@article{cai_krzystowczyk_braunberger_li_neal_2024, title={Techno-economic analysis of chemical looping air separation using a perovskite oxide sorbent}, volume={132}, ISSN={["1878-0148"]}, DOI={10.1016/j.ijggc.2024.104070}, abstractNote={Air separation is a costly process that is difficult to operate efficiently at small scales. Chemical looping air separation (CLAS) is a promising process for small-footprint oxygen production with low energy consumption. CLAS has potential applications in a promising carbon capture technology, oxyfuel combustion (oxy-combustion). In oxy-combustion, high-concentration oxygen from an air separation unit is used to combust a carbonaceous fuel into an easily-separated, nitrogen-free exhaust stream. In this paper, a techno-economic analysis was conducted in conjunction with reactor modeling to determine the cost of oxygen from a CLAS plant as a modular air separation unit for a 5 MW thermal coal-based oxy-combustion plant. The effects of different length-to-diameter ratios were investigated. The cost of oxygen from CLAS was projected to be as low as $65/ton O2 under baseline assumptions, which was much lower than typical current delivered oxygen at similar scales. Although higher in capital cost, CLAS also compares favorably to pressure swing adsorption, which has much larger parasitic energy losses. Further analysis indicates that air and steam demand and the sorbent reactor L/D ratio are key to optimizing the costs.}, journal={INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL}, author={Cai, Runxia and Krzystowczyk, Emily and Braunberger, Beau and Li, Fanxing and Neal, Luke}, year={2024}, month={Feb} }
 @article{cai_dou_krzystowczyk_richard_li_2022, title={Chemical looping air separation with Sr0.8Ca0.2Fe0.9Co0.1O3-delta perovskite sorbent: Packed bed modeling, verification, and optimization}, volume={429}, ISSN={["1873-3212"]}, DOI={10.1016/j.cej.2021.132370}, abstractNote={Chemical looping air separation (CLAS) represents a promising approach for efficient O2 production from the air. The present study aims at optimizing the absorber/desorber operations and the separation process with extensive experimental validation. Specifically, a one-dimensional packed bed model was developed to investigate the CLAS operation with a Sr0.8Ca0.2Fe0.9Co0.1O3-δ perovskite sorbent. The redox thermodynamics of perovskite sorbent was measured by TGA and then incorporated into a linear driving force model to describe the O2 absorption and desorption rates. Both 4-step and 5-step air separation cycle configurations, with various cyclic structures, were performed in a subpilot-scale packed bed. The model predicted O2 purity and productivity were consistent with experimental results, supporting its accuracy and applicability. Parametric analysis and multi-objective optimization were further carried out to assess the performance of CLAS. Both O2 purity and recovery increased monotonically with the cycle time, airflow rate, steam flow rate, and absorption pressure. Meanwhile, optimal O2 productivity and power consumption can only be achieved by specific combinations of these parameters. The optimized results showed that CLAS can be highly competitive when compared to conventional pressure swing adsorption (PSA) or cryogenic distillation. The 5-step cycle configuration achieved a minimum power consumption of 118 kW·h for producing 1 ton O2 with ≥ 95% purity. The maximum O2 productivity reached 0.0932 gO2/(gsorbent·h) with 390 kW·h/ton O2 of energy consumption (95% pure). The optimization results also indicate that CLAS can potentially be more efficient than cryogenic distillation even when the required O2 purity is above 99%.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Cai, Runxia and Dou, Jian and Krzystowczyk, Emily and Richard, Anthony and Li, Fanxing}, year={2022}, month={Feb} }
 @article{wang_gao_krzystowczyk_iftikhar_dou_cai_wang_ruan_ye_li_2022, title={High-throughput oxygen chemical potential engineering of perovskite oxides for chemical looping applications}, volume={2}, ISSN={["1754-5706"]}, url={https://doi.org/10.1039/D1EE02889H}, DOI={10.1039/d1ee02889h}, abstractNote={Integrating DFT, machine learning and experimental verifications, a high-throughput screening scheme is performed to rationally engineer the redox properties of SrFeO3−δ based perovskites for chemical looping applications.}, number={4}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, publisher={Royal Society of Chemistry (RSC)}, author={Wang, Xijun and Gao, Yunfei and Krzystowczyk, Emily and Iftikhar, Sherafghan and Dou, Jian and Cai, Runxia and Wang, Haiying and Ruan, Chongyan and Ye, Sheng and Li, Fanxing}, year={2022}, month={Feb} }
