季膦盐离子液体／卤化锌催化CO2环加成反应

制备了一种由氯化锌和三己基十四烷基季膦盐离子液体组成的Lewis酸／碱复合催化体系,将其用于CO2与环氧烷烃的环加成反应,表现出高催化活性。系统地考察了反应温度、反应压力、反应时间及催化剂组成的影响,结果表明,以[（C6H13）3P（C14H29）]Br／ZnCl2（物质的量之比为2：1）为催化剂,在CO2压力为2MPa,反应温度为100℃,反应15rain条件下,碳酸丙烯酯收率达到95％。研究表明该催化体系也适用于CO2与其他环氧化物的环加成反应。最后提出了该催化体系的反应机理。     

离子液体在CO2环加成反应中的应用

离子液体(ILs)作为一种新型的绿色溶剂,因其具有热稳定性好、挥发性低、结构可设计性等优点被广泛应用在CO_2环加成反应中。综述了由ILs催化CO_2与环氧化物的环加成反应制备环状碳酸酯的研究进展,从反应相态的角度将ILs催化剂分为普通ILs催化剂和负载ILs催化剂,分别阐述了其催化性能。简要分析了ILs催化剂目前存在的主要问题,并对ILs在CO_2环加成反应中的应用进行了展望。     

多孔有机聚合物催化二氧化碳合成环状碳酸酯研究进展

二氧化碳（CO₂）捕集、利用和储存（CCUS）在全球能源结构转型中是一种极具潜力的策略,能够实现能源供给、基础原料产出以及限制气候变化。多孔有机聚合物（POPs）具有高CO₂吸附容量和吸附选择性、突出的结构特性以及优异的化学可调控性,其作为极具潜力的材料广泛应用于催化CO₂参与的有机反应中。其中,CO₂与环氧化物环加成生成环状碳酸酯的反应具有100%的原子经济性,且其产物也极具工业价值。本文基于CO₂环加成反应催化机制,从催化剂的合成方法、结构性质与组成特性角度出发,综述了POPs在CO₂/环氧化物环加成反应的研究进展,包括金属配合物类、氢键供体类、离子液体类、金属配合物/离子液体和氢键供体/离子液体等有机多孔聚合物体系。通过阐述POPs在催化CO₂制备高附加值环状碳酸酯反应中的研究现状和发展趋势,为POPs的开发与应用以及CO₂综合利用的工业化探索提供具有建设性的指导意见。     

多位点离子液体聚合物催化CO2环加成反应研究

CO₂与环氧化物环加成反应制备环状碳酸酯是一条绿色经济的CO₂利用途径。针对现有CO₂与环氧化物环加成反应中非均相离子液体催化剂活性低和活性组分易流失等问题,设计制备了系列多位点离子液体超交联聚合物HCPs-[DmPhe]Br,研究了多位点协同作用、超交联聚合物组成和结构等因素对其催化CO₂与环氧化物环加成反应性能的影响。其中,同时含有双季铵-卤素离子对、羟基和叔胺结构的HCP-[DmPhe]Br-DCX离子液体超交联聚合物催化剂,在1.3 MPa, 130℃,8 h的条件下,可实现94%的碳酸丁烯酯收率,且催化剂循环稳定性好,重复使用5次,催化活性没有明显降低。另外,超交联聚合物的多孔结构以及大比表面积促进了离子液体的较好分散,使其与离子液体单体具有相当的活性。该工作对CO₂与环氧化物环加成反应高效非均相离子液体催化剂的开发与优化具有一定的借鉴意义。     

多孔材料在催化CO2与环氧化物环加成反应中的研究进展

以CO2为原料与环氧化物合成环状碳酸酯是实现CO2资源利用最为有效的途径之一，也是缓解温室效应的有效方式之一。在该反应中催化剂的选择至关重要，多孔材料由于具有相对密度低、强度高、比表面积大、稳定性好、合成方法多样等优点而被广泛应用于催化CO2环加成。重点综述了近年来无机多孔材料、多孔有机聚合物材料、金属有机骨架材料在催化CO2与环氧化物合成环状碳酸酯中的研究进展，介绍了各催化剂的优缺点并对未来多孔材料的发展进行了展望。     

