Carbon Capture And Utilization Research Articles

Mineral Carbonation of Basic Oxygen Furnace Slags

Mineral carbonation is a method in carbon capture and utilization (CCU) in which carbon dioxide reacts with natural or synthetic mineral phases to form carbonates. In this study, BOF slag consisting of alite, Ca3SiO5, belite, Ca2SiO4, melilite, (Ca,Na)2(Mg,Al)[4][Si2O7], brownmillerite, Ca(Fe,Al)2O5, calcium ferrite, Ca2FeO4 and Ca-, Mg- and Mn-bearing wuestite, (Mg,Ca,Mn,Fe)O, was crushed into different particle size fractions and exposed over various durations (1 d, 3 d, 9 d, 14 d, 24 d) at a grate to 120 °C hot off-gas with a CO2 content of 25%. However, the total inorganic carbon (TIC) content never increases above the detection limit of 0.5% throughout the experimental duration. The determination of the carbonation depth using phenolphthalein does not reveal a homogeneous carbonation front, but an irregular carbonation. This observation was confirmed by microprobe analyses using elemental mapping. The solubility of the slag increases with increasing carbonation, e.g., the leachability of sulfate increases from 7.8 to 8270 mg/kg dry matter (DM), and of calcium from 940 to 3860 mg/kg DM. The leaching of environmentally relevant element varies: the leachable concentration of molybdenum increases from 0.017 mg/kg DM to 0.089 mg/kg DM, that of chromium remains constant (ca. 0.05 mg/kg DM) whereas that of vanadium decreases from 1.1 to 0.45 mg/kg. In summary, the chosen carbonation technology must be improved to enhance carbonate yield.

Role of carbon capture and utilization (CCU) for decarbonization of industrial sector: A case study of Japan

Carbon capture and utilization (CCU), which is a process used to captured CO2 and convert it into other substances via chemical reactions with hydrogen, is considered to be the most effective carbon–neutral technology for heavy industries. Therefore, comprehensive model-based studies on the economic viability of CCU for decarbonizing the industrial sector can provide effective solutions for controlling carbon emissions from petrochemical industry. In this study, we investigated 1) the roles that CCU could play in Japan’s decarbonization pathways to meet the country’s 2050 carbon emission goals, 2) factors that influence CCU deployment, and 3) how the market penetration of zero-emission vehicles (ZEVs) could affect CCU deployment. Notably, we applied the MARKet ALlocation (MARKAL) model and extended it to integrate CCU technologies and represent chemical production processes, including those required to manufacture basic petrochemical products. Furthermore, the total optimal (minimized) system cost was determined, while considering climate policies and technological assumptions, by analyzing scenarios based on various parameters associated with CO2 emissions and CCU costs. Our study indicates that CCU has the potential to reduce the use of fossil fuel-based energy required by the petrochemical industry by 32%, thus, substantially contributing to Japan’s 2050 CO2 emissions target. Notably, CCU technology can play a key role in near-future decarbonization efforts, especially in cases where ZEV penetration is not as fast as expected.

CO2 enrichment in greenhouse production: Towards a sustainable approach.

As the unique source of carbon in the atmosphere, carbon dioxide (CO2) exerts a strong impact on crop yield and quality. However, CO2 deficiency in greenhouses during the daytime often limits crop productivity. Crucially, climate warming, caused by increased atmospheric CO2, urges global efforts to implement carbon reduction and neutrality, which also bring challenges to current CO2 enrichment systems applied in greenhouses. Thus, there is a timely need to develop cost-effective and environmentally friendly CO2 enrichment technologies as a sustainable approach to promoting agricultural production and alleviating environmental burdens simultaneously. Here we review several common technologies of CO2 enrichment in greenhouse production, and their characteristics and limitations. Some control strategies of CO2 enrichment in distribution, period, and concentration are also discussed. We further introduce promising directions for future CO2 enrichment including 1) agro-industrial symbiosis system (AIS); 2) interdisciplinary application of carbon capture and utilization (CCU); and 3) optimization of CO2 assimilation in C3 crops via biotechnologies. This review aims to provide perspectives on efficient CO2 utilization in greenhouse production.

