High Purity CO2 Research Articles

Novel CO2-negative design of palm oil-based polygeneration systems

A palm oil-based polygeneration system (POPS), which is a combination of a fixed bed hydrotreating reactor (FBHTR), a three-phase separator, and a series of cryogenic separators, is co-production process of green diesel and liquefied petroleum gas (LPG) named Design 1. The FBHTR model is validated by experiment data and its optimal operating parameters are determined by solving the response surface methodology-based optimization algorithm. Two CO2-negative designs for the POPS named Designs 2 and 3 adopt approaches of (i) the evacuated tube solar collector (ETSC) for reducing 35% flue gas from the furnace, (ii) the amine-based CO2 capture process coupling with pre- or post-separation system for producing the high-purity CO2 product, and (iii) the heat integration design for reducing the energy duties of hot/cold utilities. Design 2 is validated to achieve the maximum negative net CO2 emissions. Design 3 not only ensures the negative net CO2 emissions, but also it produces three high-purity products (98.3% green diesel, 100% LPG, and 99.9% CO2) simultaneously.

Carbon capture and utilization for industrial applications

Heavy industries such as cement, iron and steel, oil refining, and petrochemicals are responsible for about 22% of global carbon dioxide (CO2) emissions. There exist several pathways for global CO2 mitigation. Capturing, storage, and utilization of CO2 (CCS and CCU) provide an operational solution for significant emission mitigation. High purity CO2 streams are the most interesting points for CCS and CCU. Pure CO2 streams are suitable for compression, transport, and storage. Capture technology categories are typically pre-combustion, oxy-fuel combustion, and post-combustion processes. Moreover, the main challenges of the robust industrial CCS/U development are the high costs of CO2 separation from flue gas or ambient air and the conversion of CO2 in various utilization pathways. This research study includes a summary of several CCS technologies and CCU pathways, their current status, cost, and industrial deployment.

Toward economical application of carbon capture and utilization technology with near-zero carbon emission

Carbon capture and utilization technology has been studied for its practical ability to reduce CO2 emissions and enable economical chemical production. The main challenge of this technology is that a large amount of thermal energy must be provided to supply high-purity CO2 and purify the product. Herein, we propose a new concept called reaction swing absorption, which produces synthesis gas (syngas) with net-zero CO2 emission through direct electrochemical CO2 reduction in a newly proposed amine solution, triethylamine. Experimental investigations show high CO2 absorption rates (>84%) of triethylamine from low CO2 concentrated flue gas. In addition, the CO Faradaic efficiency in a triethylamine supplied membrane electrode assembly electrolyzer is approximately 30% (@−200 mA cm−2), twice higher than those in conventional alkanolamine solvents. Based on the experimental results and rigorous process modeling, we reveal that reaction swing absorption produces high pressure syngas at a reasonable cost with negligible CO2 emissions. This system provides a fundamental solution for the CO2 crossover and low system stability of electrochemical CO2 reduction.

The potential of direct air capture using adsorbents in cold climates.

Global warming threatens the entire planet, and solutions such as direct air capture (DAC) can be used to meet net-zero goals and go beyond. This study investigates using DAC in a 5-step temperature vacuum swing adsorption (TVSA) cycle with adsorbents' Li-X and Na-X, readily available industrial zeolites, to capture and concentrate CO2 from air in cold climates. From this study, we report that Na-X in cold conditions has the highest known CO2 adsorption capacity in air of 2.54mmol/g. This combined with Na-X's low CO2 heat of adsorption, and fast uptake-rate in comparison to other benchmark materials, allowed for Na-X operating in cold conditions to have the lowest reported DAC operating energy of 1.1 MWh/tonCO2. These findings from this study show the promise of this process in cold climates of Canada, Alaska, Greenland, and Antarctica to be part of the solution to global warming.

