of the goals to be fulfilled for the sustainable economy. In this study, a novel methodology was presented to synthesize multiple highly cross-linked polymers (i.e., hydrogels) through amine-thiol scrambling under mild conditions. Amine-terminated poly(ethylene glycol) (PEG-NH 2 ) was reacted with the representative conjugate acceptors to synthesize hydrogels in organic and aqueous solutions, respectively. The materials above exhibited high water-swelling properties, distributed porous structures, as well as prominent mechanical strengths. It is noteworthy that the mentioned hydrogels could be degraded efficiently in hours to release the original coupling partner, which were induced by ethylene diamine at ambient temperature through amine-amine metathesis. The recovered PEG-NH 2 reagent could be employed again to regenerate hydrogels. Due to the multiple architectures and functions in polymeric synthesis, degradation and regeneration, a new generation of “smart” materials is revealed.
研究领域:
材料科学
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化学工程
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生物材料
✓ 已验证
DOI
高影响因子
RENEWABLE ENERGY
·
2020
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IF 6.274
Tongxin Qu,Shengli Niu,Zhiqiang Gong,Kuihua Han,Yongzheng Wang,Chunmei Lu
CaO is efficient in catalyzing transesterification for biodiesel production , but its industrial application is inherently restricted by active sites leaching. To address this drawback, CaO is decorated into wollastonite to prepare the stable Ca/wollastonite catalyst. Microwave-assisted transesterification is used to produce biodiesel from palm oil, which effectively accelerates the reaction rate and improves the conversion efficiency. The Ca/wollastonite-0.8 catalyst with the mass ratio of CaO to wollastonite of 0.8 performs well with the fatty acid methyl ester (FAME) yield of 97.59%. Also, this catalyst is highly stable, where the FAME yield of 87.30% could be obtained for the fifth reused cycle. CaO is evenly dispersed on the wollastonite surface and the total basicity is high to 0.281 mmol g −1 . Meanwhile, transesterification parameters are optimized by response surface methodology with central composite design (RSM-CCD) and the maximum FAME yield of 98.46% is achieved at reaction temperature of 64.2 °C, molar ratio of methanol to palm oil of 15.54 and mass ratio of catalyst to palm oil of 9.21 wt % for 3 h. Besides, the mass ratio of catalyst to palm oil is the primary variable. Wollastonite is demonstrated to be feasible to enhance the stability of CaO in catalyzing transesterification.
研究领域:
化学工程
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可再生能源
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
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2024
·Vol. 42
·期 10
·1495-1504
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IF 4.1
Wu Shi-Long,Yang Huan-Huan,Chen Quan
In this study, we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct. The vitrimer samples thus prepared exhibit linear viscoelasticity dependent on the length of A moiety as well as the content of the crosslinks. When the average number of A monomers per end moiety m =1.1, the crosslinker can only extend the chain but not crosslink the chain. When m becomes 2.8 or higher, introducing a crosslinker first leads to the gelation, whereas excess in crosslinker molecules leads opening of the crosslinking sites and accordingly reentry into the sol regime. Surprisingly, a further increase in the length of the A moieties increases the relaxation time much weaker than the exponential increase seen for the physically crosslinked ABA-type ionomers. We attribute this difference to the distinct relaxation mechanisms: the relaxation of the vitrimer samples is based on relatively independent exchange reactions, which contrasts with the ABA-type ionomers that relax through the collective hopping of connected ionic groups from one ion aggregate to another.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
RENEWABLE ENERGY
·
2022
·
IF 8.634
Xiu Gao,Chao Chen,Wenlu Zhang,Yanping Hong,Chunrong Wang,Guoqiang Wu
A series of sulfated TiO 2 supported Mo ( x Mo/1.5ST) catalysts were synthesized successfully and evaluated for the transesterification of Jatropha seed oil (JO) to biodiesel. Extensive characterization exhibits that the well dispersed Mo oxide species, with Mo 6+ and Mo 5+ oxidation states, were formed on the surface of the sulfated TiO 2 . The results indicate the presence of many sulfates species leads to the reduction of Mo 6+ species to Mo 5+ species. Furthermore, the catalytic activity of the x Mo/1.5ST catalysts gradually increases with the increase of Mo-loading, although the sulfates content and the total acid intensity decrease. The transesterification process was fully investigated, and the 10Mo/1.5ST shows the highest yield of biodiesel of up to 97.42%. Additionally, the possible mechanism for the JO transesterification over Mo/1.5ST was described, and the fuel properties of the as-synthesized biodiesel conformed to the current international standards.
