Reuse Of CO2 Research Articles

Thermodynamic simulation of slag–refractories interactions in innovative slag-splashing processes in converters

The innovative slag-splashing process in converters enables the reuse of CO2. However, the changes in slag–refractories interactions after applying the new technique are not yet clear. In this work, an approach was developed to thermodynamically simulate the slag–refractories interactions in slag-splashing processes. Firstly, the simulation was validated. Subsequently, the differences in traditional and innovative slag-splashing processes were compared, and the effects of slag carbon addition, CO2 consumption, and refractories composition on slag–refractories interactions were investigated. It was found that after applying the new technique, the mass of the high-melting-point solid solution increased, and the liquid slag had a better bonding effect on the refractories and the external mechanical bonding layer. Increasing the slag carbon addition and CO2 consumption both led to an increase in high-melting-point solid solution. However, increasing the slag carbon addition favoured the bonding of liquid slag to the refractories, while increasing the CO2 consumption weakened the bonding ability of the liquid slag. The increase of C in MgO–C refractories resulted in an increase in Fe and CO production. Due to the deterioration of slag wettability on refractories, the increase in C is detrimental to the converter slag-splashing process.

Carbon dioxide capture by direct methanation in co-electrolysis using solid oxide cell

Reducing carbon emissions in the global economy's energy and industry sectors necessitates not just the implementation of innovative low-emission technologies but also the adoption of techniques for capturing and recycling CO2. The Power-to-X conversion allows the path to the reuse of CO2 originating from fossil fuels burning and other industrial processes, hence reducing the emission of the key greenhouse gas. The use of high-temperature electrochemical devices for such purposes is a promising solution, which has been already deployed as subsidized demo projects. In the present work, the direct electrolysis of the H2O-CO2-H2 mixtures with in situ conversion of CO2 and CO to CH4 was effectively conducted in the temperature range of 575–650 °C using commercial solid oxide half-cell with YSZ-type electrolyte on Ni-YSZ support with a custom lanthanum‑strontium cobaltite anode. The degree of carbon conversion in the atmosphere enriched with hydrogen was close to 90%, but under such conditions, the products are diluted to 5–6 vol% in H2. Reducing the temperature leads to a sufficient increase in the CH4 outcome, but it is constrained by the decline of the cell performance. Electrochemical processes were monitored by impedance spectroscopy and analyzed using the distribution of the relaxation times technique. Analysis of the distribution of relaxation times of impedance spectra showed that two parallel competitive processes can be attributed to CO2 conversion. Peak with characteristic time c.a. 0.1 s might be associated with diffusion-like mass transfer through cermet support, and it plays an important role in the electrochemical conversion at elevated temperature and high current density. Conversely, the peak observed in the vicinity of 5 ms becomes the limiting stage at lower temperature and probably is related to charge transfer or absorption and surface diffusion of carbon-containing species. Electrolysis current density might reach 0.4 A cm−2 even at 600 °C without explicit damage to the electrolyte or electrodes. A brief degradation test demonstrated a minor loss in the electrochemical performance of the cell. Thus, it was demonstrated that direct electrochemical conversion of CO2 to CH4 can be achieved with sufficient productivity using a semi-commercial cell with an active surface of 16 cm2 under conditions compatible with those existing in the state-of-the-art stacks of solid oxide cells.

Molecular study on the growth mechanism of CO2-H2 binary hydrate promoted by electric field

The storage and transportation of hydrogen (H2) are widely recognized as the main challenge of hydrogen utilization technology. The hydrate-based method is one of the safe and environmentally friendly hydrogen storage methods. However, the harsh generation conditions and slow growth rate of H2 hydrate hinder its industrial application. Therefore, exploring methods to reduce the reaction conditions of H2 hydrate and improve growth efficiency is worth further research. This study investigated the effect of different intensities of electrostatic fields (0–0.9 V/nm) on the growth of CO2-H2 binary hydrates through molecular dynamics (MD) simulation. Representative parameters such as growth configuration, number of cages, dipole moment, four body angular order parameters, mean square displacement, occupancy rate, etc. were analyzed. The T, P conditions used for the simulation were 255 K, 80 MPa, and 400 ns in duration. The results suggest that a certain range of electric field strength can increase the growth rate of CO2-H2 binary hydrates and reduce the conditions required for hydrogen hydrate formation. The growth-promoting effect of the electric field is primarily manifested in the increased growth rate of binary hydrates. Detailed analysis reveals that electric field of a certain strength can to some extent promote the multiple occupancy of H2 within cage structures, thereby enhancing the hydrate's ability to capture H2. These molecular insights are beneficial for the application of electrostatic field in hydrate-based technologies to improving the storage efficiency of H2 hydrate and the reuse of CO2.

