CATALYSIS COMMUNICATIONS
·
2019
·
IF 3.674
Feng Wang,GuoQin Qi,ChuanQi Zhang,HeCheng Ren,Hua Ma,Yu Guo
A series of Na-doped Pt/Al 2 O 3 catalysts with 0.2 wt% of Pt loading and 0–6 wt% Na loading was prepared to investigate the HCHO complete oxidation at room temperature. Powder XRD, BET and XPS were used to characterize the bulk structure and texture of catalysts, as well as the ratio of hydroxyl oxygen to lattice oxygen. A long-term catalyst stability test (50 h on reaction stream) was conducted under severe conditions of a large space velocity of 180,000 mL/h/g, a high HCHO concentration of 80 ppm and dry conditions (relative humidity of 0%). An appropriate amount of doped-Na (2 wt%) contributed to a remarkable improvement of activity and stability of the Na-doped 0.2 wt% Pt/Al 2 O 3 catalyst.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2018
·
IF 2.196
Xiancai Jiang,Xiaotong Xiang,Haifeng Hu,Xiangchao Meng,Linxi Hou
In this research, pristine and boron-doped biochar/Al2O3 adsorbents for fluoride removal from aqueous solutions were prepared by employing chitosan (CS), poly(vinyl alcohol) (PVA), and AlCl3·6H2O as the raw materials. CS was dissolved in AlCl3·6H2O aqueous solution, and the CS/PVA aerogel was prepared by a freezing process. The biochar/Al2O3 was obtained by the carbonization process at high temperature. AlCl3·6H2O was used as both the solvent for CS and the source for Al2O3. The structure of biochar/Al2O3 was characterized by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The adsorption performance of biochar/Al2O3 for fluoride was evaluated by the batch adsorption experiment. Furthermore, the effect of HBO3 cross-linking on the adsorption property of biochar/Al2O3 was studied. The results showed that the HBO3 cross-linking process would promote the adsorption performance of biochar/Al2O3. The adsorption kinetics and equilibrium properties are well-described with a pseudo-second-order equation and Freundlich model, respectively. The Qe for biochar/Al2O3 could reach 196.1 mg/g. The high adsorption capacity would enable the biochar/Al2O3 to be useful for real contaminated water treatment. This paper provides a valuable and economic solution for the utilization of CS.
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APPLIED CATALYSIS A-GENERAL
·
2018
·
IF 4.521
Yiqi Xu,Yishu Jiang,Hao Xu,Qingtao Wang,Weimin Huang,Haihua He,Yuanyuan Zhai,Shuxia Di,Lingling Guo,Xiaoliang Xu,Jia Zhao,Feng Feng,Qunfeng Zhang,Xiaonian Li
Designing the electron-rich palladium active site is of great importance to enhance the selectivity of ethylene in acetylene semi-hydrogenation. In this work, ionic liquids, the effective electronic modifier, were mingled with palladium solution to be immobilized on Al 2 O 3 by incipient impregnation method. X-ray photoelectron spectra characterization was conducted to characterize the structure of catalysts, suggesting that some ionic liquids can form unique carbene structure. The catalytic results showed that those immobilized ionic liquids that can form unique carbene structure exhibited much higher selectivity of ethylene than those cannot. The above results were obtained because carbene can donor the electron to palladium, enriching the electron density of palladium and therefore facilitating the desorption of ethylene. The findings of the unique carbene structure derived from ionic liquids in this work provide an efficient strategy to design the catalyst to improve the selectivity of the intermediate in other partial hydrogenationreactions.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Xiaoxuan Pang,Yajiang Xian,Wei Wang,Pengcheng Zhang
Aluminum matrix Boron carbide composites is an important thermal neutron shielding material. In order to prepare 12 wt% B 4 C/6061Al composite with higher mechanical properties by powder metallurgy method, the new composite reinforced by Nano-Al 2 O 3 particles was fabricated by hot isostatic pressing in the semi-solid temperature range. The tensile properties and strengthening effects of the composite were investigated in this research. The tensile stress-strain curve of the composites was tested by material testing machine, and the microstructure and tensile fracture morphology of composites were analyzed by scanning electron microscopy (SEM) and transmission electron microscopes (TEM). The results indicated that the tensile strength of the composite was greatly improved by the addition of Nano-Al 2 O 3 , but the elongation decreased obviously. Nano-Al 2 O 3 particles had seriously affected the microstructure and fracture morphology of the composite and lead to the more obvious brittle fracture characteristics . Strengthening mechanisms of Nano-Al 2 O 3 particles reinforced 6061Al/B 4 C composite have been discussed, which reveals that grain boundary strengthening mainly plays the most important role.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2018
·Vol. 124
·期 6
·1-8
·
IF 1.604
Lin Changwei,Tang Yu,Song Jun,Han Lei,Yu Jingbo,Lu Anxian
In the present study, series of garnet-type Li 6.75+ x La 3− x Sr
x
Zr 1.75 Nb 0.25 O 12 solid electrolytes [LLSZN with various Sr contents ( x = 0.05–0.25)] have been prepared via conventional solid-state method. The effects of Sr contents on their phase structure and ionic conductivity have been systematically investigated on the combined measurements of X-ray diffraction and scanning electron microscopy and alter current impedance spectroscopy. Our results reveal that a phase transition from tetragonal to cubic structure occurs when both Sr and Nb elements is introduced, and such a cubic structure can be stable over the whole Sr contents variation, which is suggested to provide a beneficial impact on the performance of LLSZN. Accordingly, both relative density and total ionic conductivity exhibit a favorable tendency of increasing first and then decreasing with increased Sr contents, wherein a peak value at 93.46% and 5.09 × 10 −4 S cm −1 , respectively, can be well achieved. Particularly, the maximum ionic conductivity is almost twice that of the compared sample (2.93 × 10 −4 S cm −1 ), and possess the minimum activation energy ~ 0.30 eV. Such a modification method, featured with higher efficiency and lower cost, is expected to be helpful for the development of solid electrolyte.
