Operating Temperature Window Research Articles

Medium and high temperature H2S removal via phosphazene polyoxometalate ionic liquids: Performance evaluation and mechanism exploration

The development of non-aqueous solvent desulfurizer is crucial to addressing the challenges associated with traditional liquid-phase wet desulfurization technologies. Based on this, we prepared a series of phosphazene polyoxometalate ionic liquids (PPILs) based of 1-butyl-3-methylimidazolium chloride using different kinds of phosphazenes (PNs) combined with polyoxometalate (POM), and used for hydrogen sulfide (H2S) dynamic absorption experiments. The effects of PN type and ratio, temperature and desulfurizer concentration on the desulfurization performance of different PPILs were explored. Among them, PPILs@IBuPN-9 as the optimal desulfurizer could keep almost 100 % desulfurization efficiency in the medium and high temperature range (100–200 °C). The results showed that the combination of PNs with POM significantly improved and widened the H2S removal performance and the operational temperature window of the desulfurizer. Besides, PPILs@IBuPN-9 required only air regeneration to maintain relatively stable cycle performance for at least four times and the sulfur capacity could be efficiently increased during multiple regenerations. It was found that the hydrogen bonding sites on IBuPN network formed significantly enhanced the H2S capture ability of PPILs and the sulfur capacity was substantially improved by S2− substitution of oxygen atoms in the POM according to the characterization results and density functional theory calculations. This study promotes the deep integration of polyoxometalate chemistry with ionic liquids in the field of gas purification and promotes the development of non-aqueous phase desulfurization process.

Dynamically Confined Active Silver Nanoclusters with Ultrawide Operating Temperature Window in CO oxidation.

Supported metal nanoclusters are often highly active in many catalytic reactions but less stable particularly under harsh reaction conditions. Here, we demonstrate that this activity-stability trade-off can be efficiently broken through rational design of surrounding microenvironment of the supported nanocatalyst including gas adsorbate overlayer and underneath support surface chemistry. Our studies reveal that chemisorbed oxygen species on Ag surface and surface hydroxyl groups on oxide support, which are dynamically consumed during reaction but sustained by reaction environment (O2 and H2O vapor), drive spontaneous redispersion of Ag particles and stabilization of highly active Ag nanoclusters. Such a dynamic confinement effect from gas-catalyst-support interaction enables the Ag nanoclusters to exhibit complete catalytic oxidation of CO over a wide temperature window of 25 - 500 °C under dry conditions and 200 - 800 °C under wet conditions as well as remarkable stability at 300 °C over 1000 h.

Dynamically Confined Active Silver Nanoclusters with Ultrawide Operating Temperature Window in CO oxidation

Supported metal nanoclusters are often highly active in many catalytic reactions but less stable particularly under harsh reaction conditions. Here, we demonstrate that this activity‐stability trade‐off can be efficiently broken through rational design of surrounding microenvironment of the supported nanocatalyst including gas adsorbate overlayer and underneath support surface chemistry. Our studies reveal that chemisorbed oxygen species on Ag surface and surface hydroxyl groups on oxide support, which are dynamically consumed during reaction but sustained by reaction environment (O2 and H2O vapor), drive spontaneous redispersion of Ag particles and stabilization of highly active Ag nanoclusters. Such a dynamic confinement effect from gas‐catalyst‐support interaction enables the Ag nanoclusters to exhibit complete catalytic oxidation of CO over a wide temperature window of 25 ‐ 500 °C under dry conditions and 200 ‐ 800 °C under wet conditions as well as remarkable stability at 300 °C over 1000 h.

Construction of CuCoCe ternary catalyst via a porous organic polymer template approach for efficient CO-PROX with wide operating temperature window

Preferential CO oxidation (CO-PROX) is a promising approach for removing trace CO from hydrogen-rich streams, effectively preventing Pt anode poisoning in proton-exchange membrane fuel cells (PEMFCs). To effectively eliminate CO within the PEMFC operating temperature range, catalysts must exhibit high CO conversion and O2 selectivity. Expanding the operating temperature window of these catalysts is crucial. This study presents the synthesis of a CuCoCe ternary catalyst (CuCo/Ce-P) using an imidazole-functionalized porous organic polymer as a sacrificial template. Compared to the CuCoCe ternary catalyst prepared without a template (CuCo/Ce), CuCo/Ce-P exhibits significantly enhanced catalytic activity, with a T50 reduction from 85 °C to 55 °C and an expanded operating temperature window of approximately 40 ℃. Characterization results indicate that the imidazole-functionalized porous organic polymer facilitates improved dispersion of active species by anchoring metal ions through electron-rich groups, enhances intermetallic interactions, promotes electron transfer, and significantly improves the oxygen-deficient capacity of the CuCoCe ternary catalyst. Consequently, the catalyst exhibits a greater number of active interfaces, leading to enhanced catalytic activity and a wider operating temperature window.

