FUEL
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2020
·
IF 5.578
Hao Sun,Kang Sun,Fei Wang,Yanyan Liu,Linfei Ding,Wei Xu,Yunjuan Sun,Jianchun Jiang
This study reports a one-step facile synthesis of a novel heterogeneous granule base catalyst, dubbed CaO/AC that contains small calcium oxide (CaO) nanoparticles embedded within hierarchical activated carbon (AC). The CaO/AC hybrid exhibited a 98.59 wt% fatty acid methyl esters yield, with 89.75% less catalyst compared to pristine CaO. In addition, the CaO/AC granular catalyst, which was easily recovered without any post-treatment, presented sustainable catalytic activity after two cycles of transesterification. The calcium cations penetrated into the cell wall of coconut shell by vacuum impregnation, and the carbonization of cell wall suppressed the agglomeration of calcium compound, which was essential for the catalytic self-activation of Ca-doped coconut shell. The pyrolysis atmosphere and dwelling time were investigated to demonstrate the dual function of calcium. Owing to the catalytic effect of Ca during the self-activation process, the hierarchical activated carbon with improved mesopores was manufactured. On the other hand, CaO nanoparticles with an average size of 14.7 nm were in-situ encapsulated within the mesopores of hierarchical carbon matrices. The additional formation of mesopores and high dispersion of CaO nanoparticles were responsible for the enhanced inner mass transfer and the number of accessible alkaline sites in transesterification of triglycerides, leading to the high catalytic activity and stability of CaO/AC.
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POLYMER TESTING
·
2020
·
IF 3.275
Lefan Li,Qiao Wang,Xiaoxu Liang,Zongjin Li,Siyao Guo,Guoxing Sun
Most studies on enhanced polymer gels look at modifying the interaction between the polymer matrix and fillers. Here, a new strategy is proposed for the fabrication of a new kind of polyacrylamide/Ca(OH) 2 nanocomposite organogel with tunable mechanical properties and temperature tolerance. By changing the solvent component, the properties of an organogel can be modulated without adding further reinforcing agent. Two commonly used organic solvents, glycerin (GL) and ethylene glycol (EG), were used in different weight ratios (GL:EG = 100:0, 70:30, 50:50, 30:70, 0:100) to achieve modulation of the organogel properties. At 25 °C the compressive strength could be regulated in the range 18–29 MPa at 95% strain, and it could be kept in the range 12–46 MPa within the temperature range −25 °C–110 °C. Increasing the proportion of GL, which has a high boiling point, the high and low temperature tolerance of the organogel was strengthened significantly. The EG served as a lubricant and enhanced the tensile recoverability from 77% to 84%. Overall, the properties of the organogel were the best when the GL:EG ratio was 70:30. The solvent-switchable organogel fabricated in this study is a good candidate for extending the field of application of gel materials.
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ENERGY & FUELS
·
2020
·
IF 3.421
Junhua Zhang,Zhaohua Qi,Yao Liu,Junnan Wei,Xing Tang,Liang He,Lincai Peng
Catalytic transfer hydrogenation (CTH) of 5-hydroxymethylfurfural (HMF) into 2,5-bis(hydroxymethyl)furan (BHMF) is an important method for the catalytic upgrading of biomass-derived platform compounds to fuels and chemicals, and the development of effective and economical catalysts for this purpose is of great significance. In this work, we designed and prepared a new carbon-nanosheets (CNS)-supported Zr/Ca bimetallic catalyst (ZrCa@CNS) with low cost by a “gel-blowing” strategy. Comprehensive studies revealed that ZrCa(2)@CNS-600 exhibited good catalytic activity on the CTH of HMF into BHMF via Meerwein–Ponndorf–Verley (MPV) reduction, and an 84.2% BHMF yield with a 91.2% HMF conversion was obtained in isopropyl alcohol at 190 °C in 10 h. ZrCa(2)@CNS-600 exhibited good heterogeneity, reusability, and stability, and it is readily recovered from the reaction mixture by filtration and consecutively recycled/reused for six times without an obvious loss in its catalytic activity.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
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IF 14.229
Sheng Guo,Haojie Wang,Wei Yang,Hussain Fida,Liming You,Kun Zhou
In this work, a cost-effective and eco-friendly calcium-doped α-Fe 2 O 3 (Ca-Fe 2 O 3 ) with abundant oxygen vacancies was fabricated using a scalable precipitation-calcination method to activate peroxymonosulfate (PMS) for wastewater purification. Density functional theory calculations revealed that the incorporation of Ca 2+ into the α-Fe 2 O 3 structure enhances the electron transfer from α-Fe 2 O 3 to PMS, facilitating the activation of PMS. The degradation of Rhodamine B by 5%Ca-Fe 2 O 3 proceeded with a reaction constant 8 times higher than that of pristine α-Fe 2 O 3 . This can be attributed to the increased generation of 1 O 2 and O 2 • − , increased specific surface area and enhanced electrical conductivity. The applicability of the 5%Ca-Fe 2 O 3 /PMS system was investigated including its operating parameters and stability, and the intermediates involved in the reaction were identified. The 5%Ca-Fe 2 O 3 /PMS system exhibited excellent degradation efficiency in natural water samples. This work opens up new perspectives for designing highly efficient catalysts and renders iron oxides potential candidates for environmental remediation.