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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
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2019
·Vol. 138
·期 1
·233-241
·
IF 2.471
Wei Sheng,Duan Zhijun,Xia Yongpeng,Huang Chaowei,Ji Rong,Zhang Huanzhi,Xu Fen,Sun Lixian,Sun Yixin
High-performance phase change materials (PCMs) are regarded as a promising strategy in thermal energy storage applications. However, pure PCMs exhibit some inherent disadvantages such as leakage, low thermal conductivity and poor thermal cycling stability. Herein, this work presents novel microencapsulated PCMs with nano-Al 2 O 3 -enhanced shell materials due to the high thermal conductivity and mechanical properties of nano-Al 2 O 3 . And nano-Al 2 O 3 was contributed uniformly to the shell materials through self-assembly of functional materials, forming a connected thermal conductive network for the microencapsulated PCMs and resulting in an enhancement on the thermal conductivity of the microencapsulated PCMs. Results show that thermal conductivity of the obtained microencapsulated PCMs with 8 mass% nano-Al 2 O 3 is improved up to 0.5977 W m −1 k −1 which is about 287.4% compared with that of the pure PCMs. Moreover, the obtained microcapsules enhanced by nano-Al 2 O 3 possess good phase change behavior and excellent thermal cycling stability, whose melting enthalpy can achieve 170.5 J g −1 and almost has no change after 12 times of thermal cycles.
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ChemCatChem
·
2019
·Vol. 11
·期 16
·3903-3912
·
IF 4.495
Nian Lei,Xiaochen Zhao,Baolin Hou,Man Yang,Maoxiang Zhou,Fei Liu,Aiqin Wang,Tao Zhang
Graphical Pt at it, again ! The highest 1,3-PDO yield was obtained over the Pt/WO x /Al 2 O 3 catalyst with a medium domain size of WO x and a Pt/W atomic ratio of 1/4∼1/2, which favored the dispersion of Pt and maximized the number of Pt−WO x interface sites, and consequently promoted the in-situ production of strong Brønsted acid sites. Selective cleavage of secondary C−O bond is an important yet challenging strategy in glycerol valorization, and the product 1,3-propanediol (1,3-PDO) is of great value in polyester industry. Herein, we report a series of Pt/WO x /Al 2 O 3 catalysts for selective hydrogenolysis of glycerol in a fixed-bed reactor and obtain the highest space-time yield of 1,3-PDO (191.7*10 −3 g 1,3-PDO h −1 g −1 cat. ) to date. Both Pt and W have substantial effects on the 1,3-PDO yield with the optimum Pt/W atomic ratio of 1/2∼1/4. Spectroscopy characterizations as well as chemisorption experiments reveal that at the medium domain size of WO x , hydrogen spillover can take place to the greatest extent due to the improved dispersion of Pt and the suitable reducibility of WO x . Dehydration/dehydrogenation tests of 2-butanol suggest that strong Brønsted acid sites are created via hydrogen dissociation at the Pt−WO x interface and spillover to the neighboring oxygen atom. Such in situ formed protons are critical to the selective cleavage of secondary C−O bonds of polyols.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2017
·
IF 3.615
Jun Zhang,Dan Yue,Tifeng Xia,Yuanjing Cui,Yu Yang,Guodong Qian
A novel metal-organic framework film MIL-124 film was prepared on porous α-Al 2 O 3 ceramic plate by in situ synthesizing. After introducing Eu 3+ ions to the free -COOH sites of the MIL-124 ligand channels, a luminescent MOF film MIL-124@Eu 3+ was obtained. Based on the chemical reaction between NH 3 and the -COOH, the formation of -COONH 4 which was demonstrated by FT-IR spectrum, affected the energy transfer between Eu 3+ ions and ligand, quenching the characteristic emission of MIL-124@Eu 3+ film. The limit of detection to ammonia was calculated as 26.2 ppm in ambient air. The XRD results demonstrated the long-term stability of this ammonia sensor. The excellent performance and economical synthesizing strategy of the MIL-124@Eu 3+ film exhibited potential application of this sensor for detecting ammonia gas.
