Combined Carbon Capture Research Articles

Combined Carbon Capture and Utilization with Peer-to-Peer Energy Trading for Multi-Microgrids Using Multi-Agent Proximal Policy Optimization

Combined Carbon Capture and Utilization with Peer-to-Peer Energy Trading for Multi-Microgrids Using Multi-Agent Proximal Policy Optimization

Combined carbon capture and catalytic oxidative dehydrogenation of propane to propylene conversion through a plug-flow dual-phase membrane reactor

Combined carbon capture and conversion (3C) technologies play a vital role in our battle against global warming and climate. Using electrochemical cells for 3C is an attractive option due to their intrinsically high efficiency and selectivity. Here we report an electrochemical membrane reactor for CO2/O2 capture from flue gas and instant conversion of propane to propylene over a catalyst bed. The membrane consists of a dual metal-carbonate phase, which allows CO2/O2 (in 2:1 mol ratio) co-transport through the membrane. The reactor is in tubular plug-flow geometry, which enables a continuous and gradual addition of CO2/O2 into a flowing propane stream along the axial length of the membrane, thus achieving an excellent balance between conversion and selectivity, while avoiding overoxidation and suppressing coking. The plug-flow membrane reactor exhibits a C3H6 yield of ∼30 %, C3H8 conversion of ∼35 % and C3H6 selectivity of 85 % at 600 °C for an impressive 173 h of continuous operation with minimal degradation.

A Novel Coal-Based Calcium Carbide-Acetylene System Process Based on Multistage Carbon Capture and Waste Slag Recycling Design: A Multiobjective Optimization Evaluation Perspective

Large amounts of raw material consumption, high energy consumption, and severe pollution have always been the key factors restricting the stable development of the coal-to-calcium carbide industry. Therefore, this paper presents a novel combined carbon capture and utilization and solid waste recycling system of the coal-based calcium carbide-acetylene production (CCAP) process to improve these deficiencies. This improved CCAP system consists of a gasifier, carbide furnace, acetylene furnace, the newly designed coupling module of a recarbonization furnace and calciner, and mineralization units. The thermodynamic model of the CCAP system is developed to calculate the effective atomic yield, carbon consumption, CO2 emission, etc. to evaluate the performance. The improved system performed better with the effective atomic yield (98.50%), CO2 capture rate (69.57%), CO2 emission (1.1064 t CO2·(t–1C2H2)), CO2e emission (7.2092 t CO2e·(t–1C2H2)), and carbon consumption (3.2101 t Coal·(t–1C2H2)) than the referenced system with 64.57%, 0, 2.25 t CO2·(t–1C2H2), 20.4122 t CO2e·(t–1C2H2), and 5.43 t Coal·(t–1C2H2), respectively. The exergy analysis shows that the improved system performed better for efficient energy utilization with an exergy efficiency of 48.97% for a large-scale chemical process. Besides, the trade-off between the maximum effective atomic yield, minimum carbon consumption, CO2 equivalent emission, and total annual cost (TAC) is conducted through multiobjective optimization. By three-objective optimization, the improved system could achieve a lower TAC of 8.51 × 106 $/year, CO2e emission of 4.1573 t CO2e·(t–1C2H2), and carbon consumption of 1.9874 t Coal·(t–1C2H2) simultaneously, which decreased by 38.78%, 79.63%, and 63.40%, respectively, than that of the referenced system. The all-around performance of the improved CCAP system after multiobjective optimization has been dramatically improved, making it more competitive in energy conservation, emission reduction, and resource recovery.

Influence of Imidazolium Pyrrole-2-Carbonitrile on the Electrochemical Reduction of CO2 on Silver Metal in Acetonitrile

Electrochemical reduction of CO2 into value-added fuels or chemical feedstocks is one of several viable strategies for mitigating carbon dioxide waste. However, CO2 is thermodynamically stable molecule requiring high energy to activate it making this process energy demanding. Therefore, selective catalysts and stable electrolytes with high CO2 solubility are desired. Ionic liquids (ILs) are versatile solvents with tunable properties including high CO2 solubility and electrochemical stability. Literature suggests that ILs co-catalyze the CO2 reduction reaction and can alter the reaction route through its specific interactions with CO2 and reaction intermediates. Therefore, in this study, we examined the influence of 1-ethyl-3-methylimidazolium 2-cyanopyrolide ([EMIM][2-CNpyr]) IL on CO2 reduction in acetonitrile on Ag surface. [EMIM][2-CNpyr] has the carbene, N-heterocyclic, and amine functionalities to complex with CO2. The performed linear sweep voltammetry experiments shows the onset potential of CO2 reduction is -1.82 V (vs. Ag/Ag+) in the presence of the IL. This is confirmed to be due to the presence of the IL when compared to the control experiments with tetraethylammonium perchlorate which is a non-reactive supporting salt. The bulk electrolysis with 1.5 M [EMIM][2-CNpyr] in acetonitrile over Ag cathode showed reduction of CO2 to carbon monoxide (CO) with high selectivity (>80 %) at -2.1 V (vs. Ag/Ag+) and stable current density (~ 6 mA·cm−2) for at least 12 h without any electrolyte decomposition as confirmed by NMR analysis. The fundamental understanding of the interfacial microenvironment is needed and spectro-electrochemical studies are currently underway to probe these interfaces and to develop similarly high performing electrolytes for implementation of combined carbon capture and utilization in the future.