Synthesis of low-temperature NH3-SCR catalysts for MnOx with high SO2 resistance using redox-precipitation method with mixed manganese sources

It remains a big challenge to enhance the SO2 resistance of catalyst in low-temperature NH3-SCR reduction. In this work, a series of MnOx-a%Mn (a = 0, 1, 3, 5, 10) catalysts were prepared by introducing manganese acetylacetonate during the reaction between lactic acid and KMnO4, based on the molar ratio of manganese acetylacetonate to KMnO4. Notably, MnOx-5 %Mn exhibited more than 95 % NO conversion and 100 % N2 selectivity at 80–240 °C. Moreover, the catalyst demonstrated excellent sulfur resistance by sustaining over 90 % NO conversion at 140 °C at the presence of 100 ppm SO2 for more than 6 h. Furthermore, XPS characterization indicated that adding manganese acetylacetonate enhanced electron transfer efficiency and improved the reduction capacity of the catalyst due to the interconversion between Mn3+ and Mn4+, which improved electron transfer efficiency. The enhanced reduction capacity of the catalyst promoted the formation of oxygen vacancies and surface-adsorbed oxygen species (Oα), avoiding over-oxidation of NH3. The results elucidated that manganese acetylacetonate could optimize the overall performance by modulating the synergistic effect between the oxidizing ability and surface acidity of the catalyst. Therefore, the MnOx-5 %Mn catalyst possessed a broad operational temperature window (40–240 °C) and SO2 resistance in the NH3-SCR reaction, indicating its potential for practical application.

Comparing low-temperature NH3-SCR activity, operating temperature window and kinetic properties of the Mn-Fe-Nb/TiO2 catalysts prepared by different methods

In order to overcome the shortcomings of traditional V-based catalysts, such as poor low-temperature activity, narrow temperature window, and toxicity. Therefore, the Mn-Fe-Nb/TiO2 catalysts were prepared using impregnation (IM), citric acid complexation (CA), co-precipitation (CP), hydrothermal synthesis (HY), and sol–gel (SG) methods to develop novel NH3 selective catalytic reduction (NH3-SCR) catalysts with excellent low-temperature activity, a wide temperature window, and environmental friendliness. Their NH3-SCR catalytic activity was evaluated, followed by a detailed analysis of their morphology, structure, specific surface area, chemical state, redox properties, acidity, and interactions using X-ray diffraction (XRD), Bruaner-Emmet-Teller (BET), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), and Fourier transform infrared spectroscopy (FTIR) techniques. The 5Mn-7Fe-4Nb/TiO2-SG catalyst, prepared via sol–gel, exhibited the highest denitrification (de-NOx) activity and the widest operating temperature window, achieving over 80% Nitric oxide (NO) conversion at 180–350 °C and a peak conversion of 97% at 250 °C. The XRD, BET, SEM, and HR-TEM characterization results showed that the catalyst prepared using the sol–gel method had the smallest particles, the highest specific surface area, and the greatest dispersion. XPS and NH3-TPD results revealed that the catalyst prepared using the sol–gel method possessed the highest surface adsorbed oxygen (Oα) content and the largest number of acidic sites. H2-TPR and FTIR analyses indicated that the catalyst prepared using the sol–gel method enhanced the reduction capacity and possessed the strongest interaction forces among support-active-promoter components. Steady-state kinetic tests confirmed that in the NH3-SCR reaction, the rate-determining step was the adsorption activation of NO on the catalyst surface. The sol–gel method reduced the activation energy for de-NOx reactions, enhancing the low-temperature activity of the catalyst.

