JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
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2019
·Vol. 139
·期 3
·1931-1939
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IF 2.471
Qu Dezhi,Gao Hongwei,Wang Qiuxia,Bai Yongping,Li Ning
Crystallization kinetics are very important for polymeric materials due to the fact that they determine the final degree of crystallinity and the morphology of the final product after processing. The kinetic of non-isothermal crystallization of poly(butylene-co-isosorbide succinate) (PBIS) was investigated using differential scanning calorimetry. Ozawa, Jeziorny and Mo methods were used to describe the non-isothermal crystallization process of PBIS. Both the Ozawa constant and the Avrami constant were obtained by Ozawa method and Jeziorny method, respectively. The crystallization activation energy (∆ E ) for non-isothermal crystallization process of PBIS, analyze based on the differential isoconversional method of Friedman and Kissinger, was found to increase with the relative crystallinity.
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FUEL PROCESSING TECHNOLOGY
·
2019
·
IF 4.507
Ke Wang,Youwei Zhao,Peter T. Clough,Pengfei Zhao,Edward J. Anthony
Structurally modified and improved NaBr-co-doped Li 4 SiO 4 ceramics were developed for CO 2 absorption in low-CO 2 -concentration atmospheres. Pure and NaCl-doped Li 4 SiO 4 ceramics were also prepared for comparison. The samples were analyzed by X-ray diffraction, Scanning Electron Microscopy, N 2 adsorption, X-ray photoelectron spectroscopy, differential scanning calorimetry , and thermogravimetric analyses (dynamic and isothermal). The sorption kinetics were obtained using a double exponential model. The results showed that both Na and Br can be introduced into the Li 4 SiO 4 structure and doped on Li and oxygen sites, respectively. The doped sample presented a Li 2 O-enriched surface, guaranteeing abundant Li O sites and are significantly different from previous anionic (CO 3 , F and Cl) doping of Li 4 SiO 4 , Br doping also generated macroporous features with small particle size, these favorable characteristics promoted the surface chemisorption kinetics. Moreover, DSC analysis confirmed the formation of the molten phases during CO 2 absorption, which helps improve the lithium diffusion kinetics . Here, 0.1 mol NaBr doping was used to reach a maximum absorption capacity (>30.0 wt%) in 15 vol% CO 2, suggesting that NaBr-doped Li 4 SiO 4 ceramics have great potential for CO 2 capture at high temperature.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2019
·
IF 5.589
Ai-Yue Wang,Kai Sun,Liping Wu,Ping Wu,Wenchao Zeng,Zhongmin Tian,Qun-Xing Huang
Different biomass materials (walnut shell, coconut shell or cottonwood sawdust) were co-pyrolyzed with carbon-enriched oily sludge to produce aqueous phase sulfamethoxazole (SMZ) adsorption materials. The co-pyrolysis char was activated with K 2 CO 3 to modify its micro-structure and functional groups. Results show that ACs prepared from the mixture contained more mesopores than biomass-based ACs, more porous and higher yield than oily sludge-based ACs. One-step activation method was more attractive than two-step activation in larger specific surface area (up to almost 4 times), wider pore size distribution (2–3 nm), stronger SMZ adsorption ability (higher than 2 times). The maximum BET surface area was 1342 m 2 /g for the ACs prepared from the mixture of walnut shell and oily sludge by one-step activation and it had the maximum SMZ adsorption capacity up to 361.9 mg/g, which is higher than previous reported values. The capacity of SMZ adsorption of ACs was mainly attributed to pore size distribution, specific surface area and functional groups. Among them, the appropriate content of C O and C O functional groups, larger specific area and more pores range from 2 to 3 nm lead to higher adsorption capacity.