 @article{krzystowczyk_haribal_dou_li_2021, title={Chemical Looping Air Separation Using a Perovskite-Based Oxygen Sorbent: System Design and Process Analysis}, volume={9}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.1c03612}, abstractNote={Oxygen is a critical industrial gas whose global market is projected to reach $48 billion/year within this decade. However, oxygen production is highly energy-intensive because of the limited efficiency of the commercial cryogenic air separation technology. The present study systematically investigated a chemical looping air separation (CLAS) approach as an alternative to cryogenic distillation. In particular, a Sr0.8Ca0.2Fe0.4Co0.6O3−δ (SCFC) oxygen sorbent was used as the basis for both experimental and simulation studies. To demonstrate the sorbent robustness, experimental studies were carried out over 10,000 redox cycles in a bench-scale testbed. Excellent sorbent stability and >90% oxygen purity were achieved using steam as the purge gas. Oxygen purity can be further increased to >95% by optimizing the operating conditions and pressure swing absorption cycle structure. Based on the experimental results, a CLAS system design and a process model were established. The process model estimates a base case CLAS energy consumption of 0.66 MJ/kg O2. This represents a 15% decrease compared to cryogenic air separation (0.78 MJ/kg O2). It is noted that most of the thermal energy consumed by CLAS is at relatively low temperatures (∼120 °C). When accounting for the quality of this low-grade heat, an energy consumption as low as 0.40 MJ/kg O2 can be anticipated for a practical system. Sensitivity analysis was also performed on the various CLAS operational and design parameters such as reactor sizes, pressure drop, thermodynamic driving forces, oxygen uptake and release rates, heat loss, and the energy consumption for steam generation. It was determined that CLAS has excellent potential to be an efficient oxygen production technology. This study also highlights the importance of developing advanced sorbents with suitable redox thermodynamics and fast redox kinetics for improved efficiency and smaller reactor sizes.}, number={36}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Krzystowczyk, Emily and Haribal, Vasudev and Dou, Jian and Li, Fanxing}, year={2021}, month={Sep}, pages={12185–12195} }
 @article{wang_krzystowczyk_dou_li_2021, title={Net Electronic Charge as an Effective Electronic Descriptor for Oxygen Release and Transport Properties of SrFeO3-Based Oxygen Sorbents}, volume={33}, ISSN={["1520-5002"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85103753397&partnerID=MN8TOARS}, DOI={10.1021/acs.chemmater.0c04658}, abstractNote={Perovskite oxides, as oxygen sorbents, exhibit excellent potential in thermochemical redox applications such as chemical looping air separation (CLAS), resulting from their excellent redox properti...}, number={7}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Wang, Xijun and Krzystowczyk, Emily and Dou, Jian and Li, Fanxing}, year={2021}, month={Apr}, pages={2446–2456} }
 @article{dou_krzystowczyk_wang_robbins_ma_liu_li_2020, title={A- and B-site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation}, volume={13}, ISSN={["1864-564X"]}, url={https://doi.org/10.1002/cssc.201902698}, DOI={10.1002/cssc.201902698}, abstractNote={Abstract}, number={2}, journal={CHEMSUSCHEM}, publisher={Wiley}, author={Dou, Jian and Krzystowczyk, Emily and Wang, Xijun and Robbins, Thomas and Ma, Liang and Liu, Xingbo and Li, Fanxing}, year={2020}, month={Jan}, pages={385–393} }
 @article{dou_krzystowczyk_wang_richard_robbins_li_2020, title={Sr1-xCaxFe1-yCoyO3-delta as facile and tunable oxygen sorbents for chemical looping air separation}, volume={2}, ISSN={["2515-7655"]}, url={https://doi.org/10.1088/2515-7655/ab7cb0}, DOI={10.1088/2515-7655/ab7cb0}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF PHYSICS-ENERGY}, publisher={IOP Publishing}, author={Dou, Jian and Krzystowczyk, Emily and Wang, Xijun and Richard, Anthony R. and Robbins, Thomas and Li, Fanxing}, year={2020}, month={Apr} }
 @article{dou_krzystowczyk_mishra_liu_li_2018, title={Perovskite Promoted Mixed Cobalt-Iron Oxides for Enhanced Chemical Looping Air Separation}, volume={6}, ISSN={["2168-0485"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055169872&partnerID=MN8TOARS}, DOI={10.1021/acssuschemeng.8b03970}, abstractNote={Chemical looping air separation (CLAS) is a promising approach to produce high purity oxygen from air. Redox kinetics and oxygen carrying capacity of oxide-based oxygen carrier materials play a critical role in the overall performance of CLAS. In view of the fast lattice oxygen transport property of mixed-conductive perovskite materials, composites of La0.8Sr0.2CoxFe1–xO3 (LSCF) perovskite and mixed Co–Fe oxides (CF) were investigated for chemical looping air separation. The effects of Fe and perovskite addition were systematically examined by varying Co/Fe and LSCF/CF ratios. Increase of Fe in mixed Co–Fe oxides significantly increases oxidation kinetics of LSCF-CF composites while decreasing the rate of oxygen release. An optimized average redox rate was achieved by balancing the oxygen uptake (oxidation) and release (reduction) rates through tuning Co/Fe ratio, with the maximum occurring at a ratio of 9:1. Unpromoted Co–Fe mixed oxide exhibited a working oxygen capacity of 1.6 wt % at 850 °C. With the ...}, number={11}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Dou, Jian and Krzystowczyk, Emily and Mishra, Amit and Liu, Xingbo and Li, Fanxing}, year={2018}, month={Nov}, pages={15528–15540} }