Tailoring the proceeding of the NH3-SCO and NH3-SCR reactions over FeOx catalysts by modifying with NbOx

This study presents the synthesis of a series of FeOx-NbOx mixed oxide catalysts for the selective catalytic reduction (SCR) of NO by NH3. By meticulously controlling the Fe/Nb molar ratio, we have rationally tailored the proceeding of the main reaction of NO reduction and the side reaction of NH3 oxidation to NOx. The incorporation of NbOx introduced a significant number of acid sites, which enhanced the adsorption of NH3 on the catalyst surface, particularly at elevated temperatures. Additionally, the oxidative capacity of the catalyst was moderated by the addition of NbOx, hindering the over-oxidation of NH3 to NO or NO2, thus preserving more NH3 to act as a reductant for NO reduction. Consequently, the NbOx-enriched samples exhibited improved deNOx performance. However, an excessive amount of NbOx led to a notably weakened oxidative ability, which negatively impacted the activation of reactants and resulted in decreased NO conversion at lower temperatures. The optimized catalyst presented >80% NO conversion and >95% N2 selectivity within a temperature range of 250-400 °C. These findings offer valuable insights for the development of new catalysts with an extended operational temperature window.

Enhanced denitrification performance of Mo/Mn co-doped 5 %Fe/TiO2 catalysts via citric acid-assisted impregnation

This study investigates the denitrification performance of Fe5Mn3Mo3/TiO2 catalysts prepared using citric acid-assisted impregnation (CA) and conventional impregnation (IM) methods in the context of NH3-selective catalytic reduction (SCR) reaction. Specifically, the influence of citric acid quantity on the catalytic activity is studied, with a special emphasis on Fe5Mn3Mo3/TiO2-0.5CA variant. Our results demonstrate that Fe5Mn3Mo3/TiO2-0.5CA exhibits superior low-temperature activity and prolonged stability compared to the conventional impregnation method. Remarkably, operating temperature window based on 80 % denitrification activity is T80 = 190–405 °C. Furthermore, the Fe5Mn3Mo3/TiO2-0.5CA maintains a noteworthy 98 % NO conversion at 300 °C for a duration of 100 hours. The excellent performance is attributed to the highly dispersed nature of the active species, the large specific surface area, the low apparent activation energy, and a robust interaction between the active components and the substrate. XPS analysis reveals a significantly higher Oα/(Oα+Oβ) ratio for Fe5Mn3Mo3/TiO2-0.5CA, underscoring the effectiveness of citric acid modification in promoting the formation of Fe2+ species. This research provides valuable insights into the design and optimization of catalysts for efficient denitrification processes.

A novel lanthanum ion-assisted fluorapatite precipitation approach for efficient fluoride removal from water

Excess amounts of fluoride ions (F-) in water/wastewater bring great hazards to human health and the environment. The traditional method such as precipitation by calcium ions does not work well for low-concentration F- removal. Herein, we developed a lanthanum ion (La3+)-assisted fluorapatite precipitation approach to treat F--containing water, aiming at high removal efficiency. Through an orthogonal experimental design and single-factor experiment, the optimized reaction conditions were obtained as the molar ratio of (Ca2++La3+): PO43-: F-=7.5: 4: 1, Ca2+: La3+ = 90: 10, and reaction pH of 9. Under such reaction conditions, F- in water (10 mg L−1) could be well controlled under 1 mg L−1, fulfilling relevant environmental standards. No remarkable F- removal efficiency loss was found in the presence of typical anions (e.g., halides, bicarbonate, sulfate). The developed F- removal approach also worked well in a wide F- concentration range (10–200 mg L−1) and reaction temperature range (5–45 °C). Further reaction mechanism study proved that the formation of LaFx(OH)3-x colloids was the key step, which could accumulate F- ions in water into colloids. The subsequently added Ca2+ and PO43- destroyed the stable colloids, and then promoted the formation of fluorapatite with simultaneous La3+ doping, which existed as precipitate and allowed the easy separation from the reaction solution. As a by-product, the as-produced La3+-doped fluorapatite was evaluated as an adsorbent for organic pollutant removal, which possessed a high adsorption capacity (763.4 mg g−1) for the model pollutant of Congo red. Considering the facile operation process, high F- removal efficiency, wide operation temperature window, and anti-inference for co-existing anions, the La3+-assisted fluorapatite precipitation approach possessed great potential for F--containing water/wastewater treatment.