What makes people accept carbon capture and utilization products? Exploring requirements of use in the German population

Carbon Capture and Utilization (CCU) is often referred to as an important cornerstone in the context of counteracting climate change. It aims to capture CO2 from various sources and to store it in valuable products more or less permanently. While the environmental impact of this technology has already received much scientific attention, this work takes a social science perspective on the matter. Using an empirical mixed-methods approach consisting of an exploratory focus group study (N = 13) and a validating quantitative questionnaire study (N = 198), public perceptions and acceptance of CCU were assessed in Germany by identifying motivators, barriers, and usage requirements. As CCU products, clothing, cosmetics, and food packaging were under study. Potential cost savings from shortened supply chains or manufacturing steps were the biggest motivator for using CCU. However, environmental impacts resulting from the degradation and reuse of CO2 were also recognized and the conservation of fossil resources was also acknowledged. The biggest barrier, in contrast, was the concern about possible manipulation of consumers through marketing. Participants feared that CCU would be publicly portrayed as better than it actually is. In addition, a high energy input in the production of CCU products was expected and doubts were expressed about the longevity of the positive environmental impacts of CCU. General acceptance within the sample was quite high, however, the level of CCU awareness was rather low. Our results show a considerable lack of public knowledge about and information regarding the environmental impact of CCU, among other factors, despite this very topic garnering plenty of scientific attention. A need for publicly accessible information materials uniquely tailored toward potential consumer target groups was revealed.

Modeling Chemical Microenvironments in Porous Copper Electrodes for CO2 Reduction at Elevated Current Densities

Electrochemical CO2 reduction (CO2R) presents a promising pathway toward the reuse of CO2 emitted during the production of industrial commodities (e.g., cement, steel, and plastics) to form value-added commodities and fuels at ambient temperatures and pressures with renewably generated electrons. Copper (Cu) catalysts demonstrate the ability to convert CO2 to multicarbon (C2+) products. Additionally, 3-D structured porous Cu electrodes can facilitate the operation of CO2R to C2+ at significantly elevated current densities by enhancing the delivery of CO2 to catalytic active sites on Cu, offering the potential to translate lab-scale understanding to industrial operation. Nonetheless, there still exist selectivity limitations in porous electrode systems due to poor control of the chemical microenvironment, (i.e., the local pH, CO2 activity, and CO intermediate management), in these complex electrodes. Therefore, resolving microenvironment in porous Cu electrodes will be critical to advancing these systems towards industrialization.In this talk, we explore the use of continuum modeling to resolve and understand the effects of mass transfer and chemical environment in electrochemical CO2 reduction in porous Cu electrodes. We explore two scenarios of porous Cu electrodes performing electrochemical CO2 reduction. The first is the operation of a device employing a bipolar membrane (BPM) in reverse bias, wherein modeling reveals that the proton flux generated by the BPM substantially lowers the pH of the porous electrode and promotes selective CH4 and HCOOH generation. The second is the use of a micro-structured porous electrode that employs an anion-exchange membrane and more selectively generates C2+ products. 2-D modeling reveals heterogeneities in the porous electrode enable hotspots of increased pH that locally enhance C2+ selectivity. Ultimately, this talk underscores the powerful ability of continuum modeling to resolve microenvironments at spatial resolutions beyond what is achievable experimentally, as well as to link changes in microenvironment to changes in local selectivity. These simulations will rationalize and guide the engineering of microenvironment in next-generation porous electrodes for CO2 reduction to C2+ products at industrial scales.

