FUEL
·
2021
·
IF 6.609
Kun Zhao,Xiaojie Fang,Zhen Huang,Guoqiang Wei,Anqing Zheng,Zengli Zhao
Chemical looping gasification provides a novel technology to enable clean conversion of coal with inherent CO 2 capture. In this study, four types of NiFe 2 O 4 and CuFe 2 O 4 synthesized by sol–gel method and solid-phase method were used as oxygen carriers to promote the H 2 production from gasification of lignite. The effects of the types of oxygen carrier and oxygen carrier to coal (O/C) ratio on chemical looping gasification of lignite were first investigated by a thermogravimetric analyzer (TGA) combing with various analytical methods. The results show that, among four types of oxygen carrier, the NiFe 2 O 4 synthesized by sol–gel method exhibits the highest gasification reactivity with lignite char at an O/C ratio of 1, since its highly cubic spinel structure is beneficial to improve the mobility of lattice oxygen. Furthermore, the operating conditions for chemical looping gasification of lignite were optimized and the gasification performance of four types oxygen carriers was compared by using a fixed bed reactor. It is found that NiFe 2 O 4 synthesized by sol–gel method exhibits the highest total gas yield of 24.47 mol/kg and H 2 /CO ratio of 0.77 during chemical looping gasification of lignite under the optimal operating conditions, ascribed to Fe-Ni synergistic effect which provided higher gasification reactivity with lignite char. The addition of steam drastically improves the total gas yield and H 2 /CO ratio of syngas from 24.47 mol/kg and 0.77 to 64.98 mol/kg and 2.79, suggesting that the H 2 /CO ratio of syngas can be flexibly adjusted to meet the need of downstream process via controlling the amount of steam added. These findings provide an efficient method to obtain H 2 -rich syngas via chemical looping gasification of lignite.
研究领域:
能源科学
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Jitong Deng,Yanan Zhang,Hongjing Han,Yongjun Zhang,Haiying Wang,Xuzhong Gong,Yanguang Chen
The chemical looping conversion of CH4 has been one of the most promising technologies for achieving the “two-carbon” strategy. Fe2O3 oxygen carrier cannot maintain the excellent release performance of lattice oxygen at high temperature due to the sintering and carbon deposition. Therefore, quaternary La1–xSrxFe1–y CoyO3 perovskite was selected as the transfer support of oxygen ions. By using the MOF precursor method, ternary La0.8Sr0.2FeO3 was prepared via the introduction of metal Sr into the binary LaFeO3. The adsorption energy of CH4 on the La0.8Sr0.2FeO3 was the lowest (−0.054 eV), compared with separate Fe2O3 and LaFeO3, and the adsorption energy of free H at the adjacent Fe site was the lowest (1.650 eV). Furthermore, the La1–xSrxFe1–yCoyO3 perovskite was successfully synthesized by the doping of Co into the ternary La0.8Sr0.2FeO3. La0.8Sr0.2Fe0.8Co0.2O3 was chosen to composite Fe2O3 oxygen carrier. As m(Fe2O3):m(La0.8Sr0.2Fe0.8Co0.2O3) = 1:1, the lattice oxygen conversion rate was less than 47% and the selectivity of CO2 reached 99.5% through the synergistic effect of lattice oxygen and oxygen vacancies. Fe2O3–La0.8Sr0.2Fe0.8Co0.2O3 increased the lattice oxygen conversion by 17.6%, compared with Fe2O3–La0.8Sr0.2FeO3. After the CH4 chemical looping conversion cycles five times, Fe2O3–La0.8Sr0.2Fe0.8Co0.2O3 still had favorable structural stability and oxidation performance, and the lattice oxygen conversion rate still reached >95%.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Yane Zheng,Kongzhai Li,Hua Wang,Dong Tian,Yuhao Wang,Xing Zhu,Yonggang Wei,Min Zheng,Yongming Luo