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INTERNATIONAL JOURNAL OF THERMOPHYSICS
·
2018
·Vol. 39
·期 5
·1-11
·
IF 0.829
Fan Desong,Sun Si,Guo Li
A novel thermal control coating was presented based on the thermochromism of manganite. The pigment of K-doped manganite nanoparticles was dispersed into polymer matrix to prepare the coating with curing below 200 \(^{\circ }\) C. The nanoparticles size mainly distributes around 100–200 nm, and it shows a comparable stoichiometric ratio. The phase transition of the nanoparticles was observed from ferromagnetic metallic to paramagnetic insulator state. With increasing K doping level, the phase transition temperature increases, achieving controllable adjustment. Coating surface with and without pore defect was obtained by different polymer matrix. A sharp emittance variation was observed with increasing temperature in K-doped coating. The variation magnitude of emittance is up to 0.46, which is attractive to space thermal control. It is suggested that the pigment content of 50 wt% is sufficient to realize a large emittance variation.
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Journal of Materials Chemistry C
·
2018
·Vol. 6
·期 47
·12879-12887
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IF 5.976
Zhuang Li,Fei Liang,Yangwu Guo,Zheshuai Lin,Jiyong Yao,Guochun Zhang,Wenlong Yin,Yicheng Wu,Chuangtian Chen
Demands for UV birefringent materials are growing dramatically owing to the rapid development of ultraviolet technology. Here, a new family of UV birefringent materials, Ba2Mg(C3N3O3)2 (BMCY) and Ba2Ca(C3N3O3)2 (BCCY), have been successfully discovered. It is the first time that the excellent birefringent properties of cyanurates have been studied. These materials exhibit an extremely large birefringence (Δn = 0.728–0.351 and 0.771–0.346 from 230 nm to 800 nm for BMCY and BCCY, respectively), much larger than that of the commercial UV birefringent crystal α-BaB2O4 (α-BBO) (Δn = 0.12@532 nm). Our study indicates that the impressive optical properties of BMCY and BCCY stem from the strengthened optical anisotropy of the planar (C3N3O3)3− group compared with the isoelectronic (B3O6)3− group. Besides, its congruent-melting properties make it feasible to grow a bulk crystal by the Bridgman–Stockbarger technique. The extraordinary properties of BMCY and BCCY may shed light on a new path to explore birefringent materials for practical application.
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PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
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2018
·Vol. 215
·期 11
·1701061
·
IF 1.795
Binrong Li,Jinyu Chu,Yi Li,Minjia Meng,Yanhua Cui,Qidi Li,Yonghai Feng
Photocatalytic degradation is an effective method for fast removal of dye-contaminated water. In the present work, a bismuth oxide/zinc sulfide-cellulose acetate photocatalytic membrane (Bi 2 O 3 /ZnS-CA) is successfully fabricated via the phase-inversion method with a Bi 2 O 3 /ZnS heterojunction as the photocatalyst. The Bi 2 O 3 /ZnS-CA membranes shows high photocatalytic activity in degradation of Rhodamine B (RhB) under visible-light irradiation due to the Bi 2 O 3 /ZnS heterojunction structure contributing to the high efficiency of photogenerated charge separation. The photodegradation efficiency of Bi 2 O 3 /ZnS-CA membrane is significantly enhanced (about 30% improvement) and the photodegradation kinetic is four times faster than that of the Bi 2 O 3 -CA and the ZnS-CA membranes. Moreover, the Bi 2 O 3 /ZnS-CA membrane exhibits excellent permeation flux (649.7 L m −2 h −1 ) and high porosity (69.94%). The Bi 2 O 3 /ZnS-CA membrane also shows good adsorption performance of RhB, which could enhance the interaction between RhB and the catalyst. This work provides a new sight to construct highly effective visible-light-driven photocatalytic membranes for continuous organic dye treatment.
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NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 24
·15072-15078
·
IF 3.269
Lihua Wang,Huan Yang,Jiazi Hou,Wanxi Zhang,Chunhui Xiang,Lili Li
Core–shell structured cellulose acetate-polycaprolactone/chitosan (CA-PCL/CS) composite nanofibers were electrospun via coaxial electrospinning. Different solvents were used in core solutions, which led to different electrical conductivities in core solutions. The effect of the electrical conductivity on the morphology and structure of core–shell fibers was studied emphatically. As shown in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, the increasing electrical conductivity of core solutions would result in smaller diameter ratios of core to shell, thinner overall diameters and more inhomogeneous diameter distributions. Additionally, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) all demonstrated that the interactions between cores and shells weakened with the increase of electrical conductivity of core solutions, and this might lead to different diameter ratios of cores to shells in the fibers. The results provide a basis for further design and optimization of processing conditions to control the nanostructure of core–shell composite nanofibers.