A Thermal Tanks-in-Series Model for Simulating over-Discharge Cycling in Lithium-Ion Batteries

Energy storage will play a crucial role in the transition to clean and renewable sources of energy production to meet future consumption demands.1 Lithium-ion (Li-ion) batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities for applications like electric vehicles and grid storage.2 Li-ion batteries for high voltage operations, where several cells are connected in series, can experience inadvertent over-discharge due to differences between cells3,4. These differences can arise due to many reasons including changes in internal resistance and deviation in electrochemical degradation that can cause divergence of cell open circuit potentials. Over-discharge is a condition when the manufacturer recommended lower voltage limit is crossed while discharging4, which results in various side effects such as electrolyte decomposition, capacity degradation, cathode morphology change and possible internal short circuit3,5. Increase in anode potential during over-discharge leads to copper dissolution from the anode current collector and subsequent plating within cell components. The Solid Electrolyte Interface (SEI) can decompose during excessive deintercalation and reform during charging, reducing the lithium inventory. Excessive heat generation during cycle life testing after occurrences of over-discharges has been found in some cases to lead to temperatures >150 °C6,7.Temperature plays a key role in the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. A physics-based modeling approach coupled with a thermal model can be employed to understand the effect of over-discharge on the electrochemical behavior of Li-ion batteries and provides insights into the interplay of various degradation mechanisms that cause capacity fade.The Thermal Tank-In-Series9,10(TTiS) model is a systematically volume-averaged form of the standard pseudo-2-dimensional (p2D)11 model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy, as it is sensitive to changes in the battery’s state of charge (SOC) and cell temperature, which helps predict the overpotential changes to the cell electrodes and thermodynamics.We use the TTiS model to identify the dominant fade mechanisms in 3 sets of experimental cycling and temperature data for the: i) normal operating window (2.5V – 4.2V), ii) 5 initial cycles of over-discharge (1.5V – 4.2V) followed by normal operation until 20% capacity fade and iii) 5 cycles of periodic over-discharge every 20 cycles, until 20% capacity fade. Analysis on the effect of C-rate, ambient temperature and voltage window of operation will facilitate understanding the temperature behavior and overpotentials in a cell sandwich. Key considerations required in extending a model to simulate over-discharge will also be examined. References S.P. S. Badwal, S. S. Giddey, C. Munnings, A. I. Bhatt, and A. F. Hollenkamp, Frontiers in Chemistry, 2, 28 (2014).G. Pistoia. Lithium-Ion Batteries: Advances and Applications. First ed. Elsevier, Amsterdam (2014).R. Guo, L. Lu., M. Ouyang, X. Feng. Sci Rep 6, 30248 (2016).G.Zhang, X. Wei, S. Chen, J. Zhu, G. Han, and H. Dai. J. Power Sources, 521, 230990. (2022).C. Fear, D. Juarez-Robles, J. A. Jeevarajan, and P. P. Mukherjee, J. Electrochem. Soc., 165, A1639–A1647 (2018).D. Juarez-Robles, Purdue Univ. Ph.D. Thesis (2019).H. Maleki and J. N. Howard, J. Power Sources, 160, 1395–1402 (2006).H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017).A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020).A. Subramaniam, S. Kolluri, C. D. Parke, M. Pathak, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 013534 (2020).M. Doyle, T. F. Fuller, and J. Newman, J. Electrochem. Soc., 140, 1526 (1993)

Effects of MOx modification (M = Mn, Ce, and Fe) on the SCR catalytic properties of the CrOx-WOx mixed oxide catalysts

In this study, a series of MOx-modified (M = Mn, Fe, and Ce) CrOx-WOx mixed oxides were synthesized via the sol-gel technique for the selective catalytic reduction of NOx with NH3. Given the addition of MnOx or CeOx, the availability of the catalyst surface acid sites tended to decline, which negatively affected the proceeding of the deNOx process. Moreover, the retention of oxidative ability by introducing MnOx also favored the over-oxidation of NH3, which accelerated the additional formation of NOx and created a crucial barrier for the increment in the higher-temperature deNOx activity. Apparently, <80 % of the NOx could be effectively eliminated from the working gas within the whole temperature range for the CrCeW and CrMnW samples. By contrast, doping FeOx was able to introduce ample acid sites onto the catalyst surfaces, which was beneficial for the adsorption of NH3 and subsequently the facilitation of the progression of the deNOx process. Furthermore, the weakened oxidizability suppressed the over-oxidation of NH3. Consequently, a broad operating temperature window was obtained for the FeOx-doped catalyst; >90 % NOx conversion efficiency was achieved in the temperature range of 230–450 °C. During the deNOx process, the Eley-Rideal mechanism dominated over the four investigated samples.