Committed to implementing CCU? A comparison of the policy mix in the US and the EU

Carbon capture and utilization (CCU) technologies aim to use carbon dioxide (CO2), either captured from industrial point sources or from the atmosphere, instead of fossil carbon in the production of a variety of valuable goods. CCU has the potential to contribute to emission reductions and to lower raw material consumption as well to foster transitional processes toward a circular economy. To enable societies to take full advantage of this potential, policy support is needed in overcoming current barriers and fostering CCU implementation as a feasible option for the industry. Based on a literature and online investigation, this paper identifies and compares the current policy mixes for CCU in the US and the EU, focusing on policy strategies and existing and proposed policy instruments. The analysis shows that US strategy documents, with very few exceptions, do not mention CCU specifically in the context of the country's 2030 or 2050 climate targets. In the EU, in contrast, the future role of CCU is clearly linked to achieving climate-neutrality by 2050. The main policy instruments to incentivize the implementation of CCU in the US are tax credits (45Q). Moreover, funding exists for research and development efforts. In the EU, many reform proposals are currently underway that could benefit CCU technologies. At present, policy support, for instance through the Renewable Energy Directive, mainly aims at renewable fuels of non-biological origin while in other areas CCU support remains at odds with principles such as “energy efficiency first”. The EU does, however, have a broad range of funding opportunities available for research, development and demonstration projects. The paper uses the cross-regional comparison of policy mixes to formulate policy recommendations to improve policy mixes for CCU. A clearer strategic commitment to CCU, its incorporation into green public procurement guidelines, incorporating CCU across different funding schemes for sustainable energy transition, and ambitious new targets for renewable electricity and green hydrogen, for instance, could help develop the policy mixes further to provide a supportive framework for CCU.

Decarbonisation options of existing thermal power plant burning natural gas

Nowadays power industry faces deepest crises ever with unprecedented prices shocks and climate challenges at the same time. From one hand we realise the need of energy transformation of power industry towards more sustainable future with climate neutral technologies. From the other hand it become obvious that this change could not happen immediately, and transition period is needed with some fossil fuel technology still playing an important role as a back-up for renewable energy sources. The biggest question what the best and cost-efficient way is to decarbonise existing thermal power generation. We try to address it on the example of existing combined cycle gas turbine (CCGT) power plant fuelled by natural gas. Clearly the following possible options were identified: 1) replacement of natural gas with alternative gases, such as green hydrogen, bio or synthetic methane, 2) carbon capture and underground storage (CCS) in geological formations, 3) carbon capture, liquefaction and export, 4) carbon capture and utilization (CCU) or 5) replacement of power generation technology. In this publication we try to compare these different options, despite they are not clearly comparable. For the analysis we take natural gas fired CCGT plant Riga TPP-2 in Latvia with installed capacity of 881 MW (in condensing mode).Option 1. In order to completely (100 % in energy values) replace natural gas by green hydrogen, we need electroliers with capacity of at least 2600 MW. Very roughly this is an investment of at least 2,6 billion EUR for hydrogen production, storage and supply. Additionally, we shall take into account necessary modernisation of CCGT plant to be capable for 100 % hydrogen firing as well as necessity to construct additional wind or solar capacity. Conversion efficiency from power to gas is approximately 60 %, while from gas to power – around 55-57 %. Overall conversion efficiency is 33-35 %. The main advantages of this option are a) possibility for wide use of renewable energy sources (wind and solar) in hydrogen production, b) avoidance of carbon dioxide emissions during the electricity production, c) possibility to supply a surplus of hydrogen to transport sector and industry, d) avoidance of all problems associated with CCS option, including the ban for geological storage of CO2. The main disadvantages of this option: a) very high costs of hydrogen production, b) very low conversion efficiency, c) necessity to convert CCGT plant for hydrogen combustion and to install considerable wind and solar capacity.