研究领域:
化学工程
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可再生能源
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2025
·
IF 7.3
Yujun Zhou,Nan Nan Xia,Jialu Zhang,Tianxiang Li,Jianmin Wang,Qin Wu
The repeated bonding properties of wood adhesives directly influence the service life of wood. The covalent cross-linked networks of conventional thermosetting wood adhesives endow them with excellent performance but suppress the mobility of molecular chains, hindering the repeated bonding after adhesive failure via molecular chain reorganization. Here, we develop a thermoplastic hyperbranched polyurethane wood adhesive, which contains a prepolymer composed of cashew phenol, polyol, and isocyanate groups as the branching chains, a hyperbranched polyester as the core, and lipoic acid with disulfide (S–S) bonds as the terminal groups. When this adhesive breaks or cracks under external force and the broken surfaces are joined together, the molecular chains on both sides of the adhesive converge toward the breakage points driven by the highly branched structure of the hyperbranched polymer, promoting contact between the S–S bonds on both sides. Under heating conditions, dynamic reversible exchange reactions occur, stitching the cracks, and enabling the adhesive to bond repeatedly. Benefiting from this advantage, HPU-LA (100%) can retain more than 85% of its original bonding strength even after undergoing five repeated bonding cycles at 80 °C. This study addresses the issue of resource waste caused by the nonreusability of conventional adhesives as well as has notable research implications for extending the service life of wood.
研究领域:
材料科学
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林业工程
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Meng Li,Xiao Zhang,Peng Wang,Ping Yang
Research on anion exchange reactions (AERs) indicated that the reaction rate has a significant influence on the photoluminescence properties and crystal structures of the resulting CsPb(Br/I)3 nanocrystals (NCs). Controllable AERs were achieved by controlling the reaction rate. Using controllable AERs, metastable γ-CsPbI3 NCs were directly obtained from the aged orthorhombic CsPbBr3 NCs. Rietveld refinement indicated that the crystal structure of parent CsPbBr3 was maintained without any phase transition or degradation. The prepared γ-CsPbI3 NCs exhibited good stability at room temperature. X-ray photoelectron spectroscopy analysis demonstrated the presence of Br and the high binding energy of Pb–Br bonding. Pb–Br bonds maintained the parent orthorhombic CsPbBr3 structure and increased the stability of γ-CsPbI3 NCs. Controllable AERs provide versatile methods to maintain the parent perovskite structure and synthesize CsPbI3 NCs with a more rigid crystal structure. They pave the way for the preparation of NCs, which are difficult to synthesize directly.