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ACS Catalysis
·
2024
·
IF 11.3
Jinsong Luo,Tianci Xiao,Wu Wen,Jun Bao,Chengyuan Liu,Yang Pan
The pursuit for higher light olefin selectivity and extended catalyst lifetime has been a hot topic in the methanol-to-olefins (MTO) process. The incorporation of Ca in HZSM-5 (Ca-modified HZSM-5) could exhibit outstanding catalytic stability and high C3+ olefins yield. In this work, synchrotron radiation photoionization mass spectrometry was applied to study the lifetime enhancement mechanism of Ca-modified HZSM-5. It is interesting to note that the mechanism differs in the cases of different Ca-loading. Under low Ca-loading, the main reason for lifetime enhancement is the modification of acid sites, which limited hydrogen transfer reactions and subsequent coking process. While higher Ca-loading would introduce CaO species over HZSM-5, which showed prominent activity for HCHO elimination. The decomposition of HCHO would suppress the HCHO-mediated aromatic formation pathway during the MTO process, therefore alleviating the coking process. Moreover, the elimination mechanism of HCHO over CaO was investigated using in situ IR measurements. This study provides some additional insights into the role of acid sites and CaO during the Ca-modified HZSM-5 catalyzed MTO process.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Qing Sun,Jiao Yan,Xiaofang Hu,Jiale Yu,Jian Zhang,Jiawei Sheng
A facile urea-assisted hydrothermal method was developed for synthesizing Co(Ca)-silicate nanosheets@13X (CoCa-13X) as catalyst materials for peroxymonosulfate activation. Urea gradually dissolves 13X to form the silicate anion, and anchors Co 2+ ions to the surface of 13X, while introducing Ca 2+ ions to form in situ Co/Ca-silicates. The degradation efficiency and reusability of the compound catalyst for metronidazole (MNZ) were investigated. The results demonstrated that at an initial concentration of 25 mg/L, the CoCa-13X-PMS system exhibited excellent catalytic degradation performance towards MNZ, and the degradation rate reached 99.52 % within 5 min. Furthermore, the CoCa-13X-PMS system maintained high catalytic activity against various organic pollutants and even at high concentrations of pollutants (up to 30 mg/L). Free radical quenching experiments revealed simultaneous participation of SO 4 • – and 1 O 2 in the oxidation process simultaneously. Additionally, the degradation mechanism and pathway of MNZ were studied and proposed, along with evaluation of biotoxicity associated with its degradation intermediates. This method offers a novel strategy for synthesizing silica zeolite-based cobalt catalysts with exceptional PMS activity for removal of organic pollutants.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Haichuan He,Xiao Yu,Wei Wang,Liu Deng,Hao Zeng,Liqiang Wang,Ke Zeng,Jianhan Huang,Minghui Yang,You-Nian Liu
Bismuth-based materials have emerged as promising electrocatalysts for the electrochemical reduction of carbon dioxide (eCO 2 RR) to HCOOH. However, it remains challenges to meet the practical application requirements and identify the active sites of bismuth-based catalysts in eCO 2 RR. Herein, bismuthate (MBi 2 O 4 , M = Ca, Cu, Zn) derived nanosheet-like electrocatalysts with metal-modified edge defects are developed. During electrochemical processes, MBi 2 O 4 pre-catalyst undergoes surface reconstruction to expose more active Bi 0 sites and to form abundant metal-modified edge defects, which facilitate the modulation of charge state of adjacent Bi sites and improve the adsorption of *OCHO intermediate, thereby enhancing the selectivity of eCO 2 RR towards HCOOH. The Ca-modified defect-rich Bi catalyst exhibits a maximum HCOOH Faradaic efficiency of 94.3 % at an industrially relevant current density of 400 mA cm −2 , together with high stability/reproducibility of 55 h. This work proposes a new strategy for construction of Bi-based catalysts and explores its structural reconstruction mechanism during the electrocatalytic process, opening a new window for design of eCO 2 RR catalysts.
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POLYMER TESTING
·
2017
·
IF 2.464
Jing Cao,Na Wen,Yuying Zheng
Ca-montmorillonite (Ca-MMT) was first modified with different amount of two different kinds of surfactants to obtain organo-montmorillonites (OMMTs) directly via ion exchange between Ca 2+ and alkyl ammonium cations. Then remained Ca 2+ in OMMTs was reacted with pimelic acid (HA) to obtain CaHA-OMMTs. PP/CaHA-OMMT composites were prepared. Results of FT-IR demonstrate the existence of long-chain alkyl in OMMTs, and CaHA in CaHA-OMMTs. The reaction between HA and OMMT could lead to an increase in d-spacing value of clay. CaHA-OMMTs with high CaHA contents and obviously increased d-spacing values were obtained. Results of WAXD and TEM show exfoliated clay platelets in PP/CaHA-OMMT composites. The obviously increased T c , and the high β-phase content in PP/CaHA-OMMT composites demonstrate the high β-nucleation efficiency of CaHA-OMMTs. Composites with higher content of β-phase epitaxial crystallized on exfoliated clay platelets display largely improved impact strength .
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