含酚吡啶基多孔离子聚合物催化二氧化碳合成环状碳酸酯

利用傅-克烷基化反应一步合成了含酚吡啶基多孔离子聚合物(Py-PiP OH),采用FTIR、XPS、SEM、XRD和TG对其结构、形貌和热稳定性进行了表征。通过N₂和CO₂吸附-脱附测试分别对Py-PiP OH进行孔道参数和CO₂吸附性能进行了分析。结果表明,Py-PiP OH框架中富含酚羟基、吡啶离子液体单元和微孔结构。Py-PiP OH比表面积(S_BET)为155.4 m₂^/g,在273 K和0.1 MPa条件下,CO₂吸附量为37.1 cm₃^/g。100 ℃、1.0 MPa和不加任何助催化剂条件下,Py-PiP OH在CO₂环加成反应中表现出优异的催化剂性能,反应12 h可获得96.3%的氯甲基二氧杂戊环酮收率。当以模拟废气(15% CO₂+85% N₂,体积比)为原料时,在100 °C和3.0 MPa下反应24 h,氯甲基二氧杂戊环酮的收率依然可达90.3%。考察了温度、压力等反应条件对环氧氯丙烷和CO₂环加成反应的影响。此外,Py-PiP OH具有良好的底物普适性,且重复使用5次后,催化活性和选择性没有明显下降。     

季铵型多孔超交联离子聚合物催化二氧化碳环加成合成环状碳酸酯

以双(三苯基膦)氯化铵为单体,通过傅-克烷基化反应制备一种季铵型多孔超交联离子聚合物(QA-PHIP)。采用傅里叶变换红外光谱、扫描电镜和N₂吸附-脱附等对QA-PHIP进行表征。结果表明,QA-PHIP的比表面积为903.7 m²·g^-1,在0.1 MPa和0℃条件下CO₂的吸附量为52.1 cm³·g^-1。将QA-PHIP应用于催化CO₂与环氧化物合成环状碳酸酯的反应,考察反应温度和催化剂用量等因素对催化性能的影响。QA-PHIP表现出良好的催化性能,在120℃和1.0 MPa条件下反应12 h,可获得99.6%的环氧氯丙烷转化率和97.3%的氯甲基二氧杂戊环酮收率。QA-PHIP表现出良好的底物扩展性和重复使用性。     

硅胶负载酸性离子液体催化CO_2环加成反应

制备了4种硅胶负载酸性离子液体,将其作为催化剂用于环氧烷烃和CO2的环加成反应,表现出高催化活性。系统地考察了不同负载离子液体的催化性能、反应压力、反应温度、反应时间和催化剂用量的影响,结果表明,硅胶负载的酸性离子液体在该环加成反应中具有良好的催化活性,环氧丙烷转化率均大于95%。在以[Smim]HSO4(0.5 g)作为催化剂时,碳酸丙烯酯的选择性为最大值90.6%。使用该催化剂0.5 g,以2.5 m L环氧丙烷(PO)作为反应物,在CO2压力1 MPa,反应温度140℃,反应5 h的条件下,环氧丙烷的转化率为96.3%。循环使用6次后,活性没有明显降低。提出了可能的反应机理。     

二乙烯三胺/氯化胆碱低共熔溶剂催化CO2环加成反应

以二乙烯三胺(DETA)为氢键供体,氯化胆碱(CHCl)为氢键受体,采用一锅法合成DETA/CHCl低共熔溶剂(DES)催化剂并应用于催化CO_2与氧化苯乙烯(SO)的环加成反应。通过优化反应参数得到最佳反应条件为n(DETA)∶n(CHCl)=2∶1,x(催化剂)=2%,t=120℃,p(CO_2)=1.5 MPa,t=3 h,产物收率最高为87%。同时催化剂对不同环氧化物具有良好的普适性。     

ZnBr2–Ph4PI as highly efficient catalyst for cyclic carbonates synthesis from terminal epoxides and carbon dioxide

The catalyst systems composed of ZnBr₂ and different phosphonium salts were examined for solvent-free synthesis of cyclic carbonates from CO₂ and terminal epoxides under mild conditions. Among the catalysts investigated, ZnBr₂–Ph₄PI was found to be the best while those of ZnBr₂–phosphine oxide (Bu₃PO or Ph₃PO) show no catalytic effect. It is apparent that the halide ions of phosphonium salts have an essential role to play in the reaction. The catalytic activity of ZnBr₂–Ph₄PI increases with a rise of Ph₄PI to ZnBr₂ molar ratio up to 6, above which there is little change in catalytic activity. We observed that with a rise in ZnBr₂ to Ph₄PI molar ratio, there is increase in epoxide conversion but decline in TOF_PO (estimated based on the site number of Zn²⁺). The effect of water on the reaction was investigated for the first time. We found that the presence of even a trace amount of water would result in a marked decline in reactivity, and the observation provides a valid explanation for why reproducibility of results is poor among researchers so far. The influences of other parameters such as reaction temperature and CO₂ pressure on the catalytic performance of ZnBr₂–PPh₄I were also studied. It is shown that the catalyst is sensitive to reaction temperature, and a rise of reaction temperature up to 130 °C favors the formation of cyclic carbonates. We observed that activity increases with rise in CO₂ pressure and reaches a maximum at an initial CO₂ pressure of 2.5 MPa. Moreover, a plausible reaction mechanism has been proposed.     

