CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Hanbang Liu,Liping Yang,Danhua Yuan,Guangye Liu,Jiacheng Xing,Yunpeng Xu,Zhongmin Liu
For air separation, the separation method relying on adsorbents has attracted wide attention as a low energy consumption process, and the development of O 2 -selective adsorbents is of great significance. Metal-organic frameworks with coordinatively unsaturated transition metal sites have great potential in O 2 -selective adsorption, but most of them cannot be completely regenerated at ambient temperature or can only be effective at very low temperatures. Herein, we report two mixed-ligand metal–organic framework adsorbents [M(AIP)(BPY) 0.5 ·H 2 O] n ·2nH 2 O with coordinatively unsaturated cobalt(II) and nickel(II) sites, which can preferentially adsorb O 2 versus N 2 , and their IAST O 2 /N 2 selectivities are both significantly greater than 1 at 25 °C. These materials exhibited excellent stability and had no loss of adsorption capacities even after immersion in water for 7 days. More importantly, O 2 adsorption–desorption cycle experiments showed that these adsorbents can be completely regenerated at ambient temperature after adsorbing O 2 , and the breakthrough experiments further confirmed their dynamic O 2 /N 2 separation potential and regeneration ability. The results of theoretical calculations suggested that the interactions between adsorbents and O 2 are stronger than those of N 2 , and they have relatively obvious differences in the N 2 and O 2 interaction energies. This work provides inspirations for searching for metal–organic frameworks that can selectively adsorb O 2 at ambient temperature.
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INORGANICA CHIMICA ACTA
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2022
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IF 3.118
Wei Wang,Jing-Zhe Li,Shi-Jian Luo,Zi-Xuan Yao,Kuan-Guan Liu
Using the atomic precisely structurally characterized clusters as electrocatalysts can provide some possible structure information about the active intermediate during the electrocatalytic N 2 reduction reaction (NRR) process. A Cu4 cluster, named [(bpy) 4 Cu 4 (C 10 H 8 SO 3 ) 4 (OH) 4 ]•4H 2 O ( 1 ), has been synthesized and fully characterized by IR, SXRD, XPS, EPR, et al. Single crystal structural analysis reveals that the core structure of the cluster has a step-scheme conformation with two μ 2 -OH and two μ 3 -OH groups. Electro-catalysis studies of this cluster show that it can achieve a highest NH 3 yield of 2.18 μg h −1 mg −1 and a FE of 0.97 % at −0.6 V. The excellent NRR performance may be attributable to the additional μ 3 -OH groups, based on the contrastively study of the other electrocatalysts of the Cu powder and the Cu 2 complex, named [(μ 2 -OH)(μ 2 -Cl)(bpy) 2 Cu 2 Cl 2 ] ( 2 ), with one μ 2 -OH group in its structure. This work provides some structure information about the possible active sites during the NRR process and inspires us to develop new cluster as efficient electrocatalysts for advancing sustainable NH 3 production. Using the atomic precisely structurally characterized clusters as electrocatalysts can provide some possible structure information about the active intermediate during the electrocatalytic N 2 reduction reaction (NRR) process. A Cu4 cluster, named [(bpy) 4 Cu 4 (C 10 H 8 SO 3 ) 4 (OH) 4 ]•4H 2 O ( 1 ), has been synthesized and fully characterized by IR, SXRD, XPS, EPR, et al. Single crystal structural analysis reveals that the core structure of the cluster has a step-scheme conformation with two μ 2 -OH and two μ 3 -OH groups. Electro-catalysis studies of this cluster show that it can achieve a highest NH 3 yield of 2.18 μg h −1 mg −1 and a FE of 0.97 % at −0.6 V. The excellent NRR performance may be attributable to the additional μ 3 -OH groups, based on the contrastively study of the other electrocatalysts of the Cu powder and the Cu 2 complex, named [(μ 2 -OH)(μ 2 -Cl)(bpy) 2 Cu 2 Cl 2 ] ( 2 ), with one μ 2 -OH group in its structure. This work provides some structure information about the possible active sites during the NRR process and inspires us to develop new cluster as efficient electrocatalysts for advancing sustainable NH 3 production.
