Catalytic CO2 Fixation Research Articles

Linker-defect assisted catalytic fixation of CO2 in a dual-linker metal–organic framework

Linker-defect assisted catalytic fixation of CO2 in a dual-linker metal–organic framework

Experimental and kinetic evaluation on cobalt Salen conjugated organic polymers for CO2 cycloaddition reactions and iodine vapor adsorption

The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The Ea was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics.

Anchoring high-density cooperative catalytic sites within triethylenediamine-based ionic-liquid polymers via microenvironment modulation for efficient CO2 fixation

The precise microenvironment modulation of ionic sites to promote the catalytic performances of ionic-liquid polymers for CO2 transformation has been highly attractive but rarely attempted. Herein, we reported a strategy to synthesize the triethylenediamine-derived ionic-liquid polymer (PDD-S) featured with branched structure and high site density (4.10 mmol·g−1). In distinct with the conventional synthetic routes, this method involved the pre-grafting and subsequent self-polymerization of ionic monomer, which suppressed the competitive reactions and broke the limitations of precursor selection, while ensuring the high content and even distribution of ionic sites within the polymeric framework. Furthermore, during CO2 cycloaddition with epoxides we showed that these unique structural features allowed the adequate exposure of active sites under the dual effects of steric hindrance and charge repulsion. The PDD-S exhibited noteworthy catalytic performance, with a carbonate yield of 97.3 %, under the moderate conditions (100 °C, 4 h, 1 MPa) in the absence of any metal, co-catalyst, or solvent. Additionally, the desirable reusability, epoxide universality, and structural stability were also attained. The experiments combining with the activation energy and DFT theoretical calculations, attributed the synergistic interplay of tertiary N, quaternary ammonium, and Cl- anions to the acceleration of ring-opening process, thereby promoting the CO2 transformation. The newly developed approach offers one perspective to the controllable fabrication of ionic-liquid polymers for catalytic fixation of CO2.

Synthesis of cyclic carbonates by photothermal catalytic coupling of CO2 and epoxides under solvent-free conditions

The conversion of CO2 to cyclic carbonate under mild conditions is an effective strategy to achieve carbon neutrality. This work reports the formation of cyclic carbonates by coupling CO2 with epoxides using a photothermal catalyst (CoFe2O4@PDA) with added organic ligands of bimetals under atmospheric pressure, solvent-free, 70 °C and UV light irradiation. The addition of ligands substantially enhanced the photothermal catalytic performance of the catalysts as verified by various characterizations. Subsequent experimental results under optimal conditions showed excellent yields of the catalysts for the conversion of epoxides with different groups to the corresponding cyclic carbonates. The cycling results also indicate good recyclability of the catalyst. This pathway in using light as a driving reaction to fix CO2 for the synthesis of cyclic carbonate provides a new idea for subsequent photothermal catalytic fixation of CO2.

A Dual-Purpose Ce(III)-Organic Framework with Amine Groups and Open Metal Sites: Third-Order Nonlinear Optical Activity and Catalytic CO2 Fixation.

The present work focuses on the synthesis and properties of a novel multifunctional cerium(III) MOF, [Ce2(data)3(DMF)4]·DMF (data2-: 2,5-diaminoterephthalate), abbreviated as NH2-Ce-MUM-2. Its crystal structure reveals an intricate 3D 4,5-connected framework with a xah topology. This MOF features unique properties, such as open metal sites, presence of free amino groups, and high stability. Two main applications of NH2-Ce-MUM-2 were investigated: (i) as a heterogeneous catalyst in the CO2 fixation into cyclic carbonates and (ii) as a material with third-order nonlinear optical activity. As a model reaction, the cycloaddition of CO2 to propylene oxide to give the corresponding cyclic carbonate was explored under mild conditions, at the atmospheric pressure of carbon dioxide and in the absence of cocatalyst and added solvent. Various reaction parameters were investigated toward optimization and exploration of substrate scope, revealing up to 99% product yields of cyclic carbonate products. Besides, the structure of NH2-Ce-MUM-2 is highly stable, permitting its recyclability and reusability in further catalytic experiments. The significant contributions of free amino groups and open metal sites within this catalyst were particularly considered when proposing a potential mechanism for the reaction. Z-Scan measurements were used to evaluate the nonlinear optical (NLO) properties of NH2-Ce-MUM-2 at various laser intensities. A high two-photon absorption (TPA) under greater incident intensities shows that NH2-Ce-MUM-2 might be applicable in optical switching devices. Besides, the self-focusing effects of NH2-Ce-MUM-2 under various incident intensities were highlighted by the nonlinear index of refraction (n2). By reporting the synthesis and characterization of a novel MOF, along with its highly promising catalytic and NLO behavior, the current study introduces an additional example of multifunctional material into a growing family of metal-organic frameworks.