Functional porous poly(ionic liquid)s catalyst for highly integrated capture and conversion of flue gas CO2

Most of the strategies developed to convert CO2 to high value-added chemicals require high purity of CO2. To reduce the energy consumption of CO2 purification, this work reports the preparation of a poly(ionic liquid)s catalyst Ag@Co-PIN-NH2 with dual functions of adsorption and activation. The –NH2 functional group was introduced into the organic polymer framework and the Ag(I) active phase was deposited on the framework carrier through anionic exchange reaction. The highly polar surface and highly dispersed active phase of Ag@Co-PIN-NH2 facilitated the carboxylative cyclization and hydration of propargylic alcohols with exclusive chemo-selectivity under low pressure and concentration of CO2 (1 bar, 15 % CO2 in 85 % N2, v/v simulated flue gas). Furthermore, Ag@Co-PIN-NH2 exhibited broad substrate scope, excellent catalytic diversity and reusability. This work provides momentous reference information for conversion of carbon resources in industrial flue gas into valuable chemicals.

(Digital Presentation) Electrochemical Regeneration of Spent Alkaline Absorbent from Direct Air Capture

The atmospheric carbon dioxide (CO2) concentration has increased by nearly 49% compared to preindustrial levels. This increase is primarily ascribed to anthropogenic activities and has caused rapid climate change in recent years. Direct air capture (DAC) technologies, aiming to remove CO2 directly from the atmosphere, are indispensable for mitigating the climate risks.One of the most studied DAC technologies is wet scrubbing with alkaline hydroxide solutions (e.g., KOH). Recently, we developed an electrochemical system that can regenerate spent alkaline absorbents from DAC and desorb high-purity CO2 gas under atmospheric pressure. The electrochemical cell consisted of three compartments, i.e., an anode compartment, an “acidifying” compartment, and a cathode compartment (Figure 1). During the operation, protons (H+) produced from the H2 oxidation at the anode are transported to the acidifying compartment where the spent absorbent coming from the air contactor is fed. The decreasing pH of the acidifying solution facilitates the conversion of bicarbonate/carbonate ions to carbonic acid (H2CO3 *, including dissolved CO2). When the chemical potential of oversaturated H2CO3 * is higher than the partial pressure of CO2 in the gas phase, CO2 can be desorbed. In the cathode compartment, the K+ from acidifying compartment combines with the locally produced hydroxides (OH−) to regenerate the alkaline absorbent. Overall, the electrochemical cell creates a pH swing in two adjacent compartments. CO2 gas is desorbed at low pH while the alkaline absorbent is regenerated at high pH.In the acidifying compartment, the cations changed from K+ to H+ that can displace the equilibrium of the carbon species towards the desorption of CO2 gas. However, this phenomenon brings two limitations to large-scale application of the system. Firstly, the depleting of K+ and HCO3 -/CO3 2- leads to the decrease of conductivity of the acidifying solution, which induces the increase of ohmic losses in the cell. Moreover, the desorbed CO2 gas bubbles in the cell also contributes to the electrical resistance of the cell. Therefore, the current work investigates optimization strategies to reduce the energy consumption of the system.The first strategy is to desorb CO2 into a lower CO2 partial pressure gas phase instead of atmospheric pressure. A decrease in the CO2 partial pressure from 0.9 to 0.3 bar displayed a maximum increase of 13% in gas production due to higher driving force for desorption and a maximum decrease of 7% in cell potential due to reduced gas bubble presence in the cell. The second strategy adds background electrolyte (phosphate or sulfate) into the absorbent. The adding of background electrolyte provided extra conductivity in the acidifying solution when most of the K+ and CO2 have been removed. Furthermore, the background electrolyte reduced the pH of the acidifying solution, which benefits the desorption of CO2. The lowest specific energy consumption achieved in this study was 249 kJ mol-1 CO2 captured under 150 A m-2. This low energy consumption makes the technology competitive among its counterparts. Finally, an equilibrium model has been developed that simulates the performance of the system and indicates further improvement potentials.This work demonstrates the proof of concept of a novel electrochemical direct air capture process. Our main conclusions show that the process has a competent energy consumption and potential for upscaling with the tested optimization strategies. Figure 1

Non-3d metal modulated zinc imidazolate frameworks for CO2 cycloaddition in simulated flue gas under ambient condition