Chemical-looping reforming of methane (CLRM) offers an effective approach for coproducing syngas and pure hydrogen. In this work, CeO 2 nano particles (2–3 nm) are well dispersed on the wall surface of three-dimensional ordered macroporous (3DOM) LaFeO 3 , obtaining a highly efficient oxygen carrier for the CLRM technology. The physical and chemical properties of the oxygen carriers were characterized by SEM, TEM, H 2 -TPR, XPS, XRD, CH 4 -TPR and CH 4 -TPD techniques. It is found that the presence of CeO 2 on LaFeO 3 results in the formation of Ce 3+ and Fe 2+ due to the CeO 2 -LaFeO 3 interaction. The coexistence of Ce 3+ and Fe 2+ irons induces abundant oxygen vacancies on the mixed oxides, which strongly improves the reducibility, oxygen mobility and reactivity for methane oxidation. The presence of CeO 2 also improves the resistance towards carbon deposition formation, and this allows the CeO 2 /LaFeO 3 materials own high available oxygen storage capacity (available OSC, the maximum amount of oxygen consumed by methane reduction without the formation of carbon deposition). It is also noted that the agglomeration of CeO 2 nano particles would reduce the reactivity of oxygen carriers. Among all the obtained samples, the 10% CeO 2 /LaFeO 3 sample exhibits the highest yields of syngas (9.94 mmol g −1 ) and pure hydrogen (3.38 mmol g −1 ) without the formation of carbon deposition, which are much higher than that over the pure LaFeO 3 sample (5.73 mmol g −1 for syngas yield and 2.00 mmol g −1 for hydrogen yield). In addition, the CeO 2 /LaFeO 3 oxygen carrier also showed high stability during the successive CLRM testing either in the activity (yields of syngas and pure hydrogen) or structure (macroporous frameworks) aspect.
研究领域:
能源科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Weidong Sun,Guofeng Zhao,Ya Gao,Jiaqi Si,Ye Liu,Yong Lu
Chemical looping concept paves way toward intrinsically safe and efficient oxidative coupling of methane (CL-OCM) process, because it permits the reaction to proceed via repeating reduction-oxidation cycle in two reactors. It is calling for a ground-breaking catalyst with enough high selective CH 4 -converting lattice-oxygen carrying capacity but represents a grand challenge. Herein, we report an efficient catalyst obtainable by decorating an oxygen carrier FeMnO 3 with Na 2 WO 4 , with good cycling performance, achieving a high space time yield of 29.8 g C2-C3 kg cat. −1 h −1 with 20% CH 4 conversion and 80% C 2 -C 3 selectivity at 800 °C and a low catalyst/CH 4 weight ratio of 13.5. CL-OCM process is established by “FeMnO 3 ↔ [MnFe 2 O 4 + MnO]” redox cycle. Na 2 WO 4 -decoration gets lattice oxygen stored in FeMnO 3 transformed from non-selective to selective due to mitigation of lattice-oxygen evolution. Scaled up CL-OCM testing with 10-gram catalyst also yields comparable results seen in the case of using 1-gram catalyst, validating great application potential.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Carbon Energy
·
2025
·
IF 24.2
Zhao Sun,Kun Lei,Louise R. Smith,Nicholas F. Dummer,Richard J. Lewis,Haifeng Qi,Kieran J. Aggett,Stuart H. Taylor,Zhiqiang Sun,Graham J. Hutchings
Advanced oxygen carrier plays a pivotal role in various chemical looping processes, such as CO 2 splitting. However, oxygen carriers have been restricted by deactivation and inferior oxygen transferability at low temperatures. Herein, we design an Fe–O v –Ce–triggered phase-reversible CeO 2− x ·Fe·CaO ↔ CeO 2 ·Ca 2 Fe 2 O 5 oxygen carrier with strong electron-donating ability, which activates CO 2 at low temperatures and promotes oxygen transformation. Results reveal that the maximum CO 2 conversion and CO yield obtained with 50 mol% CeO 2− x ·Fe·CaO are, respectively, 426% and 53.6 times higher than those of Fe·CaO at 700°C. This unique multiphase material also retains exceptional redox durability, with no obvious deactivation after 100 splitting cycles. The addition of Ce promotes the formation of the Fe–O v –Ce structure, which acts as an activator, triggers CO 2 splitting, and lowers the energy barrier of C═O dissociation. The metallic Fe plays a role in consuming O 2− lattice transformed from Fe–O v –Ce, whereas CaO acts as a structure promoter that enables phase-reversible Fe 0 ↔ Fe 3+ looping.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Shiwei Ma,Shiyi Chen,Huijun Ge,Tao Song,Ping Lu,Wenguo Xiang