Permanently Polarized Materials: An Approach for Designing Materials with Customized Electrical Properties

The development of experimental procedures to transform conventional materials into new materials with unique properties has become a necessity in many fields, as for example catalysis, electronics, electrochemistry and biomedicine, among others. In recent years, the thermal stimulated polarization (TSP) treatment, which consists of applying a constant voltage at a high temperature, has been applied to hydroxyapatite, Ca5(PO4)3OH (HAp), leading to permanently polarized HAp (p-HAp). The enhanced electrical properties of p-HAp, which are the consequence of the controlled generation of vacancies, the specific orientation of the remaining OH– groups and the surface charge accumulation have been used for the catalytic fixation of CO2, CH4 and/or N2 under very mild conditions (<120 °C) and with accurate selectivity toward different reaction products (up to 95%). In this Perspective, we stablish the fundamentals of permanently polarized materials, providing the generalized concepts of the permanent polarized state and some representative examples of applying the TSP approach to a wide variety of materials. More specifically, we provide empirical evidence of the polarized state after applying the TSP treatment to quartz nanopowder, binary metal oxides (TiO2 and ZrO2) and different synthetic polymers, confirming the obtaining of enhanced electrical properties and the associated structural changes. Finally, the implications, challenges and perspectives of the polarized state are discussed considering different fields, such as catalysis, biomedicine, optics and electronics, sensors and energy storage devices.

Synthesis, Assembly, and Applications of Magic-Sized Semiconductor (CdSe)13 Cluster.

ConspectusAtomically precise metal chalcogenide clusters (MCCs) are model molecular compounds of scientifically and technologically important semiconductor nanocrystals, which are known as quantum dots (QDs). The significantly high ambient stability of MCCs of particular sizes, as compared to that of slightly smaller or larger sizes, made them be termed "magic-sized clusters" (MSCs). In other words, MSCs with specific sizes between sizes of precursors (typically, metal-ligand complexes) and nanocrystals (typically, QDs) appear sequentially during the colloidal synthesis of nanocrystals, while the other cluster species decompose to precursor monomers or are consumed during the growth of the nanocrystals. Unlike nanocrystals with an ambiguous atomic-level structure and a substantial size distribution, MSCs possess atomically monodisperse size, composition, and distinct atomic arrangement. Chemical synthesis and exploration of properties of MSCs are of great significance since they help systematically understand the evolution of fundamental properties as well as build structure-activity relationships at distinct molecular levels. Furthermore, MSCs are anticipated to offer atomic-level insights into the growth mechanism of the semiconductor nanocrystals, which is highly desirable in the design of advanced materials with new functions. In this Account, we cover our recent efforts in the advancement of one of the most important stoichiometric CdSe MSCs, (CdSe)13. In particular, we present its molecular structure derived from a single crystal X-ray crystallographic study of the closest MSC, Cd14Se13. The crystal structure of MSC enables not only the understanding of the electronic structure and prediction of the potential sites for heteroatom dopants (e.g., Mn2+ and Co2+) but also the identification of favorable synthetic conditions for the selective synthesis of desired MSCs. Next, we focus on enhancing the photoluminescence quantum yield and stability of Mn2+ doped (CdSe)13 MSCs through their self-assembly, which is facilitated by the rigid diamines. In addition, we show how atomic-level synergistic effects and functional groups of the assemblies of alloy MSCs can be utilized for a highly enhanced catalytic CO2 fixation with epoxides. Benefiting from the intermediate stability, the MSCs are explored as single-source precursors to low-dimensional nanostructures, such as nanoribbons and nanoplatelets, through the controlled transformation. Distinct differences in the outcome of the solid-state and colloidal-state conversion of MSCs suggest the need for careful consideration of the phase and reactivity of MSCs as well as the type of dopant to achieve novel structured multicomponent semiconductors. Finally, we summarize the Account and provide future perspectives on the fundamental and applied scientific research of MSCs.