(Digital Presentation) Highly Efficient and Selective CO2 Electroreduction to CO on Novel Metal-Nitrogen-Carbon (M-N-C) Catalyst

The electrocatalytic reduction of CO2 (CO2RR) to CO is an important component of emerging Carbon Capture and Utilization (CCU) technologies. This process often relies on expensive and rare metals such as silver and gold-based materials for high selectivity and conversion rate to CO1,2. It is desired to move away from these metals towards earth-abundant solid materials (e.g., carbon-based) which may serve as heterogeneous electrocatalysts for CO2RR. Herein, a series of novel carbon-based materials with exceptional selectivity/activity for the targeted production of CO is presented. This new class of hybrid catalyst materials have high CO2RR activity which is comparable to the state of the art atomically dispersed Metal-N-C synthesized by the sacrificial support method (SSM). The advantage of this new class of catalysts is that the use of harsh solvents such as nitric acid and potassium hydroxide which are usually required to remove the silica precursor is completely avoided. Not only does this make the immediate process more environmentally friendly, but it also significantly shortens the catalyst synthesis time which increases its industrial viability. The structure and activity of a series of catalysts with different metallic dopants (Fe, Co, Ni, Mn) are investigated. Using this new synthesis technique, a faradaic efficiency for CO formation (FEco) of 96.5 % at -0.3 V vs. RHE is achieved. FEco remains greater than 75 % over the potential range studied from -0.3 V to -1.1 V vs. RHE. By comparison, Fe-N-C by SSM method reaches a maximum FEco of 94.4 % at -0.7 V vs. RHE and FEco remains greater than 85 % over the same potential range.

Development of Power-to-X Catalytic Processes for CO2 Valorisation: From the Molecular Level to the Reactor Architecture

Nowadays, global climate change is likely the most compelling problem mankind is facing. In this scenario, decarbonisation of the chemical industry is one of the global challenges that the scientific community needs to address in the immediate future. Catalysis and catalytic processes are called to play a decisive role in the transition to a more sustainable and low-carbon future. This critical review analyses the unique advantages of structured reactors (isothermicity, a wide range of residence times availability, complex geometries) with the multifunctional design of efficient catalysts to synthesise chemicals using CO2 and renewable H2 in a Power-to-X (PTX) strategy. Fine-chemistry synthetic methods and advanced in situ/operando techniques are essential to elucidate the changes of the catalysts during the studied reaction, thus gathering fundamental information about the active species and reaction mechanisms. Such information becomes crucial to refine the catalyst’s formulation and boost the reaction’s performance. On the other hand, reactors architecture allows flow pattern and temperature control, the management of strong thermal effects and the incorporation of specifically designed materials as catalytically active phases are expected to significantly contribute to the advance in the valorisation of CO2 in the form of high added-value products. From a general perspective, this paper aims to update the state of the art in Carbon Capture and Utilisation (CCU) and PTX concepts with emphasis on processes involving the transformation of CO2 into targeted fuels and platform chemicals, combining innovation from the point of view of both structured reactor design and multifunctional catalysts development.

Bifunctional Artificial Carbonic Anhydrase for the Integrated Capture and Electrochemical Conversion of CO2

To valorize waste and atmospheric CO2, carbon capture and utilization (CCU) technologies are currently receiving a lot of attention. Alkali base solutions have shown to be efficient capture solutions, and the electrochemical CO2 reduction (eCO2R) is a promising approach to convert CO2 using renewable energy. However, the capture and conversion have been investigated almost exclusively as separate processes to date. This strategy has the disadvantage that CO2 must be desorbed and compressed after capture, which increases the capital and operational costs of the technology significantly. To improve the valorization potential of CCU technologies, integrating both the capture and electrochemical conversion steps by directly utilizing the postcapture solution as an electrolyte (in the form of bicarbonate) for the eCO2R is a highly promising approach. However, bicarbonate electrolysis cannot compete yet in terms of energy efficiency with analogous CO2-fed electrolyzers. Nevertheless, given its huge potential, there is interest in optimizing the overall technology by, for instance, decreasing the costs of capturing the CO2 by shortening the operational time or promoting the electrochemical conversion of CO2 in bicarbonate solutions. In this study, we have synthesized and optimized for the first time ever bioinspired catalysts that were able to fulfill and improve steps in a combined CO2 capture and conversion system. In the best-case scenario, the rate of the conversion of CO2 to bicarbonate (mimicking the capture step in CCU) increased by 91% when the biomimetic catalyst [Zn(cyclen)]2+ was present in the capture solution. On the other hand, the same catalyst promoted the electrochemical conversion of CO2 to formate from a bicarbonate postcapture solution by inhibiting the competing hydrogen evolution reaction (HER). The partial current density toward the HER decreased from 18 mA cm–2 in control experiments to 0.7 mA cm–2 in the presence of [Zn(cyclen)]2+.