Hybrid solar-driven hydrogen generation by sorption enhanced–chemical looping and hydrocarbon reforming coupled with carbon capture and Rankine cycle

Hydrogen (H2) production from fossil fuels using Hydrocarbon Reforming Methods (HRM) accounts for nearly 95% of Global H2 production. Unlike hybrid Chemical Looping Steam Reforming (CL-SR) systems, the Integrated Solar-Driven Sorption Enhanced–Chemical Looping of Hydrocarbon Reforming (SE-CL-HR) utilises solar thermal energy from the Concentrating Solar Power (CSP) system to drive the endothermic decomposition of feedstocks. Furthermore, the simulated hybrid systems utilise recovered heat to generate electricity, reuse of by-product CO2 for more syngas production and finaly, CO2 capture by reaction of CaO to form CaCO3. This work focused on simulating hybrid CSP systems and SE-CL-HR plants with Heat Transfer Fluid (HTF) output temperatures between 750 and 1050 °C. In this study, System Advisor Model (SAM) and MATLAB software are used to develop the CSP system. While the CSP result saved in the MATLAB workspace gets exported to Simulink to feed SE-CL-SMR, SE-CL-POX and SE-CL-ATR Aspen plus models. The integrated system was fed with CH4 as the working fluid of the solar furnace. Stoichiometric and Gibbs free-energy minimisation were employed to investigate the effect of operating parameters. The output of the integrated system shows ≥9.5% exergy efficiency in comparison to conventional HRM. In addition, CO2 capture by CaO and high-pH water (Ca, Mg, Na+, O2, OH− and Cl−) to produce CaCO3, MgCO3 and other valuable products was also investigated in a process simulation. The research results revealed that for 8.1 tons/hr of CH4 and 277.1 tons/hrH2O (steam) flowrates, 62 tons/hr of H2 can be generated and 338.5 tons/hr of CO2 emission can be reused and captured by the adoption of these new innovative technologies.

CO2-CH4 Reforming Based on Nickel-based Catalysts

The current environmental problems are serious in nature. Due to greenhouse impact and a series of chain reactions caused by the massive emission of carbon dioxide (CO2) into the atmosphere, the ecological environment of the earth has been seriously damaged. The removal and reuse of CO2 is a current hot topic. The use of two greenhouse gases, CO2 and methane (CH4). And these two greenhouse gases can be used to produce different industrial products. However, the CO2-CH4 reforming reaction is difficult. The introduction of a catalyst in the reaction can avoid the problems of low conversion rate, long time and high energy consumption. At present, nickel-based catalysts are being greatly concerned in this reaction due to their low cost and high efficiency. Based on this background, this research focuses on four preparation methods for nickel-based catalysts, including deposition precipitation method, reflux impregnation method, solution combustion method and ammonia evaporation method. Three types of nickel-based catalysts, including single metal nickel-based catalysts, bi-metallic nickel-based catalysts, and multi-component nickel-based catalysts, are introduced about their activity performances in the CO2-CH4 reforming reaction. To sum up, the introduction of nickel-based catalysts can promote the directional regulation of reaction products, which can be carried out faster, saving energy and reducing consumption, which has very important research significance.

Synthesis of ethanol, methanol and carboxylic acids using copper-based catalysts

Recently, organic synthesis using carbon dioxide (CO2) has been actively studied for possible countermeasures against global warming caused by greenhouse gas emissions. The recycling and reuse of CO2 can reduce the amount of CO2 in the atmosphere and avoid further damage to the earth’s ecological environment. For example, many kinds of methods are advanced to prepare useful chemicals from CO2, where these useful chemicals include ethanol, methanol and carboxylic acid. The introduction of catalysts in CO2-based chemical synthesis can speed up the reaction and also tune the product species. The transition metal complexes have become essential in those synthesis reactions. As catalysts, they have a broad prospect because it is cheap in price, vast in reserves and less harmful to the environment. This research summarizes the function of copper-based catalysts in synthesis of different compounds, such as ethanol, methanol and carboxylic acid. The use of these catalysts is expected to provide a new idea for subsequent CO2-based organic synthesis.