Selective Visible-Light Photocatalytic Oxidation of Sulfides and Catalytic CO2 Fixation by Two-Interpenetrated Photoresponsive MOF-150

Sulfides and CO2 are the main pollutants that cause environmental acidification and the greenhouse effect. However, the rational use of these pollutants can not only save resources but also improve the environment. The two-interpenetrated MOF-150 was prepared by the photoresponsive 4,4′,4″-nitrilotribenzoic acid (H3NTB) ligand and Zn4O clusters, and it exhibits excellent optical activity derived from H3NTB. Especially as the substrate, thioanisole is oxidized to sulfoxide with medicinal value after 10 h of Xe light irradiation, and the conversion rate of 98% and the selectivity of 100% are obtained. Higher photocatalytic performance is also observed when the substrate is extended to other sulfides (7 examples). At the same time, MOF-150 has an excellent performance in the capture and recycling catalytic fixation of CO2. With epichlorohydrin as the reaction substrate, the cycloaddition efficiency of CO2 can reach over 99%. When it is extended to other epoxides, satisfactory cycloaddition efficiency was also obtained (7 examples). Therefore, MOF-150 is a promising heterogeneous catalyst with high catalytic efficiency and selectivity for a wide range of substrates.

Insights into the BPO4‐Driven Catalytic Mechanism for the Formation of Cyclic Carbonates from CO2 and Epoxides

AbstractThe growing concern about climate change has aroused great interest in the scientific community to carry out a large number of investigations pointing to find new strategies of using the carbon dioxide (CO2) to produce useful and harmless molecules. A computational study on the catalytic fixation of CO2 to epoxides with the aim of obtaining cyclic carbonates is presented in this article. The boron phosphate (BPO4) and some halides have been used as the catalyst and co‐catalysts, respectively. The reaction mechanisms have been rationalized based on density functional theory (DFT) energies and the polarizable continuum model (PCM) to simulate the effect of different solvents. This study provides a deeper understanding on the BPO4 catalyst and its role on conversion of CO2 into cyclic carbonates by exploring the topography of the potential energy surfaces and analyzing the geometrical and electronic structures of the relevant stationary points along different reaction pathways. In addition, a solvent effect comparison was made between n‐hexanol, Et2O and 2‐butanol.

RETRACTED: Mixed-ligand coordination polymers: Catalytic CO2 fixation and treatment activity on the intestinal polyps by inducing the intestinal epithelial cells apoptosis

Abstract By virtue of a dual-ligand strategy, two transition metal coordination polymers of {[Ni2(NDC)2(L1)(H2O)2(H2O)]·(DMF)2(H2O)}n (1, L1 = 3,3′-azobis pyridine) and [Mn(NDC)(L2)(H2O)]n (2, L2 = 1,4-bis(1H-benzo[d]imidazol-1-yl)butane) have been synthesized via the corresponding metal salts reacting with the 1,4-naphthalene dicarboxylic acid (H2NDC) in the existence of distinct nitrogen-donor co-ligands. Given the permanently microporous nature, moderate CO2 sorption capacity as well as high density of the open metals positions, the activated 1 revealed the chemical fixation of the cyclic carbonates and carbon dioxide or an efficient activity of catalysis in the existence of the cocatalyst under the mild and solvent-free conditions. To evaluate the activity of the compound against intestinal polyps, following experiments were conducted. The Cell Counting Kit-8 (CCK-8) method was implemented to evaluate the inhibitory effects of these two compounds against the intestinal epithelial cells. Next, the western blotting was conducted and the apoptotic protein Bcl-2 expression levels was determined as well.

Co(III)-Salen immobilized cellulose nanocrystals for efficient catalytic CO2 fixation into cyclic carbonates under mild conditions

Searching for green, recyclable and highly efficient catalyst for the synthesis of cyclic carbonates from CO2 is of great importance because it is profitable for reducing the greenhouse effects and meets the principles of green chemistry. Herein, a series of cellulose nanocrystals, either the pristine or modified ones (TEMPO oxidized and Co(III)salen immobilized), were explored as catalysts for cycloaddition of epoxides and carbon dioxide. The impact of surface properties on the performance of the as-made catalysts was investigated. Co(III)-salen grafted cellulose nanocrystals was proven to be the most effective catalyst in this study, which could afford excellent yield up to 99 % after 24 h even under low CO2 pressures of 0.1 MPa. They can be easily recovered and reused for at least 4 times, demonstrating their excellent stability. We found that the surface functional groups such as enriched sulfate or carboxylic groups could also account for the enhanced catalytic activity. This work highlights the applications of green and sustainable nanoparticles in a cycloaddition reaction and offers a sustainable solution in industrial catalysis related to CO2 conversions.

Facile synthesis of crystalline viologen-based porous ionic polymers with hydrogen-bonded water for efficient catalytic CO2 fixation under ambient conditions.