Life cycle assessment of a novel electrocatalytic process for the production of bulk chemical ethylene oxide from biogenic CO2

Carbon capture and utilization (CCU) technologies support future energy and climate transition goals by recycling carbon dioxide (CO2) emissions. The use of biogenic CO2 from renewable sources, is an avenue for the production of fully renewable products. Fossil-based materials can potentially be replaced in the long term while allowing for the use of so called “waste” streams. To foster the development of a circular economy more insights need to be gained on the life cycle impact of CCU technologies. This study analyzed a CCU process chain, with focus on the utilization of volatile renewable electricity and biogenic CO2. We performed a cradle-to-gate life cycle assessment, evaluating various environmental impact categories (CML 2001 methodology) and primary energy demand (PED) with GaBi LCA software by sphera®. The targeted olefin is ethylene oxide (C2H4O), which is a crucial intermediate chemical for the production of various synthetic materials, such as polyethylene terephthalate (PET). As functional unit, 1 kg ethylene oxide was chosen. In the novel process at first ethylene (C2H4) and hydrogen peroxide (H2O2) are produced from water and CO2via an electrocatalytic process (Power-to-X process). In a second step, the two intermediates are synthesized to ethylene oxide. The theoretical implementation of a medium-scale process under average European conditions was considered in 12 scenarios that differed in energy supply and CO2 source. Sensitivity analyses were conducted to evaluate the influence of the energy and resource efficiencies of the production steps. The process was compared to its fossil benchmark, an existing conventional EO production chain. Concerning the global warming potential (GWP), negative emissions of up to −0.5 kg CO2 eq./kg product were calculated under optimized process conditions regarding energy and conversion efficiency and using biogenic CO2. In contrast, the GWP exceeded the fossil benchmark when the European grid mix was applied. The PED of 87 MJ/kg product under optimized conditions is comparable to that of other Power-to-X processes, but is high compared to fossil-based ethylene oxide. Based on the results we conclude that the energy efficiency of the electrocatalytic cell and renewable energy as input are the main levers to achieve a low environmental impact.

Deep eutectic systems for carbonic anhydrase extraction from microalgae biomass to improve carbon dioxide solubilization

This work is the first proof-of-concept of the use of carbonic anhydrase (CA) enzyme from microalgae biomass, extracted with deep eutectic systems (DES), with the goal of engineering a solution that will lead to a breakthrough in the Carbon Capture and Utilization (CCU) strategy. Three distinct microalgae were processed – Tisochrysis lutea, Chlorella vulgaris, and Spirulina sp. – with three DES – Choline chloride-Urea (ChCl-U), Choline chloride-Poly(ethylene glycol) (ChCl-PEG), and Poly(ethylene glycol)-Urea (PEG-U). To evaluate the most promising microalgae-DES, CA activity was evaluated with a specific enzymatic activity kit and through CO2 solubility assays. Preliminary results indicate that: DES is a suitable solvent medium for CA extraction from microalgal biomass, preserving its activity (specific CA activity up to 0.70 mU.mg−1); CA extraction efficiency differs between DES and microalgal species, indicating the potential for further research; from the tested DES, the ones containing PEG were favorable to maintain CA activity (CO2 solubility up to 4 g CO2.g−1 DES). This work paves the way towards a disruptive CCU approach.

Incremental approach for the life-cycle greenhouse gas analysis of carbon capture and utilization

Electro-fuels (e-fuels) are examples of carbon capture and utilization (CCU) hydrocarbon products that are derived from captured carbon dioxide (CO2), while using renewable electricity as the energy feedstock. The environmental impacts of CCU products (e.g., e-fuel) are systematically quantified through life-cycle analysis (LCA). Previous studies evaluating LCA of e-fuels proposed frameworks with an expanded system boundary approach that included the entire supply chain of the production process generating the CO2 for CCU, in addition to the supply chain of the CCU product. This expanded system boundary approach evaluates two system boundaries, and uses deduction methods to calculate the carbon intensity (CI) of the CCU product (e-fuel). This paper proposes a simpler system boundary using an incremental approach that can calculate identical CI of the CCU product (e-fuel), while avoiding the extensive calculations in the expanded system boundary framework. The proposed incremental approach allocates the burdens of the CO2 capturing process to the CO2 feedstock supplying the CCU production process (e.g., e-fuel production). The CI of the captured CO2 supplied to CCU process is determined by the energy and material requirements for the CO2 capturing process and transportation to the CCU plant. Thus, the CI of CO2 supplied to CCU process can be directly linked to the CI of e-fuel without the need to conduct LCA of the preceding process that generates the CO2 for CCU.

