Climate change is one of the main threats to modern society. This phenomenon is associated with an increase in greenhouse gas (GHGs, mainly carbon dioxide—CO2) emissions due to anthropogenic ...activities. The main causes are the burning of fossil fuels and land use change (deforestation). Climate change impacts are associated with risks to basic needs (health, food security, and clean water), as well as risks to development (jobs, economic growth, and the cost of living). The processes involving CO2 capture and storage are gaining attention in the scientific community as an alternative for decreasing CO2 emissions, reducing its concentration in ambient air. The carbon capture and storage (CCS) methodologies comprise three steps: CO2 capture, CO2 transportation, and CO2 storage. Despite the high research activity within this topic, several technological, economic, and environmental issues as well as safety problems remain to be solved, such as the following needs: increase of CO2 capture efficiency, reduction of process costs, and verification of the environmental sustainability of CO2 storage.
This review introduces the syntheses of metal-organic framework (MOF) composites and their applications in CO2 capture and conversion, including CO2 chemical fixation, hydrogenation, photoreduction, ...electroreduction and photoelectroreduction.
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Reliable technologies for CO2 capture and conversion (C3) are of vital importance for the establishment of a sustainable society. Metal-organic framework (MOF) composites have shown their compelling potentials for C3 due to the plentiful reticular chemistry of MOF structures and the synergistic catalysis between MOFs and the functional guests. This review focuses on the syntheses and catalytic applications towards C3 of MOF composites, which is divided into three sections. The first section gives a brief introduction about synthetic strategies of MOF composites. The second section discusses the recent progress of MOF composites in C3, including CO2 chemical fixation, hydrogenation, photoreduction, electroreduction and photoelectroreduction. The third section summarizes the challenges and future prospects of MOF composites for C3. We hope that this review cannot only provide an inspiration for the rational design of MOF composites for C3, but also stimulate more and more research works in this emerging area.
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•CO2 was used as an inexpensive feedstock for various fuels and chemicals production.•Explained various utilization approaches and their mechanisms for CO2 mitigation.•Discussed the ...various CO2 conversion processes.•Current status and Scope for further research on CO2 conversion has been discussed.
Carbon dioxide (CO2) is a odourless and colourless gas which plays a noteworthy role in the climate and weather changes. Different natural and anthropogenic activities induces CO2 emission in the environment. Though CO2 causes global warming, it acts as an essential element for photosynthesis process in plants. CO2 can also be used as an inexpensive feedstock for the production of various fuels and chemicals. Many approaches like electrochemical, thermal, biochemical, chemo-enzymatic and photocatalytic methods are available by means of which the harmful CO2 is captured from the environment. Similarly, via different chemical, physical and biological processes, it can be converted into useful products like fuels and chemicals. This review mainly focuses on various utilization approaches and their mechanisms for CO2 mitigation. In addition, CO2 conversion processes like hydrogenation, esterification, methanation, reforming, and reverse water-gas shift (RWGS) reactions, their mechanisms and their current status along with future perspectives were comprehensively discussed.
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•First comprehensive overview on low temperature CO2 methanation.•Overview on CO2 methanation fundamentals, catalysts and reactor technologies.•Identified challenges and opportunities ...in each of the areas reviewed.•A critical process simulation result for low temperature CO2 methanation.
CO2 utilization technologies can not only provide a pathway to reduce greenhouse gas emissions but may also enable renewable energy to be incorporated into important materials used in the society such as fuel and chemicals. Power to gas (PtG) technologies, especially Power to methane has been deemed as one of the promising pathways for the conversion of CO2 into valuable gaseous fuel. Many reports have reviewed the academic literature related to CO2 methanation. While the benefits of high temperature methanation for overall process efficiency are well understood, the potential for low-temperature methanation is less understood. In particular the opportunities that arise from coupling a low-temperature methanation process with low temperature hydrogen production technologies, such as PEM electrolysis, have received little attention. It is therefore considered valuable to provide a critical review of the state of the art of this technology at low temperature conditions for the interests of broader research community. In this paper we focus on the recent work around low temperature CO2 methanation including reaction thermodynamics and kinetics, catalyst materials including supports and promoters, and suitable reactor technologies. We discuss each of these critical aspects of the technology and identify key challenges and opportunities for low temperature CO2 methanation (methanation conducted at temperatures less than 300 °C). As part of this paper, we also present the results of an ASPEN Plus simulation study based on data available from the literature to highlight the potential energy efficiency gains of a low temperature methanation process.