Recent progress in Cr-based catalysts for oxidative dehydrogenation of light alkanes by employing CO2 as a soft oxidant

Abstract CO2 can be used as a soft oxidant for oxidative dehydrogenation of light alkanes (CO2-ODH), which is beneficial to realize the reuse of CO2 and meet the demand for olefins. The core of this reaction is the catalyst. Cr-based catalysts have attracted much attention for their excellent catalytic performance in CO2-ODH reactions due to their various oxidation states and local electronic structures. In this paper, the synthesis and modification methods of Cr-based catalysts for CO2-ODH are reviewed. The structure–activity relationship and reaction mechanism are also summarized. Moreover, the reasons for the deactivation of Cr-based catalysts are analysed and the main challenges faced by Cr-based catalysts in the CO2-ODH process, as well as the future development trend and prospect, are discussed.

Biomass hydrothermal conversion under CO2 atmosphere: A way to improve the regulation of hydrothermal products

In this study, batched hydrothermal experiments on corn stalk were conducted at 240–330 °C under CO2 or inert (N2) atmosphere. The distribution and characteristics of gaseous, solid, and liquid products were analyzed in detail to comprehensively investigate the effects of CO2 on the hydrothermal conversion of biomass, especially on the cellulose and lignin in biomass. The results demonstrate that compared with N2, CO2 slightly increased the liquid and gas yields and significantly improved the control effect of temperature on bio-oil components. Under CO2 atmosphere, bio-oil achieved effective enrichment of ketones and phenols at 240 °C and 300 °C, respectively, and their highest relative contents reached 44.8% and 62.0%, respectively. In addition, the hydrochar obtained under CO2 atmosphere showed higher crystallinity, which is conducive to its subsequent utilization. This study explored the feasibility of introducing CO2 into the biomass hydrothermal process to realize the high-value utilization of biomass waste and the reuse of CO2.

CaO recovered from eggshell waste as a potential adsorbent for greenhouse gas CO2

The growing number of industrial carbon emissions have resulted in a significant increase in the greenhouse gas carbon dioxide (CO2), which, in turn, will have a major impact on climate change. Therefore, the reduction, storage, and reuse of CO2 is an important concern in modern society. Calcium oxide (CaO) is known to be an excellent adsorbent of CO2 in a high-temperature environment. However, since deterioration of the adsorbent is likely to occur after repeated cycles of adsorption under high temperature conditions, it would be desirable to mitigate this phenomenon, in order to maintain the stability of CaO. In the present study, common eggshell waste was used as the starting material. The main component of eggshell waste is calcium carbonate (CaCO3), which was purified to produce CaO. Different surfactants and amino-containing polymers were added to synthesize CaO-based adsorbents with different configurations and pore sizes. The amount of CO2 adsorbed was determined using a thermogravimetric analyzer (TGA). The results showed that the CO2 adsorption capacity of the synthetic CaO recovered from purified eggshell waste could reach 0.6 g-CO2/g-sorbent, indicating a good adsorption capacity. CaO modified with a dopamine-containing polymer was shown to have an adsorption capacity of 0.62 g-CO2/g-sorbent. Moreover, it showed an excellent adsorption capacity of 0.40 g-CO2/g-sorbent, even after 10 cycles of CO2 adsorption. The present study suggests that using eggshell waste to synthesize CaO-based adsorbents for effective CO2 adsorption can not only reduce environmental waste, but also have the potential to capture greenhouse gas CO2 emissions, which conforms to the principles of green chemistry.

Capture and Reuse of Carbon Dioxide (CO2) for a Plastics Circular Economy: A Review

Plastic production has been increasing at enormous rates. Particularly, the socioenvironmental problems resulting from the linear economy model have been widely discussed, especially regarding plastic pieces intended for single use and disposed improperly in the environment. Nonetheless, greenhouse gas emissions caused by inappropriate disposal or recycling and by the many production stages have not been discussed thoroughly. Regarding the manufacturing processes, carbon dioxide is produced mainly through heating of process streams and intrinsic chemical transformations, explaining why first-generation petrochemical industries are among the top five most greenhouse gas (GHG)-polluting businesses. Consequently, the plastics market must pursue full integration with the circular economy approach, promoting the simultaneous recycling of plastic wastes and sequestration and reuse of CO2 through carbon capture and utilization (CCU) strategies, which can be employed for the manufacture of olefins (among other process streams) and reduction of fossil-fuel demands and environmental impacts. Considering the previous remarks, the present manuscript’s purpose is to provide a review regarding CO2 emissions, capture, and utilization in the plastics industry. A detailed bibliometric review of both the scientific and the patent literature available is presented, including the description of key players and critical discussions and suggestions about the main technologies. As shown throughout the text, the number of documents has grown steadily, illustrating the increasing importance of CCU strategies in the field of plastics manufacture.