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Journal of Materials Chemistry A
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2021
·Vol. 9
·期 32
·17442-17450
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IF 12.732
Yintong Zhang,Feng Du,Ruyi Wang,Xintong Ling,Xiaoyong Wang,Qing Shen,Yujie Xiong,Tao Li,Yong Zhou,Zhigang Zou
The electrocatalytic nitrogen oxidation reaction (NOR) is a promising alternative to the industrial synthesis of nitrate. However, with the enhancement of NOR activity by modification methods, the competitive oxygen evolution reaction (OER) is always improved simultaneously. Here, a hybrid electrocatalyst composed of Au nanoparticles and oxygen vacancy-enriched niobium oxide nanobelts (Au–Nb2O5−x) was prepared on niobium foil for N2 fixation into NO3−. The results of X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) demonstrate that electron transfer occurs between Au nanoparticles and the oxygen vacancies in Nb2O5−x nanobelts, which adjusts the electronic structures of oxygen vacancies near the Au/Nb2O5−x interface. Electrochemical and N2 temperature-programmed desorption (TPD) tests indicate that the optimization of the electronic structure suppresses the activity of the competitive OER on oxygen vacancy sites and facilitates nitrogen adsorption on the surface of Au–Nb2O5−x, which significantly enhances the NOR performance of the electrocatalyst.
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REACTIVE & FUNCTIONAL POLYMERS
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2019
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IF 3.074
Xing Yang,Yayun Zheng,Lan Wang,Qingping Guo,Haiquan Shan,Zongxiang Xu,Jujie Luo
This work involves the preparation and characterization of poly(styrene-b-isoprene-b-styrene)-poly(dimethylsiloxane- co -methylhydrosiloxane) (SIS-c-PDMS-co-PMHS) crosslinked membranes towards CH 4 /N 2 separation. SIS-c-PDMS-co-PMHS was synthesized via a simple hydrosilylation reaction with various PDMS-co-PMHS contents. The structure of crosslinked membranes was investigated by Fourier transform infrared spectroscopy , indicating the degree of hydrosilylation reaction. The morphology of sample membranes was observed in detail by means of Scanning Electron Microscope analysis . Thermodynamic stability and the crosslinked behavior of crosslinked membranes were explored by thermogravimetric analysis and Soxhlet extraction experiments. Furthermore, single gas (CH 4 , N 2 ) permeability was measured using the time-lag method. The CH 4 permeability of crosslinked membranes with 70 wt% PDMS-co-PMHS could reach 503 Barrer at 25 °C and 1 bar, which is significantly greater than that of SIS (25.9 Barrer), while the CH 4 /N 2 ideal selectivity hardly changed. Notably, CH 4 permeability further improved by 77.6% (893.4 Barrer) as the temperature increased to 55 °C. For the CH 4 /N 2 (50/50 vol%) mixed gas, the SIS-c-PDMS-co-PMHS-70 sample membrane exhibited ideal gas separation performance relative to that of the pure SIS membrane (CH 4 : 447.4 vs. 24.2 Barrer，N 2 : 188.1 vs. 9.46 Barrer).
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2013
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IF 2.206
Jiangfeng Yang,Junmin Li,Wei Wang,Libo Li,Jinping Li
Three hydrophobic microporous high-silica zeolites, DDR (with an 8-membered ring), silicalite-1 (a 10-membered ring), and beta (a 12-membered ring) were synthesized. The Si/Al ratios were 230, 1350, and 35, respectively. The samples were characterized by X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis, water vapor adsorption, and volumetric nitrogen adsorption. They were tested for their CO2, CH4, and N2 adsorption properties at pressures of up to 10 bar at 288–313 K after activation, and the results were correlated with the Langmuir model. The heat of adsorption was calculated using the Clausius–Clapeyron equation based on the adsorption isotherms. These data were used to estimate the separation selectivities for CO2/CH4 and CH4/N2 binary mixtures at 298 K, using the ideal adsorbed solution theory (IAST) model. Experimental results showed that DDR and beta have good selectivities for CO2/CH4, because they have narrow pores (DDR) or more balance metal ions (relatively low Si/Al ratios beta) effect separately. The synthesized silicalite-1 has the lowest SCO2/CH4 but has the most suitable orifices for methane adsorption and the highest SCH4/N2. In addition, the breakthrough data for CH4/N2 mixtures further indicates that silicalite-1 is more suitable for the CH4 enrichment than the commercially used sorbents zeolite-5A and 13X. From the reproducibility of CH4 and N2 adsorption isotherms on silicalite-1, we can infer that which has the potential to be a commercial sorbent by the stable adsorption properties.
