RSC Advances
·
2022
·Vol. 12
·期 36
·23183-23192
·
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
·
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
·
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
·
2021
·Vol. 331
·期 1
·365-373
·
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
·
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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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2021
·Vol. 37
·期 3
·565-570
·
IF 1.307
Jian Shaoju,Tian Zhiwei,Zhang Kaiyin,Duan Gaigai,Yang Weisen,Jiang Shaohua
C e/ZnO decorated carbon nanofibers(CNFs) heteroarchitectures(Ce/ZnO/CNFs) have been synthesized using electrospinning technique followed hydrothermal method, which have a high visible light photocatalytic activity. The samples were characterized by means of SEM, FTIR and XRD. The photocatalytic performance of Ce/ZnO/CNFs was tested with the methylene blue in the presence of visible light irradiation. In this work, we have analyzed the effects of Ce doping amount, initial methylene blue(MB) concentration and dosage of Ce/ZnO/CNFs on photocatalytic efficiency of the composite. The results showed that the photocatalyst containing 1.0% Ce in molarity(CZC1) obtained by autoclaving at 150 °C has the best photocatalytic degradation of MB than other as-synthesized samples. Ce/ZnO/CNFs catalysts exhibit a good stability and reusability, which would be an economical and environmentally friendly photocatalyst for various practical applications.
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RENEWABLE ENERGY
·
2020
·
IF 6.274
Hui Yong,Xin Wei,Jifan Hu,Zeming Yuan,Ming Wu,Dongliang Zhao,Yanghuan Zhang
A composite catalyst Fe@C was successfully prepared by chemical blowing and carbonization method, at the same time its defect level, pore distribution and specific surface area were investigated. In addition, the Mg–Ce–Y + x wt.% Fe@C ( x = 1, 3, 6, 10) composites also were synthesized by mechanical ball-milling. The effect of the Fe@C content on hydrogen absorption and desorption property of the Mg–Ce–Y alloy was characterized by XRD, SEM , TEM, PCI , and DSC method. The activated composites exhibit an excellent absorption and desorption kinetic performance, which attributeed to the efficient catalysis of Fe@C composite catalyst. The Mg–Ce–Y + 6 wt % Fe@C composite exhibits the fastest hydrogen absorption/desorption kinetics and relatively lower decomposition temperature and it can absorb 90% of the maximum hydrogen capacity within 2 min and only takes 12 min to release the same amount of hydrogen under 300 °C. Besides, the dehydrogenation activation energy is reduced to 84.9 kJ/mol and the initial hydrogen release temperature is less than 250 °C, which is owing to the outstanding synergistic catalyst effect of Fe@C on Mg-based hydrogen storage alloy . However, the thermodynamic properties of the composites have not been improved, of which the enthalpy change is 80.6 kJ/mol.
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CATALYSIS TODAY
·
2021
·
IF 6.766
Liangliang Zhang,Yang Feng,Huihui He,Yang Liu,Jiena Weng,Peng Zhang,Wei Huang
In this article, we report a series of hexanuclear rare-earth MOFs based on Ce (III) and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, namely Ce-PCN-224, with a new zln topology through linker induce strategy. Ce-PCN-224 exhibits permanent porosity, high water and thermal stabilities, and the ability to adsorb dye molecules in the aqueous environment. Moreover, after post-metallation with Fe, Co, and Ni, Ce-PCN-224(Fe) and Ce-PCN-224(Co) were proved to be efficient heterogeneous catalysts for the cycloaddition of CO 2 with epoxides, attributed to the combination of multiple Lewis acidic sites.
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JOURNAL OF RARE EARTHS
·
2021
·
IF 3.712
Ye Zhang,Yong Gao,Peng Wang,Duo Na,Zhenming Yang,Jinsong Zhang
Extraction reactor is a major research area of interest within the field of rare earths extraction and separation. SiC foam offers excellent material characteristics as well as three-dimensional (3-D) reticulated structure; however, very little research has been carried out on its application in extraction reactor so far. In this work, a static mixer reactor based on SiC foam was designed and demonstrated to extract and separate Ce(III) and Pr(III) from nitric acid media by using 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) as extractant. The structure–performance relationship between SiC foam and extraction performance was studied by experiment combined with computational fluid dynamics (CFD) simulation. The experiment data are in good agreement with the simulation results. Contrast experiment by using a Kenics mixer was carried out, and SiC foam shows better extraction and mass transfer performance. Using the optimal structural SiC foam (pore size D = 2.3 mm, open porosity ε = 85%, foam length L = 80 mm), high extraction efficiency η (Pr(III): 94.6%, Ce(III): 88.5%) and separation factor β (2.27) between Ce(III) and Pr(III) is achieved at a high total throughput of 200 mL/min. Besides, overall volumetric mass transfer coefficient K L a of Pr(III) and Ce(III) are 0.519 and 0.378 s −1 at the residence time τ of 3.6 s, respectively, which reach the high level of microchannel reactors and are better than conventional extractors and other static mixers. SiC foam is found to be applicable as a static mixer for efficient and high-throughput extraction and separation of rare earths.
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NANOTECHNOLOGY
·
2020
·Vol. 31
·期 12
·125402
·
IF 3.551
Tianyun Chen,Rongrong Zhang,Bo Ye,Qinghua Yang,Huajian Xu,Lei Zheng,Longgang Wang
In this work, a cerium doped CoP nanoparticles (NPs) embedded in carbon nanotubes (CNTs) for efficient and durable hydrogen evolution was developed. The detailed preparation process was described as the followings. First, cerium was introduced into ZIF-67 to form Ce-doped ZIF-67 by a joint nucleation method. Then, the Ce-doped Co-CNTs was synthesized by carbonization of Ce-doped ZIF-67. During the process, the Co2+ was reduced to form Co NPs and the elegant nanostructure of CNTs was formed by the catalytic effect of Co NPs. Finally, by using Ce-doped Co-CNTs as the precursor, the target catalyst (Ce0.05-doped CoP CNTs) was obtained through a chemical vapour deposition (CVD) process in the presence of NaH2PO2. Results of the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the target catalyst maintained the original rhombic dodecahedron morphology of ZIF-67 and the CoP NPs were embedded in CNTs and distributed uniformly throughout the catalyst. In electrochemical measurements, the catalyst showed the best performance for HER in 0.5 M H2SO4 solution. The onset potential, Tafel slope, electron transfer resistance (Rct) and double-layer capacitance (Cdl) of the target catalyst was 49 mV, 78 mV dec−1, 19.2 Ω and 10.5 mF cm−2, respectively. Meanwhile, the catalyst yielded a current density of 10 mA cm−2 merely at an overpotential of 146 mV. Furthermore, it maintained 90% of the original current density in a chronoamperometry measurement and showed no obvious decay even after 2000 cycles scans in a long-term durability test.
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