ChemCatChem
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2018
·Vol. 10
·期 19
·4438-4449
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IF 4.674
Xiaosong Hu,Wei Qin,Qingxin Guan,Wei Li
Graphical CO 2 to CO, too : CeO x promotes the activation of CO 2 and the adsorption of oxidative species, resulting in the improvement of the catalytic performances and the formation of methanol, while ZnO is favorable to the production of carbon monoxide. Both the methanol and carbon monoxide can be highly efficient produced from carbon dioxide hydrogenation relying on the synergistic effect of Cu, ZnO, and CeO x present in the CuZnCeO x catalyst. CO 2 hydrogenation will be essential for a sustainable society if methanol and CO can be efficiently obtained using appropriate catalysts. In this paper, a highly efficient CuZnCeO x catalyst was synthesized using a parallel flow coprecipitation method, and was evaluated in CO 2 hydrogenation to produce methanol and CO. Interestingly, the catalyst shows excellent activity and stability, and the selectivity of the products can be controlled by the amount of CeO x . Characterization results show that a significant synergistic effect between Cu and metal oxides (ZnO and/or CeO x ) was observed at the composite catalysts. Cu plays a critical role in the activation of H 2 , and CeO x strongly adsorbs CO 2 . CeO x improved the dispersion of Cu nanoparticles and promoted the spillover of atomic hydrogen, which was beneficial to the generation of methanol. Meanwhile, ZnO exhibited weak adsorption ability for CO 2 , which was beneficial for the generation of CO. In addition, ZnO can significantly improve the dispersion of the CeO x nanoparticles. Both the dispersion of active sites and the activation abilities of CO 2 are critical for catalyst activity and product selectivity. Thus, the ternary catalyst CuZnCeO x shows higher performance than the binary catalysts (CuZnO x and CuCeO x ) in the CO 2 hydrogenation reaction. This paper provides a viable way to produce selectively methanol or CO from CO 2 hydrogenation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Peilong Lu,Yijun Yang,Jiannian Yao,Meng Wang,Sobia Dipazir,Menglei Yuan,Jingxian Zhang,Xi Wang,Zhujun Xie,Guangjin Zhang
While converting carbon dioxide (CO 2 ) into value-added carbon products by electrolyzing offers a promising approach to mitigate global warming and store energy, poor selectivity and stability of catalysts still impede this conversion. Single-atom catalyst exhibits exceptional selectivity for CO 2 electroreduction reaction in response to inhibiting hydrogen evolution reaction (HER), which is the major obstacle to the development of CO 2 reduction. Herein we introduce a facile approach to obtain Ni-N x sites encapsulating into carbon nanotubes with a nickel loading as high as 6.63 wt%. This catalyst exhibits high Faradaic efficiency approximately 95% for CO 2 electroreduction to carbon monoxide (CO) in the wide potential range from −0.7 to −1.0 V, and the current density reaches 57.1 mA cm −2 at −1.0 V versus a reversible hydrogen electrode (RHE). Experiments and characterization results demonstrate that nickel chemical state and content play a vital role for CO 2 electrocatalytic performance. Moreover, the simplifying of the synthesis may shed a new light on design single atom catalysts of electrochemistry in addition to CO 2 reduction.
