CO2 Capture by Calcium Looping at Relevant Conditions for Cement Plants: Experimental Testing in a 30 kWth Pilot Plant

Decarbonization of Power and Industrial Sectors: The Role of Membrane Processes

Carbon dioxide (CO₂) is the single largest contributor to climate change due to its increased emissions since global industrialization began. Carbon Capture, Storage, and Utilization (CCSU) is regarded as a promising strategy to mitigate climate change, reducing the atmospheric concentration of CO₂ from power and industrial activities. Post-combustion carbon capture (PCC) is necessary to implement CCSU into existing facilities without changing the combustion block. In this study, the recent research on various PCC technologies is discussed, along with the membrane technology for PCC, emphasizing the different types of membranes and their gas separation performances. Additionally, an overall comparison of membrane separation technology with respect to other PCC methods is implemented based on six different key parameters-CO₂ purity and recovery, technological maturity, scalability, environmental concerns, and capital and operational expenditures. In general, membrane separation is found to be the most competitive technique in conventional absorption as long as the highly-performed membrane materials and the technology itself reach the full commercialization stage. Recent updates on the main characteristics of different flue gas streams and the Technology Readiness Levels (TRL) of each PCC technology are also provided with a brief discussion of their latest progresses.

CO2 Capture at Medium to High Temperature Using Solid Oxide-Based Sorbents: Fundamental Aspects, Mechanistic Insights, and Recent Advances

Carbon dioxide capture and mitigation form a key part of the technological response to combat climate change and reduce CO₂ emissions. Solid materials capable of reversibly absorbing CO₂ have been the focus of intense research for the past two decades, with promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this review, we explore the fundamental aspects underpinning solid CO₂ sorbents based on alkali and alkaline earth metal oxides operating at medium to high temperature: how their structure, chemical composition, and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines, including materials discovery, synthesis, and in situ characterization, to present a coherent understanding of the mechanisms of CO₂ absorption both at surfaces and within solid materials.

An investigation into the adverse effects of O2, SO2, and NOx on polyethyleneimine functional CO2 adsorbents

In this study, we investigated the influence of O2, SO2, and NOx on branched and linear polyethyleneimine (PEI) functional silica CO2 adsorbents (BPEI-SiO2 and LPEI-SiO2, respectively). O2 was much more likely to oxidize BPEI-SiO2, compared with LPEI-SiO2, to form C=O and C=N groups and led to a 23.0% decrease in the CO2 adsorption capacity after 990 min of cumulative contact with 10% O2. In contrast, LPEI-SiO2 lost only approximately 3.6% of its CO2 adsorption capacity, although O2 oxidized LPEI-SiO2 to form C=O groups. SO2 can cause severe degradation of BPEI-SiO2 and LPEI-SiO2 by forming heat-stable NH3+—and/or NH2+—containing adducts and by promoting the formation of urea linkages. After cumulative contact with 10, 50, and 200 ppm SO2 for 990 min, BPEI-SiO2 lost 18.2%, 61.4%, and 89.0% of its CO2 adsorption capacity, and LPEI-SiO2 lost 18.5%, 60.6%, and 78.5% of its CO2 adsorption capacity, respectively. NO2 at 10 ppm and NO at 200 ppm caused almost no loss in CO2 adsorption capacity after cumulative contact for 990 min, but both led to degradation of adsorbents. NO2 can cause irreversible formation of NH3+—and/or NH2+—containing adducts, acid products, N-nitro compounds (N–NO2), C-nitroso compounds (C–N=O), and C-nitro (C–NO2) compounds, and can promote the formation of urea linkages. NO can lead to the formation of NH3+—and/or NH2+—containing adducts and N-nitroso (N–N = O) compounds.

A comparative dynamic study of seawater pretreatment using experimental and pilot bubble tower

In the previous study, greenhouse gas CO₂ was successfully used as the precipitator to realize its carbonation by calcium ions in seawater with the help of magnesium oxide. In this study, the reaction process was firstly analyzed by a proposed reaction mechanism, and then the dynamic simulation of the gas-liquid-solid system was carried out via kinetic Monte Carlo simulation. Based on the reaction mechanism, the continuous experimental study was realized in a bubble column. The effects of air flow rate, carbon dioxide flow rate and temperature on the effectiveness evaluation indexes of decalcification efficiency, total mass transfer coefficient and carbon sequestration rate were studied. Finally, a bonnet tower with a diameter of 1 m and a height of 8 m was built to carry out the pilot test. In the laboratory experiments, the calcium removal rate reached 94%, the carbon sequestration rate reached 63.6%, and pure micron calcium carbonate products were obtained. The decalcification rate reached 95% in the pilot test, which is consistent with the results of the laboratory experiment.

Efficient NO reduction by carbon-deposited CaO in the carbonation step of calcium looping for the CO2 capture

Carbon-deposited CaO realizes efficient NO removal and CO2 capture in carbonator of calcium looping.

CO2 Capture, Use, and Storage in the Cement Industry: State of the Art and Expectations

The implementation of carbon capture, use, and storage in the cement industry is a necessity, not an option, if the climate targets are to be met. Although no capture technology has reached commercial scale demonstration in the cement sector yet, much progress has been made in the last decade. This work intends to provide a general overview of the CO2 capture technologies that have been evaluated so far in the cement industry at the pilot scale, and also about the current plans for future commercial demonstration.

