Employing Carbon Dioxide Research Articles

Biotreatment of Industrial Pollutant (Carbon Dioxide) and its Role in Bioplastics Production

Polyhydroxyalkanoates (PHAs) are a class of biopolymers with characteristics resembling those of petrochemical-based plastics that have gained recent attention and a growing amount of research effort due to their environmental friendliness. Numerous bacteria, including Alcaligenes spp., Pseudomonas spp., Staphylococcus spp., and algae create (PHAs) in the presence of carbon and limiting nutrients like nitrogen, and these biopolymers can successfully replace industrial plastics. Therefore, the goal of this study is to employ carbon dioxide, an industrial pollutant emitted into the environment, as a cheap carbon source to lower production costs and remove pollution at the same time. Only three of the nine bacterial isolates utilized were able to synthesize the polymer in the presence of CO2, and the best isolate was belonging to the genus Alcaligenes after 48 hours of incubation at 30°C and pH 7, which are the optimal conditions for polymer synthesis. Bacterial growth resulted in the production of 5.2gm/l of PHA and 6.2gm/l of biomass under these conditions.

Technical and Economic Evaluation of Bioactive Compounds from Schinus terebinthifolius Using Supercritical Carbon Dioxide

This study evaluated the technical and economic feasibility of using supercritical CO2 extraction for the production of bioactive compounds from Schinus terebinthifolius. Supercritical fluid extraction techniques employing carbon dioxide were employed to extract valuable compounds from S. terebinthifolius. The extraction was performed under different operating conditions, showing an increase in yield with higher pressures and temperatures. The bioactive compounds in the extract demonstrated significant potential in terms of their antioxidant and antimicrobial properties, making them valuable for applications in food preservation. The economic evaluation revealed a positive net present value (NPV) and favorable return on investment (ROI) within a two-year timeframe. The break-even point was determined to be below 25% production capacity, supporting the economic feasibility of the process. Overall, the utilization of supercritical CO2 extraction for bioactive compounds from S. terebinthifolius offers a sustainable and environmentally friendly extraction method while ensuring the extract’s integrity and quality. Although the operational costs and extractor contributions require consideration, the findings support the economic viability and commercial potential of this technique. Further research and development can enhance the efficiency and cost-effectiveness, making it an attractive option for various commercial applications.

A novel R744 multi-temperature cycle for refrigerated transport applications with low-temperature ejector: Experimental ejector characterization and thermodynamic cycle assessment

A novel vapor-compression system concept employing carbon dioxide as the refrigerant is proposed to serve the needs of a typical medium-size refrigerated truck used for multi-temperature (MT and LT) goods delivery. The system design is based on the implementation of an ejector as the only component increasing the refrigerant pressure from the LT evaporation pressure to the MT evaporation pressure, thus providing cooling effect at two different temperature levels with only one stage of compression. The ejector was experimentally tested and its ability to effectively entrain mass flow rate from low pressure suction conditions (corresponding to a LT evaporation temperature of −25 °C) was assessed. Lower external ambient temperatures and consequent lower expansion energy available at the ejector motive nozzle leads to a reduction of the maximum achievable pressure lift. Moreover, a significant degradation of the ejector performance towards the highest pressure lifts is experienced. Based on the ejector experimental data, a numerical evaluation of the proposed cooling unit performance has been performed, highlighting that in design conditions (LT evaporation at −25 °C) the cooling unit provides a LT freezing power ranging between 1.1 kW and 2.3 kW and a corresponding minimum MT cooling power ranging between 5.1 kW and 3.8 kW, depending on the chosen ejector lift. The MT cooling power can be further increased by increasing the compressor mass flow rate. The system COP is maximized at the maximum available lift provided by the ejector.

Techno-economic optimization of novel energy-efficient solvent deasphalting process using CO2 as a stripping agent

The solvent deasphalting (SDA) process is specifically designed to selectively remove asphaltene from heavy oil feedstocks. However, high energy consumption resulting from the separation processes used to recover the extraction solvent from the mixture of oil products and solvent is a challenge in the SDA process. In this study, a novel SDA process in which the solvent recovery steps were modified by employing carbon dioxide instead of steam as the stripping agent was developed. In addition, the operating and heat integration parameters of the novel CO2-assisted SDA process were optimized using bilevel optimization to minimize the total annualized cost. A genetic algorithm was applied to optimize the process operating variables in the upper-level problem, including the temperature and pressure of solvent recovery units. In the lower-level problem, heat integration parameters—the minimum temperature difference (ΔTmin) and the heat load distribution of hot and cold utilities—were optimized. The optimization results demonstrated that the novel SDA process is more energy-efficient and economical than the conventional SDA process.

