Ambient CO2 Pressure Research Articles

Promoting Selective CO2 Electroreduction to Formic Acid in Acidic Medium with Low Potassium Concentrations under High CO2 Pressure

AbstractElectrocatalytic CO2 reduction reaction (CO2RR) offers a sustainable pathway for the production of chemicals and fuels. Acidic electrolysis has been shown to be a promising strategy in order to avoid CO2 loss via the formation (bi)carbonate during reaction. Previous studies have been carried out in ambient CO2 pressure systems and have stressed the importance of adding high concentration of alkali cation (K+) in the catholyte to inhibit the hydrogen evolution reaction (HER) and achieve higher selectivity of CO2RR. Herein, CO2 reduction to HCOOH was performed in strong acid (pH 1) using a dendritic bismuth catalyst in a home‐designed high‐pressure electrochemical cell. At a CO2 pressure of 30 bar, we could achieve a high Faradaic efficiency of 100 % at 100 mA cm−2 at a KCl concentration of 3.0 M. With this first system that combines high pressure of CO2 and highly acidic catholyte, we show that pressurization offers an appropriate strategy to limit both HER and K+ dependence. Indeed we obtained a Faradaic efficiency of 34 % in the absence of K+ cations and 75–80 % in the presence of 1.0 M KCl under an applied current density of 100 mA cm−2.

Taming diamines and acyl chlorides by carbon dioxide in selective mono-acylation reactions

Selective monoacylation and unsymmetric diamide formation reactions using acyl chlorides and diamines under ambient CO2 pressure (400 ppm – 1 atm), enabling facile synthesis of bioactive molecules.

Carbon dioxide sequestration of iron ore mining waste under low-reaction condition of a direct mineral carbonation process.

Mining waste that is rich in iron-, calcium- and magnesium-bearing minerals can be a potential feedstock for sequestering CO2 by mineral carbonation. This study highlights the utilization of iron ore mining waste in sequestering CO2 under low-reaction condition of a mineral carbonation process. Alkaline iron mining waste was used as feedstock for aqueous mineral carbonation and was subjected to mineralogical, chemical, and thermal analyses. A carbonation experiment was performed at ambient CO2 pressure, temperature of 80°C at 1-h exposure time under the influence of pH (8-12) and particle size (< 38-75µm). The mine waste contains Fe-oxides of magnetite and hematite, Ca-silicates of anorthite and wollastonite and Ca-Mg-silicates of diopside, which corresponds to 72.62% (Fe2O3), 5.82% (CaO), and 2.74% (MgO). Fe and Ca carbonation efficiencies were increased when particle size was reduced to < 38µm and pH increased to 12. Multi-stage mineral transformation was observed from thermogravimetric analysis between temperature of 30 and 1000°C. Derivative mass losses of carbonated products were assigned to four stages between 30-150°C (dehydration), 150-350°C (iron dehydroxylation), 350-700°C (Fe carbonate decomposition), and 700-1000°C (Ca carbonate decomposition). Peaks of mass losses were attributed to ferric iron reduction to magnetite between 662 and 670°C, siderite decarbonization between 485 and 513°C, aragonite decarbonization between 753 and 767°C, and calcite decarbonization between 798 and 943°C. A 48% higher carbonation rate was observed in carbonated products compared to raw sample. Production of carbonates was evidenced from XRD analysis showing the presence of siderite, aragonite, calcite, and traces of Fe carbonates, and about 33.13-49.81g CO2/kg of waste has been sequestered from the process. Therefore, it has been shown that iron mining waste can be a feasible feedstock for mineral carbonation in view of waste restoration and CO2 emission reduction.

Facile Construction of Carboxyl-Functionalized Ionic Polymer towards Synergistic Catalytic Cycloaddition of Carbon Dioxide into Cyclic Carbonates

The development of bifunctional ionic polymers as heterogeneous catalysts for effective, cocatalyst- and metal-free cycloaddition of carbon dioxide into cyclic carbonates has attracted increasing attention. However, facile fabrication of such polymers having high numbers of ionic active sites, suitable types of hydrogen bond donors (HBDs), and controlled spatial positions of dual active sites remains a challenging task. Herein, imidazolium-based ionic polymers with hydroxyl/carboxyl groups and high ionic density were facilely prepared by a one-pot quaternization reaction. Catalytic evaluation demonstrated that the presence of HBDs (hydroxyl or carboxyl) could enhance the catalytic activities of ionic polymers significantly toward the CO2 cycloaddition reaction. Among the prepared catalysts, carboxyl-functionalized ionic polymer (PIMBr-COOH) displayed the highest catalytic activity (94% yield) in the benchmark cycloaddition reaction of CO2 and epichlorohydrin, which was higher than hydroxyl-functionalized ionic polymer (PIMBr-OH, 76% yield), and far exceeded ionic polymer without HBDs groups (PIMBr, 54% yield). Furthermore, PIMBr-COOH demonstrated good recyclability and wide substrate tolerance. Under ambient CO2 pressure, a number of epoxides were smoothly cycloadded into cyclic carbonates. Additionally, density functional theory (DFT) calculation verified the formation of strong hydrogen bonds between epoxide and the HBDs of ionic polymers. Furthermore, a possible mechanism was proposed based on the synergistic effect between carboxyl and Br− functionalities. Thus, a facile, one-pot synthetic strategy for the construction of bifunctional ionic polymers was developed for CO2 fixation.