CeO2 is a typical fluorite oxide with desirable lattice oxygen conductivity and can be applied as an active support for the Fe-based oxygen carrier in chemical looping hydrogen generation (CLHG). However, Fe2O3/CeO2 always suffers from low thermal stability and sintering. Doping foreign cations could be a proper way to improve its reactivity and cyclic stability. In this work, Zr4+ and Sm3+, with a smaller ionic radius and lower valence than Ce4+, respectively, were doped into Fe2O3/CeO2 using the co-precipitation method, and the doping effects on the reactivity and redox stability of Fe2O3/CeO2 in CLHG were investigated. Fe2O3/Ce0.6Sm0.15Zr0.25O1.925 provided the best redox reactivity, and the purity of generated hydrogen for all oxygen carriers reached nearly 100% (the detection limit of CO/CO2 was 0.01% in volume). The reactivity followed the sequence Fe2O3/Ce0.6Sm0.15Zr0.25O1.925 > Fe2O3/Ce0.8Sm0.2O1.9 > Fe2O3/Ce0.75Zr0.25O2 > Fe2O3/CeO2. However, the concentration of oxygen vacancy was ranked as Fe2O3/Ce0.8Sm0.2O1.9 > Fe2O3/Ce0.6Sm0.15Zr0.25O1.925 > Fe2O3/Ce0.75Zr0.25O2 > Fe2O3/CeO2. The Zr doping boosted the reactivity of Fe2O3/CeO2 mainly by enhancing its sintering resistance, whereas the Sm doping achieved it mainly by promoting the oxygen conductivity, whose ability to improve the thermal stability of Fe2O3/CeO2 was rather limited. Both Zr and Sm doping could suppress the outward migration of Fe cations in the particles, resulting in higher sintering resistance. Furthermore, Zr and Sm could dissolve into CeO2 for prepared Fe2O3/Ce0.6Sm0.15Zr0.25O1.925; however, the bleeding out of both dopants was observed with Sm0.5Zr0.5O1.75 formation, which could be detrimental to the redox stability of the oxygen carrier.
研究领域:
材料科学
·
能源工程
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Li Zhang,Yue Hu,Weibin Xu,Chuande Huang,Yang Su,Ming Tian,Yanyan Zhu,Huimin Gong,Xiaodong Wang
Iron-based oxides are promising oxygen carriers for chemical looping syngas production from methane; however, facile coke formation over reduced metallic Fe0 largely limits the syngas productivity. This work demonstrates that the introduction of Sn promoters into BaFe1–xSnxO3−δ perovskite oxides significantly restrains coke formation and improves the syngas yield to above 19.2 mmol/g with a H2/CO ratio of 2, which is 2.9-fold in comparison to BaFeO3−δ. Characterization results suggest that Sn cations are well-confined in the perovskite matrix by substitution of Fe. The Fe cations serve as main active sites for C–H bond activation with Sn cations as an oxygen reservoir, which donate the neighboring lattice oxygen to active Fe for selective methane oxidation. Besides, an intimate Fe–Sn interaction induces the formation of the FeSn alloy rather than metallic Fe0 under a reducing atmosphere, which restrains methane pyrolysis and notably improves the coke resistance. When Sn loading (x) increases to above 0.6, all Fe cations can be deeply reduced to the metallic state without coke accumulation and oxygen storage capacity reaches as high as ca. 6.5 mmol/g with nearly 100% syngas selectivity, which breaks the “seesaw” effect between oxygen supply and syngas selectivity for traditional iron-based materials. These results provide meaningful guidance for fabricating prospective oxygen carriers or catalysts with better anti-coke property for the chemical looping process or specific catalytic reactions.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Yajing Wang,Yane Zheng,Yuhao Wang,Kongzhai Li,Yaming Wang,Lihong Jiang,Xing Zhu,Yonggang Wei,Hua Wang