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Sustainable Materials and Technologies
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2024
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IF 8.6
Lei Guo,Yan-He Chen,Li-Mei Xu,Xiao-Lu Chen,Jin-Qiu Shen,Jian-Yong Zhang,Zhen-Jiang Liu
Herein, a fern-like p-n heterojunction by anchoring Ni 3 Fe-LDH nanoplates onto Co 3 O 4 nanoneedles have been optionally constructed. Essentially, p-n heterojunction ensured to induce strong built-in electric field, and inherit interfacial electron redistribution. Based on their compatible and well-matched electronic band structures, a staggered type-II photo-generated electron/holes transfer pathway have been elaborated by density functional theory calculation (DFT), in situ irradiation X-ray photoelectron spectroscopy (XPS), and fluorescent decay. This band bending and charge migrating module conferred the architecture with strong redox ability, sufficient exciton dissociation, and admirable optoelectronic characteristics. Moreover, the heterostructure acquired broad absorption spectrum to exhibit outperforming photocatalytic effect. Totally, this electron redistribution at the hierarchical interface, a type-II scheme charge-transfer pathway and the oxygen defects would lead to high efficiency in solar light assisted N 2 reduction. Typically, Co@Ni 3 Fe-2 catalyst exhibited the highest NH 3 production rate of 16.15 μg h −1 mg cat. −1 and Faraday efficiency (FE) of 31.57% at −0.6 V vs. RHE in 0.1 M Na 2 SO 4 solution. Fortunately, with light exposure, the NH 3 production rate and FE could increase by 27.9% and 18.1% than that under dark. This work would provide a plausible attitude towards the design of high efficient photocatalyst for artificial photosynthesis with multi-functionalized coupling effect.
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JOURNAL OF MEMBRANE SCIENCE
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2024
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IF 8.4
Caifeng Xia,Qikang Yin,Xinle Sun,Qinglong Liu,Sen Liu,Shuxian Wei,Siyuan Liu,Weifeng Lv,Zhaojie Wang,Xiaoqing Lu
As a unique polymer of intrinsic microporosity, PIM-1 has great potential in mixed matrix membranes (MMMs) for gas separation with ultra-high permeability. However, the separation performance, e.g. CO 2 /N 2 separation, is still limited by its poor selectivity. In this work, PIM-1-based MMMs containing tartaric acid anion intercalated layered double hydroxides (TA-LDH) nanofillers are successfully prepared. The uniformly dispersed TA-LDH in the PIM-1 matrix contributes to optimizing the stacking of polymer chains for accessible pores, which is conducive to CO 2 diffusion. In addition, the assistant experiment and theoretical calculation point out that the -COO - , –OH between the TA-LDH layers had an affinity for CO 2 , creating a two-dimensional fast transport channel between the enlarged interlayer space. Compared with the pristine PIM-1 membrane, the CO 2 permeability and CO 2 /N 2 selectivity of 0.7 % TA-LDH/PIM-1 membrane is increased by 43.19 % and 105.48 %. The excellent gas separation performance with CO 2 permeability of 8343.18 Barrer and CO 2 /N 2 selectivity of 39.02 exceeds the 2019 Robson upper limit. This paves a new way to improve the gas separation performance of PIM-1-based MMMs and suggests high perspectives for real applications.
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JOURNAL OF MEMBRANE SCIENCE
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2020
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IF 7.183
Rong Rong,Yanwei Sun,Taotao Ji,Yi Liu
Zirconium-based MOF (Zr-MOF) membranes have attracted widespread attention due to their highly tailorable pore aperture and adsorption behavior achieved by functional group decoration and ligand/cluster-missing defect regulation as well as extraordinary chemical/thermal stability. Nevertheless, it has remained a great challenge to further improve the separation performance of Zr-MOF membranes due to very limited available zirconium sources and heating modes. In this study, we prepared polycrystalline UiO-66 membranes exhibiting unprecedented CO 2 /N 2 selectivity (31.3). The use of layered ZrS 2 , a representative of transition-metal dichalcogenides (TMDCs), as zirconium source during tertiary solvothermal growth was found to be indispensable for improving the separation performance of UiO-66 membranes. As far as we know, the CO 2 /N 2 selectivity reported in this study was the highest among all pristine polycrystalline MOF membranes measured under ambient conditions. More importantly, our study highlighted the importance of concurrent metal source and fabrication process innovation in performance enhancement of polycrystalline MOF membranes.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2023
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IF 4.2
Yang Li,Mingyuan Li,Zhihong Lin,Moris S. Eisen,Dario R. Dekel,Xuezhong He
An ultrathin amine-rich selective layer comprising the fixed-site carrier from polyvinylamine (PVAm) and the mobile carrier with an amino acid salt was successfully coated on top of the polysulfone (PSf) substrate for enhanced CO2-facilitated transport. PVAm with an ultrahigh molecular weight was synthesized via the inverse emulsion polymerization method, which allows the excellent dissipation of the reaction heat and reduces gel formation drastically. Several batches of PVAm with different hydrolysis degrees and molecular weights were successfully synthesized. The mobile carriers of 2-(1-piperazinyl)ethylamine salts of sarcosine (PZEA-Sar) were synthesized and introduced to strengthen the facilitated transport contribution, while cellulose nanocrystals (CNCs) were incorporated into the polymer matrix to enhance the mechanical strength and also increase the free volume of the polymer matrix. The amine-rich composite membranes made from 0.5 wt % PVAm/PZEA-Sar-0.5 wt % CNC with a high-molecular-weight PVAm of 4.4 MDa at a degree of hydrolysis (DOH) of 78% demonstrate a significantly enhanced CO2 permeance of 160 GPU with a good CO2/N2 selectivity of 48 at 35 °C and a feed pressure of 2 bar. The developed amine-rich facilitated transport membrane shows excellent potential for industrial carbon capture.