Nickel-phenanthroline Complex Supported on Mesoporous Carbon as a Catalyst for Carboxylation under CO2 Atmosphere

Carbon dioxide is a highly potential renewable C1 source for synthesis of fine chemicals. Utilization of CO2 in carboxylation reactions requires catalysts, such as: nickel complex for CO2 activation. However, the use of homogeneous catalysts in the reaction is still less efficient due to the difficulty of separating the product and catalyst from reaction mixture. Therefore, it is necessary to heterogenize the nickel complex in a solid support such as mesoporous carbon. In this report, mesoporous carbon (MC) prepared from phloroglucinol and formaldehyde through soft template method was used as a solid support for Ni-phenanthroline complex (Ni-phen). The catalyst was characterized by Fourier Transform Infra Red (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscope - Energy Dispersive X-Ray (SEM-EDX), and Surface Area Analyzer (SAA). The result of SAA characterization showed that the pore diameter of MC was 6.7 nm and Ni-phen/MC was 5.1 nm which indicates that the materials have meso-size pores. Ni-phen/MC material was then used as a heterogeneous catalyst in the carboxylation reaction of phenylacetylene under an ambient CO2 pressure. The reactions were carried out in several variations of conditions such as temperature, time and catalyst types. Based on the results of the reaction, the best conditions were obtained at 25 °C for 8 h of reaction time using Ni-phen/MC catalyst. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Triazine-based Organic Polymer-catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO2 Pressure.

In this work we have achieved epoxide to cyclic carbonate conversion using a metal-free polymeric catalyst under ambient CO2 pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA-ANIS) was prepared from cyanuric chloride (CYA-Cl) and o-dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N2 gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO2 up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as co-catalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di-epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co-catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH2 Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO2 incorporation into the halo-alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.

Carboxylation of terminal alkynes promoted by silver carbamate at ambient pressure

Simple and easily available silver and copper carbamates were investigated as catalysts for the carboxylation of terminal alkynes. Ag(O2CNMe2), combined with Cs2CO3, afforded propiolic acids at ambient CO2 pressure in satisfying yields.

A One-Pot Synthesis of N-Aryl-2-Oxazolidinones and Cyclic Urethanes by the Lewis Base Catalyzed Fixation of Carbon Dioxide into Anilines and Bromoalkanes.

The multicomponent assembly of pharmaceutically relevant N-aryl-oxazolidinones through the direct insertion of carbon dioxide into readily available anilines and dibromoalkanes is described. The addition of catalytic amounts of an organosuperbase such as Barton's base enables this transformation to proceed with high yields and exquisite substrate functional-group tolerance under ambient CO2 pressure and mild temperature. This report also provides the first proof-of-principle for the single-operation synthesis of elusive seven-membered ring cyclic urethanes.

Carboxylation of terminal alkynes at ambient CO2 pressure in ethylene carbonate

The CuI-catalyzed carboxylation of terminal alkynes with CO2 and alkyl halides using ethylene carbonate as the solvent under mild conditions was studied. DFT calculations reveal that the energy barrier for CO2 insertion into the sp-hybridized Cu-C bond could be reduced by employing ethylene carbonate as the solvent. Notably, the procedure was conducted under ambient CO2 pressure without any external ligands. A broad range of substrates with electron-withdrawing groups or electron-donating groups gave the corresponding products in reasonable yields.

Synthesis of Arylglycine and Mandelic Acid Derivatives through Carboxylations of α-Amido and α-Acetoxy Stannanes with Carbon Dioxide

Incorporation reactions of carbon dioxide (CO(2)) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO(2) pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO(2) pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α-amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.

ChemInform Abstract: Ambient Carboxylation on a Supported Reversible CO2 Carrier: Ketone to β‐Keto Ester.

AbstractA reversible CO2 carrier is described which performs carboxylation of active methylene groups at ambient CO2 pressure and temperature.