DBTT and recrystallization behavior analyses for rolled and forged potassium-doped tungsten alloys

Tungsten-potassium (WK) alloys are regarded as one of the candidates for plasma-facing materials (PFMs) intended for the divertor and first wall of future fusion reactors. Determining the range of the ductile-to-brittle transition temperature (DBTT) and the recrystallization temperature (RCT) for the WK alloy is critical as it is closely related to the safe operational temperature window of the fusion reactor. Variable temperature tensile tests were conducted on rolled and high energy rate forging (HERF) WK alloy specimens to elucidate their DBTT. Additionally, gradient high-temperature isochronal annealing was performed on the HERF samples, coupled with Vickers hardness characterization, to ascertain their distinct RCT for various orientation planes within the same alloy. Subsequently, the DBTT of the as-rolled WK alloy is determined to be approximately between 100 °C and 150 °C, while that of the HERF WK alloy is found to be around lower than 200 °C. Furthermore, the RCT of the ND plane of the HERF WK alloy is approximately 1600 °C, whereas that of the RD counterpart exceeded 1700 °C. The internal mechanisms underlying these phenomena are comprehensively analyzed in this study. This work has identified the safe service temperature window for future fusion reactors with this kind of advanced WK alloy and provided a new perspective for determining the RCT of many other W-based materials.

Superior sodiophilicity and molecule crowding of crown ether boost the electrochemical performance of all-climate sodium-ion batteries

Sodium-ion batteries (SIBs) as one of the promising alternatives to lithium-ion batteries have achieved remarkable progress in the past. However, the all-climate performance is still very challenging for SIBs. Herein, 15-Crown-5 (15-C-5) is screened as an electrolyte additive from a number of ether molecules theoretically. The good sodiophilicity, high molecule rigidity, and bulky size enable it to reshape the solvation sheath and promote the anion engagement in the solvated structures by molecule crowding. This change also enhances Na-ion transfer, inhibits side reactions, and leads to a thin and robust solid-electrolyte interphase. Furthermore, the electrochemical stability and operating temperature windows of the electrolyte are extended. These profits improve the electrochemical performance of SIBs in all climates, much better than the case without 15-C-5. This improvement is also adopted to μ-Sn, μ-Bi, hard carbon, and MoS2. This work opens a door to prioritize the potential molecules in theory for advanced electrolytes.

Expanding the operational temperature window of a superconducting spin valve

Expanding the operational temperature window of a superconducting spin valve

Fluorine Chemistry in Rechargeable Batteries: Challenges, Progress, and Perspectives.

The renewable energy industry demands rechargeable batteries that can be manufactured at low cost using abundant resources while offering high energy density, good safety, wide operating temperature windows, and long lifespans. Utilizing fluorine chemistry to redesign battery configurations/components is considered a critical strategy to fulfill these requirements due to the natural abundance, robust bond strength, and extraordinary electronegativity of fluorine and the high free energy of fluoride formation, which enables the fluorinated components with cost effectiveness, nonflammability, and intrinsic stability. In particular, fluorinated materials and electrode|electrolyte interphases have been demonstrated to significantly affect reaction reversibility/kinetics, safety, and temperature tolerance of rechargeable batteries. However, the underlining principles governing material design and the mechanistic insights of interphases at the atomic level have been largely overlooked. This review covers a wide range of topics from the exploration of fluorine-containing electrodes, fluorinated electrolyte constituents, and other fluorinated battery components for metal-ion shuttle batteries to constructing fluoride-ion batteries, dual-ion batteries, and other new chemistries. In doing so, this review aims to provide a comprehensive understanding of the structure-property interactions, the features of fluorinated interphases, and cutting-edge techniques for elucidating the role of fluorine chemistry in rechargeable batteries. Further, we present current challenges and promising strategies for employing fluorine chemistry, aiming to advance the electrochemical performance, wide temperature operation, and safety attributes of rechargeable batteries.

New insights into the various SCR performances of the CeOx-FeOx mixed-oxide catalysts prepared using different iron precursors