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RSC Advances
·
2016
·Vol. 6
·期 56
·51221-51228
·
IF 3.289
Yanliang Yang,Jiping Ma,Xiuquan Jia,Zhongtian Du,Ying Duan,Jie Xu
Al2O3 modified by alkaline earth metals M–Al2O3 (M = Mg, Ca, Sr, Ba) was synthesised by coprecipitation method. The nickel-based catalysts supported by M–Al2O3 were prepared by impregnation method. The catalysts were characterized by TEM, N2 adsorption/desorption, XRD, H2-TPR, NH3-TPD and XPS, and used for the direct hydrogenation of furfural to tetrahydrofurfuryl alcohol (THFA) in water. The reaction was demonstrated to proceed through furfuryl alcohol as an intermediate. The modification of Al2O3 by alkaline earth metals has a significant effect on the activity and selectivity of THFA. A high yield of THFA was obtained over Ni/Ba–Al2O3 under optimized conditions. Moreover, the catalyst is recyclable and reusable at least four times without significant loss of the conversion of furfural and selectivity of THFA.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2017
·
IF 4.233
Di Zhang,Lijun Xue,Yongqiang Xu,Lijuan Song,Xinmei Liu
Mesoporous γ-Al 2 O 3 supports with different pore structures were prepared by the cation-anion double hydrolysis method. Based on these samples, MoO 3 /γ-Al 2 O 3 catalysts were made via impregnation. The adsorptions of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and collidine over the supports and catalysts were studied by FT-IR. The supports or catalysts with larger pores can adsorb more 4,6-DMDBT. The methyl groups on adsorbate molecules are very close to the sulfur atom , resulting in apparent steric hindrance . Increasing the pore size can promote the interaction between the adsorbates and supports or catalysts, enhancing the C C bond and weakening the C S bond of 4,6-DMDBT. 4,6-DMDBT molecules were coordinated with the unsaturated Mo atoms over the catalysts to form π-complexation adsorption. There was much difference between thiophene and 4,6-DMDBT adsorption. The adsorption of collidine over the catalysts also illustrated that there existed steric hindrance. Significantly, the catalyst with hierarchical mesopores was beneficial for the adsorbates with larger molecular dynamics diameter. Compared with the pore size, the specific surface area was not the key factor to affect the adsorptions of 4,6-DMDBT and collidine. The hydrodesulfurization reaction of 4,6-DMDBT illustrated that the catalysts with larger pore size or hierarchical pore structure presented higher desulfurization efficiency (above than 80%).
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PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2016
·
IF 3.205
Zhiming Gao,Lin Cui,Hongwei Ma
Four methods were adopted to prepare samples 20%NiO/Al 2 O 3 with calcination fixed at 500 °C, which were then reduced into 20%Ni/Al 2 O 3 and used as catalysts for reaction of selective methanation of CO in H 2 -rich gas (CO-SMET). XRD and TPR measurements indicate that nickel aluminates were formed in the calcined samples and their formation was influenced by preparation methods. Higher temperatures were required to reduce the calcined samples more efficiently and to achieve a higher catalytic activity for CO-SMET. Among the four methods, the precipitation method using ammonium carbonate as precipitant produced the highest catalytic activity both for CO methanation and for CO 2 methanation after reduction at 800 °C for 2 h. The calcined sample 20%NiO/Al 2 O 3 prepared with the method was therefore used as support and impregnated with Ru 3+ solution. Ru addition promoted reduction of Ni 2+ ions in the calcined sample even at the low temperatures of 400 °C and 500 °C. The catalyst 1%Ru–20%Ni/Al 2 O 3 reduced at 500 °C thus had a superior performance, removing CO to ca. 30 ppm with a selectivity as high as 75% at reaction temperature of 220 °C.
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THIN SOLID FILMS
·
2017
·
IF 1.879
Xueyao Xie,Xin Yin,Lixin Song,Pingfan Du,Ni Li,Lin Qi,Jie Xiong
The flexible Al 2 O 3 /carbon composite nanofibers (ACNFs) film was synthesized by electrospinning. And the effects of carbonization temperature on the structures and properties of ACNFs were investigated. All the obtained ACNFs had rough surface and random orientations, and the alumina nanostructures were closely jointed to the carbon nanofibers . Besides, the crystallinity of alumina and carbon increased with carbonization temperature. As a result, the flexural property of ACNFs film decreased, and the electrical property greatly increased with the increase of carbonization temperature. When the carbonization temperature was 900 °C, the flexible ACNFs composite film was used as a counter electrode for flexible dye-sensitized solar cells. A power conversion efficiency of 2.84% was achieved. If the catalyst activity of the film was further improved, the conversion efficiency may be further improved.
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