Journal of Environmental Chemical Engineering
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2022
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IF 7.968
Shoubing Chai,Yingjie Li,Wan Zhang,Zirui He
In carbonation stage of calcium looping process, NO could be reduced by CO using CaO as a catalyst, allowing simultaneous CO 2 and NO removal. However, to achieve efficient NO removal, the required CO/NO molar ratio in the carbonator is very high (up to 30:1), which leads to lots of unreacted CO in the exhaust gas. In this work, to maintain high efficiency of NO removal at low CO concentration in carbonator, Ce-doped CaO was employed to simultaneously enhance NO and CO 2 removal performance. The effects of Ce-doped CaO on simultaneous CO 2 and NO removal in bubbling fluidized bed reactor were investigated during the carbonation stage of calcium looping process. When the molar ratio of CO/NO is about 3.57:1, Ce-doped CaO obtains an 83% CO 2 capture efficiency and a 97% NO removal efficiency in 20 cycles in chemical reaction controlling stage. The average CO concentration in exhaust gas of Ce-CaO was reduced by 79% at the same NO removal efficiency as Mn-doped CaO. The presence of Ce 3+ makes the charge imbalance of the material, resulting in more charge transfer from the Ce-CaO surface to the molecules. The density functional theory reveals that Ce doping reduces the energy barriers of the conversion of NO to N 2 and the CO 2 adsorption, promoting the simultaneous NO/CO 2 removal in carbonation stage. Therefore, under a low molar ratio of CO/NO in carbonation stage of calcium looping, Ce considerably improves the simultaneous CO 2 and NO removal action of CO and CaO.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2022
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IF 4.831
Jia Li,Huizhu Zhang,Dongxue Yu,Weie Wang,Wei Song,Libin Yang,Xin Jiang,Bing Zhao
Considering the variable valence characteristics of rare earth elements, they can be in a variety of valence forms coexistence. Doping of rare earth element with different valence states may produce different energy levels to tune the semiconductor energy band structure. We utilize rare earth element Ce doping TiO 2 for the development of high-performance semiconductor surface-enhanced Raman scattering (SERS) substrates based on an energy-level tuning strategy. Ce doping not only forms multiple energy levels including Ce 3+ and Ce 4+ metal doping energy levels in the bandgap of TiO 2 , but also enriches the surface state level of TiO 2 itself, which together promote the separation of photogenerated carriers and improve charge transfer efficiency between substrates and absorbed molecules. This endows TiO 2 semiconductor substrate with a higher SERS enhancement factor, which can reach 2.2 × 10 6 . The detectable concentration of methylene blue can be as low as 10 −10 mol/L. Moreover, the semiconductor substrate exhibits excellent uniformity and stability. This study not only provides a new strategy to develop excellent semiconductor SERS substrate with multiple energy levels, but also lays the foundation for promising practical application of semiconductor substrate.
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JOURNAL OF MOLECULAR LIQUIDS
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2022
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IF 6.633
Tingting Chen,Yingjie Xu,Bin Chen,Huiquan Xiao
In this work, the efficient preparation of zeolitic imidazolate framework-8 (ZIF-8) from Zn 2+ and 2-methylimidazole (2-MI) promoted by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was presented. The mechanism obtained from NMR, MS, DFT calculations, and conductivity shows that [DBUH][2-MI] ionic liquid formed in-situ from proton transfer between DBU and 2-MI can ionize 2-MI to [2-MI] - and form electrostatic interaction between Zn 2+ and [2-MI] - , resulting in the efficient self-assembly of Zn 2+ and 2-MI to form ZIF-8. Moreover, the effect of the amount of DBU on ZIF-8 indicates that too much DBU will cause excessive deprotonation of 2-MI, leading to agglomerate of ZIF-8. Accordingly, the optimal ratio to form ZIF-8 is n(DBU): n(2-MI): n(Zn 2+ ) = 2: 25: 1.25, which is also employed to prepare cerium-containing ZIF-8. Moreover, ZnO and Ce/ZnO nanomaterials are prepared by using ZIF-8 and cerium-containing ZIF-8 as precursors respectively, and their structure and morphology are characterized by XRD, FT-IR, SEM, and TEM. Interestingly, Ce content in Ce/ZnO obtained by EDS spectrum is basically consistent with the actual doping amount, indicating that DBU can effectively control the doping of Ce in ZIF-8. Finally, the photocatalytic degradation ability of ZnO and Ce/ZnO for Rhodamine B under visible light and sunlight is investigated in detail.
