JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 134
·期 5
·
IF 1.866
Xianwu Jing,Hongsheng Lu,Baogang Wang,Zhiyu Huang
A triblock copolymer, containing a polyethylene glycol (PEG) block and two symmetrical poly(2-(dimethylamino)ethyl methacrylate) (PDM) blocks, was synthesized by using PEG-based macroinitiator with copper-mediated living radical polymerization. The conductivity tests showed that the copolymer exhibited switchable responsiveness to CO 2 , i.e., a relatively high conductivity of solution can be switched on and off by bubbling and removing of CO 2 . According to the nuclear magnetic resonance results, the CO 2 -switchable conductivity variation could be attributed to protonation and deprotonation of tertiary amine groups in PDM blocks. Moreover, at a proper weight concentration 0.5%, the copolymer aqueous solution displayed a CO 2 -switchable viscosity variation. Scanning electron microscopy, cryogenic transmission electron microscopy, and dynamic light scattering characterization jointly demonstrated that the viscosity variation was the result of a CO 2 -switchable vesicle-network aggregate structure transition. This structure transition can actually be attributed to a hairpin-line molecular configuration conversion in terms of the reasonable mechanism discussion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44417.
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AICHE JOURNAL
·
2016
·Vol. 63
·期 1
·257-265
·
IF 2.98
Haizhou Lin,Qingang Xiong,Yuan Zhao,Jingping Chen,Shurong Wang
In this work, a green reaction system of CO 2 -water-isopropanol was developed for 5-hydroxymethylfurfural (HMF) production. The conversion of fructose in a CO 2 -water system was first investigated, and the results showed this system could promote the formation of HMF compared to a pure water system. Then, isopropanol was introduced into the CO 2 -water system and the HMF formation became better because the solvent effect of isopropanol increased the tautomeric composition of fructofuranose, which was easy to form HMF. The existence of isopropanol was found to greatly suppress secondary reactions where HMF was converted to levulinic acid and insoluble humin. Meanwhile, the effects of reaction parameters on the conversion of fructose to HMF in the CO 2 -water-isopropanol system were analyzed, and a high HMF yield of 67.14% was obtained. Finally, to further illustrate the merits of CO 2 -water-isopropanol system, productions of HMF from other carbohydrates were tested and satisfactory yields were achieved. © 2016 American Institute of Chemical Engineers AIChE J , 63: 257–265, 2017
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2016
·Vol. 81
·期 3
·844-849
·
IF 1.473
Guo Xingzhong,Ding Li,Ren Jing,Yang Hui
Abstract Nanocrystalline lithium zirconate (Li 2 ZrO 3 ) was successfully prepared by an epoxide-mediated sol–gel process. The compositions and morphologies of Li 2 ZrO 3 were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and the CO 2 capture-regeneration properties of Li 2 ZrO 3 were investigated by thermogravimetric analysis. The introduction of propylene oxide as an acid scavenger increases the pH value of the system to mediate the sol–gel transition. The as-dried xerogel is amorphous and the nano-sized Li 2 ZrO 3 crystallites with a tetragonal phase precipitate after heat-treatment at 650 °C. The nanocrystalline tetragonal-Li 2 ZrO 3 exhibits a better CO 2 capture properties, possessing an adsorption capacity as high as 21 wt.% at 550 °C and a good stability confirmed by CO 2 capture-regeneration cycles. Graphical Abstract Nanocrystalline Li 2 ZrO 3 possessing good CO 2 capture properties was successfully prepared by an epoxide-mediated sol–gel process.
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APPLIED ENERGY
·
2016
·
IF 5.746
Min Xiao,Helei Liu,Raphael Idem,Paitoon Tontiwachwuthikul,Zhiwu Liang
This work examined the relationship between the structure of various commercial tertiary amines and their activity in CO 2 absorption/desorption in terms of rate of CO 2 absorption, equilibrium CO 2 loading, p K a and heat of CO 2 absorption in order to establish possible guidelines for selection of tertiary amine components for amine blends. Results show that any electron donating group linked directly to the nitrogen atom increases their reactivity with CO 2 . In addition, the presence of steric hindrance effect and good water solubility also show enhancements in activity. In contrast, the existence of a hydroxyl group leads to a decrease in all the activity of the tertiary amine. The heat of CO 2 absorption of tertiary amines, which is closely related to the regeneration energy, can be reduced by decreasing the number of hydroxyethyl groups or by positing the hydroxyl group at the proper carbon relative to the nitrogen atom.