Mathematical modelling and statistical optimization of fast cultivation of Agardhiella subulata: Response surface methodology

The production of algae within a short period has become an emerging issue among researchers due to its diversified usage. At the same time, researchers are working extensively on how to upsurge algae production using carbon dioxide. The motto of this study is to develop a fast algae production system utilizing carbon dioxide and employing mathematical as well as statistical analysis to optimize production. Response surface methodology (RSM) constructed on the central composite design (CCD) was applied to assess the potential contributions of cultivation time, irradiance light, and carbon dioxide concentration during the cultivation process. In addition, their interaction effects were evaluated in the cultivation period. In this study, the cultivation period was the most significant contributor to algae cultivation, followed by light and carbon dioxide. The highest A. Subulata of 0.24 g was attained with 418 μmol/m2/s, 7 days, and 19 mg/l for light intensity, cultivation time, and carbon dioxide concentration, respectively. The experimental data were analyzed using the modified Logistics, modified Gompertz, modified Schnute, and modified Richards models, and it was determined that the modified Logistics model fits the experimental data better than the other three models, as evidenced by the low values of RMSD (0.0286), AIC (-2.409), and BIC (-4.251) and high value of R2 (0.98). Increasing algae production employing carbon dioxide will help to promote a sustainable environment and attain sustainable development goals (SDGs).

Recent Advances in the Synthesis of Five-Membered Cyclic Carbonates and Carbamates from Allylic or Propargylic Substrates and CO2

The organic carbamates and carbonates are highly desirable compounds that have found a wide range of applications in drug design, medicinal chemistry, material science, and the polymer industry. The development of new catalytic carbonate and carbamate forming reactions, which employ carbon dioxide as a cheap, green, abundant, and easily available reagent, would thus represent an ideal substitution for existing methods. In this review, the advancements in the catalytic conversion of allylic and propargylic alcohols and amines to corresponding five-membered cyclic carbonates and carbamates are summarized. Both the metal- and the organocatalyzed methods are reviewed, as well as the proposed mechanisms and key intermediates of the illustrated carbonate and carbamate forming reactions.

Analysis of the thermodynamic performance of transcritical CO2 power cycle configurations for low grade waste heat recovery

Organic Rankine cycles employing carbon dioxide (CO2) for waste heat recovery became popular in the last years thanks to its excellent heat transfer characteristics and small environmental footprint. Low-grade waste heat (<240 °C) represents the major portion of excess heat globally, but it is hard to recover due to the small temperature gap of heat source and heat sink leading to a poor efficiency of the Rankine cycle. Therefore, numerous modifications of the power cycle layout were proposed by academia and industry — reheated expansion, recuperation and intercooled compression among them. This work compares ten cycle architectures for a defined waste heat source (60–100 °C) and heat sink (20 °C). Firstly, CO2 cycle architectures from literature are examined with its original operational parameters. Secondly, the predefined low-grade heat source is implemented into the cycle. The cycles are assessed regarding efficiency, mass flow and pressure. Results show that for source temperatures higher than 80 °C, recuperation and reheated expansion enhance the cycle performance whereas intercooled compression negatively affects the efficiency. The conventional configuration operated most efficiently for temperatures until 80 °C. A road map of thermodynamic efficiencies of CO2 cycle architectures for low-grade waste heat recovery up to 100 °C is delivered.

Carbon-dioxide-precooled hydrogen liquefaction process: An innovative approach for performance enhancement–Energy, exergy, and economic perspectives

Hydrogen is an important clean energy carrier that can facilitate and promote clean energy production and mitigate greenhouse gas emissions. However, long-term storage and long-distance transportation of hydrogen are challenging owing to its low energy density, which can be effectively enhanced via liquefaction, an energy- and cost-intensive process. Commercial hydrogen liquefaction processes exhibit specific energy consumptions in the range of 12.0–15.5 kWh/kg with an exergy efficiency of 19.0%–23.6%. This study presents an energy-efficient and cost-effective process configuration for producing liquid hydrogen through stepwise cooling and subsequent ortho–para conversion. The energy intensive precooling cycle is divided into two sub-cycles employing carbon dioxide as a refrigerant. This process exploits the benefits of carbon dioxide in a simple yet efficient configuration. A specific energy consumption of 7.63 kWh/kg was achieved, along with an exergy efficiency of 31.4%. The coefficient of performance and figure of merit of this study was 0.16 and 0.31, respectively. Economic evaluation yielded total equipment and total annualized costs of $12.3 million and $24.2 million/year, respectively. The proposed process can assist in achieving a sustainable and green energy economy by enhancing the overall hydrogen value chain through competitive and efficient hydrogen storage and transportation.

