二氧化碳的间接利用:碳酸乙烯酯应用研究进展

以二氧化碳(CO2)为主的温室气体排放所导致的全球气候和生态系统变异问题正得到普遍重视,全球CO2年排放量已达数百亿吨[1].控制CO2排放量,对其回收、固定、利用及再资源化,已成为世界各国严重关切的问题.同时,从资源化角度出发,CO2是世界上最为丰富和廉价的碳一(C1)资源[2,3],因此,大力发展二氧化碳的绿色化利用技术,开发绿色高新精细化工产业链,提高产品的附加值,具有重要的意义.     

Development in the green synthesis of cyclic carbonate from carbon dioxide using ionic liquids

This brief review presents the recent development in the synthesis of cyclic carbonate from carbon dioxide (CO₂) using ionic liquids as catalyst and/or reaction medium. The synthesis of cyclic carbonate includes three aspects: catalytic reaction of CO₂ and epoxide, electrochemical reaction of CO₂ and epoxide, and oxidative carboxylation of olefin. Some ionic liquids are suitable catalysts and/or solvents to the CO₂ fixation to produce cyclic carbonate. The activity of ionic liquid is greatly enhanced by the addition of Lewis acidic compounds of metal halides or metal complexes that have no or low activity by themselves. Using ionic liquids for the electrochemical synthesis of the cyclic carbonate can avoid harmful organic solvents, supporting electrolytes and catalysts, which are necessary for conventional electrochemical reaction systems. Although the ionic liquid is better for the oxidative carboxylation of olefin than the ordinary catalysts reported previously, this reaction system is at a preliminary stage. Using the ionic liquids, the synthesis process will become greener and simpler because of easy product separation and catalyst recycling and unnecessary use of volatile and harmful organic solvents.     

乙酸盐上二氧化碳和二醇合成环状碳酸酯

在乙腈体系中,以不同的乙酸盐作催化剂,研究了CO2与二醇合成环状碳酸酯的反应.乙腈在反应过程中不仅是溶剂,而且还起到了脱水剂的作用,促进了反应的进行.以1,2-丙二醇为反应物对催化剂进行筛选,发现无水乙酸锌具有最高的催化活性.在无水乙酸锌上考察了二氧化碳和不同二醇的反应,结果表明,五元环碳酸酯的产率明显高于六元环碳酸酯,其中碳酸丙烯酯的产率最高.以1,2-丙二醇为反应基质,无水乙酸锌为催化剂,确定了最佳反应条件,1,2-丙二醇100 mmol,乙睛10 mL,催化剂2.5 mmol,反应压力10 MPa,温度170 ℃,反应12 h.在此条件下,碳酸丙烯酯的产率达到了24.2%,1,2-丙二醇的转化率为38.9%.     

Heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

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Insoluble polystyrene-bound quaternary onium salt catalysts for the synthesis of cyclic carbonates by the reaction of oxiranes with carbon dioxide

The addition reaction of oxiranes ( 26a—e ) with carbon dioxide (CO₂) was performed using insoluble polystyrene beads containing pendant quaternary ammonium or phosphonium salts as catalysts under atmospheric pressure. The reaction of 26a—e with CO₂ proceeded smoothly catalyzed by 1–2 mol % of the polymer-supported quaternary onium salts to give the corresponding cyclic carbonates ( 27a—e ) in high yields at 80–90°C. In this reaction system, the catalytic activity of the polymer-supported quaternary onium salts was strongly affected by the following factors: degree of ring substitution (DRS) of the onium salt residues to the polymer, degree of crosslinking (DC) of the polystyrene beads, chain length of the alkylene spacer between the polymer back-bone and the onium salt, hydrophobicity of the alkyl group on the onium salts, and kind of onium salts. That is, the polymer-supported quaternary phosphonium salts with low DRS and DC and with long alkylene spacer chain were found to have higher catalytic activity than low molecualr weight quaternary onium salts. The above polymer-supported catalysts can easily be separated at the end of a reaction by filtration and can be reused for at least seven runs. It was also found that the rate of reaction was proportional to the products of catalyst concentration and oxirane concentration. © 1993 John Wiley & Sons, Inc.     

Toughening of poly(propylene carbonate) by carbon dioxide copolymer poly(urethane-amine) via hydrogen bonding interaction

A carbon dioxide copolymer poly(urethane-amine)(PUA) was blended with poly(propylene carbonate)(PPC) in order to improve the toughness and flexibility of PPC without sacrificing other mechanical properties. Compared with pure PPC, the PPC/PUA blend with 5 wt% PUA loading showed a 400% increase in elongation at break, whilst the corresponding yielding strength remained as high as 33.5 MPa and Young's modulus showed slightly decrease. The intermolecular hydrogen bonding interaction in PPC/PUA blends was comfirmed by FTIR, 2D IR and XPS spectra analysis, and finely dispersed particulate structure of PUA in PPC was observed in the SEM images, which provided good evidence for the toughening mechanism of PPC.     