Interaction of Pristine Hydrocalumite-Like Layered Double Hydroxides with Carbon Dioxide

The layered double hydroxides (LDHs) of Ca²⁺ and trivalent cations, Al³⁺ and Fe³⁺, are single-source precursors to generate supported CaO, which picks up CO₂ from the gas phase in the temperature range 350-550 °C. The supports are ternary oxides, mayenite, and Ca₂Fe₂O₅. The uptake capacity of the Fe³⁺-containing LDH at 1.9 mmol g^-1 is two times the capacity of the Al³⁺-containing LDH. The product of CO₂ uptake is calcite CaCO₃. It is observed that the intercalated chloride ions reduce the thermal penalty by inducing the early decomposition of CaCO₃. In the case of the chloride-intercalated LDHs of Ca²⁺ and Fe³⁺, the CaCO₃ formed is completely decomposed at 900 °C. This is in contrast with the CaCO₃ formed from bare CaO, which shows no sign of decomposition at 900 °C under similar conditions. This work shows that the hydrocalumite-like LDHs are candidate materials for CO₂ mineralization.

Comparison of Technologies for CO2 Capture from Cement Production—Part 1: Technical Evaluation

A technical evaluation of CO2 capture technologies when retrofitted to a cement plant is performed. The investigated technologies are the oxyfuel process, the chilled ammonia process, membrane-assisted CO2 liquefaction, and the calcium looping process with tail-end and integrated configurations. For comparison, absorption with monoethanolamine (MEA) is used as reference technology. The focus of the evaluation is on emission abatement, energy performance, and retrofitability. All the investigated technologies perform better than the reference both in terms of emission abatement and energy consumption. The equivalent CO2 avoided are 73–90%, while it is 64% for MEA, considering the average EU-28 electricity mix. The specific primary energy consumption for CO2 avoided is 1.63–4.07 MJ/kg CO2, compared to 7.08 MJ/kg CO2 for MEA. The calcium looping technologies have the highest emission abatement potential, while the oxyfuel process has the best energy performance. When it comes to retrofitability, the post-combustion technologies show significant advantages compared to the oxyfuel and to the integrated calcium looping technologies. Furthermore, the performance of the individual technologies shows strong dependencies on site-specific and plant-specific factors. Therefore, rather than identifying one single best technology, it is emphasized that CO2 capture in the cement industry should be performed with a portfolio of capture technologies, where the preferred choice for each specific plant depends on local factors.

Comparison of Technologies for CO2 Capture from Cement Production—Part 2: Cost Analysis

This paper presents an assessment of the cost performance of CO2 capture technologies when retrofitted to a cement plant: MEA-based absorption, oxyfuel, chilled ammonia-based absorption (Chilled Ammonia Process), membrane-assisted CO2 liquefaction, and calcium looping. While the technical basis for this study is presented in Part 1 of this paper series, this work presents a comprehensive techno-economic analysis of these CO2 capture technologies based on a capital and operating costs evaluation for retrofit in a cement plant. The cost of the cement plant product, clinker, is shown to increase with 49 to 92% compared to the cost of clinker without capture. The cost of CO2 avoided is between 42 €/tCO2 (for the oxyfuel-based capture process) and 84 €/tCO2 (for the membrane-based assisted liquefaction capture process), while the reference MEA-based absorption capture technology has a cost of 80 €/tCO2. Notably, the cost figures depend strongly on factors such as steam source, electricity mix, electricity price, fuel price and plant-specific characteristics. Hence, this confirms the conclusion of the technical evaluation in Part 1 that for final selection of CO2 capture technology at a specific plant, a plant-specific techno-economic evaluation should be performed, also considering more practical considerations.

Calcination kinetics of cement raw meals under various CO2 concentrations

The calcium looping CO₂ capture process, CaL, represents a promising option for the decarbonisation of cement plants, due to the intrinsic benefit of using the spent CO₂ sorbent as a feedstock for the plant.

Inherent potential of steelmaking to contribute to decarbonisation targets via industrial carbon capture and storage

Accounting for ~8% of annual global CO₂ emissions, the iron and steel industry is expected to undertake the largest contribution to industrial decarbonisation. Despite the launch of several national and regional programmes for low-carbon steelmaking, the techno-economically feasible options are still lacking. Here, based on the carbon capture and storage (CCS) strategy, we propose a new decarbonisation concept which exploits the inherent potential of the iron and steel industry through calcium-looping lime production. We find that this concept allows steel mills to reach the 2050 decarbonisation target by 2030. Moreover, only this concept is revealed to exhibit a CO₂ avoidance cost (12.5–15.8 €₂₀₁₀/t) lower than the projected CO₂ trading price in 2020, whilst the other considered options are not expected to be economically feasible until 2030. We conclude that the proposed concept is the best available option for decarbonisation of this industrial sector in the mid- to long-term.

Carbon budget is diminishing to comply with the target under 2 °C scenario. Facing the limited capacity to improve energy efficiency, the authors show that steelmaking with inherent decarbonisation process can potentially help achieve 2050 emission reduction targets under 2 °C scenario before 2030.