Porous structure of crystalline polymers by exclusion effect of carbon dioxide

We investigated the morphology of high-density polyethylene (HDPE) and poly(vinylidene fluoride) (PVDF) crystallized under carbon dioxide (CO₂) by light scattering measurements and microscopic observations. The crystallization of HDPE was delayed and the ordering of the spherulite was smaller by dissolving CO₂ rather than air at ambient pressure. A fine-layered porous structure having a size of 500 nm was obtained in HDPE, while a large rod-like porous structure radiating in the spherulite was obtained in PVDF. Such a characteristic porous structure is attributed to the exclusion of CO₂ from the crystal growth front to the intercrystalline amorphous region and the growth of bubbles by the supersaturation of CO₂ in the constrained amorphous region. The exclusion effect is covered by the Keith-Padden theory through consideration of the self-diffusion in polymer-CO₂ systems; the exclusion and the growth of bubbles occur as lamellar stacks in HDPE whereas they occur as bundles of lamellar stacks in PVDF.     

Chemical fixation of CO2 in carbonates: Routes to valuable products and long-term storage

Carbon dioxide emissions to the atmosphere can be reduced by chemical fixation in organic or inorganic carbonates. Many compounds can be commercially produced on an industrial scale using CO₂, allowing for turning a (nowadays problematic) waste gas into economic profit. Besides this, the carbonation of magnesium silicates and calcium silicates is an option for long-term storage of CO₂ at a capacity that exceeds that of other options for CO₂ storage by several orders of magnitude, with the inherent benefit that post-storage monitoring of the stored CO₂ is not necessary. The first part of this paper gives an overview of commercial carbonate chemical production routes that do (or in a near future can) make use of the CO₂ that is produced at a large scale from human activities. The second part addresses the process technology, market potential and other aspects of mineral carbonation for long-term CO₂ storage as an alternative for, for example, storage in underground aquifers.     

Sorption of Carbon Dioxide onto Sodium Carbonate

Abstract

Sodium carbonate was used as a sorbent to capture CO₂ from a gaseous stream of carbon dioxide, nitrogen, and moisture. The breakthrough data of CO₂ were measured in a fixed bed to observe the reaction kinetics of CO₂‐carbonate reaction. Several models such as the shrinking‐core model, the homogeneous model, and the deactivation model in the non‐catalytic heterogeneous reaction systems were used to explain the kinetics of reaction among CO₂, Na₂CO₃, and moisture using analysis of the experimental breakthrough data. Good agreement of the deactivation model was obtained with the experimental breakthrough data. The sorption rate constant and the deactivation rate constant were evaluated by analysis of the experimental breakthrough data using a nonlinear least squares technique and described as Arrhenius form.     

Porous polyimides from polycyclic aromatic linkers: Selective CO2 capture and hydrogen storage

Porous polyimides are important class of macromolecules owing to their excellent redox behaviour, efficient capture of CO₂ and H₂ gases, interesting photocatalytic properties and superior thermal and chemical stabilities. Here we describe in detail, the synthesis and gas storage properties of a series of porous polyimides (Tr-NPI, Tr-PPI, Tr-CPI, Td-PPI and Td-CPI) with various network topologies derived from polycyclic aromatic hydrocarbon linkers. These polyimides are synthesized in a single step by the condensation of corresponding polycyclic aromatic dianhydrides (NDA, PDA and CDA) with structure directing amine (TAPA and TAPM) monomers, having trigonal and tetrahedral geometry. The structure of all the polymers was fully characterized by various techniques. The present work also introduces for the first time porous polyimides containing rigid polycyclic aromatic compounds such as coronene. All the polyimides presented here exhibit high thermal stability and show selectivity towards CO₂ uptake at room temperature (293 K), due to the presence of aromatic clouds and CO₂ phillic oxygen and nitrogen functionalities on their pore surface. Moreover these polymers also showed significant uptake of H₂ gas (77 K). The present work has significant implications on the design of robust porous organic solids from small molecules for efficient capture of CO₂ and H₂ gases.     