The Investigation of Microstructure, Photocatalysis and Corrosion Resistance of C-Doped Ti–O Films Fabricated by Reactive Magnetron Sputtering Deposition with CO2 Gas

By employing carbon dioxide as one source of reaction gases, carbon-doped Ti–O films were fabricated via reactive magnetron sputtering deposition. The chemical bonding configurations and microstructure of the films were analyzed by Raman spectrum and SEM, respectively. The effect of pH on the photocatalytic activities of the films was determined via evaluation of the decolorization rate of methyl orange under alkali, acid and neutrality conditions using UV light irradiation. Electrochemical impedance spectroscopy and potentiodynamic polarization tests were employed to determine the anti-corrosion properties. Compared with the C-free Ti–O film, the C-doped Ti–O films exhibit superior corrosion resistance. Furthermore, the results of the photodegradation experiment suggest that the C-doped Ti–O films have excellent photocatalytic activities and, for methyl orange, those with higher carbon content exhibit hyper-photodegradative effect under the alkali condition.

Boosting high-voltage cyclic stability of nickel-rich layered cathodes in full-cell by metallurgy-inspired coating strategy

Increasing the cutoff voltage is an effective way to boost the energy density of lithium ion full-cells which use the layered nickel-rich oxides. However, the practical application of nickel-rich cathode is severely hindered by the structural degradation and grave capacity loss. Herein, we find that the deterioration of full-cell capacity retention is correlated with the lithium loss in the anode solid electrolyte interphase (SEI) especially at high voltage. The Ni and Mn ions dissolved from the cathode deposit in the anode SEI triggers lithium trapping, and consequently expedites the consumption of cyclical lithium ions. Be based on this finding, an innovative metallurgy-inspired approach of creating a uniform hydroxide layer on the cathode surface and inhibiting separate nucleation of hydroxide that employ carbon dioxide as acidic inducing precipitant, is introduced. Finally, the ultra-thin Al2O3-encapsulated cathodes are obtained after annealing process. Benefiting from the prominent physical-chemical protection function of nanoscale oxide layer, the developed cathode exhibits outstanding cycle durability in full-cell with a capacity retention of ~80% after 800 cycles at 25 °C. Notably, the modified full-cell possesses well thermal stability go through nail penetration test. This work offers an industrial-scale coating paradigm toward high performance nickel-rich cathode for application in full-cells.

Iron‐Rich Natural Mineral Gibeon Meteorite Catalyzed N‐formylation of Amines using CO2 as the C1 Source

AbstractN‐formylated amines (formamides) are important intermediates and the development of efficient and sustainable N‐formylation reactions have attracted considerable attention. Here, we demonstrate that an iron‐rich Gibeon meteorite is an efficient heterogeneous catalyst for this reaction employing carbon dioxide as the source of the formyl CO group. The Gibeon meteorite catalyst is stable, reusable, and affords a wide range of formamides with outstanding chemoselectivity (near‐quantitative yields) under mild conditions (1 – 10 bar CO2 and 25oC). A tentative mechanistic cycle has been proposed for the reaction. This work demonstrates the effectiveness of natural materials as catalysts and how they can be used to inspire the development of synthetic catalysts.

Homogeneous Light‐Driven Catalytic Direct Carboxylation with CO2

AbstractCarbon dioxide is a ubiquitous and inexpensive one‐carbon source for chemical synthesis, and the efficient incorporation of CO2 into organic molecules is of widespread research interest both for economic and ecological reasons. The methodologies to employ carbon dioxide as a single‐carbon unit to construct molecules relevant for agrochemical and pharmaceutical research include many elegant approaches, including asymmetric transformations. Even though remarkable achievements have been made in the field of light‐driven catalysis, especially photoredox catalysis, homogeneous light‐driven catalytic carboxylation by employing CO2 as the key reagent has only become a subject of increasing attention in recent years. Therefore, this concise review will discuss the latest advances in this research area.

The performance analysis of the transcritical Rankine cycle using carbon dioxide mixtures as the working fluids for waste heat recovery

The aim of this study is to investigate the economic performance improvement of a transcritical Rankine cycle system employing carbon dioxide mixtures for waste heat recovery. Five lower global-warming-potential working fluids, namely difluoromethane, fluoroethane, propane, tetrafluoroethane, and tetrafluoropropene, are selected to blend with carbon dioxide. In addition to thermodynamic analysis, the apparatus and maintenance costs of the waste heat recovery system are considered to evaluate the levelized energy cost for the economic performance study. The results indicate that the system cycled with carbon dioxide/fluoroethane exhibits the most effective economic performance, and is superior to that cycled with carbon dioxide/difluoromethane, carbon dioxide/tetrafluoropropene, carbon dioxide/tetrafluoroethane, carbon dioxide/propane, and pure carbon dioxide by 0.7, 13.89, 15.27, 20.88, and 21.52%, respectively. In the transcritical Rankine cycle operated with the carbon dioxide mixtures, not only are energy costs reduced, but the high pressure and temperature are also decreased. Furthermore, the optimal expander inlet pressures for the transcritical Rankine cycle with a minimal levelized energy cost are always smaller than those with maximal thermal efficiencies. Finally, economic performance correlations are proposed for the waste heat recovery system, utilizing various waste heat source temperatures.