Cycloaddition of CO 2 and epoxide into cyclic carbonate is one of the most efficient ways for CO 2 conversion with 100% atom-utilization. Metal–organic frameworks are a kind of potential heterogeneous catalysts, however, high temperature, high pressure, and high-purity CO 2 are still required for the reaction. Here, we report two new Zn(II) imidazolate frameworks incoporating MoO 4 2– or WO 4 2– units, which can catalyse cycloaddition of CO 2 and epichlorohydrin at room temperature and atomospheric pressure, giving 95% yield after 24 h in pure CO 2 and 98% yield after 48 h in simulated flue gas (15% CO 2 + 85% N 2 ), respectively. For comparison, the analogic Zn(II) imidazolate framework MAF-6 without non-3d metal oxide units showed 71% and 33% yields under the same conditions, respectively. The insightful modulation mechanisms of the MoO 4 2– unit in optimizing the electronic structure of Zn(II) centre, facilitating the rate-determined ring opening process, and minimizing the reaction activation energy, were revealed by X-ray photoelectron spectroscopy, temperature programmed desorption and computational calculations. Two new zinc imidazolate frameworks integrated with non-3d metal MoO 4 2− and WO 4 2− units were prepared, which displayed significantly enhanced catalytic activities toward CO 2 cycloaddition reaction under ambient condition, even with simulated flue gas.

Direct Air Capture Using Electrochemically Regenerated Anion Exchange Resins.

Direct air capture (DAC) aims to remove CO2 directly from the atmosphere. In this study, we have demonstrated proof-of-concept of a DAC process combining CO2 adsorption in a packed bed of amine-functionalized anion exchange resins (AERs) with a pH swing regeneration using an electrochemical cell (EC). The resin bed was regenerated using the alkaline solution produced in the cathodic compartment of the EC, while high purity CO2 (>95%) was desorbed in the acidifying compartment. After regenerating the AERs, some alkaline solution remained on the surface of the resins and provided additional CO2 capture capacity during adsorption. The highest CO2 capture capacity measured was 1.76 mmol·g–1 dry resins. Moreover, as the whole process was operated at room temperature, the resins did not show any apparent degradation after 150 cycles of adsorption–desorption. Furthermore, when the relative humidity of the air source increased from 33 to 84%, the water loss of the process decreased by 63%, while CO2 capture capacity fell 22%. Finally, although the pressure drop of the adsorption column (5 ± 1 kPa) and the energy consumption of the EC (537 ± 33 kJ·mol–1 at 20 mA·cm–2) are high, we have discussed the potential improvements toward a successful upscaling.

BiO 2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO 2 Reduction to Formate

BiO _2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO ₂ Reduction to Formate

Epoxide functionalization of a pentaethylenehexamine adsorbent supported on macroporous silica for post-combustion CO2 capture

N-functionalized solid adsorbents have been studied for post-combustion CO2 capture. Most studies have focused only on the adsorption condition of the adsorbents. Few studies have focused on the regeneration condition of adsorbents. Regeneration is required under the condition of 100 % CO2 for high-purity CO2 separation. Regeneration under inert conditions such as N2 or He, not under the condition of 100 % CO2 regeneration are required additional cost for high-purity CO2 separation. In this study, a macroporous silica (MPS) support, which combined a high surface area, large porosity and large pore volume, was selected as the support to achieve high CO2 capture performance. Pentaethylenehexamine (PEHA) was selected because of its high amine content, high adsorption capacity, high thermal stability, and low cost. The epoxide functionalization of PEHA was used to suppress the urea formation under regeneration conditions. The working capacity and cyclic stability of epoxide functionalization of MPS-based PEHA adsorbents were investigated. A working capacity of 1.8 mmol g−1 was maintained by repeating adsorption and desorption experiments 20 times under an adsorption condition of 15 % CO2 and a desorption condition of 100 % CO2. Additionally, the stability of the adsorbent under a 100 % CO2 regeneration condition was confirmed by maintaining the working capacity constant during 20 repeated adsorption and desorption cycle experiments. When the adsorption time was reduced to minimize H2O adsorption, the regeneration heat of the adsorbent was 2.86 GJ tCO2-1. These results demonstrated that the regeneration ability was excellent under the condition of 100 % CO2, which is the actual process application condition. This approach is promising for industrial applications of CO2 capture technology.