Stable benzimidazole-incorporated porous polymer network for carbon capture with high efficiency and low cost

Porous Polymer Networks (PPNs) are an emerging category of advanced porous materials that are of interest for carbon dioxide capture due to their great stabilities and convenient functionalization processes. In this work, an intrinsically-functionalized porous network, PPN-101, was prepared from commercially accessible materials via an easy two-step synthesis. It has a BET surface area of 1095 m²/g. Due to the presence of the benzimidazole units in the framework, its CO₂ uptake at 273 K reaches 115 cm³/g and its calculated CO₂/N₂ selectivity is 199, which indicates its potential for CO₂/N₂ separation. The great stability, large CO₂/N₂ selectivity and low production cost make PPN-101 a promising material for industrial separation of CO₂ from flue gas. Its H₂ and CH₄ uptake properties were also investigated.     

Poly(4‐vinylimidazolium)s/Diazabicyclo[5.4.0]undec‐7‐ene/Zinc(II) Bromide‐Catalyzed Cycloaddition of Carbon Dioxide to Epoxides

Poly(4‐vinylimidazolium)s, derived from the self‐immobilization of 4‐vinylimidazoliums, with diazabicyclo[5.4.0]undec‐7‐ene (DBU) and zinc bromide (ZnBr₂) are used as a highly efficient catalyst for the chemical fixation of carbon dioxide. This catalytic system has been applied for the preparation of cyclic carbonates from terminal epoxides and carbon dioxide. Many functional groups, including chloro, vinyl, ether, and hydroxy groups are well tolerated in the reactions. Moreover, the catalytic system was found to catalyze the conversion of more sterically congested epoxides which are generally considered to be challenging substrates for fabricating the cyclic organic carbonates. In addition, the disubstituted epoxides are found to react with retention of configuration. The polymer precatalyst is easily recovered and reused. A plausible reaction mechanism is proposed.

     

CO2 Adsorption and Desorption for CO2 Enrichment at Low-Concentrations Using Zeolite 13X

Adsorption of CO₂ using zeolite 13X as adsorbent has been studied extensively, but little attention has been paid to CO₂ adsorption at very low concentrations such as in the ambient air. Furthermore, there is almost no information on CO₂ desorption characteristics. In a carbon enrichment for plant stimulation system, ambient CO₂ is enriched from 400 to 1000 ppm to provide an enriched CO₂ stream for plant growth in greenhouses. To provide essential design data, systematic performance tests were carried out to evaluate both the adsorption and desorption capacity, enrichment factor, moisture content, and cyclic performance. It was found that the adsorption capacity and CO₂ concentration in the enriched air are a function of adsorption temperature and the difference of adsorption and desorption temperatures, for a given adsorbent loading at a properly selected gas flow rate.     

Synthesis and Characterization of Estolide Esters Containing Epoxy and Cyclic Carbonate Groups

The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by ¹H and ¹³C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm^?1 and δ 82 ppm in the FTIR and ¹³C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.     

Functionalization of 3D covalent organic frameworks using monofunctional boronic acids

Co-crystallizing a monomer capable of forming a three-dimensional covalent organic framework (3D COF) with a truncated analog represents a robust strategy to functionalize the pores of these crystalline polymer networks. Here we elaborate this approach by demonstrating that monofunctional arylboronic acids serve as effective truncation/functionalization agents for COF-102, a boroxine-linked 3D network derived from the dehydration of a tetrahedral tetrakis(boronic acid) monomer. The COF-102 network forms under typical solvothermal conditions, even in the presence of a large excess of 4-tolylboronic acid, which is incorporated into the polymer's boroxine linkages up to a maximum loading level of ca. 33 mol%. This finding indicates the maximum truncation level for the COF-102 network and suggests that framework crystallization is irreversible. At high feed ratios of the monofunctional boronic acid, the isolated COF-102-tolyl powders are initially contaminated by significant amounts of tris(4-tolyl)boroxine, which is removed through a solution-based activation process to provide COF-102-tolyl samples with high functionalization density, long-range order, and permanent porosity. We also demonstrate the generality of this truncation study by evaluating several other readily available arylboronic acids, each of which are incorporated into the COF similarly. Together these findings demonstrate the simplicity and generality of this truncation/functionalization approach, as well as its fundamental limits.