Techno-economic analysis of integrated carbon capture and utilisation compared with carbon capture and utilisation with syngas production

Currently, excessive CO2 emissions have become a global challenge due to their influence on the climate. According to the Paris Agreement, global warming should be limited to 1.5 °C by 2100. Carbon capture and utilisation (CCU) are attractive as they can both reduce CO2 content and utilise CO2 as a carbon resource. However, in conventional CCU processes, CO2 needs first to be extracted and purified for the following utilisation. In contrast, the recently reported Integrated Carbon Capture and Utilisation (ICCU) was designed to realise the overall process in one reactor, where CO2 is captured by adsorbents (e.g., CaO) and utilised in-situ with the introduction of a reducing agent (e.g., H2). This ICCU technology can promote CO2 conversion with fewer intermediate steps, leading to a reduction in overall cost. Energy and economic analysis of ICCU are thus urgently required. According to several recent research, the operational cost of ICCU has been reported to be cheaper than that of CCU. However, a comprehensive view of ICCU is still expected due to further application. This paper focuses on comparing ICCU and conventional CCU processes based on Aspen simulations covering mass balance (i.e., CaCO3 consumption, purge production, annual CO production), energy balance, the total annual cost and the CO cost, etc. Analysis shows that the ICCU process can produce more CO (1.20 Mt year−1), less purge (0.21 Mt year−1), and less consumption of CaCO3 (0.62 Mt year−1) with higher energy efficiency (37.1 %) than the CCU process. The results also show that the total annual cost of ICCU is $867.07 million, corresponding to a total cost of CO of $720.25 per tonne. In contrast, CCU has higher costs, with a total annual cost of $1027.61 million and a total cost of CO of $1004.53 per tonne. The Cost of CO2 Avoided of ICCU (317.11$/ton) is much lower than that CCU (1230.27 $/ton). Therefore, ICCU was confirmed as a better choice for further industrial applications. In addition, H2 is shown to have a significant influence on economic performance, which remains a challenge for further application.

Enhancing the synergism of Fe3O4 and Fe5C2 to improve the process of CO2 hydrogenation to olefines

CO2 hydrogenation to olefines is a feasible carbon capture and utilization (CCU) route. The process includes sequential reactions of reverse water gas shift (RWGS) reaction and Fischer-Tropsch synthesis (FTS) reaction. The acceleration of FTS is crucial to improve the olefines yield. A microemulsion anti-solvent extraction (MAE) method was proposed to prepare Fe-based catalyst on the support of Al2O3. Ethanol solution of Fe(NO3)3 was encapsulated in microdroplets, and then loaded on Al2O3 by the extraction of ethanol from the microdroplets to isooctane phase. The average size of micro droplets was 7.5 nm. After calcination, the particle size of Fe2O3 was 6 nm. After carburization with CO, the interface formed between Fe3O4 and Fe5C2 was restricted in a narrow space with a mean size of 12 nm. Through TEM-Mapping, XRD, XPS and TPC characterization, the distribution uniformity of Fe and the neighboring degree of Fe3O4 and Fe5C2 on the as-prepared catalyst MAE-Fe1K1 was improved effectively. An enhanced synergistic effect between Fe3O4 and Fe5C2 was obtained. The catalytic performance evaluation results showed that yield of C2-C4 olefins reached 0.063 mmol·gFe−1·s−1 after 12 h of reaction. It exhibited better catalytic performance than most catalysts reported in the literatures. The results showed that the proposed microemulsion anti-solvent extraction strategy is an effective method to prepare Fe-based catalyst for CO2-FTO reaction with an excellent catalytic performance.