Life Cycle Assessment for Full Chain CCU Demonstration in the Align-CCUS Project –Dimethyl Ether and Polyoxymethylen Dimethyl Ethers Production from CO2 and its Usages in the Mobility and Electricity Sectors

As part of three years of research and development in the European ALIGN-CCUS project, a CCU demonstration plant was erected at the lignite-fired block K of the RWE power plant at Niederaussem, Germany. It was the aim to demonstrate the full chain of CCU - beginning with the capture of CO2 from the power plant flue gas stream, via the one-step synthesis of dimethyl ether (DME) through to its usage for electricity generation in a peak power diesel engine generator. A secondary target was the synthesis of polyoxymethylen dimethyl ethers (OMEs) and their use in the mobility sector. A thorough Life Cycle Inventory was collected based on real process data for the first time, supported by process modelling with AspenPlus. This includes the inventory for construction and operation of all elements of the demonstrator chain: the power plant with its monoethanolamine (MEA)-based post-combustion capture facility, the newly developed synthesis unit based on a one-step reactor using a bifunctional catalyst (up to 50 kg DME per day) and the reconversion of the produced DME into electricity by an adapted diesel power generator (60-80 litre per hour DME consumption, output 240 kWel). Additionally to the DME-route, the synthesis and usage of OME3-5 as a fuel in an adapted 2 l diesel motor for mobility application were part of the investigation. The extensive inventory enabled a Life Cycle Assessment (LCA) according to ISO standards showing results for both applications. Benchmarking technologies like diesel- and e-mobility and gas turbines for peak power supply enable a comparative analysis identifying advantages and disadvantages of the CCU route. A sensitivity analysis is used to identify weak points along the routes together with future development targets and potentials. To investigate a broad array of results, several varying scenarios, especially regarding energy supply were considered. The use of renewable electricity sources for electrolytic hydrogen production, but also for other processes of the CCU chain was investigated. A range of different impact categories were considered: Global Warming Potential (GWP), Particulate Matter Formation Potential (PM), Fossil Depletion Potential (FDP), Photochemical Ozone Creation Potential (POCP) and Terrestrial Acidification Potential (AP). The results show that the investigated CCU technology routes are highly emission-intensive when using the current German electricity mix: the reuse of CO2 and the reduction of fossil fuel consumption that goes along with it, is outweighed by the energy-intensive nature of the synthesis processes. Using renewable energy sources can drastically reduce GHG emissions, especially to a point where the implementation of a mostly renewable energy supply for the process chain offers a viable mitigation option compared to the investigated benchmark technologies. Findings regarding sensitive LCI data, development targets and technological potentials are discussed in the results.

Characteristics of Carbonate Formation from Concentrated Seawater Using CO2 Chemical Absorption Methodology.

Carbon capture and storage is a popular CO2-reduction technology, and carbon capture and utilization (CCU) technology has been reported frequently over the years. However, CCU has certain disadvantages, including the requirement of high energy consumption processes such as mineral carbonation. In addition, stable metal sources are required to fix CO2. This study used concentrated seawater to supply metal ions. In addition, the selected 5 wt % amine solution changed CO2 into aqueous CO2 to reduce the additional energy required to form the metal carbonate under moderate conditions. As a result, precipitates were formed because of the reaction of carbonate radicals with metal ions in the seawater. These precipitates were analyzed by X-ray diffraction and field-emission scanning electron microscopy, and they were found to mostly consist of CaCO3 and NaCl. Furthermore, it was verified that the conversion solution maintained its CO2-loading capacity even after the solids and liquid were filtered twice. Therefore, the proposed method permits a substantial reuse of CO2 and waste seawater when sufficient metal ions are supplied. Therefore, methods to improve their purity will be developed in future studies.

