APPLIED SURFACE SCIENCE
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2018
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IF 4.439
Lu Li,Pan Li,Yanjie Wang,Lin Lin,Aamir Hassan Shah,Tao He
The defects like oxygen vacancy in a photocatalyst are critical factors to influence the photocatalytic reactivity since they can have an impact on the behavior of photogenerated charge carrier. Since oxygen vacancy can be readily formed in the ceria due to reversible conversion of the oxidation states between Ce 4+ and Ce 3+ , here ceria is used as the target material. A versatile and facile co-precipitation method was adopted to synthesize hydrangea-like Ce 1−x Zr x O 2 (x = 0.00, 0.025, 0.05 and 0.10). The amount of oxygen vacancy in the obtained catalysts can be modulated by altering the molar fraction of doped Zr. The composition, morphology, physico-chemical properties of the as-synthesized Ce 1−x Zr x O 2 were characterized by using different techniques. It is found that Zr doping into the ceria crystal lattice can lead not only to an enhanced specific surface area and surface adsorption capacity for CO 2 , but also to an increased concentration of oxygen vacancy that can exist in the bulk and on the surface. The Zr-doped ceria exhibits an enhanced activity for photoreduction of CO 2 , which can be explained based on the influence mechanism of oxygen vacancy. This work shows that the oxygen vacancy in the ceria can be modulated via a feasible Zr doping approach, which may help design the photocatalysts with high activity for CO 2 photoreduction.
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高影响因子
FUEL PROCESSING TECHNOLOGY
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2018
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IF 3.956
Tian-qi Lei,Yan-hu Cheng,Chang-xi Miao,Wei-ming Hua,Ying-hong Yue,Zi Gao
Dehydrogenation of ethane to ethylene in the presence or absence of CO 2 over silica-doped TiO 2 supported Ga 2 O 3 catalysts was investigated. The silica doping of TiO 2 support greatly improved the dehydrogenation activity in the absence of CO 2 , which can be ascribed to the increased acid sites. The initial activity in the presence of CO 2 decreased after the silica doping, due to the reduction in reverse water-gas shift ability. However, the selectivity as well as the stability increased, resulting in higher steady ethylene yield. A dynamic process consisting of alternative oxidative dehydrogenation/regeneration cycles by gasifying the carbon deposit with air for 10 min after each cycle of 6 h reaction was also performed and relatively stable ethane conversion ~30% and ethylene yield ~25% can be achieved. The different catalytic behaviors are probably associated with the different state of gallium species, caused by the different interaction between the Ga 2 O 3 and support.
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APPLIED ENERGY
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2018
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IF 7.9
Lidong Wang,Songhua Yu,Qiangwei Li,Yifeng Zhang,Shanlong An,Shihan Zhang
The phase splitting solvent as a promising alternative to MEA for CO 2 capture has received an increasing attention due to its low energy consumption. In this paper, the mixture of diethylenetriamine (DETA) and sulfolane was employed to absorb CO 2 from the simulated flue gas . Its phase splitting behavior was investigated. The species in each separated phase were identified using nuclear magnetic resonance (NMR), revealing that the upper layer was a CO 2 -rich phase and mainly consisted of DETA and DETA-carbamate. Whereas, the lower layer was CO 2 -lean phase with the sulfolane presented individually. The CO 2 absorption kinetics was also measured in a wetted-wall column as a function of temperatures, CO 2 loadings, and gas flow rate . Their impacts on the enhancement factor and mass transfer resistance were calculated by the Vapor-Liquid Equilibria (VLE) model, implying that the main CO 2 mass transfer resistance gradually transferred from the gas side to the liquid side with the CO 2 loading increasing from 0 to 2.21 mol L −1 . During the CO 2 absorption process, sulfolane acted as an inert solvent for substituting the role of water and separated from the absorption product. Consequently, the sensible heat and vaporization heat were substantially decreased by 59% and 12%, respectively. Hence the total heat duty was lowered by 19% which might noticeably advance the CO 2 capture technology.