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Journal of CO2 Utilization
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2022
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IF 8.321
Nicui Yuan,Yuxin Mei,Yuwei Liu,Yating Xie,Baining Lin,Yonghua Zhou
The development of efficient and highly selective photocatalysts is a key point for the photocatalytic conversion of CO 2 . In this paper, a composite catalyst UiO-66-NH 2 /Ce(HCOO) 3 (simplified to UNH/Ce(HCOO) 3 ) was fabricated by one pot method with CeCO 3 OH as the precursor. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) characterizations results confirmed that UNH was dispersed on the surface of Ce(HCOO) 3 and strongly interacted with it via Ce-N bond. The yield of CH 4 on the optimal UNH/Ce(HCOO) 3 catalyst reached 3 times of that on pristine UNH, up to 128.81 μmol g −1 , with the CH 4 selectivity of 71.9 %, and the R electron reached 286.46 μmol g −1 h −1 . The UV–vis diffuse reflection spectra and photoelectrochemical tests results confirmed that the improved photocatalytic CO 2 reduction performance and high CH 4 selectivity could be attributed to the formation of the type-Ⅱheterojunction of UNH/Ce(HCOO) 3 with abundant Ce 3+ , which expanded the visible light absorption range, accelerated the separation and transfer rates of photogenerated charges, and thus efficiently promoted the multi-electron reduction reaction of CO 2 to CH 4 . In addition, the reaction temperature affected profoundly the cycle performance of the catalyst. The results presented here illustrated the possibility for improving the stability of UNH/Ce(HCOO) 3 -1.80 by decreasing reaction temperature.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2022
·Vol. 24
·期 35
·21157-21164
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IF 3.945
Z. Z. Liu,K. P. Li,X. B. Yang,Y. Q. Zhang,Z. X. Xie,Z. Q. Duan,B. Zhou,Y. M. Hu
Pt counter electrodes (CEs) have been widely used in dye-sensitized solar cells (DSSCs) due to their high conductivity and electrocatalytic activity. However, industrialization of DSSCs is limited by shortcomings of Pt CEs such as being expensive, and weak corrosion resistance in electrolytes. Reported in this paper is two simple approaches to Pt-free Cu1.8S1−xSex CEs. Nanocrystalline Cu1.8S1−xSex CEs were fabricated via two processes, that is, a solvothermal process to Cu1.8S1−xSex powder followed by CE fabrication, and a solvothermal process and CE fabrication to Cu1.8S films followed by selenylation to Cu1.8S1−xSex CEs. Photoelectric conversion efficiencies (PCE) of 4.02% and 4.16% were achieved respectively by the as-fabricated Cu1.8S1−xSex CEs. Compared with the cells with Cu1.8S CEs fabricated by the same processes, increases of 19% and 45% were achieved, respectively. The PCE improvement comes from the enhancement of charge transfer at the CE/electrolyte interface induced by the selenylation of the CEs.
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RSC Advances
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2022
·Vol. 12
·期 36
·23183-23192
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IF 4.036
Xiaoyan Cao,Lingxin Kong,Zhenggui Gu,Xiao Xu
The application of recyclable heterogeneous catalysts in the production of polypropylene glycol monomethyl ether (MPPG) is of great significance to the green chemical industry. In this study, the CeO2/MgAl-LDH(P123) composite was prepared using a nucleation/crystallization isolation method and aqueous reconstruction method, and CeO2/MgAl-LDO(P123) solid base catalyst was prepared by calcination with it as precursor. Thereafter, the morphology, crystal structure, functional group, and thermal stability of the catalyst were characterized using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, temperature-programmed desorption of carbon dioxide, thermogravimetry, and X-ray photoelectron spectroscopy. The results showed that the catalyst had a larger specific surface area, pore size and pore volume and more basic sites, providing sufficient catalytic activity for the polymerization process. The experimental results for the fabrication of MPPG using CeO2/MgAl-LDO(P123) as catalyst and methanol and propylene oxide as reaction raw materials showed that the conversion of propylene oxide reached 92.04% and the molecular weight of MPPG was 405 under the optimal reaction conditions. Moreover, the conversion of propylene oxide was maintained above 83.69% after the catalyst was reused six times. This study offers a new prospect for the green synthesis of MPPG products.