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ELECTROCHIMICA ACTA
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2017
·
IF 4.798
Miao Xu,Liang Huang,Youxing Fang,Lei Han,You Yu,Shaojun Dong
Co-based electrocatalysts were prepared by facilely low-temperature multi-step calcination using ordered mesoporous carbons (OMCs) and cobalt salt as the precursors. According to the chemical reaction of cobalt compound , the calcined product of each step could be used as different catalysts, which could complete the full water splitting in alkaline solution together. The introduction of ordered mesoporous carbon not only make the morphology was well inherited, but also enhanced the catalytic activity. The OMCs/CoP exhibited overpotential of 134 mV in acidic media and 143 mV in basic media with a current density of 10 mA cm −2 for hydrogen evolution reaction (HER). While, in basic solution, the OMCs/Co 3 O 4 had an overpotential value of 350 mV at 10 mA cm −2 for oxygen evolution reaction (OER). Moreover, the different Co-based electrocatalysts were assembled into one system for the full water splitting in 1 M KOH solution. This work provided a facile and efficient candidate for water splitting.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2017
·
IF 3.582
Yinghui Sun,Guojie Zhang,Jiwei Liu,Peiyu Zhao,Peng Hou,Ying Xu,Riguang Zhang
CH 4 CO 2 reforming to syngas was investigated over three different activated carbon catalysts. To better understand the influence of the supports on the catalytic properties , catalysts were analyzed by some characterization methods, such as nitrogen adsorption–desorption isotherms, XRD , H 2 -TPR, NH 3 -TPD, CO 2 -TPD, FTIR, TEM and EDX . The results showed that the catalyst with AC 2 as the support provided the best catalytic activity . The CH 4 conversion and CO 2 conversion were 92% and 98% at 900 °C, respectively; best selectivity with the H 2 /CO ratio was close to 1 among the three supports used. It also showed a better stability at 900 °C. H 2 -TPR analysis showed that Co species in Co/AC 2 catalyst were strong interaction with the support. It was observed that active metals were well dispersed on the AC 2 support by the TEM. In addition, the ratio of CH 4 /CO 2 also had great influence on the CH 4 and CO 2 conversion.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 38
·5780-5786
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IF 3.474
Kun Ding,Xiao Zhang,Juping Li,Ping Yang,Xin Cheng
Ultrathin α-Co(OH)2 nanosheets (NSs) were hydrothermally synthesized without using surfactants and templates. Interestingly, the ultrathin α-Co(OH)2 NSs evolved from graphene-like NSs to hexagonal nanoplates (NPs) and then transformed into a needle-like Co(CO3)0.5(OH)·0.11H2O phase with increasing reaction temperature and time. The phase and morphology evolution depended strongly on the CO32− ions in the solution. We ruled out the possibility that CO32− originated from the adsorption of CO2 in air and proposed the possible phase transition mechanism from α-Co(OH)2 to Co(CO3)0.5(OH)·0.11H2O, which was due to the decomposition of hexamethylenetetramine driven by dynamics and thermodynamics. The morphology evolution could be regarded as the dissolution–recrystallization–redissolution–recrystallization of α-Co(OH)2. The electrochemical behavior tests demonstrated that the ultrathin α-Co(OH)2 electrode exhibited an excellent specific capacitance of 833.4 F g−1 at 5 A g−1; however, the specific capacitance of the needle-like Co(CO3)0.5(OH)·0.11H2O electrode was 247.2 F g−1 at the same current density. This excellent electrochemical property is attributed to the crystalline phase and ultrathin nature of the materials.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Wenhui Li,Xiaowa Nie,Xiao Jiang,Anfeng Zhang,Fanshu Ding,Min Liu,Zhongmin Liu,Xinwen Guo,Chunshan Song
Screening of various supports reveals that Co catalysts supported on ZrO 2 and Al 2 O 3 show good initial activity for CO 2 methanation. Co/ZrO 2 and Co/Al 2 O 3 catalysts prepared by impregnation with different metal loadings were further examined comparatively. The 10Co/ZrO 2 catalyst showed high activity with CO 2 conversion of 92.5% and CH 4 selectivity of 99.9% without deactivation after 300 h time on stream (TOS). However, the 10Co/Al 2 O 3 catalyst gave a lower CO 2 conversion of 77.8% which decreased to 38.6% after 300 h TOS. The catalysts were characterized by STEM/EDS (scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy), in situ XRD(X-ray diffractometer), H 2 -TPR(temperature programmed reduction), XPS (X-ray photoelectron spectroscopy), chemisorption of H 2 , CO, CH 4 , CO 2 and NH 3 -TPD (temperature programmed desorption). Re-dispersion of Co species on the ZrO 2 support during reduction by H 2 was observed by STEM/EDS. New Co-Zr phase formed on the Co-ZrO 2 interface was directly observed by TEM for the first time; the Co/ZrO 2 catalyst exhibited high stability with high activity for CO 2 conversion. In situ XRD, H 2 -TPR and XPS results indicate the promoting effect of ZrO 2 on the reduction of Co 3 O 4 to Co metal along with the negative effect of Al 2 O 3 . The oxygen vacancies on the ZrO 2 detected by XPS may help to activate CO 2 and H 2 O and resist deactivation. Co/Al 2 O 3 catalyst deactivates rapidly due to coke deposition and spinel formation.
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Journal of Environmental Chemical Engineering
·
2017
·
IF 0
Gaoxiang Qi,Lian Xiong,Mutan Luo,Qianlin Huang,Chao Huang,Hailong Li,Xuefang Chen,Xinde Chen
Co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae was used to enhance solvents (acetone-butanol-ethanol, ABE) production from cassava without amylolytic enzymes addition. Under the simultaneous inoculation condition of C. acetobutylicum and S. cerevisiae with the inoculation level of 5% (v/v) for both strains, 21.74 g/L solvents was produced from 75 g/L cassava with the yield of 0.36 g solvents/g glucose. The solvents titer and yield obtained in the co-culture process increased by 14.3% and 9.1%, respectively, compared to those achieved in ABE fermentation. For further improvements in total solvents titer and yield from cassava, ABE fermentation and co-culture process from higher cassava concentration media were conducted. 42.56 g/L total solvents was achieved from 150 g/L cassava by co-culture with the yield of 0.46 g solvents/g glucose. The solvents titer and yield obtained in the co-culture process increased by 141.0% and 43.8%, respectively, compared to those obtained from ABE fermentation. The results showed great potential for the use of co-culture of C. acetobutylicum and S. cerevisiae for solvents production from starchy substrate.