Techno-Economic Optimization of Multistage Membrane Processes with Innovative Hollow Fiber Modules for the Production of High-Purity CO2 and CH4 from Different Sources.

Within the current climate emergency framework and in order to avoid the most severe consequences of global warming, membrane separation processes have become critical for the implementation of carbon capture, storage, and utilization technologies. Mixtures of CO2 and CH4 are relevant energy resources, and the design of innovative membranes specifically designed to improve their separation is a hot topic. This work investigated the potential of modified polydimethylsiloxane and ionic liquid–chitosan composite membranes for separation of CO2 and CH4 mixtures from different sources, such as biogas upgrading, natural gas sweetening, or CO2 enhanced oil recovery. The techno-economic optimization of multistage processes at a real industrial scale was carried out, paying special attention to the identification of the optimal configuration of the hollow fiber modules and the selection of the best membrane scheme. The results demonstrated that a high initial content of CH4 in the feed stream (like in the case of natural gas sweetening) might imply a great challenge for the separation performance, where only membranes with exceptional selectivity might achieve the requirements in a two-stage process. The effective lifetime of the membranes is a key parameter for the successful implementation of innovative membranes in order to avoid severe economic penalties due to excessively frequent membrane replacement. The scale of the process had a great influence on the economic competitiveness of the process, but large-scale installations can operate under competitive conditions with total costs below 0.050 US$ per m3 STP of treated feed gas.

Tunable syngas production from biomass: Synergistic effect of steam, Ni–CaO catalyst, and biochar

The production of tunable syngas from biomass will further establish the role of biomass-derived syngas as a versatile platform for liquid fuels and value-added chemical synthesis. This study introduced steam, Ni–CaO catalyst, and biochar into a proposed two-stage sorption-enhanced catalytical thermochemical conversion process, aiming to obtain the tunable syngas through the in-situ stepwise generation of high purity H2 and CO. The presence of steam and Ni–CaO catalyst shows unprecedented performance in enhancing the H2 generation due to the promotional tar steam reforming/cracking and water-gas shift reactions at the first stage, and the control experiments indicate that the steam performs a higher selectivity to H2 than the Ni–CaO catalyst. The introduction of biochar with a supplementary carbon source, remarkably promotes the CO generation at the second stage, which could be further pronounced by the addition of Ni–CaO catalyst. A synergistic effect of steam, Ni–CaO catalyst, and biochar contributes to a significant enhancement in H2 and CO generation with an inherently separated generation of H2 (88.2 ± 2.3 vol% of purity) and CO (55.6 ± 1.3 vol% of purity). And the combined use of steam, Ni–CaO catalyst, and biochar could lead to a superior syngas quality with high LHVsyngas and energy recovery efficiency.

High purity CO2 from direct air capture using a single TVSA cycle with Na-X zeolites

The capture and concentration of 0.04% CO2 from a dry ambient air stream by temperature vacuum swing adsorption (TVSA) was investigated in order to produce high purity CO2. Initial investigation into the pure gas adsorption included the determination of CO2, N2, O2, and Ar adsorption isotherms with Na-X zeolite and their fit to the temperature dependent Toth isotherm model equation. These studies allowed for the evaluation of the TVSA cycle and showed the potential of reducing the pressure and/or elevating the temperature during the blowdown step in order to produce high purity CO2. Fixed bed adsorption desorption breakthrough curves for TVSA cycle were obtained to investigate the pressure and temperature effects on the blowdown step. High purity CO2 was experimentally produced between a concentration of 99.5% and 99.96% by lowering the blowdown pressure. By controlling the blowdown temperature, the concentration of the product was increased from 99.8% to 99.95%, however with a significant loss of CO2. This effect of N2, O2, and Ar desorbing during the blowdown step with CO2 desorbing during the evacuation step is shown graphically by measuring the concentration and flow rate of the exiting gas species. The results from this study show the potential for producing a valuable product of high purity CO2 from atmospheric concentrations, which can be used in many applications, particularly ones where CO2 infrastructure does not exist or where there is a burden in utilizing a CO2 cylinder.