Chemical-looping reforming of methane (CLRM) offers an effective approach for the production of syngas . A series of Ce x Zr y Cu 1−x−y (x = 0.6, 0.7, y = 0–0.35) mixed oxides were successfully prepared by sol-gel method, and characterized by means of XRD , H 2 -TPR, BET, XPS , Raman and CH 4 -TPR. The addition of Cu and Zr ions caused the distortion of CeO 2 lattice and induced more oxygen vacancies , which promoted the mobility of lattice oxygen in the materials. Ce x Zr y Cu 1−x−y mixed oxides also owned smaller grain size and better thermal stability than pure CeO 2 -CuO mixed oxides. Among the series of Ce x Zr y Cu 1−x−y mixed oxides, the reducibility of Ce 0.6 Zr x Cu 0.4−x and Ce 0.7 Zr x Cu 0.3−x samples gradually increased with the Cu content. It was found that the Ce 0.7 Zr 0.2 Cu 0.1 sample owned the most abundant oxygen vacancies on the surface. The Ce x Zr y Cu 1−x−y mixed oxides with lower Cu content (≤0.1) produced higher amount of H 2 and CO while smaller CO 2 . Ce 0.7 Zr 0.2 Cu 0.1 sample still retained better structural stability and thermal stability after 20 times cycled reaction.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
2022
·Vol. 46
·期 7
·9733-9747
·
IF 4.672
Yingwei Xiong,Jinglan Wang,Min Jin,Xiaohong Wang
Summary Fe 2 O 3 is recognized as a promising oxygen carrier, but the susceptibility to sintering over the redox cycles limits its application. Although depositing Fe 2 O 3 on CeO 2 can simultaneously improve the activity and durability, the formation of CeFeO 3 will decrease the oxygen capacity and thus the efficiency of chemical looping water-gas shift reaction. Doping foreign elements can effectively mitigate the reaction between Fe 2 O 3 and CeO 2 and improve redox reactivity. This work employs Gd 3+ and Sm 3+ as doping elements and investigates the doping effect on hydrogen generation of Fe 2 O 3 /CeO 2 in water-gas shift with chemical looping. The characterizations demonstrate that both Gd and Sm are incorporated into the lattice of CeO 2 and increase the oxygen defect concentration, which boosts the redox reactivities. In addition, the interaction between the dopants and CeO 2 promotes the reduction depth by suppressing the solid reaction between Fe 2 O 3 and CeO 2 and improves the reoxidation reaction between reduced oxygen carriers with steam. As a result, Fe 2 O 3 /Ce 0.8 Sm 0.1 Gd 0.1 O 1.9 shows a high hydrogen yield (8.73 mmol.g −1 ) and hydrogen production rate (582.2 μmol.g −1 .min −1 ), which is 1.67 times higher than that of Fe 2 O 3 /CeO 2 . The performance remains stable over 40 cycles. The introduction of foreign cations may provide an effective method and significantly impact the oxygen carrier design.
研究领域:
材料科学
·
能源化学
✓ 已验证
DOI
高影响因子
Journal of Cleaner Production
·
2023
·
IF 11.1
Lujie Zuo,Shufan Yu,Rongjun Zhang,Hongwei Li,Yu Wu,Rufat Abiev,Zhao Sun,Zhiqiang Sun
Methanol is a competitive candidate for in-situ hydrogen supply; however, the techniques of methanol-to-hydrogen production are suffered from high reforming temperatures and catalyst deactivation . In this work, the chemical looping oxidative reforming of methanol is conducted using a Pd–Cu-based catalytic oxygen carrier (PdO–CuO–CuMn 2 O 4 ). Synergistic enhancement of lattice oxygen induction and Pd–Cu alloy activation is confirmed, thereby achieving efficient methanol reforming at a temperature as low as 200 °C. Under such low temperatures, the hydrogen production rate can reach an average of 11.2 times higher than that of CuO/ZnO/Al 2 O 3 . Moreover, the catalytic oxygen carrier remains relatively satisfying redox durability after 30th cycle. SEM and AFM measurements reveal the high degree of roughness at the PdO–CuO–CuMn 2 O 4 surface, in which the methanol activation can be effectively promoted. XRD and XPS measurements verify the formation of Pd–Cu alloy, as proved by the charge transfer from Pd to Cu. During the redox looping, Pd–Cu alloy is formed and re-separated to be PdO and CuO, thus remaining homogenous distribution of the active phase on an atomic scale. Meanwhile, the lattice oxygen also plays a crucial role in methanol activation, synergistically enhancing the low-temperature reforming of methanol. This study provides a new implication for designing functionalized catalytic oxygen carrier materials , which will substantially promote in-situ hydrogen supply for proton exchange membrane fuel cells.