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TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
·
2016
·
IF 1.34
Ya-hui YANG,Ren-rui XIE,Hang LI,Can-jun LIU,Wen-hua LIU,Fa-qi ZHAN
A novel WO 3– x /TiO 2 film as photoanode was synthesized for photoelectrocatalytic (PEC) reduction of CO 2 into formic acid (HCOOH). The films prepared by doctor blade method were characterized with X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The existence of oxygen vacancies in the WO 3– x was confirmed with an X-ray photoelectron spectroscopy (XPS), and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3 h of photoelectrocatalytic reduction, the formic acid yield of the WO 3– x /TiO 2 film is 872 nmol/cm 2 , which is 1.83 times that of the WO 3 /TiO 2 film. The results of PEC performance demonstrate that the introduction of WO 3– x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO 2 into formic acid.
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CATALYSIS TODAY
·
2017
·
IF 4.636
Zhibiao Shi,Haiyan Yang,Peng Gao,Xiaopeng Li,Liangshu Zhong,Hui Wang,Hongjiang Liu,Wei Wei,Yuhan Sun
A series of TiO 2 supported Co–Cu catalysts with the weight percent of potassium oxides ranged from 0 to 3.5 wt.% were synthesized. This work investigates the influence of potassium promoter on CO 2 hydrogenation to long-chain (C 5+ ) hydrocarbons. The introduction of suitable amount of K into the CoCu/TiO 2 catalyst remarkably promoted the formation of C 5+ hydrocarbons and suppressed methane formation. The temperature-program desorption measurements demonstrate that the addition of K increases the chemisorption of CO 2 , whereas H 2 adsorption is decreased, which enhanced production of liquid fuels. However, these effects were not obvious with the addition of excess amount of K due to the slight change of surface K content. A maximum C 5+ yield with CO 2 conversion of 13% and C 5+ selectivity of 35.1 C-mol% is obtained over the CoCu/TiO 2 catalyst with 2.5 wt.% of potassium promoter loading, which also exhibits a substantial stability.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2017
·Vol. 100
·期 7
·2832-2839
·
IF 2.841
Wenhao Xia,Biyi Xu,Huanan Duan,Xiaoyi Tang,Yiping Guo,Hongmei Kang,Hua Li,Hezhou Liu
Li 7 La 3 Zr 2 O 12 (LLZO) has been reported to react in humid air to form Li 2 CO 3 on the surface, which decreases ionic conductivity. To study the reaction mechanism, 0.5-mol Ta-doped LLZO (0.5Ta–LLZO) pellets are exposed in dry (humidity ~5%) and humid air (humidity ~80%) for 6 weeks, respectively. After exposure in humid air, the formation of Li 2 CO 3 on the pellet surface is confirmed experimentally and the room-temperature ionic conductivity is found to drop from 6.45×10 −4 S cm −1 to 3.61×10 −4 S cm −1 . Whereas for the 0.5Ta–LLZO samples exposed in dry air, the amount of formed Li 2 CO 3 is much less and the ionic conductivity barely decreases. To further clarify the reaction mechanism of 0.5Ta–LLZO pellets with moisture, we decouple the reactions between 0.5Ta–LLZO with water and CO 2 by immersing 0.5Ta–LLZO pellets in deionized water for 1 week and then exposing them to ambient air for another week. After immersion in deionized water, Li + /H + exchange occurs and LiOH H 2 O forms on the surface, which is a necessary intermediate step for the Li 2 CO 3 formation. Based on these observations, a reaction model is proposed and discussed.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Ying Wang,Lina Zhang,Xiaoyan Zhang,Zizhong Zhang,Yuecong Tong,Fuying Li,Jeffrey C.-S. Wu,Xuxu Wang
A novel hollow spherical 3D structure of β-SiC with an open mouth was successfully fabricated by an environmentally friendly approach starting from ethylsilicate interaction with the P123 and glucose. The proposed growth mechanism of SiC hollow spheres was revealed step by step with SEM and XRD. When the as-prepared SiC was applied for the photocatalytic reduction of CO 2 with pure water, it was found to be highly active for the conversion CO 2 into mainly CH 4 hydrocarbon products due to its unique electronic structure, hollow morphology and high BET surface area. Moreover, the photocatalytic activity of the hollow spherical SiC can be greatly improved by loading Pt cocatalyst. The optimal 2.0 wt% Pt loading led to a stable CH 4 evolution as high as 16.8 μmol/g/h (or 376.4 μl/g/h) with the simulated solar light irradiation, which is higher than that of many reported metal oxides (Pt/TiO 2 , CdS/WO 3 , Zn 2 GeO 4 , CeO 2 and g-C 3 N 4 /NaNbO 3 et al.) under similar experimental conditions. This work provides a new strategy for the architecture of thermally and chemically stable non-metallic carbide with unique hollow spherical structure to be a potential nonmetallic photocatalyst for CO 2 reduction into CH 4 .