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CHINESE JOURNAL OF CATALYSIS
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2018
·
IF 3.525
Xiying Fu,Pengtao Xie,Yiwei Lian,Leqin He,Wei Zhao,Tao Chang,Shenjun Qin
A series of zwitterionic-type quaternary ammoniums (ZTQAs) with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO 2 and various terminal epoxides. The prolonged alkyl chain of ZTQAs exhibited temperature-responsive self-separation in propylene carbonate (PC). The interaction between ZTQAs and KI was confirmed by X-ray photoelectron spectroscopy and quantum chemical calculations. This interaction strengthened the nucleophilicity of the I − ion, favoring the catalytic reaction . The 3-(dimethyltetradecylammonium) propane sulfonate (DTPS)/KI showed an excellent yield of PC (95.1%) at 125 °C, 1.5 MPa, and 1 mol% loading of catalyst. The precipitate formed spontaneously from the catalytic system, providing high catalytic activity of the homogeneous catalyst, as well as easy recovery of the heterogeneous catalyst.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2018
·
IF 3.927
Kai Yang,Yan Dai,Wenji Zheng,Xuehua Ruan,Hao Li,Gaohong He
Graphene oxide (GO) has been employed as filler in mixed matrix membranes (MMMs) to enhance gas selectivity as its high-aspect ratio structure makes the path of gas diffusion longer and tortuous, improving diffusivity selectivity of gases with different molecular sizes. However, the stacking and folding structure of GO nano-sheets leads to gas barrier effects which reduce gas permeability. In this paper, a strategy of modifying continuous ZIF-8 layer with ultra-microporosity and high gas permeability on the surface of GO nano-sheets was proposed to increase the size and connectivity of gas transfer passage. ZIF-8@GO nano-sheets were successfully prepared by two-step ultrasonic synthesis method of growing ZIF-8 on GO surface at room temperature and the flexibility of nano-sheets could be easily tuned by different reaction times. CO 2 permeability of ethyl cellulose (EC)/ZIF-8@GO MMMs achieves continuous enhancement with the increased loading of ZIF-8@GO compared with pure GO based MMMs which shows rare effective improvement in CO 2 permeability. EC/ZIF-8@GO membrane containing 20 wt% fillers exhibits CO 2 permeability of 203.3 Barrer together with CO 2 /N 2 selectivity of 33.4, increased by 139% and 65% from that of pristine EC membrane respectively, and this performance is also higher than that of MMMs containing independent GO or ZIF-8. Having distinct improvement of CO 2 separation performance, the modification strategy using ultra-porosity MOFs to enhance gas transfer of 2D nano-sheets is promising for fabrication of high performance CO 2 separation membranes.
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JOURNAL OF SURFACTANTS AND DETERGENTS
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2018
·Vol. 21
·期 3
·375-387
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IF 1.454
Junlin Su,Wenxin Dong,Sulin Zhou,Mingyi Deng
In underbalanced drilling, a switchable foam fluid is essential to reduce the drilling cost. A switchable foaming agent was synthesized by carbonyl–amine condensation and characterized by Fourier transform infrared and 1 H nuclear magnetic resonance (NMR) spectroscopy. Thermogravimetric analysis and differential scanning calorimetry showed that the tolerable temperature limit of the surfactant was 128 °C. The effectiveness of CO 2 /N 2 switching was confirmed by analysis of the electrical conductivity and surface tension. Utilizing the foaming agent, 3 different foam systems (unstable, stable, and hard) were designed for drilling after formula optimization. Experimentally, the self-circulation indicated that the foaming fluids still maintained great foaming performance even after multiple cycles. The experiment also indicated that the suspension of the foam systems was 50–90 times that of water and had a significant resistance to salts (NaCl, CaCl 2 ). Besides, the foam systems found that the suitable foaming temperature was 40–100 °C and that the hard foam system could maintain the foaming performance up to 120 °C. In the oil resistance experiment, the foaming ability of the foam systems decreased obviously above a kerosene content of 5% (w/v), whereas a certain foaming performance still could be ensured below 10% kerosene.
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Inorganic Chemistry Frontiers
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2018
·Vol. 5
·期 7
·1524-1532
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IF 5.106
Jun-Hao Zhou,Da-Wei Lan,Sheng-Song Yang,Yu Guo,Kun Yuan,Lin-Xiu Dai,Ya-Wen Zhang
Bimetallic hollow structures can be efficiently used to improve the utilization of noble metals in electrocatalysts, but few studies have reported the application of bimetallic hollow nanocomposites for the electrochemical reduction of CO2. Herein, we demonstrated the synthesis of hollow Au–Cu nanoparticles of size ranging from 50 nm to 100 nm with a wall thickness of 4.95 ± 0.81 nm for efficient CO2 reduction reaction (CO2RR) via galvanic replacement and the Kirkendall effect between copper and gold. In the fabrication procedure, a gold precursor was pre-dissolved in TOP to lower the reduction potential of Au3+, which could then be reduced by Cu0. The obtained hollow Au–Cu NPs were then supported on carbon black for CO2RR measurement, and it exhibited a maximum CO FE of 53.3% at −0.7 V (vs. RHE), which was very close to that of Au NP/C, but the gold mass current density of hollow Au–Cu NP/C was much higher. The hollow Au–Cu NP/C also showed good stability in long-time measurements for CO2RR. To find out how the superior catalytic performance was achieved, hollow Au–Cu NP/C was then annealed in O2 and N2. It was found that after being annealed, the catalysts almost totally lost the activity towards CO2RR, which may be due to the partial segregation of Cu species on the nanoparticle surface as well as a decrease in the surface defect density with the improvement in crystallinity. Thus, it was concluded that high dispersion of more Au atoms on the nanoparticle surface together with the presence of more surface defect sites could account for the superior CO2RR performance of the as-synthesized hollow Au–Cu NP/C.