Putting Bioenergy With Carbon Capture and Storage in a Spatial Context: What Should Go Where?

This paper explores the implications of siting a bioenergy with carbon capture and storage (BECCS) facility to carbon emission performances for three case-study supply chains using the Carbon Navigation System (CNS) model. The three case-study supply chains are a wheat straw derived BECCS-power, a municipal solid waste derived BECCS-waste-to-energy and a sawmill residue derived BECCS-hydrogen. A BECCS facility needs to be carefully sited, taking into consideration its local low carbon infrastructure, available biomass and geography for successful deployment and achieving a favorable net-negative carbon balance. On average, across the three supply chains a 10 km shift in the siting of the BECCS facility results in an 8.6–13.1% increase in spatially explicit supply chain emissions. BECCS facilities producing low purity CO2 at high yields have lower spatial emissions when located within the industrial clusters, while those producing high purity CO2 at low yields perform better outside the clusters. A map is also generated identifying which of the three modeled supply chains delivers the lowest spatially explicit supply chain emission options for any given area of the UK at a 1 MtCO2/yr capture scale.

Enhanced performance of red mud for chemical-looping combustion of coal by the modification of transition metal oxides

Red mud has been considered a promising candidate of low-cost oxygen carriers (OCs) for chemical looping combustion (CLC) technology due to its relatively high Fe2O3 content, but it shows poor stability during long-term redox cycling. In the present work, NiO, MnO2 and CuO are used as additives to tune the components of red mud used for the CLC of coal. The results show that the addition of NiO (e.g. 15 wt%) can significantly improve the reactivity of red mud for coal combustion, but it suffers a sharp decline after a chemical looping. In the case of MnO2, it significantly improves the selectivity for coal oxidation to CO2, which yields relatively high-purity CO2 in the combustion step. The presence of CuO in the red mud oxygen carriers obviously enhances the reactivity, selectivity and redox stability. The sample with 20 wt% CuO (20Cu-RM) shows a stable carbon capture rate with a CO2 purity higher than 90% during the long-term chemical looping process. The XRD and H2-TPR characterization results for the cycled 20Cu-RM sample shows that part of Cu element was separated from CuFe2O4 spinel structure and may act as active phase for improving redox performance.

CO2 utilization: a brief review of main routes and the potential to Brazilian scenario industry

Within the chemical and fuel production chains, four raw materials are basically used as a source of carbon: oil, natural gas, coal and biomass, the latter being a renewable source. But, taking into account the objective of reducing the effects caused by greenhouse gases (GHG), it is necessary to develop processes and technological concepts that aim to recycle carbon dioxide (CO2) emitting mainly large stationary sources. In addition to carbon capture and storage, the concept of "CO2 utilization" makes room for recycling CO2 avoiding its atmospheric emission and, in addition, a new carbon building block for chemicals and fuels. In this context, the Brazilian scenario stands out for industrial cases with high CO2 purity, such as the sugar-energy sector where new technologies for converting CO2 into valuable chemicals can be tested. Thus, this review presents an overview of the main routes developed for the conversion of CO2, ranging from those with low level of technological readiness (TRL) such as photochemistry and plasma catalysis to the most advanced ones such as thermocatalytic and biological conversions, polymerizations and mineralizations.

High Purity Co2 from Direct Air Capture Using a Single Tvsa Cycle with Na-X Zeolites

High Purity Co2 from Direct Air Capture Using a Single Tvsa Cycle with Na-X Zeolites