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Chenlong Liu,Dong Chen,Jangam Ashok,Plaifa Hongmanorom,Wenju Wang,Tianle Li,Zhigang Wang,Sibudjing Kawi
Chemical looping steam reforming of bio-oil is novel conversion technology utilizing waste energy, which is an advantage to reduce cost and improve environmental. However, complex reaction process between oxygen carrier and bio-oil constrain its development. In this study, perovskite based La 0.8 M 0.2 Ni 0.8 Fe 0.2 O 3 (M = Ca, Ce and Zr) were investigated as an oxygen carrier for chemical looping steam reforming of bio-oil model reaction. The perovskites were prepared via sol-gel method and the effect of doping for reforming of acetic acid as bio-oil model compound is also investigated. Among all the perovskite tested, Ce doped La 0.8 Ce 0.2 Ni 0.8 Fe 0.2 O 3 oxygen carrier gave superior and stable catalytic performance for 1440 min at 600 °C and steam/carbon mole ratio (S/C = 2). The fresh and spent oxygen carriers were characterized using XRD , H 2 -TPR, CO 2 -TPD, TG-DTG, Dielectric constant , Raman, XPS and XANES . Doping with base metal generally, improved coke resistance ability of the perovskite. CO 2 -TPD and XPS analysis reveal that the highest carbon resistance for La 0.8 Ce 0.2 Ni 0.8 Fe 0.2 O 3 perovskite is due to enhanced stronger surface basicity and oxygen adsorption. From DFT simulation and Dielectric constant results, the better activity for La 0.8 Ce 0.2 Ni 0.8 Fe 0.2 O 3 is attributed to its adsorption ability of reactants, oxygen and electron transfer from sub-surface to surface of the perovskite.
研究领域:
能源科学
·
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2025
·
IF 8.3
Shuting Min,Chenxuanzi Wang,Mingxuan Zhong,Yibo Guo,Bo Xiao,Tingting Xu,Xun Wang
In this study, a series of composite oxygen carriers (OCs) of NiFe 2 O 4 /Sr 4 Fe 6 O 13 (xNiySr 4 ) was synthesized by solid-phase synthesis method. The performance evaluation for syngas and hydrogen production was investigated in chemical looping reforming coupled with thermochemical water splitting using ethanol as fuel. The presence of NiFe 2 O 4 enhanced the lattice oxygen activity and intensified the reduction of Sr 4 Fe 6 O 13 . The Ni–Fe alloy was produced in fuel reactor (FR) and then promoted water splitting in steam reactor (SR) for hydrogen production. The presence of Sr 4 Fe 6 O 13 regulated the reactivity of NiFe 2 O 4 , which prevented the ethanol complete oxidation in FR and enhanced the syngas production. Additionally, the introduction of Sr 4 Fe 6 O 13 decreased the content of NiFe 2 O 4 and suppressed carbon deposition, which resulted in a high purity of hydrogen in SR. Moreover, the existence of Sr 4 Fe 6 O 13 mitigated the sintering of NiFe 2 O 4 . The composite oxygen carrier of NiFe 2 O 4 /Sr 4 Fe 6 O 13 exhibited better cyclic stability than the single NiFe 2 O 4 and Sr 4 Fe 6 O 13 oxygen carrier. The 0.4NiFe 2 O 4 /0.6Sr 4 Fe 6 O 13 oxygen carrier, termed as 4Ni6Sr 4 , exhibited a good performance for syngas and hydrogen production performance at 800 °C. A high syngas purity of 74.36% was observed with a yield of 1.05 Nm³/kg ethanol in FR. The hydrogen yield and purity in SR were 6.51 mmol/g OC and 96.60%, respectively.
研究领域:
能源科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）