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Journal of Energy Chemistry
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2018
·
IF 3.886
Houfu Lv,Yingjie Zhou,Xiaomin Zhang,Yuefeng Song,Qingxue Liu,Guoxiong Wang,Xinhe Bao
Solid oxide electrolysis cell (SOEC) can electrochemically convert CO 2 to CO at the gas-solid interface with a high current density and Faradaic efficiency, which has attracted increasing attentions in recent years. Exploring efficient catalyst for electrochemical CO 2 reduction reaction (CO 2 RR) at the cathode is a grand challenge for the research and development of SOEC. Sr 2 Fe 1.5 Mo 0.5 O 6- δ (SFM) is one kind of promising cathode materials for SOEC, but suffers from insufficient activity for CO 2 RR. Herein, Gd 0.2 Ce 0.8 O 1.9 (GDC) nanoparticles were infiltrated onto the SFM surface to construct a composite GDC-SFM cathode and improve the CO 2 RR performance in SOEC. The current density over the GDC infiltrated SFM cathode with a GDC loading of 12.8 wt% reaches 0.446 A cm −2 at 1.6 V and 800 °C, which is much higher than that over the SFM cathode (0.283 A cm −2 ). Temperature-programmed desorption of CO 2 measurements suggest that the infiltration of GDC nanoparticles significantly increases the density of surface active sites and three phase boundaries (TPBs), which are beneficial for CO 2 adsorption and subsequent conversion. Electrochemical impedance spectroscopy results indicate that the polarization resistance of 12.8 wt% GDC-SFM cathode was obviously decreased from 0.46 to 0.30 Ω cm 2 after the infiltration of GDC nanoparticles.
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ENERGY & FUELS
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2018
·
IF 3.024
Chao Cai,Ning Fu,Ziwei Zhou,Mengchen Wu,Zhenglong Yang,Rui Liu
A tannic acid-Fe coordination compound has been prepared via a simple mechanochemical method. The compound could be used as precursors for the fabrication of porous carbon, which was successfully applied as adsorbent for CO2 capture. The obtained porous adsorbent, NFePC-10-A, exhibited relatively high CO2 uptake capacities of 5.8 and 3.4 mmol g–1 at 0 and 25 °C, respectively. In addition, the initial isosteric heat of adsorption and selectivity for CO2/N2 were as high as 63.16 kJ mol–1 and 22.7 (0 °C). Meanwhile, the adsorbent underwent an efficient reusability, indicating a good potential for practical use. This feasible strategy might provide a novel precursor for the large-scale production of bio-derived carbonaceous adsorbents with tailored texture and porosity for CO2 capture and storage.
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JOURNAL OF MEMBRANE SCIENCE
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2018
·
IF 6.578
Ning Zhang,Hong Wu,Fuchao Li,Shuyu Dong,Leixin Yang,Yanxiong Ren,Yingzhen Wu,Xingyu Wu,Zhongyi Jiang,Xingzhong Cao
Mixed matrix membranes (MMMs) hold great promise in overcoming the tradeoff between membrane permeability and selectivity. The rational design of fillers to well coordinate physical and chemical selectivities remains challenging. Here, we explore a heterostructured filler by in-situ growth of ZIF-8 on LDH surface (ZIF-8@LDH), which was then embedded into Pebax to fabricate MMMs for CO 2 /CH 4 separation. The proximity effect of the heterostructured filler endows MMMs with superior gas separation performance compared with the control MMMs containing single filler ZIF-8, LDH and dual fillers (where ZIF-8 and LDH are separately incorporated). On one hand, ZIF-8 and abundant hydroxyl groups on LDH afford favorable affinity toward CO 2 , significantly enhancing the physical selectivity of CO 2 /CH 4 . On the other hand, the oriented distribution of ZIF-8 on LDH elevates CO 2 concentration around LDH and increases the efficiency of CO 2 facilitated transport, leading to remarkably enhanced chemical selectivity. Particularly, the optimum separation performance is achieved for MMMs containing 2 wt% of ZIF-8@LDH with a CO 2 permeability of 1307 Barrer and a CO 2 /CH 4 selectivity of 31.6. The unique attributes of heterostructured filler may be extended to fabricate a variety of MMMs for high performance molecular separations.