In this work, we report a series of crystalline viologen-based porous ionic polymers (denoted VIP-X, X = Cl or Br), that have in situ formed dicationic viologens paired with halogen anions and intrinsic hydrogen-bonded water molecules, towards metal-free heterogeneous catalytic conversion of carbon dioxide (CO2) under mild conditions. The targeted VIP-X materials were facilely constructed via the Menshutkin reaction of 4,4′-bipyridine with 4,4′-bis(bromomethyl)biphenyl (BCBMP) or 4,4′-bis(chloromethyl)biphenyl (BBMBP) monomers. Their crystalline and porous structures, morphological features and chemical structures and compositions were fully characterized by various advanced techniques. The optimal catalyst VIP-Br afforded a high yield of 99% in the synthesis of cyclic carbonate by CO2 cycloaddition with epichlorohydrin under atmospheric pressure (1 bar) and a low temperature (40 °C), while other various epoxides could be also converted into cyclic carbonates under mild conditions. Moreover, the catalyst VIP-Br could be separated easily and reused with good stability. The remarkable catalytic performance could be attributed to the synergistic effect of the enriched Br− anions and available hydrogen bond donors –OH groups coming from H-bonded water molecules.

Metalated-bipyridine-based porous hybrid polymers with POSS-derived Si-OH groups for synergistic catalytic CO2 fixation.

Herein, we construct a new series of N-heterocyclic ligand bipyridine-based porous hybrid polymers (denoted Bpy-PHPs) from the Heck reaction of a rigid building unit octavinylsilsesquioxane (VPOSS) and 5,5'-dibromo-2,2'-bipyridine. Surprisingly, the typical sample Bpy-PHP-4 was found to be a metal-/halogen-free heterogeneous catalyst in the cycloaddition reaction of CO2 with a few epoxides under atmospheric pressure. After coordination with ZnBr2, the resultant ZnBr2@Bpy-PHP-4 afforded largely enhanced heterogeneous catalytic activities upon the conversion of carbon dioxide (CO2) and various epoxides into cyclic carbonates without using any co-catalysts under mild conditions. The moderate catalytic activities of Bpy-PHP-4 may be due to the presence of hydrogen bond donors (HBDs), i.e., polyhedral oligomeric silsesquioxane (POSS)-derived Si-OH groups and N active sites from Bpy linkers. In comparison, the high catalytic efficiency of ZnBr2@Bpy-PHP-4 should be attributed to the synergistic catalysis of Si-OH groups, N active atoms, and Bpy-coordinated ZnBr2. Moreover, the catalyst ZnBr2@Bpy-PHP-4 can be easily recovered and reused ten times without any significant loss of catalytic activities. This work affords an efficient metal-based porous hybrid polymer heterogeneous catalyst for the cycloaddition reaction of CO2 and epoxides under mild and co-catalyst-free conditions.

High yield cycloaddition of carbon dioxide to epoxides catalyzed by metal–organic frameworks

A series of metal–organic frameworks (MOFs) based on trimesic acid (also knows benzene tricarboxylic acid [btc]) have been synthesized by a solvothermal procedure which exhibit excellent catalytic fixation of CO2. Cycloaddition of CO2 to epoxides to produce cyclic carbonates is quite promising. The chemical fixation of CO2 reported here is solvent free and carried out under moderately mild conditions. All the MOFs [Zn-btc (1), Co-btc (2), Ni-btc (3), and Cu-btc (4)] were synthesized under same experimental conditions yet possess different structural and catalytic properties. All the catalysts follow first-order kinetics, and Zn-btc (1) proved to be the most catalytically active catalyst among all, with ∼100% yield with a total turnover number of 18,845 mol−1 and an initial turnover frequency (hour−1) of 946 with respect to the cyclic carbonate. All MOFs (1–4) show almost 100% conversion in these reactions. The same reaction using other metal (Co, Ni, Cu)-btc compounds has also resulted in products with more than 94% yield, creating an extra impact on the importance of the work.

Metal-Organic-Framework-Derived Hollow N-Doped Porous Carbon with Ultrahigh Concentrations of Single Zn Atoms for Efficient Carbon Dioxide Conversion.