Modelling and simulating CO and CO2 methanation over Ru/γ-Al2O3 catalyst: An integrated approach from carbon capture to renewable energy generation

The looping of carbon capture with power-to-gas technology is getting tremendous focus for the efficient inception of the methanation process. This will not only meet the growing energy demand but also reduce fossil fuel dependency and the climate change effects associated with it. In this work, a simulation approach was developed to model the methanation of CO and CO2 on a ppm basis over a ruthenium catalyst. The fast equilibrium reaction of CO2 to CO and slow kinetically-controlled hydrogenation of CO to CH4 was modelled within the same reactor. The catalyst particles of 0.5% Ru on γ-Al2O3 pellet supports were simulated on the Aspen Tech program. The fixed bed reactor was split into segments, consisting of equilibrium and kinetic reactors to model the relevant reactions. The effect of the reaction temperature, feed composition, and reactor volume was investigated. These parameters affected the reactor’s conversion with the reaction rate and the number of reactor segments required for convergence. An approach was developed to size a reactor for specific CO and CO2 conversions. With a reactor size of 13.85 m3, a 99.0% and 97.55% conversion of CO and CO2, respectively was achieved with 96.50% CH4 yield. This proved to have a high level of accuracy, with a maximum difference between the graphical and simulated conversions of 1.96%. Furthermore, the reaction mechanism was also elucidated, showing associative adsorption based CO2 and CO methanation over Ru-catalyst, forming oxygenated intermediates that subsequently hydrogenated to CH4. Altogether, results suggest this combined carbon capture approach and its utilization with power-to-gas technology can effectively contribute to sustainable renewable energy.

Modeling of CO2-LPG WAG with asphaltene deposition to predict coupled enhanced oil recovery and storage performance

Combined carbon capture and storage and CO2-enhanced oil recovery (CCS-EOR) can reconcile the demands of business with the need to mitigate the effects of climate change. To improve the performance of CCS-EOR, liquefied petroleum gas (LPG) can be co-injected with CO2, leading to a reduction in the minimum miscibility pressure. However, gas injection can cause asphaltene problems, which undermines EOR and CCS performances simultaneously. Here, we systematically examine the mechanisms of asphaltene deposition using compositional simulations during CO2-LPG–comprehensive water–alternating-gas (WAG) injection. The LPG accelerates asphaltene deposition, reducing gas mobility, and increases the performance of residual trapping by 9.2% compared with CO2 WAG. In contrast, solubility trapping performance declines by only 3.7% because of the greater reservoir pressure caused by the increased formation damage. Adding LPG enhances oil recovery by 11% and improves total CCS performance by 9.1% compared with CO2 WAG. Based on reservoir simulations performed with different LPG concentrations and WAG ratios, we confirmed that the performance improvement of CCS-EOR associated with increasing LPG and water injection reaches a plateau. An economic evaluation based on the price of LPG should be carried out to ensure practical success.

Toward Combined Carbon Capture and Recycling: Addition of an Amine Alters Product Selectivity from CO to Formic Acid in Manganese Catalyzed Reduction of CO2.

Owing to the energetic cost associated with CO2 release in carbon capture (CC), the combination of carbon capture and recycling (CCR) is an emerging area of research. In this approach, "captured CO2," typically generated by addition of amines, serves as a substrate for subsequent reduction. Herein, we report that the reduction of CO2 in the presence of morpholine (generating mixtures of the corresponding carbamate and carbamic acid) with a well-established Mn electrocatalyst changes the product selectivity from CO to H2 and formate. The change in selectivity is attributed to in situ generation of the morpholinium carbamic acid, which is sufficiently acidic to protonate the reduced Mn species and generate an intermediate Mn hydride. Thermodynamic studies indicate that the hydride is not sufficiently hydritic to reduce CO2 to formate, unless the apparent hydricity, which encompasses formate binding to the Mn, is considered. Increasing steric bulk around the Mn shuts down rapid homolytic H2 evolution rendering the intermediate Mn hydride more stable; subsequent CO2 insertion appears to be faster than heterolytic H2 production. A comprehensive mechanistic scheme is proposed that illustrates how thermodynamic analysis can provide further insight. Relevant to a range of hydrogenations and reductions is the modulation of the hydricity with substrate binding that makes the reaction favorable. Significantly, this work illustrates a new role for amines in CO2 reduction: changing the product selectivity; this is pertinent more broadly to advancing CCR.