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Journal of CO2 Utilization
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2018
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IF 5.503
Jiaxiong Liu,Dehua He
ZnWO 4 -ZnO catalysts with different W content were prepared by conventional hydrothermal and wet impregnation methods and applied in the direct synthesis of glycerol carbonate from CO 2 and glycerol. The crystallite structure, texture property, morphology, redox and acid-base properties and the surface chemical situation of the catalysts were characterized by XRD, BET, TEM, H 2 -TPR, NH 3 /CO 2 -TPD and XPS. The possible activation routes of CO 2 and glycerol were analyzed with DRIFTS and FTIR. ZnWO 4 -ZnO composite catalysts showed better catalytic performances with respect to ZnO in the carbonylation of glycerol with CO 2 . The improved activity of ZnWO 4 -ZnO catalysts was associated with the formation of ZnWO 4 , the interaction between ZnWO 4 and ZnO, and the enhanced moderate acidic property. DIRFTS results showed that chelating bidentate carbonate species was the main adsorption pattern for CO 2 on ZnO, while the introduction of W led to the bridged bidentate carbonate, which became the main adsorption pattern on ZnWO 4 -ZnO. As for the activation of glycerol, zinc glycerolate played an important role in the reaction process. Based on the reaction and characterization results, a plausible reaction route involved a seven-membered ring esters intermediate was suggested for the reaction of CO 2 and glycerol over ZnWO 4 -ZnO catalysts.
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Advanced Materials Interfaces
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2018
·Vol. 5
·期 22
·1801015
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IF 4.834
Yang-Fan Xu,Xu-Dong Wang,Jin-Feng Liao,Bai-Xue Chen,Hong-Yan Chen,Dai-Bin Kuang
Artificially photocatalytic reduction of CO 2 into valuable chemicals, responding to the call of carbon neutral economy, has aroused considerable interests so far. Among those photocatalysts screened, an emerging and promising alternative of inorganic CsPbBr 3 perovskite has recently been reported. Here, to attain preferable photocatalytic performance, an amorphous-TiO 2 -encapsulated CsPbBr 3 nanocrystal (CsPbBr 3 NC/a-TiO 2 ) hybrid is demonstrated through a solution processing strategy. After optimizing the a-TiO 2 matrix amount by tuning the tetrabutyl titanate precursor volume, the CsPbBr 3 NC/a-TiO 2 composite exhibits a marvelous 6.5-fold improvement on the consumption of photoelectrons in photocatalytic CO 2 reduction reaction when compared with the individual CsPbBr 3 NC. Such significant enhancement is ascribed to the accelerated electron–hole separation and the multiplied CO 2 adsorption. Thus, as an available prototype, this work offers a rational encapsulation design for efficient halide perovskite photocatalyst.
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APPLIED CATALYSIS A-GENERAL
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2018
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IF 4.521
Shaozhong Li,Yu Wang,Bin Yang,Limin Guo
Mesostructured catalysts with optimized microstructure and surface properties endowed them attractive catalytic performance. Herein, the mesostructured AlCeO supports with different weight ratio of Al 2 O 3 and CeO 2 have been prepared on the basis of a self-assembly sol-gel process, then 15 wt.% Cu was loaded onto the mesostructured AlCeO supports by incipient wetness impregnation method. The mesostructured AlCeO supports with varied ratio of Al 2 O 3 to CeO 2 resulted in the very different Cu particle size, and for the optimized catalyst Cu/AlCeO-7 (the amount of Al 2 O 3 in AlCeO support was 70 wt.%), the Cu crystal size was around 7 nm based on the characterization of XRD and TEM. The Cu/AlCeO-7 catalyst had strong metal-support interactions (SMSI) and more Cu-ceria interface, which was confirmed by the XPS. Furthermore, the Cu/AlCeO-7 catalyst showed the highest exposed Cu surface area ( S Cu ) (25.5 m 2 /g cat ) from the analysis results of H 2 -TPR and dissociative chemisorption of nitrous oxide. The CO 2 -TPD results demonstrated the Cu/AlCeO-7 had strong surface basicity. Hence, Cu/AlCeO-7 catalyst showed the highest space time yield of methanol (STY MeOH ). The CO 2 conversion (Cu/AlCeO-7, V(H 2 )/V(CO 2 ) = 3/1, GHSV = 6000 mL h −1 g −1 and P = 4 MPa) was up to 22.5% at 553 K, the methanol selectivity can reach 94% at 473 K, and the STY MeOH was up to 7.2 mmol g cat. -1 h -1 at 493 K. The as-prepared mesostructured Cu/AlCeO-7 exhibited a promising catalyst candidate for CO 2 hydrogenation to methanol.