Water as an efficient medium for the synthesis of cyclic carbonate

Herein, we report a novel method for the synthesis of cyclic carbonate in water. By tuning the amount of water, cycloaddition of CO₂ to epoxide in aqueous medium leads to cyclic carbonates with moderate to excellent yields and high selectivities. In addition, the presence of water could remarkably improve the activity of ionic liquids by which the turnover frequency of the reaction is about 4-5 times higher in the presence than in the absence of water. The relationship between the higher catalytic reactivity and water was proposed.     

Cycloaddition of epoxide and CO2 to cyclic carbonate catalyzed by VO(IV) porphyrin

The cycloaddition of epoxide and CO₂ to synthesize cyclic carbonate catalyzed by VO(IV) porphyrin was achieved under 1.4 MPa at 150°C. The effects of reaction temperature, time, CO₂ pressure, co‐catalyst and porphyrin framework were investigated. The catalytic results showed that moderate to high yields of cyclic carbonates were obtained under the optimal reaction conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Mechanical properties of emulsion polymer blends

Polymer blend technology has been one of the most investigated areas in polymer science in the past 3 decades. The one area of polymer blends that has been virtually ignored involves simple emulsion blends, although several articles have recently appeared that address film formation and mechanical characteristics. In this study, we investigated the mechanical property behavior of emulsion blends composed of low/high‐glass‐transition‐temperature polymers (where low and high mean below and above the test temperature, respectively). The emulsions chosen for this study had similar particle sizes, and the mixtures were rheologically stable. Two conditions were chosen, a binary combination of polymers that were thermodynamically immiscible and another system that was thermodynamically miscible. The mechanical property results over the entire composition range were compared with the predictions of the equivalent box model (EBM) with the universal parameters predicted by percolation theory. An array of randomly mixed and equal‐size particles of differing moduli was expected to show excellent agreement with theory, and the emulsion blends provided an excellent experimental basis for testing the theory. For the immiscible blend, the EBM prediction for the modulus showed excellent agreement with experimental results. With tensile strength, the agreement between the modulus and theory was good if the yield strength for the higher glass‐transition‐temperature polymer was employed in comparison with the actual tensile strength. The phase inversion point (where both phases were equally continuous) was at a 0.50 volume fraction of each component (based on an analysis employing Kerner's equation), just as expected for a random mixture of equal‐size particles. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1093–1106, 2001     

Polymer‐supported pyridinium catalysts for synthesis of cyclic carbonate by reaction of carbon dioxide and oxirane

Polymer‐supported pyridinium salts, prepared by quaternarization of crosslinked poly(4‐vinylpyridine) with alkyl halides, effectively catalyze the reaction of carbon dioxide (1 atm) and glycidyl phenyl ether (GPE) to afford the corresponding five‐membered cyclic carbonate (4‐phenoxymethyl‐1,3‐dioxolan‐2‐one). Poly(4‐vinylpyridine) quarternarized with alkyl bromides show high catalytic activities, and the reaction of carbon dioxide (1 atm) and GPE at 100 °C affords 4‐phenoxymethyl‐1,3‐dioxolan‐2‐one quantitatively in 6 h. The rate constant in the reaction of GPE and carbon dioxide in N‐methyl pyrrolidinone using poly(4‐vinylpyridine) quarternarized with n‐butyl bromide (k_obs = 102 min^?1) is almost comparable with those for homogeneous catalysts with good activities (e.g., LiI), and the rate of the reaction obeys the first‐order kinetics. A used catalyst may be recovered by centrifugation, and the recycled catalyst also promotes the reaction of GPE and carbon dioxide. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5673–5678, 2007     

Effective synthesis of cyclic carbonates from carbon dioxide and epoxides by phosphonium iodides as catalysts in alcoholic solvents

Phosphonium iodides effectively catalyzed the reaction of CO₂ and epoxides under mild conditions such as ordinary pressure and ambient temperature in 2-propanol, and the corresponding five-membered cyclic carbonates were obtained in high yields.     

Synthesis of dimethyl carbonate from methanol and supercritical carbon dioxide

The synthesis of dimethyl carbonate (DMC) from methanol and supercritical carbon dioxide over various base catalysts has been studied. Compounds of group-I elements (Li, Na and K) were used as base catalysts. The promoter and the dehydrating agent were also used to enhance the yield of DMC. The effects of the catalysts, promoter and dehydrating agent on the yield of DMC were investigated. By-products such as dimethyl ether (DME) and C₁–C₂ hydrocarbons were formed with the DMC as a main product. The yield of DMC with different alkali metal catalysts ranked in the following order: K > Na > Li. The catalysts of the metal-CO₃ compounds were more effective than the metal-OH compounds in DMC synthesis. The maximum DMC yield reached up to about 12 mol% in the presence of K₂CO₃ (catalyst), CH₃I (promoter) and 2,2-dimethoxypropane (dehydrating agent) at 130–140°C and 200 bar. The reaction mechanism of DMC synthesis from methanol and supercritical carbon dioxide was proposed.     

Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbcn Dioxide

Promotion of ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as temperature, pressure and amount of emimBr was discussed.     

Self-compatibilization of polymer blends prepared via functionalized concentrated emulsion polymerization

Two “functionalized” concentrated emulsions in water were prepared separately, one from a weakly polymerized mixture of styrene (S) and a small amount of acrylic acid (AA) and the other from a mixture of butyl acrylate (or butyl methacrylate) and a small amount of glycidyl methacrylate (GMA). After the two concentrated emulsions were polymerized partially, they were mixed and subjected to complete polymerization. During the latter polymerization, reactions between the carboxyl groups of the AA moieties of the S/AA copolymer and the glycidyl groups of the GMA-containing copolymer occurred, and copolymers and crosslinked structures were generated that constituted the compatibilizers of the system. The blend materials thus obtained possessed excellent toughness compared to those without functional groups. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4233–4240, 1999     

超临界二氧化碳中组氨酸催化合成环状碳酸酯

研究了超临界二氧化碳中α-氨基酸催化二氧化碳与环氧化物环加成反应合成环状碳酸酯,发现组氨酸的催化活性最高.在二氧化碳压力为8MPa、反应温度130℃、反应时间48h、组氨酸加入量为0.8mol%的条件下,二氧化物可以顺利的与各种环氧化物反应,以高的选择性和产率生成相应的环状碳酸酯.     

Cyclic amidine hydroiodide for the synthesis of cyclic carbonates and cyclic dithiocarbonates from carbon dioxide or carbon disulfide under mild conditions

Hydroiodides of amidines can catalyze the reaction of carbon dioxide and epoxides under mild conditions such as ordinary pressure and ambient temperature, and the corresponding five-membered cyclic carbonates were obtained in high yields. The reaction of epoxide with carbon disulfide was also examined under the same conditions. Detailed investigation showed that the catalytic activity was highly affected by the counter anions of the amidine salts; the iodides were effective catalysts for both of the reaction of epoxide with carbon dioxide and carbon disulfide, whereas the bromide, chloride and fluoride counterparts exhibited almost no catalysis.     

Critical temperatures and pressures of reacting mixture in synthesis of dimethyl carbonate with methanol and carbon dioxide

Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate （DMC） from methanol and carbon dioxide （quaternary mixture of carbon dioxide ＋ methanol ＋ water ＋ DMC） were measured using a high-pressure view cell. The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition （initial ratio of carbon dioxide to methanol）. Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.     

Hydroxyl-functionalized ionic liquid: a novel efficient catalyst for chemical fixation of CO2 to cyclic carbonate

A series of hydroxyl-functionalized ionic liquids (HFILs) were synthesized and characterized. They showed efficient reactivity and reusability toward the coupling of epoxide and CO₂ without any additional co-catalyst and organic solvent. Highest activity and selectivity were achieved in the presence of 1-(2-hydroxyl-ethyl)-3-methylimidazolium bromide (HEMIMB) in comparison with other similar catalysts investigated. The relationship between the higher catalytic reactivity and OH-functional group was proposed.     

Comparison between the efficiencies of two conductive networks formed in carbon black-filled ternary polymer blends by different hierarchical structures

Two different types of thermodynamically induced self-assembled hierarchical structures were formed in carbon black (CB)-filled POM/SAN/TPU and POM/SAN/PA6 ternary polymer blends when the minor third polymer components TPU and PA6, which have the highest affinity to CB among the three polymer components, were individually incorporated into CB-filled POM/SAN binary blend: TPU with imbedded CB forms the interphase, while PA6 with imbedded CB forms droplets inside the SAN phase. The efficiencies of the two types of conductive networks formed by these hierarchical structures are compared in terms of electrical percolation threshold. The percolation threshold of CB in POM/SAN (70/30) blend decreases by 59% and 54% when only 5 wt% of POM is replaced by TPU and PA6, respectively. The mechanisms of conductive network formation are different in the two cases and related to their blend morphology, one is double percolation in a tri-continuous blend and the other is triple percolation in a cocontinuous blend.     

Equilibrium structure of hydrogen-bonded polymer blends

Deuterium-labeled polystyrene modified by random distributions of the comonomer p-(1,1,1,3,3,3-hexaflouro-2-hydroxyisopropyl)-α-methyl-styrene [DPS(OH)] has been blended with poly(butyl methacrylate) (PBMA) and studied with small-angle neutron scattering (SANS). Miscibility is induced via hydrogen bonding between the DPS(OH) hydroxyl group and PBMA carbonyl groups. The data suggest that the nature of the miscible-phase structure in these blends differs from that of the usual homopolymer blends at small scattering angles, which we attribute to the short-range site specific nature of the hydrogen bond interaction. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2745–2750, 1998