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Journal of Environmental Chemical Engineering
·
2022
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IF 7.968
Guoqiang Li,Siqi Chai,Guojie Zhang,Jun Liu,Yongfa Zhang,Yongkang Lv,Ying Wang,Yuqiong Zhao
In this paper, Ce-modified Cu-based carbon materials (Cu-Ce/AC) were prepared by impregnation method using walnut shell as the carbon precursor, Cu-ammonia solution as Cu source and Ce as modifier. The catalytic wet air oxidation (CWAO) degradation of phenol wastewater was carried out in a self-assembled fixed-bed reactor. The stability of Cu-Ce/AC catalyst under different pH conditions was studied. This study combines XRD, BET, FT-IR, ICP-OES and XPS characterization techniques to study the main reasons for the deactivation of Cu-Ce/AC catalysts. The reaction mechanism of Cu-Ce/AC catalytic wet air oxidation degradation of phenol was clarified. The result indicates that although phenol was completely converted in the CWAO process, the acidic intermediate product produced were difficult to completely degraded. Therefore, the pH of the solution gradually decreased. In acidic environment, the interaction between active component Cu and carbon carrier is weak, resulting in a large amount of metal leaching into the solution. As a result, the COD conversion gradually decreases. The alkaline environment can effectively slow down the leaching of catalyst Cu while maintaining its high catalytic activity . In addition, the incompletely degraded intermediate products are easy to accumulate and deposit on the Cu-Ce/AC surface, block the micropores and cover the surface-active sites, which reduces the catalyst activity. The study also found that there is a redox cycle between Cu + , Cu 2+ Ce 3+ and Ce 4+ during phenol degradation, which enables Cu and Ce to form a strong interaction. The redox cycle can also promote the formation of oxygen vacancy (h + ), O 2 − ·, and HO·, making the degradation of phenol more thorough. At the same time, the mutual conversion between metal lattice oxygen and surface chemisorbed oxygen can generate high concentration of oxygen defect sites, which can improve the oxygen storage capacity of Cu-Ce/AC. These oxygen vacancies also provide more reactive sites to further promote adsorption and catalytic oxidation degradation of phenol and intermediate products.
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JOURNAL OF APPLIED ELECTROCHEMISTRY
·
2021
·Vol. 52
·期 3
·573-581
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IF 2.8
Zhao Ruiyu,Wang Yi Mou,Li Jie,Meng Wenhua,Yang Chunli,Sun Chongxiang,Lan Xuefang
Ni, Ce, and Ta modified Ti/SnO 2 –Sb 2 O 5 –RuO 2 anodes were first prepared by thermal decomposition strategy and applied for Orange G degradation to explore the effect of Ni, Ce, and Ta modification on electrocatalytic property. The Ta modified anode showed the highest ·OH generation capability and the lowest charge transfer resistance among all samples, conducive to electrocatalytic degradation of Orange G. Besides, the Ta modified anode shows more cracks than Ni and Ce modified anodes, which is expected to create more specific surface areas and more exposed active sites for Orange G degradation. The degradation efficiency and the total organic carbon (TOC) removal rate increased in the order Ru < Ru–Ni < Ru–Ce < Ru–Ta, with Ru–Ta showing the highest degradation efficiency of 98.6% and 44.2%, much higher than 79.6% and 27.5% of Ru, respectively.
Graphical abstract
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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
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2021
·Vol. 331
·期 1
·365-373
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IF 1.371
Li Chunhui,He Hui,He Mingjian,Gao Yang,Zhang Meng,Jiao Caishan
A detailed extraction equilibrium study is experimentally performed to understand the extraction mechanisms of Ce(IV) by 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C 4 mimNTf 2 ) in 1,2-dichloroethane. Further, the influence of adding TBP on the distribution ratio is investigated and demonstrated. The ceric aqueous chemistry in the nitric acid solution and slope analysis are combined to reveal the extraction mechanism. The monovalent anionic complex HCe(NO 3 ) 6 − is the dominant species, which extracted by C 4 mimNTf 2 . Importantly, this study demonstrates the antagonistic effect between TBP and C 4 mimNTf 2 on the extraction process.