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CHEMISTRY OF MATERIALS
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2018
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IF 9.89
Lei Cheng,Yao Jiang,Shi-Chao Qi,Wei Liu,Shu-Feng Shan,Peng Tan,Xiao-Qin Liu,Lin-Bing Sun
Photoresponsive adsorbents for CO2 capture attract significant attention, because the variation of adsorption capacity can be tailored conveniently by light irradiation. However, all photoresponsive adsorbents reported until now capture CO2 via physical interaction (weak sites). Thus, the selectivity of CO2 over other gases like CH4 is low, and the variation of CO2 adsorption capacity originates from pure structural change via isomerization of photoresponsive units. Despite great challenges, photoresponsive adsorbents for CO2 capture based on chemical interaction (strong sites) are extremely desirable. Here, we report for the first time the construction of photoresponsive adsorbents with chemical adsorption sites for CO2. The control of adsorption capacity is based on the interplay between active amine sites {A, [3-(methylamine)propyl]trimethoxysilane} and photoresponsive azobenzene molecules [P, 4-(3-triethoxysilylpropyl-ureido)azobenzene]. Density functional theory (DFT) calculations reveal that the negative surface potential of amines correlate with the adsorption capacity on CO2. Upon visible light (450 nm) irradiation, trans-isomers of azobenzene are formed and interact with amines, which leads to decreased surface electrostatic potential of amines, and CO2 can thus be adsorbed freely on exposed active sites. In contrast, ultraviolet light (365 nm) irradiation results in the isomerization of azobenzene from trans to cis conformation. The surface electrostatic potential of amines increases obviously, and the active sites are thus blocked. A maximum variation amount is obtained on the adsorbent with comparable density of A and P (0.34 group nm–2), which confirms the interplay between amine sites and photoresponsive molecules. Because amines are specific active sites for CO2, high selectivity of CO2 over CH4 is obtained, and such selectivity is tunable upon irradiation with UV–vis light. We thus demonstrate the successful control of CO2 captured by chemical sites through the interplay between amines and azobenzene molecules, which is impossible or difficult to realize via conventional structural change caused by isomerization of photoresponsive units.
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ACS Applied Materials & Interfaces
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2018
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IF 8.097
Zanru Guo,Qiang Chen,Hongjian Gu,Zhanfeng He,Wenyuan Xu,Jiali Zhang,Yongxin Liu,Leyan Xiong,Longzhen Zheng,Yujun Feng
Adsorbents that are capable of controllable pollutants adsorption and release without secondary pollution are attractive in water treatment. Here, we propose eco-friendly CO2 as a trigger to switch the charge states and collapse–expansion transition of giant microgels consisting of hydrophilic acrylamide and hydrophobic 2-(diethylamino)ethyl methacrylate and demonstrated the on–off, selective, and recyclable adsorption of anionic dyes on microgels under CO2 stimulation. Apart from easy-handling separation from the water by a simple filtration process, the maximum adsorption capacity is as high as 821 mg g–1, and the adsorption isotherms and kinetics obeyed Langmuir isotherm and the pseudo-second-order kinetics models, respectively. The anionic dye can also be separated from the mixture solution using CO2-treated microgels. Moreover, a wastewater treatment prototype with microgel-packed column was fabricated. Under continuous flow condition, the dye was removed and recovered by alternative bubbling CO2 and flushing with aqueous alkali (pH 12). Thus, this type of microgels with CO2-induced protonation–deprotonation transition can serve as a cost-effective, environmentally friendly, and efficient adsorbent for water purification applications.