This article illustrated the effects of iron precursors on the deNOx performance of the CeOx-FeOx catalysts. With regard to the catalyst prepared using Fe(NO3)3 as the iron precursor (CeFe–N), relatively poor deNOx performance was observed; <80% NOx conversion was obtained at 130–450 °C. While for the samples synthesized using FeCl3 and Fe2(SO4)3 as the iron sources (CeFe–C and CeFe–S), >90% of the NOx was effectively removed from the working gas in the temperature range of 230–350 °C and >270 °C, respectively, signifying the broadened operational temperature range. The superior oxidative ability of metal cations primarily contributed to a low activation energy, which was favorable for the activation of the reactants and the acceleration of the reaction via the "fast SCR" pathway at lower temperatures. Meanwhile, a comparatively low availability of the surface acid sites signified the limited adsorption of NH3, which thus endowed CeFe–N with a low pre-exponential factor and primarily caused the restrained proceeding of the SCR reaction. In contrast, the presence of ample acid sites and the weakened oxidative ability of metal cations successively explained the increased pre-exponential factor and activation energy of CeFe–C and CeFe–S. The synergistic effects of the previously indicated two factors enabled these two catalysts to have a higher or similar low-temperature NOx conversion compared with CeFe–N. With increasing the temperature, the additional generation of NOx was favored over CeFe–N, causing a decline in its NOx conversion efficiency. On the contrary, the inhibited proceeding of NH3 over-oxidation ensured most NH3 to serve as the reductant to reduce NOx on CeFe–C and CeFe–S, which mainly explained their comparatively broad operational temperature window.

Post-irradiation examination of commercial tantalum alloys following neutron irradiation

Post irradiation examination of two commercial tantalum alloys (based on Ta-8 %W) revealed significant irradiation hardening following neutron irradiation in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Tensile samples of commercial Ta alloys T-111 and ASTAR-811C were irradiated to a total neutron fluence (E > 0.1 MeV) in the range (2–4)x1021 n/cm2 (0.39–0.75 dpa) at an irradiation temperature near 900 °C. Tensile testing conducted at room temperature and at 800 °C revealed significant irradiation hardening under all test conditions. Samples that were tensile tested at room temperature exhibited brittle failure, whereas ductility was maintained for elevated temperature testing. The irradiation hardening and embrittlement noted for both alloys was attributed to irradiation-induced dislocation loop formation as confirmed through scanning transmission electron microscopy analysis. Corresponding energy dispersive x-ray spectroscopy revealed radiation-induced segregation of Hf in these loop populations. This Hf enrichment is shown to result in eventual co-precipitation of elongated (Hf,O)-rich precipitates along the dislocation loops. These results show that irradiation hardening is enhanced via irradiation-enhanced precipitation at elevated irradiation temperatures. Consequently, the minimum recommended operating temperature window for Ta alloys should be increased to account for observed hardening/embrittlement at irradiation temperatures as high as 900 °C (1,173 K).

CO2 Compression and Liquefaction Processes Using a Distillation Column for the Flexible Operation of Transportation

Impurities in the CO2 stream should be removed to prevent eventual phase changes in CO2 transportation because a two-phase flow caused by the phase change in the pipeline necessitates additional overpressure and can induce equipment damage. In this study, CO2 compression and liquefaction (CCL) processes with a distillation column were used to remove non-condensable impurities and were compared with those with a flash. Three different feeds with a flow rate of 50.1 t/h (400,500 t/y) were supplied to the CCL processes and compressed to 65 bar to gauge pressure (barg) and 20 °C. Although the CO2 mixtures obtained through dehydration and flashing met the purity requirements for transportation and storage recommended in literature, the flash-separated CO2 product at 65 barg demonstrated the coexistence of gas and liquid phases, which restricted the temperature window for liquid CO2 transportation. When the distillation column was used instead of the flash, the operating temperature window at 65 barg widened by 3–6 °C owing to the high purity of CO2. However, the levelized cost of CO2 liquefaction (LCCL) increased by 2–4 $/t-CO2 varying with the feed purity because the distillation column consumed more cooling and heating duties than the flash. This study highlighted that a two-phase flow existed under certain operating conditions despite a high purity of CO2 (over 97 mol%), and the distillation column enhanced the operability of liquid CO2 transportation.

Enhancing effect of Cu and Sn doping on low-temperature catalytic activity and operating temperature window of γ-Fe2O3 in NH3-SCR of NOx

The effect of Cu/Sn doping on the catalytic performance of γ-Fe2O3 was investigated and its reaction process was explored.

Enabling wide temperature battery operation with hybrid lithium electrolytes.

We demonstrate that an ionic liquid 1-ethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide combined with propylene carbonate and lithium bis(trifluoromethanesulfonyl)imide yields a hybrid electrolyte that enables a wide operational temperature window (-20 °C to 60 °C). When integrated into a lithium titanate‖lithium cobalt oxide full-cell configuration, high-rate capability is achieved at -20 °C with >40% retention at a C/2 cycling rate, and negligible capacity fade is observed during rate capability tests and long-term cycling at 60 °C.