Dry reforming of methane (DRM) is an effective route to convert two major greenhouse gas (CH4 and CO2) to syngas (H2 and CO). Herein, in this work, monometallic Ni/CeO2 and a series of bimetallic ...Co–Ni/CeO2 catalysts with Co/Ni ratios between 0 and 1.0 have been tested for DRM process at 600–850 °C, atmospheric pressure and a CH4/CO2 ratio of 1. The catalysts were characterized by X-ray diffraction, hydrogen-temperature programmed reduction, CO2-Temperature programmed desorption, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The catalyst with a Co/Ni ratio of 0.8 (labeled as 0.8 Co–Ni/CeO2) exhibited the highest catalytic activity (CH4 and CO2 initial conversion for 80% and 85% at 800 °C, respectively) and the highest stability (less carbon deposition after 600min). This improved activity can be attributed to the Co–Ni alloy, which formed after reduction. Its weak chemisorption with hydrogen results in inhibition of reverse water gas shift reaction. In addition, Co-promoted the adsorption of surface oxygen enhances carbon removal, making it more stable.
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•CeO2 supported Ni and Co–Ni catalysts were tested for dry reforming of methane.•A molar Co/Ni ratio of 0.8 provides the most active and least deactivated catalyst.•Co–Ni alloy was formed after reduction, which was responsible for its superior performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•MFB-TGA-MS was employed to explore the limestone hydrogenation for ICCU-RWGS.•4-fold increase in reaction rate using Cu-Al catalyst as the bed material.•Realizing limestone ...hydrogenation within a H/C ratio of 2:1 for FTS process.•Applying the simplified K-L two-phase fluidized bed model and shrinking core model.
The integrated CO2 capture and utilization via the reverse water–gas shift reaction (ICCU-RWGS) to produce CO represents a compelling pathway toward achieving carbon neutrality. However, achieving the desired hydrogen-to-carbon (H2/CO) ratio, particularly at 2:1, to serve as the feedstock for the Fischer–Tropsch Synthesis (FTS) process, remains a relatively unexplored area. This study employs micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) alongside a particle-injecting method to investigate direct limestone hydrogenation using isolated solid materials (limestone as the reactant and Cu-Al catalyst as the bed material) under fluidized and isothermal conditions. The Cu-Al catalyst, utilized as the bed material, has demonstrated enhanced performance in the decomposition of limestone, resulting in a 4-fold increase in reaction rate compared to the inert quartz sand at 30 vol% H2 and 800 °C. Furthermore, at both milligram and gram scales, limestone exhibits favorable H2/CO ratios, especially at 30 vol% H2 concentration and a particle size of 150–200 μm, achieving a 2:1 ratio, demonstrating its potential suitability for processes like FTS. Kinetic analysis, using the shrinking core model and a simplified K-L model, reveals activation energies of 185.2 kJ/mol (for limestone decomposition) and 100.3 kJ/mol (for the RWGS reaction), effectively predicting the entire reaction process. MFB-TGA-MS experiments and model calculations demonstrate effective conversion of unconverted CO2 by the Cu-Al catalyst bed material, resulting in a highly desired H2/CO ratio and in-situ CO2 conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•HT reduced both ARGs and MGEs by 2.3 to 7.4 logs.•ARGs/g sample increased, and ARGs/16S rRNA declined after anaerobic digestion.•The biomass, ARGs, and MGEs were enriched in ...suspended solids of digestate.•Mass reduction efficiency of this system was 97.7%.•This system could achieve energy self-sufficiency.