Reconfigurable modular microbiota systems for efficient and sustainable water treatment

Carbon capture and utilization (CCU) of microorganisms is widely expected to provide fresh insight into oil wastewater treatment due to green and sustainable processing, and the constant pursuit of high efficiency and sufficient waste utilization to combat climate change calls for the development of advanced engineering microbiology. Here, we explored and proposed a brand-new method to improve CCU in oil wastewater treatment using modular microbiota systems (MMSs). The modular assembly of microorganisms developed in this study allowed for efficient synergy and the design of carbon exchange routes on demand. The microfluidic-assisted assembly of MMSs achieved high specific surface area and good monodispersity during treatment. And the functionalized biomaterials immobilized MMSs possess adsorption to the oil pollutant and settleability for bioresources harvesting. The practical treatment process has validated feasibility and performance of this strategy. The MMSs achieved a breakthrough seven-day crude treatment efficiency (10 g/L) of 95.8 %, and the carbon utilization (lipid accumulation) of MMSs was elevated from 0.1079 g/L to 0.2081 g/L as compared to normal algae culture treatment. The MMSs showed reliable and efficient CCU in different environmental tests. Moreover, the reconfigurable modular microbiota assembly endows this method with superior scalability, which should enable diverse water treatment applications in global settings and provide a potential path for on-demand waste conversion to bioenergy.

Reflecting on the environmental impact of the captured carbon feedstock

Climate change mitigation potentials of carbon capture and utilization (CCU) closely depend on the energy and chemicals used to capture the chemically inert CO2. The potential environmental benefits of CCU are typically assessed using Life Cycle Assessment (LCA) methodology. Although LCA is a standardized method, modelling CO2 as a carbon feedstock instead of an emission introduces an ambiguous “multifunctionality issue”. Inconsistent multifunctionality practices have been applied to deal with this methodological complexity in LCAs of CCU technologies. Using one method instead of another can lead to highly positive or negative carbon footprints for the same carbon source and CO2 capture process.A comprehensive guideline to clarify the best practices to conduct LCAs of CCU technologies was published in 2020 (and updated in March 2022) in a collaborative process involving over 40 experts. In this guideline and linked scientific articles from experts involved in its development, a so-called “substitution method” is recommended to avoid suboptimal choices of CO2 sources, improve comparability and harmonize decision-making. This article critically reviews the methodological formulation of the recommended method and suggests corrections to possible inaccuracies in a future update of the guideline. Furthermore, various illustrative examples of common CO2 feedstocks were used to illustrate the meaning of adopting such a method in practice. Economic-based benchmarking of the environmental impacts of CO2 feedstocks calculated with such a method was also broadly illustrated.

A standardized methodology for economic and carbon footprint assessment of CO2 to transport fuels: Comparison of novel bicarbonate electrolysis with competing pathways

Early evaluation of carbon capture and utilization (CCU) pathways in terms of cost and emission reductions is critical in guiding future R&D and commercialization. However, such evaluation is challenging due to varying technology readiness levels (TRL) of pathways, unavailability of cost and emission data for new technologies and uncertainty of performance parameters of lab scale technologies. In this study, we propose a standardized methodology that allow comparing synthetic fuel production pathways based on early stage lab scale CO2 electrolysis technologies with mature CCU technologies and incumbent technologies. This methodology provides guidelines for defining pathways, modeling and cost and carbon footprint (CF) assessment supported by a bottom-up framework to scale- up the costs and CF of lab scale technologies. We apply the developed methodology to evaluate Fischer-Tropsh synthesis (FTS) fuel production pathways based on bicarbonate electrolysis, a novel early stage CO2 electroreduction technology with integrated CO2 capture, and reverse water gas shift (RWGS) reaction, a mature thermocatalytic CO2 conversion technology. The cost of diesel fuel production using RWGS and bicarbonate electrolysis pathways were 1.7 $/L and 1.5 $/L, respectively, which is more than 140% of current cost of diesel. Nevertheless, both pathways were able to achieve significant emissions reductions with bicarbonate electrolysis reducing 90% and RWGS reducing at 70% compared to conventional diesel. Based on the uncertainties of calculated cost, neither pathway is more economically competitive than the other. However bicarbonate electrolysis pathway offer more opportunities for emission reduction as most of its energy demand can be provided by renewable electricity. RWGS pathway with relatively higher thermal energy demand will need to rely on high level of energy recovery and integration to achieve similar emission reductions.

Photo‐Mediated Reduction of Carbon Dioxide to Formic and Other Carboxylic Acids by Ni‐Catalysis with Chelating Ligand

In this minireview, photo-mediated reductions of CO2 to formic and other carboxylic acids by Ni-chelate catalysts were discussed with mechanistic details. Formic and other carboxylic acid products are formed exclusively over CO by insertion of CO2 in Ni−H/Ni−C bonds in these Ni-catalysed light-mediated CO2 reductions. Role of chelating ligands in modulating the catalytic efficiency and product selectivity of such catalysis has also been encompassed in the minireview.