Tech-economic and environmental analysis of energy-efficient shale gas and flue gas coupling system for chemicals manufacture and carbon capture storage and utilization

Shale gas and flue gas complementary co-conversion for simultaneous value added chemicals synthesis and carbon capture, utilization and storage are crucial way to energy source utilization and carbon emission mitigation. This paper put forward a novel process design converting shale gas and flue gas into value added chemicals including sulfur, urea and methanol. Three scenarios, urea and methanol parallel, urea priority and methanol priority cases, are placed to make comparison. Process simulation and pinch analysis are employed to simulate the whole process and synthesize heat exchange network. Waste heat recovery and reuse of ready-made CO2 and N2 in flue gas greatly reduce the total energy consumption under same amount of chemicals production and CO2 capture over individual production basis. Tech-economic and environmental analysis results indicate that the urea priority scenario process is superior in economic performance and its net present value is 109.5 MM$, the methanol-urea parallel scenario has the lowest greenhouse gas emission, 367.7 kton CO2-Eq/year while the methanol priority process has highest CO2 utilization proportion 55.57%. This work is great progress for shale gas energy-efficient and economical conversion to chemicals and lower energy penalty of flue gas CCUS of coal-based power plant.

Functional Isocyanide-Based Polymers.

Research interest in the isocyanide-based reaction can be traced back to 1921 when the Passerini reaction was first reported. However, most of these research efforts did not lead to important progress in the synthesis of isocyanide-based polymers (IBPs). The major challenge resides in the lack of highly efficient polymerization methods, which limits large-scale preparation and applications. Modern organic chemistry provides efficient access to develop functional IBPs on the basis of isocyanide chemistry. However, it is still challenging to prepare the IBPs with small molecular isocyanide reaction. Our investigations into catalyst exploration and polymerization methodology have prompted the synthesis of a series of IBPs. Two classes of isocyanide monomers can be used for the construction of IBPs. The first class includes monomers with a single isocyanide. Novel catalysts for the synthetic chemistry of isocyanide allow the introduction of functional pendants into the linear polymer chains. This molecular functionalization endows the polymers with an array of new functional properties. For example, the incorporation of a chromophore on the polymeric side chain provides novel functional properties, such as aggregation-induced emission and optical activity. Diisocyanide monomers can be also utilized for the construction of heterocyclic, spiro-heterocyclic, and bispiro-heterocyclic polymers in the polymeric backbones. A new concept of "multi-component spiropolymerization" has been developed for the preparation of spiropolymers using the catalysis-free one-pot reaction. Proper structural design allows for the preparation of a heterocyclic polymeric chain with natural bioactivity and biological compatibility, generating new IBPs with biofunctionalities.In this Account, we discuss progress mainly made in our lab and related fields for the design of isocyanide monomers, exploration of new catalysts, and optimization of reaction conditions. The subsequent section discusses the characteristic properties and applications of selected examples of these functional polymers, mainly focusing on their optical applications. We have investigated the UV-sensitive IBPs that could potentially be used for lithography applications. One-pot highly efficient polymerization of diisocyanides and CO2 under mild conditions can provide a new method for realizing the reuse of CO2 and reducing the greenhouse effect. Through a combination of structural modifications, IBPs bearing dimethylbenzene moieties exhibit characteristics of black materials that can be potentially utilized as pyroelectric sensors, thermal detectors, and optical instruments. Most recently, our group synthesized a spiro-heterocyclic IBP with clusterization-triggered emission properties that can be used to discriminate cancer cells from normal cells and provides a new method for the treatment of cancer. The studies reviewed in this Account suggest that polymerization with isocyanide chemistry can be implemented in diverse functional macromolecules and materials.

Immobilization of CO2 at Room Temperature Using the Specific Sub‐NM Space of 1D Uneven‐Structured C60 Polymer Film

AbstractImmobilization and reuse of CO2 are urgent tasks for sustaining the global environment. Here it is demonstrated that CO2 can be immobilized by reaction with H2O at room temperature (RT) in the specific sub‐nm space of 1D uneven‐structured C60 polymer (1D polymer) film, even though the reaction does not occur at RT in the gas phase (activation energy: 2 eV). First‐principles calculations reveal that the CO2 molecule is stacked as a bridge between the concave portions of adjacent 1D polymer frameworks via locally induced Coulomb interactions. Such induced charge polarization activates CO2 both by weakening its double‐bonds and by lowering its lowest unoccupied molecular orbital energy due to the bending motion. In addition, the flexible π orbitals of the 1D polymer provide the optimal Coulomb field to stabilize the transition state of the CO2 + H2O reaction remarkably. These factors work together to make the reaction possible at RT.