The development of efficient and low energy-consumption catalysts for CO2 conversion is desired, yet remains a great challenge. Herein, a class of novel hollow porous carbons (HPC), featuring well dispersed dopants of nitrogen and single Zn atoms, have been fabricated, based on the templated growth of a hollow metal-organic framework precursor, followed by pyrolysis. The optimized HPC-800 achieves efficient catalytic CO2 cycloaddition with epoxides, under light irradiation, at ambient temperature, by taking advantage of an ultrahigh loading of (11.3 wt %) single-atom Zn and uniform N active sites, high-efficiency photothermal conversion as well as the hierarchical pores in the carbon shell. As far as we know, this is the first report on the integration of the photothermal effect of carbon-based materials with single metal atoms for catalytic CO2 fixation.

Metal–Organic‐Framework‐Derived Hollow N‐Doped Porous Carbon with Ultrahigh Concentrations of Single Zn Atoms for Efficient Carbon Dioxide Conversion

AbstractThe development of efficient and low energy‐consumption catalysts for CO2 conversion is desired, yet remains a great challenge. Herein, a class of novel hollow porous carbons (HPC), featuring well dispersed dopants of nitrogen and single Zn atoms, have been fabricated, based on the templated growth of a hollow metal–organic framework precursor, followed by pyrolysis. The optimized HPC‐800 achieves efficient catalytic CO2 cycloaddition with epoxides, under light irradiation, at ambient temperature, by taking advantage of an ultrahigh loading of (11.3 wt %) single‐atom Zn and uniform N active sites, high‐efficiency photothermal conversion as well as the hierarchical pores in the carbon shell. As far as we know, this is the first report on the integration of the photothermal effect of carbon‐based materials with single metal atoms for catalytic CO2 fixation.

Photo-generation of cyclic carbonates using hyper-branched Ru-TiO2.

Anthropogenic CO2 is the main contributor to the increased concentration of greenhouse gases in the atmosphere, and thus utilising waste CO2 for the production of valuable chemicals is a very appealing strategy for reducing CO2 emissions. The catalytic fixation of CO2 with epoxides for the production of cyclic carbonates has gained increasing attention from the research community in search of an alternative to the homogeneous catalytic routes, which are currently being used in industry. A novel photocatalytic heterogeneous approach to generate cyclic carbonates is demonstrated in this work. Hyper-branched microstructured Ru modified TiO2 nanorods decorated with RuO2 nanoparticles, supported on fluorine-doped tin oxide (FTO) glass were fabricated for the first time and were used to catalyse the photo-generation of propylene carbonates from propylene oxides. Propylene carbonate was used as a reference for cyclic carbonates. The photo-generation of cyclic carbonates from epoxides and CO2 was carried out at a maximum temperature of 55 °C at 200 kPa in a stainless steel photoreactor with a quartz window, under solar irradiation for 6 h. The best performing photocatalyst exhibited an estimated selectivity of 83% towards propylene carbonates under the irradiation of a solar simulator.

Transition-Metal-Catalyzed Carboxylation Reactions with Carbon Dioxide.

Driven by the inherent synthetic potential of CO2 as an abundant, inexpensive and renewable C1 chemical feedstock, the recent years have witnessed renewed interest in devising catalytic CO2 fixations into organic matter. Although the formation of C-C bonds via catalytic CO2 fixation remained rather limited for a long period of time, a close look into the recent literature data indicates that catalytic carboxylation reactions have entered a new era of exponential growth, evolving into a mature discipline that allows for streamlining the synthesis of carboxylic acids, building blocks of utmost relevance in industrial endeavors. These strategies have generally proven broadly applicability and convenient to perform. However, substantial challenges still need to be addressed reinforcing the need to cover metal-catalyzed carboxylation area in a conceptual and concise manner, delineating the underlying new principles that are slowly emerging in this vibrant area of expertise.

One-pot synthesis of an ionic porous organic framework for metal-free catalytic CO2 fixation under ambient conditions

A new ionic porous organic framework (termed IPF-CSU-1) with a remarkably high nitrogen content (20.3 wt%), and a high-density and uniform charge distribution was constructed, which served as a metal-free catalyst for CO2 conversion into cyclic carbonates in high yields (above 95%) under an ambient condition (298 K, 0.1 MPa).

Transition-Metal-Free Reductive Deoxygenative Olefination with CO2.

A new transition-metal-free reductive deoxygenative olefination of phosphorus ylides with CO2, an abundant and sustainable C1 chemical feedstock, is described. This catalytic CO2 fixation afforded β-unsubstituted acrylates and vinyl ketones in good yields with broad scope and good functional group tolerance under mild reaction conditions. Cost-effective and easily handled polymethylhydrosiloxane was used as a reductant. Bis(silyl)acetal was proved to be the key intermediate in this reductive functionalization of CO2.