Ambient carboxylation on a supported reversible CO2 carrier: ketone to β-keto ester

A reversible CO2 carrier (RCC) has been developed to perform carboxylation of ketone to β-ketoester under ambient CO2 pressure and temperature. RCC has been synthesized by immobilizing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on methylhydrosiloxane support and reacting with CO2 with 100% degree of functionalisation. RCC is found to be recyclable and shows retention of activity in 5 recycles. CO2 absorption under ambient temperature and desorption at 120 °C renders the material suitable for carrying out carboxylation reactions at 25 °C with excellent yields. The yield of the reaction can reach up to 100% with TON 200 in 4 h. The extent of the reaction primarily depends upon enol content of the substrate. β-Ketoacid produced during the reaction can be isolated and converted to its corresponding methyl ester derivative by reacting with methyl iodide.

Density Functional Theory Study of Surface Carbonate Formation on BaO(001)

Periodic density functional theory calculations were used to study the formation and stability of surface carbonate on BaO(001) at CO2 exposure. CO2 adsorbs at Lewis basic Os sites, forming anionic surface carbonate (CO3−δ) species. Upon adsorption, a portion of electrons is transferred from the surface to CO2. Although the adsorption strength of CO2 decreases with the increasing coverage (θCO2), the surface carbonate overlayer in the perpendicular pattern is stable up to one monolayer (1 ML). Dramatic surface reconstruction is found for the surface carbonate overlayer in the parallel pattern at θCO2 > 0.75 ML. The BaO(001) surface is reconstructed such that the surface Ba atoms are actually pulled out of the surface plane into the carbonate overlayer, suggesting a possible onset of phase transition from surface carbonate to crystalline bulklike carbonate when the coverage is higher than 0.75 ML. At ambient CO2 pressure, the calculated surface free energies indicate that the surface carbonate monolayer be...

Effects of Ambient CO2 Concentration on Growth and Nitrogen Use in Tobacco (Nicotiana tabacum) Plants Transformed with an Antisense Gene to the Small Subunit of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase.

Growth of the R1 progeny of a tobacco plant (Nicotiana tabacum) transformed with an antisense gene to the small subunit of ribulose-1,5-carboxylase/oxygenase (Rubisco) was analyzed under 330 and 930 [mu]bar of CO2, at an irradiance of 1000 [mu]mol quanta m-2 s-1. Rubisco activity was reduced to 30 to 50% and 13 to 18% of that in the wild type when one and two copies of the antisense gene, respectively, were present in the genome, whereas null plants and wild-type plants had similar phenotypes. At 330 [mu]bar of CO2 all antisense plants were smaller than the wild type. There was no indication that Rubisco is present in excess in the wild type with respect to growth under high light. Raising ambient CO2 pressure to 930 [mu]bar caused plants with one copy of the DNA transferred from plasmid to plant genome to achieve the same size as the wild type at 330 [mu]bar, but plants with two copies remained smaller. Differences in final size were due mostly to early differences in relative rate of leaf area expansion (m2 m-2 d-1) or of biomass accumulation (g g-1 d-1): within less than 2 weeks after germination relative growth rates reached a steady-state value similar for all plants. Plants with greater carboxylation rates were characterized by a higher ratio of leaf carbon to leaf area, and at later stages, they were characterized also by a relatively greater allocation of structural and nonstructural carbon to roots versus leaves. However, these changes per se did not appear to be causing the long-term insensitivity of relative growth rates to variations in carboxylation rate. Nor was this insensitivity due to feedback inhibition of photosynthesis in leaves grown at high partial pressure of CO2 in the air (pa) or with high Rubisco activity, even when the amount of starch approached 40% of leaf dry weight. We propose that other intrinsic rate-limiting processes that are independent of carbohydrate supply were involved. Under plentiful nitrogen supply, reduction in the amount of nitrogen invested in Rubisco was more than compensated for by an increase in leaf nitrate. Nitrogen content of organic matter, excluding Rubisco, was unaffected by the antisense gene. In contrast, it was systematically lower at elevated pa than at normal pa. Combined with the positive effects of pa on growth, this resulted in the single-dose antisense plants growing as fast at 930 [mu]bar of CO2 as the wild-type plants at 330 [mu]bar of CO2 but at a lower organic nitrogen cost.