A process combining hydrothermal treatment (HT), pyrolysis, and anaerobic digestion can efficiently treat antibiotic fermentation residues (AFR). The process characteristics and antibiotic resistance genes (ARGs) removal efficiencies of each unit have been investigated. HT of 180 °C improved the biodegradability and dewaterability of the AFR. Pyrolysis of 500 °C and upflow anaerobic sludge blanket (UASB) of 6.5 ± 0.5 kg COD•(m3•d)-1 recovered the organic matter in filter cake and filtrate of AFR. The biogas and pyrolysis gas can compensate the energy this system needs. HT of 180 °C could reduce 16S rRNA, ARGs, and mobile genetic elements (MGEs) by 2.3 to 7.4 logs. UASB increased the copy numbers of ARGs and MGEs, but the relative abundances of ARGs normalized against 16S rRNA were significantly declined. The ARGs and MGEs were enriched in suspended solids of digestate. The application of this process can promote the resources recycling of fermentation waste.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Antibiotics and antibiotic resistance genes (ARGs) are enriched in antibiotic fermentation residues (AFRs). In this study, we investigated the effect of hydrothermal treatment on dewatering, biogas ...production, and removal of ARGs in the penicillin fermentation residue (PFR). Solid, 120 µm particles in the PFR were disintegrated to 30 – 40 µm after 140 – 180 °C hydrothermal range. Of extracellular polymeric substance, 79.8 ± 0.4% was decomposed to release 82.2 ± 0.6% of bound water at 180 °C. The effective solid-liquid separation was achieved only after a hydrothermal treatment of 180 °C. More than 75% of organic matter in the filtrate was transformed into biogas by the upflow anaerobic sludge blanket (UASB). The absolute abundance of 16 S rRNA and ARGs decreased by 2.4 – 5.2 logs after hydrothermal treatment. The ratio of extracellular ARGs (eARGs) to total ARGs increased at 80 °C and decreased at higher temperature (>120 °C). The absolute abundance of ARGs increased by 0.7 – 1.6 logs in anaerobic digestion, and the relative abundances of ARGs based on 16 S rRNA plummeted by 3 logs. Most (98.7 ± 0.4%) ARGs were distributed in suspended solids and were removed by membrane filtration. Hydrothermal treatment demonstrated broad applicability to 10 varieties of AFRs.
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•79.8% of EPS was decomposed to release 82.2% of bound water.•The absolute abundance of ARGs plummeted after hydrothermal treatment.•Ratio of eARGs to ARGs decreased at 120 – 180 °C.•98.7% of ARGs were distributed in suspended solid in digestate.•Pilot-scale experiments were conducted on 10 varieties of AFRs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Hydrogenation kinetics of limestone under fluidized condition was firstly explored.•MFB-TGA-MS was employed to measure both mass and gas signals simultaneously.•Self-catalytic ...activity of calcined CaO with 79% CO2 conversion in ICCU-RWGS.•Apparent model of limestone hydrogenation was developed to analyze the kinetics.
The integrated CO2 capture and utilization (ICCU) in conjunction with the reverse water–gas shift (RWGS) reaction has emerged as a promising approach to achieve carbon neutrality. However, the scalability of CaCO3 hydrogenation in the context of large volumes of industrial flue gas is impeded by the limited understanding of its performance under fluidized and iso-thermal conditions. This study utilized micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) and in-situ measurements to investigate limestone decomposition under H2 and Ar atmospheres. Results showed that H2 atmosphere increased the limestone decomposition rate by 5-fold (79.1% CO2 conversion and ∼100% CO selectivity at 710 °C) compared to Ar, with RWGS as the dominant route and self-catalytic activity of calcined CaO. Morphology evolution revealed finer pores and textures under H2 conditions. Meanwhile, apparent kinetic models analyzed experimental data and showed a reduction in activation energy from 178.5 kJ/mol (Ar) to 161.3 kJ/mol (H2). These findings support the effectiveness of ICCU-RWGS approaches for further commercialization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The current study reports LaFe1−xNixO3−δ redox catalysts as flexible oxygen or carbon carriers for CO2 utilization and tunable production of syngas at relatively low temperatures (∼700 °C), in the ...context of a hybrid redox process. Specifically, perovskite-structured LaFe1−xNixO3−δ with seven different compositions (x = 0.4–1) were prepared and investigated. Cyclic experiments under alternating methane and CO2 flows indicated that all the samples exhibited favorable reactive performance: CH4 and CO2 conversions varied between 85% and 98% and 70–88%, respectively. While H2/CO ratio from Fe-rich redox catalysts was ~2.3:1 in the methane conversion step, Ni-rich catalysts produced a concentrated (~ 93.7 vol%) hydrogen stream via methane cracking. The flexibility of LaFe1−xNixO3−δ to produce syngas (or hydrogen) with tunable compositions was found to be governed by the iron/nickel (Fe/Ni) ratio. Redox catalysts with higher Fe contents act as a lattice oxygen carrier via chemical looping partial oxidation (CLPOx) of methane whereas those with higher Ni contents function as a carbon carrier via chemical looping methane cracking (CLMC) scheme. XRD analysis and temperature-programmed reactions revealed that both types of catalysts involve the formation of La2O3 and Ni0 /Ni-Fe phases under the methane environment. The ability to re-incorporate La2O3 and Ni/Fe into a perovskite structure gives rise to oxygen-carrying capacity whereas stable Ni0 or Ni/Fe phases would catalyze methane cracking without lattice oxygen exchange in the reaction cycles. Temperature programmed oxidation and Raman spectroscopy indicated the presence of graphitic and amorphous carbon species, which were effectively gasified by CO2 to produce concentrated CO. Stability tests over LaFe0.5Ni0.5O3 and LaNiO3 revealed that the redox performance was stable over a span of 50 cycles.