Telescoped Synthesis of γ‐Bromo‐β‐Lactones from Allylic Bromides Employing Carbon Dioxide

AbstractA direct synthesis of the title compounds involving a stepwise Zn‐mediated carboxylation of allylic bromides with CO2 delivering β, γ‐unsaturated carboxylic acids and a subsequent bromolactonization is reported. The described method demonstrates the use of readily prepared allylzinc bromides by the method of Knochel for fixation of CO2 employing commodity chemicals and zinc dust. This process was then optimized into a two‐stage, telescoped process for the direct synthesis of γ‐bromo‐β‐lactones from allyl bromides. The described strategy delivers functionalized β‐lactones with dual reactivity as acylating and alkylating agents, which have utility as synthetic intermediates and are attracting growing interest as proteomic tools for activity‐based protein profiling.

Preparation and characterisation of open-celled foams using polystyrene-b-poly(4-vinylpyridine) and poly(4-methylstyrene)-b-poly(4-vinylpyridine) diblock copolymers

In this study, the potential of amphiphilic diblock copolymers on the example of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and poly(4-methylstyrene)-b-poly(4-vinylpyridine) (P4mS-b-P4VP) for producing open-celled foams was evaluated. The porous foam structure was realised by employing carbon dioxide and water as environmental-friendly blowing agents. Rheological measurements in shear and elongation revealed a similar strain-softening behaviour of the diblock copolymers in the melt state. The transient shear and elongational viscosity of the P4mS homopolymer agreed with the linear viscoelastic prediction. On the contrary, the employed PS homopolymer showed strain-hardening. The rheological behaviour of the PS and P4mS homopolymers is consistent with their foaming ability. The PS homopolymer led to a homogeneous, closed cell structure, while the P4mS homopolymer did not foam at all. Because of strain-softening in melt elongation, the PS-b-P4VP diblock copolymer generated homogeneous, open-celled foams throughout the whole sample. In contrast, the P4mS-b-P4VP diblock copolymer generated partially open-celled structures in coexistence with compact areas. In this work, it was demonstrated that the combination of carbon dioxide and water led to open-celled diblock copolymer foams even if the major component of the block copolymer generates homogeneous closed-celled foams or is not foamable, respectively.

Carboxyzincation Employing Carbon Dioxide and Zinc Powder: Cobalt-Catalyzed Multicomponent Coupling Reactions with Alkynes.

Cobalt-catalyzed carboxyzincation reactions employing carbon dioxide and zinc metal powder are developed. By using alkynes as substrates, regio- and stereodefined (Z)-β-zincated acrylates are provided. The corresponding alkenylzinc moiety can be converted to various substituents, affording multisubstituted acrylic acids. Furthermore, by adding electron-deficient alkene to the reaction system, the four-component coupling reactions of alkyne, alkene, CO2, and the Zn atom proceed via carboxyzincation.

Straightforward and selective metal capture through CO2-induced self-assembly

A new process of rare earth metal capture employing carbon dioxide as a key component was designed and studied.

ChemInform Abstract: Nickel‐Catalyzed Double Carboxylation of Alkynes Employing Carbon Dioxide.

AbstractThe Ni‐catalyzed double carboxylation of internal alkynes with CO2, affording highly versatile maleic anhydrides as products is reported.

Nickel-catalyzed double carboxylation of alkynes employing carbon dioxide.

The nickel-catalyzed double carboxylation of internal alkynes employing carbon dioxide (CO2) has been developed. The reactions proceed under CO2 (1 atm) at room temperature in the presence of a nickel catalyst, Zn powder as a reducing reagent, and MgBr2 as an indispensable additive. Various internal alkynes could be converted to the corresponding maleic anhydrides in good to high yields. DFT calculations disclosed the indispensable role of MgBr2 in the second CO2 insertion.

Evonik develops ‘biocarbonates’ from CO2 and soybeans; further invests in precipitated silica

Creavis, the strategic innovation unit of Evonik Industries, has been developing a solution to reduce the company's net greenhouse-gas emissions in Germany and beyond by employing carbon dioxide (CO2) as a feedstock. The development work has been on-going for several years as part of a publicly funded project called H2ECO2, supported by the State of North Rhine-Westphalia and the European Union.