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PubMed
高影响因子
ENERGY & FUELS
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2018
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IF 3.024
Youan Ji,Yucui Hou,Shuhang Ren,Congfei Yao,Weize Wu
Phenols have wide applications and much commercial value, and they are obtained from oil mixtures by separation. However, the previous separation agents have low separation efficiency or corrosive halide ions or are difficult to be regenerated. In this work, we designed several tetraethylammonium amino acid (TAAA) ionic liquids (ILs) without corrosive halide ions and found that the ILs could separate phenols from oil mixtures with much higher extraction efficiency and could be regenerated using CO2. The effects of separation time, initial phenol content, TAAA type, water content in TAAA, and phenol type on separation were investigated. It has been found that TAAA can separate phenols with high separation efficiencies, and the maximum separation efficiency of phenol can reach up to 99.0% at a TAAA:phenol mole ratio of 0.60. Meanwhile, ultimate phenol contents can reach as low as 1.40 g/dm3. The initial phenol content almost has no influence on the ultimate phenol contents. For real coal tar oil mixtures, the separation efficiency of phenols can reach up to 98.6%. The TAAAs can be regenerated and reused without significant decreases in separation efficiency of phenols. The separation mechanism has also been proposed based on chemical reactions.
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JOURNAL OF MOLECULAR LIQUIDS
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2018
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IF 4.513
Yunlei Shi,Dazhen Xiong,Yongkui Chen,Huiyong Wang,Jianji Wang
Stimuli-responsive Pickering emulsions have attracted increasing interest because of the advantages of applications in numerous industrial processes. In this work, Pickering emulsions have been obtained by using negatively charged silica nanoparticles in association with very small amount of CO 2 -responsive ionic liquids as stabilizer. Ionic liquids N -alkylimidazole bicarbonates ([C n im] + HCO 3 − , n = 6, 8, 10, 12, 14) are in-situ generated by bubbling CO 2 into aqueous solution of N -alkylimidazoles (C n im, n = 6, 8, 10, 12, 14), and this process is reversible by removal of CO 2 with bubbling of N 2 . Thus the Pickering emulsions may be switched multiple times between emulsification and demulsification states by alternatively bubbling and removal of CO 2 at 25 °C. The effect of concentration and alkyl chain length of [C n im] + HCO 3 − on Pickering emulsions is investigated systematically, and the possible mechanism of CO 2 -responsive Pickering emulsion is also studied by conductivity, surface tension, zeta potential , adsorption isotherm , water contact angle and 13 C NMR spectroscopy. This CO 2 -responsive Pickering emulsion is cheap, simple, eco-friendly, and may have potential applications in emulsification and demulsification.
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ENERGY & FUELS
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2018
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IF 3.024
Chenglong Hou,Yusong Wu,Tao Wang,Xinru Wang,Xiang Gao
The substantial increase of the atmospheric CO2 concentration over the last few decades has steered toward research on direct air capture (DAC). DAC is one of the mobile-source carbon capture and storage (CCS) processes that is variant from the conventional point-source CCS in terms of easing the CO2 concentration levels and promoting negative carbon emission. We propose here a sustainable material based on the quaternization of bamboo fiber and the implication in DAC. The quaternized bamboo cellulose could adsorb CO2 at a medium relative humidity (RH) of 60–80%, with the efficiency of quaternary ammonium groups over 0.65. The CO2 capacity at higher RH strikingly decreased, which indicates the moisture-swing characteristics, and that was further validated by a desorption ratio of 0.70 under humid gas purge. The unique phenomenon that a dry atmosphere (e.g., RH < 20%) is not favored by adsorption was revealed and could be attributed to the hydrophobic feature of the sorbent inherited from natural lignocellulose. The results suggest that quaternized cellulose with a low cost may open up new possibilities for the utilization of moisture-swing CO2 adsorbents in damp circumstances.
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CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Changwei Chen,Huang Huang,Yanke Yu,Jianwen Shi,Chi He,Reem Albilali,Hua Pan
A series of hierarchical porous carbons (HPCs) with different morphologies and well-developed porosity have been successfully synthesized via a facile and flexible template-free method using hierarchical assembly of polyimide as carbon precursor. Amongst, cornflower-like hierarchical porous carbon (FC4) displays the best CO 2 capture property with an adsorption capacity up to 4.05 and 2.87 mmol g −1 at 273 and 298 K, respectively. The excellent CO 2 capture capability of FC4 can be owing to the cooperative effect of moderate meso-/macropore channels and abundant framework micropores, which are conducive to diffusion and capture of CO 2 adsorbate. Moreover, FC4 shows superior stability and recyclability and CO 2 trapping selectivity with CO 2 /N 2 initial and final adsorption ratios of 24 and 6.4, respectively. It can be anticipated that the FC4 is a promising adsorbent in the adsorption and separation of carbon dioxide under actual conditions.
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