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•LaFe1−xNixO3−δ facilitates tunable production of syngas with CO2 utilization.•Tuning the Fe:Ni ratio changes the catalyst functionality and reaction pathway.•Excellent CH4 and CO2 conversions were observed at 700 oC.•Inherently separated H2 and CO streams were produced via the carbon carrier route.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study reports molten metals (bismuth, indium, and tin) as effective modifiers for iron-based redox catalysts in the context of chemical looping-based hydrogen production at intermediate ...temperatures (450–650 °C) from low-calorific-value waste gas (e.g., blast furnace gas). The effects of the bismuth promoter on both the surface and bulk properties of iron oxides were studied in detail. Transmission electron microscopy and energy-dispersive spectroscopy (TEM-EDS), low-energy ion scattering (LEIS), Raman spectroscopy, and 18O2 exchange experiment revealed that the bismuth modifier forms an overlayer covering the bulk iron (oxides), leading to better anti-coking properties compared to reference La0.8Sr0.2FeO3- and Ce0.9Gd0.1O2-supported iron oxides. The Bi-modified sample also exhibited improved anti-sintering properties and high redox activity, resulting in a 4-fold increase in oxygen capacity compared to pristine Fe2O3 (28.9 vs 6.4 wt %) under a cyclic redox reaction at 550 °C. Meanwhile, a small amount of bismuth is doped into the iron oxide structure to effectively enhance its redox properties by lowering the oxygen vacancy formation energy (from 3.1 to 2.1 eV) and the energy barrier for vacancy migration, as confirmed by the experimental results and density functional theory (DFT) calculations. Reactive testing indicates that Bi-modified redox catalysts are highly active to convert low-calorific-value waste gases such as blast furnace gas. Our study also indicates that this strategy can be generalized to low-melting-point metals such as Bi, In, and Sn for iron oxide modification in chemical looping processes.
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IJS, KILJ, NUK, PNG, UL, UM
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•Second-metallurgy-reduced iron was used as the reactant for H2 generation.•The effect of carbon and trace metal in iron particle on H2 generation was studied.•A short-cut chemical ...looping system is effective for high purity H2.
An integrated high purity hydrogen generation process, short-cut chemical looping hydrogen generation, was proposed in this study. Iron dust of the steel industry, as the feedstock of iron-based material, was employed as the oxygen carrier. This study used second-metallurgy-reduced iron and analytical-reduced iron to validate the feasibility of oxidation performance with air and steam at different reaction temperatures. To obtain the fundamental data, thermogravimetric analyzer and packed-bed reactor had been used. Due to the difference in carbon composition and trace metal in the second-metallurgy-reduced iron, the reaction behaved completely different under different experiment conditions, especially at different converting temperatures. According to the apparent solid conversion and outlet gas concentration profiles, the oxidized reaction with air and steam would be divided into two stages, kinetically controlled regime and product diffusion regime. Besides, the purity of hydrogen produced by second-metallurgy-reduced iron and analytical-reduced iron could reach 99.2% and 99.9%, respectively. Overall, compared to analytical-reduced iron, using second-metallurgy-reduced iron provides a link between the waste recycling in steel industry to generate hydrogen with chemical looping concepts in the industrial level.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
