CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Tong Zheng,Wenjie Li,Haibin Sun,Zhenhao Zhang,Yujun Zhang,Yurun Feng,Qiangqiang Hu,Xue Guo
Dy 2 TiO 5 ceramics with small grain size range of 1.5–3 μm were successfully prepared by microwave sintering method. The phase composition, microstructure, thermal expansion, stability, corrosion resistance and neutron absorption properties of Dy 2 TiO 5 ceramics were investigated. The results show that Dy 2 TiO 5 ceramics possess high mechanical properties due to the small grain size, with a microhardness of 12.26 GPa. The addition of Mo significantly reduces the thermal expansion phenomenon of the sample. The oxide film formed on the surface of the Dy 2 TiO 5 ceramic enhances its excellent corrosion resistance. In addition, the Dy 2 TiO 5 ceramic shows excellent neutron absorption with 87.34% neutron absorption and over 94% thermal neutron absorption in 8 cm thick particles.
研究领域:
材料科学
·
核工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Xiaohan Wang,Zhiqing Yu,Jinxiao Sun,Qiang Wei,Haoran Liu,Wenbin Huang,Luyuan Zhao,Meng Si,Yasong Zhou
A series of in situ dodecyl trimethyl ammonium bromide (DTAB)-modified small-crystal Y zeolites have been successfully synthesized by DTAB addition to the seed synthesis procedure, which was used to create the small crystal size Y zeolites. Compared to the Y zeolites prepared without DTAB, the Y zeolites prepared with DTAB have a uniform morphology and mesoporous structure, a larger specific surface area (up to 32.3 m2 g–1 increase), a smaller crystal size (up to 66 nm reduction), and more Brönsted acid sites (up to 55 μmol/g increase). After loading with NiW, the corresponding NiW catalysts were utilized in the hydrocracking of n-hexadecane. It is evident from the catalytic performance that the catalysts containing DTAB-modified small-crystal zeolites have a higher yield and selectivity of primary cracking products compared with the Y zeolites without DTAB modification. Moreover, the conversion of n-hexadecane is also higher due to its low mass-transfer resistance, high dispersion, and sulfation of W species. When the molar ratio of DTAB/Al2O3 is 0.15, the corresponding catalyst has the optimum balance between cracking and hydro–dehydrogenation activity. Therefore, it has the most excellent catalytic performance and a 7.3% increase in C8–C12 yield.
研究领域:
催化材料
·
石油化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2015
·
IF 2.999
Xianhua Hou,Miao Zhang,Jiyun Wang,Shejun Hu,Xiang Liu,Zongping Shao
A high yield and low-cost high-energy wet ball milling method is used for producing nano-flake Si@SiO 2 as an anode material for Li-ion batteries. After a two-step ball milling (coarse milling and fine milling) process, the irregular plate-like micrometric Si (average particle size is 27.4 μm) is fractured into nano-flake Si@SiO 2 (average particle size is 154.8 nm) with small crystalline grains and abundant grain boundaries. Due to the significant changes of the prepared nano-flake Si@SiO 2 in the surface composition, particle size and crystal structure, the ball milled Si shows better electrochemical performance compared with the as-received micrometric Si. And the fine milled Si shows the best electrochemical properties with a high initial coulombic efficiency of 84.6% and a specific capacity of 1920.4 mA h g −1 at a current density of 100 mA g −1 after 100 cycles.
研究领域:
材料科学
·
纳米技术
·
电化学
·
能源存储
·
表面工程
✓ 已验证
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xiaojun Dai,Yan Cheng,Qiang Wei,Meng Si,Yasong Zhou
In order to prepare non-noble metal supported hydroisomerization catalyst with high catalytic performance, this work first proposed a novel three-stage crystallization method to synthesize small-crystal and hierarchical SAPO-11 molecular sieve, and prepared the corresponding NiWS supported catalyst for the hydroisomerization of n-hexadecane. The physicochemical properties of the small-crystal and hierarchical SAPO-11 molecular sieve and the NiWS supported catalyst were analyzed via a series of characterization methods. It was found that the crystal size of SAPO-11-S was reduced to 21.8 nm and the particle size was reduced to 70–140 nm. SAPO-11-S was superior to SAPO-11-C in pore properties and acidity. The reason for the increase of the number of medium-strong B acid sites in SAPO-11-S was investigated by 29 Si MAS NMR characterization, and the formation mechanism of SAPO-11-S was proposed by tracking and analyzing the crystallization process of SAPO-11-S. The decrease of crystal size of SAPO-11 molecular sieve effectively improved the sulfidation degree of active metals and the dispersion degree of the active phase of the catalyst, and promoted more active phases to form “type II active phase”. Compared with NiW/SAPO-11-C, NiW/SAPO-11-S showed higher catalytic activity and isomerization selectivity, and the maximum i-hexadecane yield of NiW/SAPO-11-S was 44.77% higher than that of NiW/SAPO-11-C.