Carboxylation reactions for integrating CO2 capture with the production of renewable monomers

AbstractResearch advances in carboxylation reactions using CO2 and light organic molecules of renewable origin are reviewed in this work, especially considering chemical catalytic approaches. Carboxylation, one of the most promising carbon capture and utilization (CCU) technologies, has a double environmental benefit, reducing greenhouse gas emissions by developing sustainable processes for commodity synthesis. The industrial interest is based on its potential use in the synthesis of biopolymer precursors from bioplatform molecules such as ethanol or furfural. Acrylic acid is obtained from ethylene (after ethanol dehydration), by a liquid phase reaction activated by organometallic catalysts. Promising yields are reported for different ligands and solvents, but a practical and sustainable implementation of these reactions is still challenging. On the other hand, the furoic acid carboxylation (furoic acid obtained by oxidation of furfural) is a solid‐gas reaction that produces 2,5furandicarboxylic acid in presence of alkaline carbonates. In this case, the economic feasibility is the main bottleneck to solve for scaling‐up, and efforts should be focused on substituting the most active alkaline carbonate (Cs) by more available alternatives. © 2022 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

The early-stage design of plasma for the conversion of CO2 to chemicals: A prospective techno-economic assessment

The persistent increase in CO2 emissions and the continued depletion of fossil resources are two major challenges of the 21st century. These challenges can be tackled with Carbon Capture and Utilization (CCU), fby capturing and using CO2 as a valuable feedstock. Plasma presents a reactive environment to convert the CO2 molecule efficiently into higher-value chemicals and is a promising CCU technology in an early development stage. This study translates the technical performance of the plasma, as observed in the laboratory, into economic cashflows on a pilot plant level. In this techno-economic assessment, the influence of three features of the plasma is analyzed: the type of feed, the space time and the type of packing material. The economic feasibility of the different plasma configurations for the conversion of CO2 and CH4 into higher-value chemicals is assessed by calculating the Net Present Value (NPV). This allows the identification of the major cost items and the prioritization of future R&D steps. Negative NPVs are observed for all configurations, due to high electricity expenses, high capital investments and insufficient revenues. Based on the NPV, the most promising reactor configuration is the unpacked reactor, supplied with pure CO2 in a short space time. However, to target higher-value chemicals and raise revenues, the presence of packing materials and a mixed feed of CO2 and CH4 is crucial. Indeed, the highest revenues are observed for the reactor filled with packing, supplied with CO2 & CH4 and at longer space time. To move forward, the right type of packing material should be found, enabling the targeted production of higher-value chemicals with higher conversion rates in a shorter space time.

Rational design of Cu(I)-anchored porous covalent triazine framework (CTF) for simultaneous capture and conversion of CO2 at ambient conditions

The selective carbon capture and utilization (CCU) as a C1 source is sought to be an important step towards environmental remediation and sustainable production of useful chemicals. In this context, herein, we report the strategic integration of noble metal-free Cu(I) catalytic sites with a nitrogen-rich, CO2-philic, bipyridine functionalized covalent triazine framework (bipy-CTF) by a post-synthetic approach. The Cu(I)@bipy-CTF showed very good performance for simultaneous capture and fixation of CO2 into α-alkylidene cyclic carbonates (α-aCCs), high-value commodity chemicals at ambient conditions. Further, the Cu(I) anchored bipy-CTF showed high CO2 affinity with the interaction energy of 44.09 kJ/mol attributed to the presence of CO2-philic, basic nitrogen sites. The presence of both CO2-philic nitrogen and alkynophilic Cu(I) sites decorated in the 1D channels of bipy-CTF provided a good catalytic activity for the chemical fixation of carbon dioxide from dilute gas (13 % CO2) to yield α-aCCs at atmospheric pressure (balloon) of CO2. Notably, Cu(I)@bipy-CTF showed high recyclability and chemical stability for multiple catalytic cycles. Overall, the present work represents a rare example of a COF-based recyclable catalyst for CO2 fixation from dilute gas into valuable chemicals under mild conditions.