We analysed the responses of 11 ecosystem models to elevated atmospheric CO₂ (eCO₂) at two temperate forest ecosystems (Duke and Oak Ridge National Laboratory (ORNL) Free‐Air CO₂ Enrichment (FACE) ...experiments) to test alternative representations of carbon (C)–nitrogen (N) cycle processes. We decomposed the model responses into component processes affecting the response to eCO₂ and confronted these with observations from the FACE experiments. Most of the models reproduced the observed initial enhancement of net primary production (NPP) at both sites, but none was able to simulate both the sustained 10‐yr enhancement at Duke and the declining response at ORNL: models generally showed signs of progressive N limitation as a result of lower than observed plant N uptake. Nonetheless, many models showed qualitative agreement with observed component processes. The results suggest that improved representation of above‐ground–below‐ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO₂ effects. Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C–N budgets. The two FACE experiments are insufficient to fully constrain terrestrial responses to eCO₂, given the complexity of factors leading to the observed diverging trends, and the consequential inability of the models to explain these trends. Nevertheless, the ecosystem models were able to capture important features of the experiments, lending some support to their projections.
•Techno-economic review of carbon capture, utilisation and storage (CCUS) systems.•Chemical looping combustion seems to be the best for CO2 capture (up to 99% vol.).•The most energy-efficient CO2 ...separation technology is adsorption.•For CO2 transport, a combination of pipelines and ships can bring greater benefits.•CO2 can be utilised for enhanced oil recovery and stored in geological formations.
Carbon capture and storage (CCS)/carbon capture, utilisation and storage (CCUS) systems are widely recognised to have the potential in reducing CO2 emissions. However, current their global deployment is still not sufficient to reach the anticipated net-zero CO2 emissions target by 2050. This article aims to provide a general techno-economic review of CCUS systems. The technology readiness, technical performance, energy requirement and cost associated with CO2 capture, separation, transport, utilisation and storage technologies were discussed and compared. The CO2 capture technological pathways include industrial separation, post-combustion, pre-combustion, oxy-fuel combustion, chemical looping combustion and direct air capture. CO2 separation technologies such as absorption, adsorption, membrane, cryogenic and biological were also covered. Then, a review on CO2 transportation by pipeline, ship, truck and rail was presented, followed by a review on CO2 utilisation pathways for direct usage and through conversion into other products. Lastly, different CO2 storage options were reviewed, which include storage through CO2-enhanced oil recovery, in depleted oil and gas fields, in saline formations, in basalt and ultramafic rocks, in coal seams through enhanced coal bed methane recovery and in the deep ocean. This article concluded that the challenges with current CCUS technologies can possibly be overcome by developing a commercially viable hybrid system comprising more than one technology. However, this approach needs to be further investigated for industrial applications.
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•CO2 properties, coordination chemistry and reactions.•CO2 as a C1-synthon for the synthesis of “intermediates and fine chemicals”.•CO2 as source of carbon for energy ...products.•Biotechnological uses of CO2: Integration of biotechnology and chemical catalysis.
The need to reduce the emission of carbon dioxide into the atmosphere is pushing toward the use of “renewable carbon”, so to avoid as much as possible burning “fossil carbon”. It would be possible to complement the natural “carbon cycle” by developing man-made industrial processes for “carbon recycling”, converting, thus, “spent carbon” as CO2 into “working carbon”, as that present in valuable chemicals or fuels. Such practice would fall into the utilization of “renewable carbon”, as the man-made process would perfectly mimic the natural process. An order of complexity higher would be represented by the integration of biotechnology and catalysis for an effective CO2 conversion, using selective catalysts such as enzymes, or even whole microorganisms, coupled to chemical technologies for energy supply to enzymes, using perennial sources as sun or wind or geothermal as primary energy.