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Zhong Li,Hongfeng Chen,Chong Chen,Qirui Guo,Xue Li,Yuting He,Huijuan Wang,Nengjie Feng,Hui Wan,Guofeng Guan
As a result of the low partial pressure of CO 2 in most industrial waste gases, capturing CO 2 especially at low pressure was a priority. A facile method was utilized to build mesoporous UiO-66s with adjustable pore sizes via crystal defect engineering. The mesopores were generated through the removal of instable Cu clusters and lauric acid after reaction. The pore sizes could be controlled via adjusting the molar ratios of Cu 2+ to Zr 4+ . Moreover, these meso-type UiO-66 MOFs reserved the stability after washing by HCl solution, which was more suitable for modification in harsh environment and CO 2 capture from flue gases or biogases. The most suitable dispersion of appended polyethyleneimine (PEI) inside pores was then achieved via the controllable pore sizes for CO 2 capture. The active –NH 2 from incorporated PEI could interact with CO 2 to enhance the uptake at low pressure and improve adsorption selectivities of CO 2 over N 2 and CH 4 . The high dispersion of PEI also allowed guest molecules to interact with more active sites, which enhanced the affinity between CO 2 and frameworks. The strong interaction between 50PEI@meso-UiO-66-0.2Cu and CO 2 was confirmed by higher isosteric heats of adsorption (Q st ). Even so, the CO 2 uptake of sample was without drop after five cycles, and the sample could be regenerated under a mild condition.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Meng Lu,Qiang Li,Jiang Liu,Feng-Ming Zhang,Lei Zhang,Jin-Lan Wang,Zhen-Hui Kang,Ya-Qian Lan
Photocatalytic conversion of CO 2 into energy carriers has been recognized as a highly promising strategy for achieving the virtuous carbon cycle in nature. The realization of this process depends on an efficient catalyst to reduce the reaction barrier. Herein, we report a series of transition metal ion modified crystalline covalent organic frameworks (COFs) for the heterogeneous photocatalytic reduction of CO 2 . By coordinating different kinds of open metal active species into COFs, the resultant DQTP (2,6-diaminoanthraquinone - 2,4,6-triformylphloroglucinol) COF-M (M = Co/Ni/Zn) exerts a strong influence on the activity and selectivity of products (CO or HCOOH). Significantly, DQTP COF-Co exhibits a high CO production rate of 1.02 × 10 3 μmol h −1 g −1 , while DQTP COF-Zn has a high selectivity (90% over CO) for formic acid generation (152.5 μmol h −1 g −1 ). This work highlights the great potential of using stable COFs as platforms to anchor earth-abundant metal active sites for heterogeneous CO 2 reduction.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Wenhui Li,Yi Liu,Minchen Mu,Fanshu Ding,Zhongmin Liu,Xinwen Guo,Chunshan Song
Various organic acids were investigated for preparing the highly dispersed cobalt catalysts on zirconia support, Co/ZrO 2 , by an acid-assisted incipient wetness impregnation. The organic acid-assisted preparation results in highly dispersed Co/ZrO 2 catalysts which demonstrate superior catalytic activity with only 2 wt.% Co loading for CO 2 methanation. Among the acids, the carboxylic acids with bigger molecular weight, more carboxyl groups and hydroxyl groups are more effective. Furthermore, the amino acids can also change the charge property of ZrO 2 surface through controlling the solution pH and increase the metal dispersion through strong electrostatic adsorption. It is worth mentioning that, among the numerous organic acids, citric acid-assisted preparation gives Co/ZrO 2 catalyst with superior catalytic activity and increased the CO 2 conversion from 38% to 85% with highest turnover frequency. The linear relationship between metal dispersion and TOF with the molar ratio of acid to cobalt n CA/Co ranging from 0 to 2 demonstrates the importance of well dispersed metal particles in the enhanced activity. However, when the n CA/Co value exceeds 2 and the metal particle size further decreases, but no further enhancement is observed and the CO 2 conversion even slightly decreased at the n CA/Co value of 5. The organic acids-assisted strategy can lead to increased metal dispersion and higher TOF for Co/ZrO 2 catalysts; the appropriate metal dispersion corresponds to the suitable Co-ZrO 2 interaction with oxygen vacancy which leads to more catalytically active sites for CO 2 adsorption and catalytic hydrogenation. The organic acid-assisted strategy provides a new design approach for highly dispersed and active catalysts.
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