研究领域:
材料科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Yumeng Liu,Zhixiang Dong,Yihai Wang,Jian Ding,Tuan Liu,Juan Long,Tuhua Zhong,Collin Pekol,Orlando Rios,Jong Keum,Min Xia,Naisheng Jiang,Yuzhan Li
Exchangeable liquid crystalline elastomers (xLCEs) bearing dynamic covalent bonds are promising candidates for soft actuators due to their unique capability to adjust both network structure and liquid crystalline (LC) alignment after polymerization. While current xLCEs with low exchange temperatures are convenient for processing, they suffer from issues such as creep and loss of LC alignment during repeated thermal actuation. Herein, we present an effective solution using dynamic anhydride chemistry within a thiol-ene-based xLCE. This approach enables a catalyst-free, low-temperature bond exchange of the xLCE after polymerization, allowing for the adjustment of LC orientation under mild conditions. More importantly, it enables on-demand deactivation of the bond exchange via anhydride hydrolysis, effectively eliminating creep and enhancing actuation stability for over 100 cycles. Furthermore, the hydrolysis process results in the formation of carboxylic acid groups, which can be converted into carboxylates via alkali treatment, thereby providing the xLCE with humidity responsiveness. These findings highlight the use of dynamic anhydride bonds in the fabrication and optimization of xLCEs with enhanced durability and functionality, which is expected to facilitate significant advancements in their applications in soft actuators and robotics.
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
Nanomaterials
·
2022
·Vol. 12
·期 12
·1972
·
IF 5.719
Yihao Li,Hepan Zhao,Wei Xue,Fang Li,Zhimiao Wang
A series of Mg-Zr composite oxide catalysts prepared by the hydrothermal process were used for the transesterification of glycerol (GL) with dimethyl carbonate (DMC) to produce glycerol carbonate (GC). The effects of the preparation method (co-precipitation, hydrothermal process) and Mg/Zr ratio on the catalytic performance were systematically investigated, and the deactivation of the catalyst was also explored. The Mg-Zr composite oxide catalysts were characterized by XRD, TEM, TPD, N2adsorption-desorption, and XPS. The characterization results showed that compared with the co-precipitation process, the catalyst prepared by the hydrothermal process has a larger specific surface area, smaller grain size, and higher dispersion. Mg1Zr2-HT catalyst calcined at 600 °C in a nitrogen atmosphere exhibited the best catalytic performance. Under the conditions of reaction time of 90 min, reaction temperature of 90 °C, catalyst dosage of 3 wt% of GL, and GL/DMC molar ratio of 1/5, the GL conversion was 99% with 96.1% GC selectivity, and the yield of GC was 74.5% when it was reused for the fourth time.Keywords:glycerol carbonate;transesterification;hydrothermal process;Mg-Zr oxides
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
PubMed
高影响因子
GIANT
·
2020
·
IF 0
Hongkun Yang,Changfei He,Thomas P. Russell,Dong Wang
Although considerable progress has been made in developing vitrimers, on-going challenges for vitrimers for high-performance applications include the improvement in mechanical properties and identification of more efficient exchange reactions. By incorporation of glycidyl polyhedral oligomeric silsesquioxane (POSS) as a nanoscale filler in epoxy, we produced epoxy-POSS nanocomposite vitrimers that show high strength, toughness, thermal stability, and efficient relaxation. With 10 wt% POSS, the ultimate tensile strength and strain at break of the epoxy-POSS nanocomposite vitrimers increased by ~64% and ~76%, respectively, while at 160 °C the stress relaxation time increased by ~260% in comparison to that of pure epoxy vitrimer. The epoxy-POSS nanocomposite vitrimers show high malleability due to the efficient transesterification reaction and re-processability with little degradation of their initial mechanical properties, suggesting opportunities for sustainable plastics.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2021
·Vol. 38
·期 2
·516-521
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IF 1.307
Kang Xiaoying,Yuan Yuan,Xu Huaping,Chen Yulan
T hermal- and light-driven diselenide metathesis reactions with different types of diselenides are investigated systematically. Their exchange reaction rates and equilibrium conversions are compared in the aspects of the different diselenide structures, activation conditions and solvents. As a result, the metathesis reactions between diselenide small molecules are demonstrated with high dynamic and sensitive features, which can be broadly tuned by varying the electron affinity and aromaticity of the diselenide substituents and external conditions( e.g. , solvent, stimulus mode). The current work thus will not only advance our understanding on diselenide metathesis chemistry, but also promote concrete and impactful studies in selenium-containing materials.
研究领域:
化学
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材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）