These days all the above approaches are under investigation with an interesting complementarity of public–private investment in research. This paper aimed at making the state of the art in CO2 conversion and giving a perspective on the potential of such technology. Each atom of C we can recycle is an atom of fossil carbon left in the underground for next generations that will not reach the atmosphere today.
Excessive emission of greenhouse gases into the atmosphere has resulted in a progressive climate change and global warming in the past decades. There have been many approaches developed to reduce the ...emission of Carbon Dioxide (CO2) into the atmosphere, among which Carbon Capture and Storage (CCS) techniques has been recognized as the most promising method. This paper provides a deeper insight about the CCS technology where CO2 is captured and stored in deep geological formations for stabilization of the earth's temperature. Principles of capturing and storage for a long-term sequestration are also discussed together with the processes, mechanisms and interactions induced by supercritical CO2 upon injection into subsurface geological sites.
This paper systematically presents the established technologies and field applications with respect to research and engineering practice of CO2 capture, enhanced oil recovery (EOR), and storage ...technology in Jilin Oilfield, NE China, and depicts the available series of supporting technologies across the industry chain. Through simulation calculation + pilot test + field application, the adaptability of the technology for capturing CO2 with different concentrations in oilfields was confirmed. The low energy-consumption, activated N-methyl diethanolamine (MDEA) decarburization technology based on a new activator was developed, and the operation mode of CO2 gas-phase transportation through trunk pipeline network, supercritical injection at wellhead, and produced gas-liquid separated transportation was established. According to different gas source conditions, liquid, supercritical phase, high-pressure dense phase pressurization technologies and facilities were applied to form the downhole injection processes (e.g. gas-tight tubing and coiled tubing) and supporting anti-corrosion and anti-blocking techniques. In the practice of oil displacement, the oil recovery technologies (e.g. conical water-alternating-gas injection, CO2 foam flooding, and high gas-oil ratio CO2 flooding) and produced fluid processing technologies were developed. Through numerical simulation and field tests, three kinds of CO2 cyclic injection technologies (i.e. direct injection, injection after separation and purification, and hybrid injection) were formed, and a 10×104 m3/d cyclic injection station was constructed to achieve “zero emission” of associated gas. The CO2 storage safety monitoring technology of carbon flux, fluid composition and carbon isotopic composition was formed. The whole-process anti-corrosion technology with anticorrosive agents supplemented by anticorrosive materials was established. An integrated demonstration area of CO2 capture, flooding and storage with high efficiency and low energy-consumption has been built, with a cumulative oil increment of 32×104 t and a CO2 storage volume of 250×104 t.
In addition to carbon capture and storage, efforts are also being focussed on using captured CO2, both directly as a working fluid and in chemical conversion processes, as a key strategy for ...mitigating climate change and achieving resource efficiency. These processes require large amounts of energy, which should come from sustainable and, ideally, renewable sources. A strong value chain is required to support the production of valuable products from CO2. A value chain is a network of technologies and infrastructures (such as conversion, transportation, storage) along with its associated activities (such as sourcing raw materials, processing, logistics, inventory management, waste management) required to convert low-value resources to high-value products and energy services, and deliver them to customers. A CO2 value chain involves production of CO2 (involving capture and purification), technologies that convert CO2 and other materials into valuable products, sourcing of low-carbon energy to drive all of the transformation processes required to convert CO2 to products (including production of hydrogen, syngas, methane etc.), transport of energy and materials to where they are needed, managing inventory levels of resources, and delivering the products to customers, all in order to create value (economic, environmental, social etc.).
Technologies underpinning future CO2 value chains were examined. CO2 conversion technologies, such as urea production, Sabatier synthesis, Fischer-Tropsch synthesis, hydrogenation to methanol, dry reforming, hydrogenation to formic acid and electrochemical reduction, were assessed and compared based on key performance indicators such as: CAPEX, OPEX, electricity consumption, TRL, product price, net CO2 consumption etc. Technologies for transport and storage of key resources are also discussed. This work lays the foundation for a comprehensive whole-system value chain analysis, modelling and optimisation.
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