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CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Zhiang Hou,Jiangfeng Chu,Cong Liu,Jinnan Wang,Aimin Li,Tong Lin,Corvini Philippe François-Xavier
Photocatalytic denitrification has attracted great attention owing to its high efficiency and environmentally friendly features. However, selectively photocatalytic reduction of high concentration nitrate to N 2 is still a challenging problem due to the competition of photons between nitrate and photocatalysts. Herein, the Ag/SiO 2 core encapsulated in the crystalline TiO 2 shell (Ag/SiO 2 @ c TiO 2 ) was constructed for improvement of photocatalytic denitrification. Finite difference time domain (FDTD) simulation demonstrated that strong light scattering improved light harvesting via optical confinement. Meanwhile, surface plasmon resonance and electron sink effect of Ag not only enhanced the photogenerated electrons density but also promoted charge carriers separation of Ag/SiO 2 @ c TiO 2 . More importantly, e cb − of TiO 2 -shell could be immediately transferred to Ag to keep the balance between Ag 0 and Ag + , which contributed to the good stability of Ag/SiO 2 @ c TiO 2 . 95.8% nitrate ( C 0 = 2000 mg/L) was removed by 5 wt%Ag/SiO 2 @ c TiO 2 with N 2 selectivity of 93.6% within 4 h. Even after five cycles, 5 wt%Ag/SiO 2 @ c TiO 2 still remained high photocatalytic denitrification efficiency (92.2%). Notably, since TiO 2 -shell prevented the reaction between Ag and Cl − , more than 92% nitrate could be removed within 5.3 h in the presence of high concentration Cl − .
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APPLIED SURFACE SCIENCE
·
2021
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IF 6.707
Xiaofeng Wang,Zhe Zhao,Yang Xu,Qingbo Li
A series of 3DOM-Mn x Ce y Ti z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn 3 Ce 1 catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO x resulted in the nonselective oxidation of NH 3 and generation of N 2 O, decreasing the N 2 selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn 3 Ce 1 Ti 1 catalyst decreased, and the NH 3 were strongly adsorbed on the acid sites, which enhanced the N 2 selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h −1 . Furthermore, both the 3DOM-Mn 3 Ce 1 and 3DOM-Mn 3 Ce 1 Ti 1 catalysts showed remarkable tolerance of H 2 O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn 3 Ce 1 Ti 1 catalyst.
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CHEMICAL ENGINEERING JOURNAL
·
2018
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IF 6.735
Chuanzhi Sun,Hao Liu,Wei Chen,Dezhan Chen,Shuohan Yu,Annai Liu,Lin Dong,Shuai Feng
A series of Sm- and/or Zr-doped MnO x -TiO 2 catalysts were prepared, and the catalysts exhibited better N 2 selectivity and SO 2 resistance than the undoped MnO x -TiO 2 catalyst for the selective catalytic reduction of NO by NH 3 (NH 3 -SCR). The reasons for the good N 2 selectivity and SO 2 resistance of the catalysts were proposed. X-ray photoelectron spectroscopy (XPS) combined with density functional theory (DFT) calculations suggested that electron transfer between the manganese and samarium species by Mn 4+ + Sm 2+ ↔ Mn 3+ + Sm 3+ redox cycles occurred in the Sm-containing catalysts. Furthermore, electron transfer from Sm 2+ to Mn 4+ suppressed electron transfer from NH 3 to Mn 4+ , inhibiting the formation of NH 2 or NH. Thus, the pathway for NH generation was removed, and the reaction of 2NH + 4NO → 3N 2 O + H 2 O was prevented. Consequently, the N 2 selectivity of the NH 3 -SCR reaction was enhanced. In situ diffused reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) combined with thermogravimetry, differential scanning calorimetry and mass spectrometry (TG-DSC-MS) results revealed that the deposition rate of sulfate species decreases after Sm doping, which was also attributed to the suppressed electron transfer from SO 2 to Mn 4+ , i.e., the oxidation of SO 2 to SO 3 . Thus, the catalysts exhibited better SO 2 resistance.
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