Study of cryogenic CO2 capture with solar-assisted VAR system

One of the major contributors to the rise in global warming potential (GWP) is the continuous accumulation of carbon dioxide (CO2) in the atmosphere. Carbon capture and storage (CCS) is a modern approach to capture CO2 from various industrial processes and store it efficiently for further use. In the cryogenic carbon capture method, CO2 is liquefied by condensation and separated from the CO2 contained gas. The CO2 capture by the cryogenic method can yield high purity CO2 and negligible secondary emissions. However, huge energy is required for the condensation process. In the present study, a low energy penalty method for a post-combustion carbon capture process by the application of the cryogenic technique is performed using process simulation. To reduce energy consumption, a solar integrated vapor absorption refrigeration (VAR) system is designed. The designed solar VAR system provides the required refrigeration cooling load for condensing CO2 in a flue gas stream. For this purpose, the flue gas mixture composed of CO2, N2, and water vapor with respective molar fractions of 15%, 75%, and 10% is considered. The mass flow rate of the flue gas considered is 673.4 kg/s at 1.1 bar and 40 °C. CO2 is separated by condensing the gas at a pressure of 40 bar and temperature of −28 °C. The heat energy required to operate the VAR is 83.3 MW at 75 °C which is supplied by the solar collector. The simulation result indicates that for a post-combustion process, a high-grade electrical energy penalty is found to be about 1.26 MJ/kg CO2 captured, which is better than the most common approaches like absorption, adsorption, and membrane methods. It is also observed that with the increase in the CO2 concentration from 15 to 25 mol% in the flue gas, the energy penalty is reduced by about 37.5%. The performance analysis is also carried out by varying the CO2 recovery rate and purity. It is observed that the energy penalty is decreased by about 10.3% with the increase of CO2 recovery from 90% to 100%. Also, the energy penalty is increased by 4.2% with the increase of CO2 purity from 95% to 100%. The specific CO2 capture process cost is found to be about 1.008 million USD/(kg.s−1).

Economic viability of full-chain CCUS-EOR in Indonesia

Carbon Capture Utilization and Storage (CCUS) is currently the primary technology to allow the use of fossil fuels with deep CO2 reduction. One technology utilizes captured CO2 for Enhanced Oil Recovery (EOR). For developing countries which rely heavily on fossil fuels, CCUS with EOR can serve as a potential solution for national climate change abatement strategies while still sustaining energy security and economic well-being. This paper examines this premise by analysing the cost and benefit of deploying CCUS projects in Indonesia, specifically focusing on gas processing facilities and a nearby oil field in East Java. The key findings are as follows: (1) the cost of CCUS project is approximately $59/tCO2, for capturing, storing and transporting 5,546 tCO2/day, significantly more than offsetting CO2 emissions from additionally produced oil to make it essentially a net CO2 sink; (2) the CCUS – EOR integrated project can provide an additional oil recovery of 54 MMSTB oilfor 15 years of operational life. (3) The cost benefit analysis resulted in a positive NPV and levelized net profit of $3.13/tCO2 for oil price $40/bbl. (4) the study highlights the total distribution of shares for oil & gas contractor and the Indonesian government under a PSC cost recovery scheme, approximating 141 million USD and 211 million USD, respectively. While under a gross split scheme, the Indonesian government share is 271 million USD and contractor share is 81 million USD. (5) Finally, our study reconfirms the economic viability for using high purity CO2 sources combined with CO2 EOR as an early opportunity for CCUS deployment in Indonesia.

Use of salt caverns in the energy transition: Application to Power-to-Gas–Oxyfuel

Power-to-Gas–Oxyfuel, or Electrolysis-Methanation-Oxyfuel, is an advanced concept that addresses some concerns of conventional Power-to-Gas: supply of high-purity CO2, release of greenhouse gases to the atmosphere and fate of the O2 from electrolysis. Due to the intermittent nature of several renewable energy sources, massive storage is needed to balance supply and demand. This paper focuses on the storage phase required for Electrolysis-Methanation-Oxyfuel. Synthetic CH4, O2 and CO2 have to be stored at different times. Due to the high fluid rates and volumes required, salt caverns are potential candidates. While salt caverns have been used for decades to store CH4, storage of CO2 and O2 has not been implemented to date. A generic seasonal scenario with a 200 MW oxyfuel unit is investigated. Numerical modelling that couples cavern thermodynamics with the thermomechanical response of the surrounding rock salt has been performed. The results, although exploratory, show that the caverns would be stable as they respect the criteria commonly used for cavern design. Moreover, combined storage of CO2 and O2 in the same cavern, rather than independent storage, would reduce the number of caverns needed and the likelihood of phase changes, but it would require separation of the two substances at the ground surface.