Utilization of produced water baseline as a groundwater monitoring tool at a CO2-EOR site in the Permian Basin, Texas, USA

Carbon dioxide (CO2) enhanced oil recovery (EOR) provides a pathway for economic reuse and storage of CO2, a greenhouse gas. One challenge with this practice is ensuring CO2 injection does not result in target reservoir fluids migrating into overlying shallow (<1000 m) groundwater formations. Effective monitoring for leakage from storage formations could involve measuring sensitive chemical indicators in overlying groundwater units and within the producing formation itself for evidence of deviation from an initial state. In this study, produced waters and overlying groundwaters were monitored over a five-year period to evaluate which geochemical signals may be useful to ensure that oilfield produced waters did not impact overlying groundwaters. During this five-year period, a mature carbonate oil reservoir in the Permian Basin transitioned from a waterflooding operation to a water-alternating-gas injection (WAG), in which the formation was flooded with CO2 and various mixtures of produced water. Significant increases in dissolved inorganic constituents [alkalinity, TDS, Na+, Cl−, SO42−] were observed in produced waters following CO2 injection; however, carbonate reservoir dissolution-precipitation reactions appear to be minimal and injected CO2 appears to be stored via solubility trapping. Although there are statistically significant geochemical variations following CO2 injection, applying isometric log-ratios to certain parameters establishes a narrow range for post-CO2 injection produced waters. This narrow range can be considered a baseline for post-CO2 injection produced waters; this baseline can be utilized to monitor overlying local groundwaters for produced water intrusion. Additionally, certain parameters [Na+, Ca2+, K+, Cl−, alkalinity, and TDS] display large concentration disparities between produced water and overlying groundwaters; these parameters would be sensitive indicators of produced water intrusion into overlying groundwaters.

A novel reductive alkali roasting of chromite ores for carcinogen-free Cr6+-ion extraction of chromium oxide (Cr2O3) – A clean route to chromium product manufacturing!

A novel reduction reaction for extracting Cr2O3 from chromite ores is demonstrated by excluding the formation of carcinogenic chromate (Cr6+) intermediates. We have investigated in detail the underpinning high-temperature reduction reaction: FeCr2O4+Na2CO3+2[C]=[Fe]+Na2Cr2O4+3CO(g), which defines the process chemistry for the formation of sodium chromite (Na2CrO2) as an intermediate product for Cr2O3 extraction. After high-temperature reduction, the magnetic separation, aqueous and acid leaching of reaction products yielded 81 wt% and 70 wt% pure Cr2O3 from low (∼4 wt%) and high (>8 wt%) silica-containing chromite ores, respectively. The process diagram explains the extraction of Cr2O3, Fe-Cr alloy, Al2O3, and MgO-Al2O3-silicate, reuse of CO2 for Na2CO3 recovery, and energy generation from CO combustion for demonstrating Cr6+-free extraction of metallic and mineral values from chromite ores.The process chemistry demonstrates the extraction of 75–80 % pure Cr2O3 from NaCrO2 by leaching with 0.05−0.5 M dilute H2SO4 in controlled pH conditions. The detailed chemical analysis of leachates after Cr2O3 extraction shows that the acid leachates with residual concentrations of ∼150 ppm Cr3+-ions can be recycled in situ for reusing water, for eliminating the risk of Cr6+-ion formation from atmospheric oxidation. The novel extraction route may be able to displace the current oxidative process for chromite ore processing by retrofitting.

Selectivity regulation of perovskite-based iron-manganese catalysts for the synthesis of light olefins from CO, CO2 and H2

There is a solution to prevent global problems caused due to carbon dioxide increase in planet atmosphere – reuse of CO2 in hydrogenation reaction. Literature analysis provides information about catalytic conversion of synthesis gas and carbon dioxide to carbohydrates in modern catalytic systems. Actual investigation of catalytic properties in GdFeO3 and GdMnO3 systems with perovskite structure has been carried out in the joint hydrogenation of carbon mono- and dioxide. Scientific novelty of research is to determine influence of the catalyst composition and reaction medium composition on the selectivity of target products.