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Science China-Chemistry
·
2016
·Vol. 59
·期 11
·1369-1375
·
IF 2.429
Liu Shunjie,Qin Yusheng,Guo Hongchen,Wang Xianhong,Wang Fosong
Synthesis of polyols from carbon dioxide (CO 2 ) is attractive from the viewpoint of sustainable development of polyurethane industry; it is also interesting to adjust the structure of the CO 2 -polyols for versatile requirement of polyurethane. However, when renewable malonic acid was used as a starter, the copolymerization reaction of CO 2 and propylene oxide (PO) was uncontrollable, since it proceeded slowly (13 h) and produced 40.4 wt% of byproduct propylene carbonate (PC) with a low productivity of 0.34 kg/g. A careful analysis disclosed that the acid value of the copolymerization medium was the key factor for controlling the copolymerization reaction. Therefore, a preactivation approach was developed to dramatically reduce the acid value to ~0.6 mg(KOH)/g by homopolymerization of PO into oligo-ether-diol under the initiation of malonic acid, which ensured the controllable copolymerization, where the copolymerization time could be shortened by 77% from 13 to 3 h, the PC content was reduced by 76% from 40.4 wt% to 9.4 wt%, and the productivity increased by 61% from 0.34 to 0.55 kg/g. Moreover, by means of preactivation approach, the molecular weight as well as the carbonate unit content in the CO 2 -diol was also controllable.
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HIGH PERFORMANCE POLYMERS
·
2017
·
IF 1.179
Xin Fu,Xueqin Li,Ruili Guo,Jianshu Zhang,Xingzhong Cao
A series of block copolymer membranes was designed using polyetheramine (PEA) and methyl-containing polyisophthalamides (MPA) for the separation of carbon dioxide (CO2)/methane (CH4) gas mixtures. PEA consists of abundant ethylene oxide units, which show good affinity with CO2, and MPA consists of methyl (Me) substituents, which can increase the fractional free volume of block copolymer membranes. The Me substituents were introduced into MPA via polymerization from isophthaloyl dichloride (IPC), 2,5-dimethyl-1,4-phenylenediamine (DPD), and 4,4′-bis(3-aminophenoxy)diphenyl sulfone (BADS). Therefore, the CO2 solubility and diffusivity in the membranes could be improved by tailoring the PEA/MPA mass ratio and BADS/DPD mole ratio, respectively. The membrane with a PEA/MPA mass ratio of 6/4 and a BADS/DPD mole ratio of 1/10 exhibited optimum CO2 separation performance with a CO2 permeability of 629 Barrer and CO2/CH4 selectivity of 23 at 2 × 105 Pa and 25°C.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2017
·
IF 2.843
Zhuo Chen,Huadi Miao,Jiaye Wu,Yushu Tang,Wang Yang,Liqiang Hou,Fan Yang,Xiaojuan Tian,Liqiang Zhang,Yongfeng Li
The scalable production of large quantities of defect-free graphene nanosheets (GNs) with low cost and excellent properties is essential for practical applications. Despite the highly intense research of this area, the mass production of graphene nanosheets with high solubility remains a key challenge. In the present work, we propose a scalable exfoliation process for hydrophilic GNs by ball-milling-assisted supercritical CO2 exfoliation in the presence of poly(vinylpyrrolidone) via the synergetic effect of chemical peeling and mechanical shear forces. The exfoliation difficulty has been reduced due to the intercalation effects of supercritical CO2 molecules. With the ball-milling assistance, the modifier has been introduced onto the edge or/and surface of the GNs. The process results in hydrophilic GNs with little damage to the in-plane structure. The GNs can be dispersed in various solvents with a concentration of up to 0.854 mg/mL (water) and remain stable for several months.
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Catalysts
·
2025
·Vol. 15
·期 1
·95
·
IF 4
Jinghong Fang,Min Wang,Xiaotong Yang,Qiong Sun,Liyan Yu
In this study, a novel Z-scheme heterojunction photocatalyst was developed by integrating g-C3N4nanoplates into ZnIn2S4microspheres. X-ray photoelectron spectroscopy analysis revealed a directional electron transfer from g-C3N4to ZnIn2S4upon heterojunction formation. Under irradiation, electrochemical tests and electron paramagnetic resonance spectroscopy demonstrated significantly enhanced charge generation and separation efficiencies in the ZnIn2S4/g-C3N4composite, accompanied by reduced charge transfer resistance. In photocatalytic CO2reduction, the ZnIn2S4/g-C3N4composite achieved the highest CO yield, 1.92 and 5.83 times higher than those of pristine g-C3N4and ZnIn2S4, respectively, with a notable CO selectivity of 91.3% compared to H2(8.7%). The Z-scheme heterojunction mechanism, confirmed in this work, effectively preserved the strong redox capabilities of the photoinduced charge carriers, leading to superior photocatalytic performance and excellent long-term stability. This study offers valuable insights into the design and development of g-C3N4-based heterojunctions for efficient solar-driven CO2reduction.
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