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CHEMOSPHERE
·
2021
·
IF 7.086
Cui Lai,Huchuan Yan,Dongbo Wang,Shiyu Liu,Xuerong Zhou,Xiaopei Li,Mingming Zhang,Ling Li,Yukui Fu,Fuhang Xu,Xiaofeng Yang,Xiuqin Huo
Peroxymonosulfate (PMS)-based advanced oxidation processes for wastewater treatment have received extensive attention in the past years. Here, a novel Mn, Ce co-modified g-C 3 N 4 (MnCe-CN) composite was successfully synthesized by one-step pyrolysis for activating PMS. The physical and chemical characterization of MnCe-CN/PMS was conducted, indicating that Mn and Ce were evenly distributed on g-C 3 N 4 and existed in the form of Mn-N structure and CeO 2 , respectively. The MnCe-CN/PMS system could effectively degrade pollutants such as acetaminophen (ACT), methylparaben (MeP), p -nitrophenol (PNP), and 2,4-dichlorophenol (2,4-DCP). Among them, 2,4-DCP could be rapidly degraded, reaching 100% within 30 min. The masking experiments and electrochemical testing results revealed that 2,4-DCP was degraded via superoxide radicals (O 2 ˙ˉ), singlet oxygen ( 1 O 2 ), and electron transfer path. The cyclic experiments and real water treatment experiments testified that the oxidative system had excellent stability and applicability. This study provides a facile synthetic method to fabricate bimetallic co-modified g-C 3 N 4 for the enhancement of PMS activation .
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
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IF 19.503
Xin Tian,Chaohe Zheng,Haibo Zhao
The current study investigates Ce-modified SrFeO 3- δ oxygen carriers for oxidative dehydrogenation (ODH) of ethane coupled with CO 2 splitting in a chemical looping manner. During 39 cycles of redox testing over the sample of 0.2Ce/SrFeO 3 , up to 29% ethane conversion and 82% ethylene selectivity are achieved, and the CO generation in the subsequent CO 2 splitting step is 0.25 mmol/g. XPS characterization results indicate decreased Fe 2+ /(Fe 3+ +Fe 4+ ) ratio as well as increased active oxygen species proportion on the near-surface of Ce-modified samples, which are responsible for the improved activity of the 0.2Ce/SrFeO 3 in ethane ODH reaction. DFT calculations further reveal that the increased ODH activity of 0.2Ce/SrFeO 3 is due to the lower surface oxygen vacancy formation energy upon Ce promotion. Moreover, the higher resistance of lattice oxygen diffusion from the bulk to the surface is the main reason for the superior ethylene selectivity attained by the CO 2 -regenerated sample than that by O 2 regeneration.
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APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Qinwei Zhang,Ruinian Xu,Ning Liu,Chengna Dai,Gangqiang Yu,Ning Wang,Biaohua Chen
In this work, a Ni-supported CeO 2 -Al 2 O 3 catalyst, called NiCeAl-RMO (reduced metal-oxide), was prepared via air calcination and H 2 reduction of NiCeAl-LDH (layered double hydroxide). The NiCeAl-RMO catalyst shows superior CO 2 methanation activity, especially at low temperature (250 °C), and it performed 78.6% CO 2 conversion with ∼ 100% CH 4 selectivity. Compared with NiAl-RMO, the NiCeAl-RMO catalyst prepared via the Ce-doping strategy has significantly improved CO 2 methanation activity. Characterizations revealed that Ce doping would increase the amount of active Ni 0 species, cause a large number of oxygen vacancies, and generate new moderate basicity sites on the catalyst. In addition, in situ DRIFTS found that, unlike the RWGS + CO methanation mechanism over NiAl-RMO, the CO 2 methanation mechanism over NiCeAl-RMO followed the formate pathway by generating bidentate carbonate species, which was revealed as a key intermediate for enhancing the low-temperature activity of CO 2 methanation.
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