Electrochemical Reduction of Carbamates and Carbamic Acids: Implications for Combined Carbon Capture and Electrochemical CO2 Recycling

Electrocatalytic reduction of CO2 to CO could represent the first step in solar-driven recycling of CO2 to fuels. While many reports focus on catalyst design or modification of additives such as Lewis or Brønsted acids, there is little focus on modification of the substrate, CO2 itself. Current carbon capture technology employs amines to capture CO2 as carbamates, suggesting that they may serve as a CO2 surrogate, streamlining carbon capture and recycling. Towards this, herein we explore the cyclic voltammetry of seven amines in the presence/absence of CO2. We show that on a glassy carbon electrode in acetonitrile (MeCN) up to −2.7 V vs Fc/Fc+ in tetrabutylammonium hexafluorophosphate (TBAPF6) electrolyte, the amines can only be reduced in the presence of CO2. The potential of the reduction is dependent on the amine identity as well as the protonation state of the resulting species, carbamate versus carbamic acid. Bulk electrolysis experiments indicate little or no reduction to CO and low Faradaic efficiency for formate. This suggests that these amines may be of use in subsequent studies with molecular electrocatalysts that take CO2 to CO and not formate.

Combined carbon capture cycles: An opportunity for size and energy penalty reduction

One of the main technical difficulties in the design and dimensioning process of carbon capture and storage (CCS) systems is the proper utilization of the low temperature energy streams within the process. Rejecting these energy streams has a negative effect on both the process energy efficiency and the penalty of the CCS in industry or power plants. This is particularly important in oxyfuel and some post-combustion technologies such as amine scrubbing or Calcium-Looping.With the objective of reducing dimensions, energy penalty and capital costs of the CO2 capture systems, this study analyses and demonstrates the beneficial effects of splitting the CO2 capture in two cycles which operate at high (Ca-looping, Ca-L) and low temperature (amine impregnated solid sorbent, AISS). The latter (bottoming-carbon cycle) makes use of the waste energy from the high temperature capture cycle (topping-carbon cycle). Flue gas flow is split and each capture system treats a percentage of flue gas stream.This study quantifies the energy improvements derived from the combination of a topping and a bottoming CO2 capture system and analyses the required dimensions and the optimum flue gases split between both systems. Results show a reduction of energy penalty when 20–30% of the flue gas is diverted from the Ca-L to the AISS system if the AISS specific energy consumption for CO2 captured is between 2000 and 3000 kJ/kgCO2.

An Integrated Carbon-Dioxide-Foam Enhanced-Oil-Recovery Pilot Program With Combined Carbon Capture, Utilization, and Storage in an Onshore Texas Heterogeneous Carbonate Field

SummaryA carbon–dioxide (CO2) –foam enhanced–oil–recovery (EOR) field pilot research program has been started to advance the technology of CO2 foam for mobility control in a heterogeneous carbonate reservoir. Increased oil recovery with associated anthropogenic–CO2 storage is a promising technology for mitigating global warming as part of carbon capture, utilization, and storage (CCUS). Previous field tests with CO2 foam report various results because of injectivity problems and the difficulty of attributing fluid displacement specifically to CO2 foam. Thus, a comprehensive integrated multiscale methodology is required for project design to better link laboratory– and field–scale displacement mechanisms. This study presents an integrated upscaling approach for designing a miscible CO2–foam field trial, including pilot–well–selection criteria and laboratory corefloods combined with reservoir–scale simulation to offer recommendations for the injection of alternating slugs of surfactant solution and CO2, or surfactant–alternating–gas (SAG) injection, while assessing CO2–storage potential.Laboratory investigations include dynamic aging, foam–stability scans, CO2–foam EOR corefloods with associated CO2 storage, and unsteady–state CO2/water endpoint relative permeability measurements. Tertiary CO2–foam EOR corefloods at oil–wet conditions result in a total recovery factor of 80% of original oil in place (OOIP), with an incremental recovery of 30% of OOIP by CO2 foam after waterflooding. Stable CO2 foam, using aqueous surfactants with a gas fraction of 0.70, provided mobility–reduction factors (MRFs) up to 340 compared with pure–CO2 injection at reservoir conditions. Oil recovery, gas–mobility reduction, producing–gas/oil ratio (GOR), and CO2 utilization at field pilot scale were investigated with a validated numerical model. Simulation studies show the effectiveness of foam to reduce gas mobility, improve CO2 utilization, and decrease GOR.

Effect of H2O on Mg(OH)2 carbonation pathways for combined CO2 capture and storage

Mg-bearing sorbents, derived from silicate minerals and industrial wastes, can act as combined carbon capture and storage media in various energy conversion systems. Mg(OH)2 carbonation in the slurry phase occurs spontaneously and recent results show improved gas–solid carbonation with comparable materials in the presence of H2O vapor; however, the reaction mechanism is still poorly understood at high temperature and pressure conditions. This study investigated the pathways of H2O enhanced Mg(OH)2 carbonation at elevated temperatures and CO2 pressures (up to 673K and 1.52MPa) in the presence of steam and in the slurry phase. For a given reaction temperature, carbonation conversion showed dramatic increase with increasing H2O loading. Comprehensive solid analyses via thermogravimetric analysis, X-ray diffraction, and UV-Raman allowed for qualitative and quantitative compositional characterization of reacted solids. The results suggest that a hydrated environment facilitates the formation of intermediate hydrated magnesium carbonate species. The hydrated carbonates form relatively quickly and can transform into anhydrous carbonates while subjected to greater H2O loading, higher temperature, and/or longer reaction time.