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ACS Sustainable Chemistry & Engineering
·
2017
·
IF 5.951
Yan Gao,Lu Ye,Shuyan Cao,Hu Chen,Yanan Yao,Jian Jiang,Licheng Sun
Perovskite hydroxide CoSn(OH)6 nanoparticles were synthesized and used for the first time in the photocatalytic reduction of CO2 to CO. Under mild reaction conditions and using [Ru(bpy)3](PF6)2 as the photosensitizer, a high photocatalytic efficiency of 19.3 μmol for CO evolution with a high selectivity of 86.46% was obtained. The photocatalytic activity and CO selectivity were further improved by adding weak Brönsted acids, as proton sources, to the system.
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Molecular Catalysis
·
2024
·
IF 3.9
Rui Lu,Jiaying Luo,Xuening Wang,An Chen,Yiwen Xie,Yang Xu,Tian Shang,Ruyan Li,Dongmei Jiang,Qingfeng Zhan
In this study, an efficient Co-doped Ag 3 PO 4 photocatalyst was prepared by the deposition method. Compared with Ag 3 PO 4 , the degradation efficiency of the optimal sample CAP-2 (the mole ratio of Co/Ag was 0.057 %) for MO (20 mgL −1 ) increased from 53.4 % to 95.0 % within 20 min, and the degradation efficiency for phenol (20 mgL −1 ) increased from 57.9 % to 91.8 % within 80 min. Moreover, the CAP-2 sample performed excellent mineralization ability and stable recycling capacity. Free radical capture experiments and electron spin resonance (ESR) measurements indicated that holes (h + ) and superoxide radicals (⋅O 2− ) were the main active radicals. Doping Co ions broadened the optical absorption, introduced impurity level to promote the separation of carriers, and generated additional ⋅O 2− owing to the mutual conversion of Co 3+ and Co 2+ , thus considerably improving Ag 3 PO 4 photocatalytic performance. This work provides a new reference for doping metal ions modified semiconductor photocatalysts to efficiently degrade organic pollutants.
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Journal of Energy Storage
·
2024
·
IF 8.9
Xinpu Zhou,Shuang Wang,Guangpeng Ma,Wenyu Bai,Xianfeng Guan,Cuicui Li,Wanzhen Wu,Shuyu Zhang
Two-dimensional material MXene (Ti 3 C 2 T x ) with multilayer structures is widely used in supercapacitors , but their structures tend to pile up and limit their performance. Therefore, a strategy is provided to synthesize the random copolymer aniline- co -pyrrole (ANPY) by in-situ polymerization of aniline and pyrrole on the MXene. The self-stacking of MXene materials can be prevented, and ANPY can be used as the intermediate layer to modulate MXene nanosheets forming more ion migration channels, which can improve the electrochemical performance of ANPY/MXene. MXene is used as a “backbone” for ANPY to adjust the chain space configuration of polymer molecules. The prepared ANPY/MXene electrodes have a high specific capacitance of 451.75 F/g increasing by 39 % on the original PANI electrode. PVA/MXene gel electrolyte and ANPY/MXene electrode are assembled to form a flexible supercapacitor capable of 91.8 % capacitance retention after 5000 cycles. It suggests that the ANPY/MXene material provides a new idea for preparing supercapacitors with good electrochemical performance.
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MOLECULES
·
2024
·Vol. 29
·期 16
·3873
·
IF 4.2
Fuhua Wei,Xue Gong,Qinhui Ren,Hongliang Chen,Yutao Zhang,Zhao Liang
In this study, Co/Cd-MOFs were synthesized via a solvothermal method. The resulting material was subjected to calcination at 900 °C for 2 h and characterized using FT-IR, XRD, and SEM techniques to assess its efficacy in moxifloxacin removal. The experimental findings revealed that the maximum adsorption capacity of Co/Cd-MOFs for moxifloxacin was observed at 350.4 mg/g within a 5 h timeframe. Furthermore, the analysis based on the pseudo-second-order kinetic model demonstrated that the adsorption process adhered to this specific model. Additionally, the adsorption isotherm analysis indicated that Freundlich multilayer adsorption provided the best description of the interaction between moxifloxacin and the Co/Cd-MOF material. These experimental and theoretical results collectively suggest that employing Co/Cd-MOFs as adsorbents holds promise for wastewater treatment applications.
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