研究领域:
催化
·
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2016
·Vol. 33
·期 6
·1931-1937
·
IF 1.408
Fu Xiaoqin,Sheng Xiaoli,Zhou Yuming,Fu Zhiwei,Zhao Shuo,Zhang Zewu,Zhang Yiwei
Well-dispersed hierarchical zeolite Y, structure-directed by ionic liquid 1-methyl-3-[3'-(trimethoxysilyl) propyl] imidazolium chloride, was synthesized for the first time using a novel ultrasonic/microwave synergistic synthesis (UMSS). The time required for the synthesis of zeolite Y by UMSS method was remarkably reduced to 6 h instead of 24 h under conventional hydrothermal conditions. The structures of all samples were characterized by XRD, BET, FT-IR, SEM and TEM. The results clearly demonstrated that the UMSS is a promising strategy to achieve zeolite Y with improved crystallinity, large BET surface area, bulky mesopore volume, well-dispersed morphology, small zeolite nanoparticle. The catalytic activity of hierarchically micro-mesoporous zeolite Y was evaluated by using the alkylation of o-xylene with styrene. Mesoporous zeolite Y synthesized by UMSS method showed significantly higher catalytic activity, stability and reusability, compared with conventional hydrothermal synthesis. It might be ascribed to its large mesoporous volume, small crystal nanoparticle and high surface area, minimizing the diffusion length as the reactant molecules diffuse into the pores, and correspondingly the products diffuse out of zeolites. This study suggests that UMSS method is a good alternative for the synthesis of micro-mesoporous zeolite Y, which may be of remarkable benefit for industrial applications.
研究领域:
材料化学
·
催化化学
·
纳米材料科学
·
工业化学
·
多孔材料
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Bo Meng,Shenyong Ren,Zhi Li,Suofu Nie,Xinyue Zhang,Weiyu Song,Qiaoxia Guo,Baojian Shen
The direct synthesis of zeolite Y with high SiO 2 /Al 2 O 3 (SAR > 6.0) and small crystal size is a great challenge. The conventional production of high silica Y usually involves organic template into the synthesis system, which takes high cost. Here, zeolite Y with SAR of 6.15 and small crystal size via introducing Co 2+ in a facile one-step hydrothermal method without organic template was achieved. The SAR increased from 5.2 to 6.15 compared to normal NaY, and the crystal size decreased to 50%. The introduction of Co 2+ in synthesis system affects the formation of 5-coordination intermediate ( M-O -Si )* around Co 2+ during crystallization process which is the critical factor to nucleation. The stability of ( Co–O –Si )* is weaker than that of ( Al–O –Si )*, which leads to the increase of SAR around Co 2+ . The microcrystals of Co(OH) 2 provide adhesive surface for the amorphous material and promote nucleation. The zeolite Y shows good performance in the cracking of 1,3,5-triisopropylbenzene because of larger surface area and more active sites being exposed. This is a new strategy for industrial synthesis of high SiO 2 /Al 2 O 3 and small crystal size zeolite Y.
研究领域:
材料科学
·
化学工程
·
催化
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Min Zhang,Shenyong Ren,Qiaoxia Guo,Baojian Shen
TS-1 is a typical microporous zeolite , which is hindering the timely diffusion of reaction products and is likely to cause secondary side reactions in heterogeneous catalytic reaction due to the micropore size. However, zeolite TS-1 with hierarchical pores of micropores and mesoporous/macropores can solve this problem to a great extent. In view of this, hierarchical zeolite TS-1 is synthesized by using tetrapropylammonium hydroxide (TPAOH) as structure directing agent and polyacrylamide (PAM) as a hierarchical pore-directing template. The texture property of hierarchical TS-1 can be optimized by changing the amount of PAM in the synthesis gel. With the increase of PAM content, the pore volume and specific surface area of the hierarchical zeolite TS-1 increases. Compared with the conventional TS-1, the hierarchical TS-1 samples have obvious pore size distribution in the range of 20–80 nm. It is interesting that the particle size of TS-1 decreases after adding PAM. When the hierarchical TS-1 is applied to the epoxidation reaction of 1-hexene with H 2 O 2 , the selectivity of the desired product 1,2-epoxyhexane is significantly increased.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 87
·54980-54985
·
IF 3.108
Zhe Tang,Zhangyi Huang,Jianqi Qi,Xiaofeng Guo,Wei Han,Mao Zhou,Shuting Peng,Tiecheng Lu
Defect-fluorite structured Gd2Zr2O7 nanoparticles were successfully synthesized via a homogeneous precipitation-solvothermal method using urea as a precipitant. The obtained nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis and transmission electron microscopy (TEM). Compared to the traditional solvothermal method, this homogeneous precipitation-solvothermal method has the advantage of producing nanoparticles with small grain sizes, a narrow size-distribution, high surface areas and little agglomeration. Particularly, the mean crystallite size of Gd2Zr2O7 obtained by this method is 20–30 nm, providing a great opportunity of using these nanoparticles as starting nano-sized building blocks for low temperature preparation of homogeneous and dense ceramics.
研究领域:
材料科学
·
纳米技术
·
陶瓷
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）