Effects of Nitrogen Source and Water Limitation on Growth, Transpiration Efficiency and Carbon-Isotope Discrimination in Peanut Cultivars

Effects on growth of nitrogen nutrition and its interactions with water availability were explored in two experiments using cultivars of peanut (Arachis hypogaea L.). In one experiment plants of the two cultivars, Tifton-8 and Chico, were given relatively high (high-N) or low (low-N) amounts of nitrogen, supplied as ammonium nitrate. The low-N plants accumulated less dry matter and used less water than the high-N plants. Transpiration efficiency, the ratio of dry matter produced to water used (W), was not significantly affected by the nitrogen treatment and neither was carbon-isotope discrimination (Δ). Isolated measurements showed leaf gas-exchange characteristics during pod filling were not affected in Tifton-8, but assimiliation rate was reduced in the low-N treatment, compared to the high-N treatment, in Chico. The ratio of intercellular CO2 pressure to ambient CO2 pressure, pi/pa, in the short term was consistent with Δ in leaves, a longer term measurement of pi/pa. The allocation of dry matter to roots was affected in Tifton-8 but not in Chico. The ratio of plant dry matter to leaf area was unaffected by nitrogen level. In another experiment, with four cultivars-Tifton-8, Chico, Robut 33-1 and TMV2-the nitrogen source was varied by giving plants ammonium nitrate or having them acquire nitrogen through nodules. Two levels of water availability were incorporated with the nitrogen treatments in a factorial design. Plants were either watered well or grown on water stored in the soil, in addition to having different nitrogen sources. In this experiment, the method of nitrogen acquisition caused different reductions in dry-matter accumulation among cultivars when plants were water-limited. Dry-matter accumulation in nodulated plants was less than in plants given ammonium nitrate, and nodulated plants had smaller values of W than plants which were given ammonium nitrate. Growing plants on stored soil water also affected dry-matter accumulation but there was no significant effect on W. The differences among cultivars in W were maintained over the two experiments so that the ranking of cultivars in W was conserved. Dry matter allocation among plant parts was affected by water limitation and by the nitrogen source. Water limitation had a greater effect on dry-matter accumulation of plants that were given ammonium nitrate than it did on dry matter of nodulated plants. Plants that were nodulated allocated more dry matter to the pods than did those that were not nodulated and this response varied among cultivars. Cultivars which accumulated the most dry matter had the greatest W but these cultivars did not necessarily allocate the most dry matter to pods. Irrespective of treatment, there was a strong negative correlation between W and Δ in both experiments. The small variations in the relationship between W and Δ among cultivars indicated that there may have been differences among cultivars in the carbon cost of nitrogen acquisition when the plants were nodulated.

Short-term carbon-isotope discrimination in C3−C4 intermediate species

Short-term discrimination in assimilation of stable isotopes of carbon was measured for leaves of the C3 speciesPhaseolus vulgaris L. cv. Hawkesbury Wonder andFlaveria pringlei Gandoger, the C4 speciesAmaranthus edulis Speg., and the C3-C4 intermediate speciesPanicum milioides Nees ex. Trin,Flaveria floridana Johnson, andFlaveria anomala B.L. Robinson. Discriminations in the C3 and C4 species were similar to those expected from theoretical considerations. When ambient CO2 pressure was 330 μbar the mean discriminations in the C3 species andPanicum milioides were similar, whereas the mean discriminations inF. floridana andF. anomala were less than discrimination in C3 species andPanicum milioides. When ambient CO2 pressure was 100 μbar the mean discriminations inPanicum milioides andF. anomala were greater, and that inF. floridana was less, than that inPhaseolus vulgaris. We conclude that the pattern of discrimination inPanicum milioides is consistent with the presence of a glycine shuttle; inF. floridana andF. anomala, discrimination is consistent with the presence of a C4 pathway coupled with the operation of a glycine shuttle.

Stomatal and non‐stomatal contribution in the decline in leaf net CO2 uptake during rapid water stress

A simple method is proposed for quantitative evaluation of Stomatal and non‐stomatal components of the decline in leaf CO2 uptake during rapid water stress. The changes in leaf conductance were measured during the stress and were used to calculate the photosynthetic rate which would be observed if Stomatal closure were the only cause of the decline in photosynthesis. Photosynthesis‐CO2 response curves, determined just before the stress, were used for this calculation. The difference between the calculated and the actual rate is a measure of the non‐stomatal effect of water stress.This analysis was tested on Sinapis alba submitted to rapid and severe water stress by excising leaves or roots. Experiments were performed at saturating light conditions under high (61 Pa), normal (34 Pa) or low (11 Pa) ambient CO2 pressure. The non‐stomatal effect on de‐rooted plants reaches a maximum at the beginning of the stress and is dependent on the CO2 pressure: after 45 min its influence is still about 100°, 70° and 8°, respectively, at high, normal and low CO2. In the excised leaf system in which desiccation was more rapid, the non‐stomatal effect accounted for nearly 100° of the assimilation decline whatever the CO2 pressure.