FUEL
·
2017
·
IF 4.601
Ye Zhang,Dawei Liu,Ligong Zhou,Mingxing Tang,Xuekuan Li,Yongxing Yang
Alpha-alumina (α-Al 2 O 3 ) materials has a wide range of applications because of its excellent properties at high temperature. Tabular α-Al 2 O 3 was unexpectedly synthesized by etching mullite from Si x Al y O z composites since our original intention was highly porous α-Al 2 O 3 . Silica-alumina xerogels with different Al/Si molar ratio as 3, 6, 9 and ∞ (pure alumina) were prepared via sol-gel route, followed by calcination at 1400 °C to obtain Si x Al y O z composites. XRD results showed that the composite existed as mullite when the Al/Si ratio equaled to 3 and as the combination of mullite and corundum (α-alumina) when the Al/Si ratio equaled to 6 and 9, while pure α-Al 2 O 3 was obtained when Al/Si ratio equaled to ∞ signed as sol-gel α-Al 2 O 3 . The mullite phase in Si x Al y O z composites could be etched completely by hydrofluoric acid under room temperature in terms of the treating time was long enough and left tabular α-Al 2 O 3 for the samples with Al/Si molar ratio as 6 and 9. The interaction between mullite and α-Al 2 O 3 during the thermo process may direct the formation of tabular morphology. Structural and property characterizations show the tabular morphology, low surface area, perfect crystallinity and weak acidity of α-Al 2 O 3 . Furthermore, the adsorption of dibenzothiophene, a molecular with planar morphology, on tabular α-Al 2 O 3 , sol-gel α-Al 2 O 3 as well as γ-Al 2 O 3 was investigated at room temperature in comparison. Tabular α-Al 2 O 3 exhibited the highest adsorption capacity and best regeneration ability than other two.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Weida Shi,Zhihao Jin,Juanjuan Wen,Xianfu Chen,Kaiyun Fu,Xiaowei Da,Minghui Qiu,Yiqun Fan
The development of tight ceramic ultrafiltration membranes for water purification facilitates is challenging because of high fabrication costs and low permeate flux . In this study, a low-energy rapid thermal process (RTP) was comprehensively investigated for fabricating of high-precision, permeable α-alumina tight ultrafiltration membranes. Compared to the conventional thermal process (CTP), RTP offers an ultra-fast heating rate and shorter holding time, effectively mitigating grain growth and pore aggregation. Moreover, the decomposition of organic matter is delayed during RTP, providing a lower interfacial energy that enables direct formation of α-alumina at a low temperature of 750 °C. During a secondary subsequent RTP, the residual phase is fully converted to α-alumina by the in-situ seeding effect. By utilizing RTP, we successfully prepared α-alumina ultrafiltration membranes within 30 min by calcination , with an average pore size of approximately 6 nm, a narrow pore distribution coefficient of 1.12, and high permeance of 219 L −1 ·m −2 ·h −1 ·bar −1 .
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2018
·Vol. 15
·期 6
·1490-1501
·
IF 1.165
Xiangli Kong,Minghui Qiu,Anran Wang,Lu Yang,Rongfei Zhou,Yiqun Fan,Deshuang Kong,Changjun Gu
The adhesion and cohesion between the coating layers and the ceramic honeycombs are usually one of the key issues in the preparation of high-performance zeolite-based/Monolith catalysts. In this work, we investigate the deposition of high-efficiency Cu-SAPO-34 catalyst on a cordierite monolith with special focus on the impact of alumina binders on the structure, mechanical adhesion and cohesion, and catalytic performance of the monolithic catalyst. Two kinds of alumina nanoparticles, α-alumina and γ-alumina, have no significant impacts on the Cu-SAPO-34 crystal structure, micropore morphology and catalytic activity. But washcoating experiments showed that the mass loss rate of the coating was less and the loading of the catalyst was higher when α-alumina was used as the binder. The reason of improving the adhesion and cohesion strength is the suitable thermal shrinkage, the uniform distribution and densification structure of α-alumina. Furthermore, optimization of the coating formulation with α-alumina as the binder has been performed. Finally, the catalyst prepared under the optimal conditions was tested by SCR and a maximum conversion rate of 97.4% was obtained. It was concluded that the use of the washcoating method with α-alumina does not affect catalytic performance while it increases bonding strength between substrate and catalysts.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Junbo Ren,Mingda Huo,Pengbo Liu,Ying Tan,Minghui Li,Wei Gao,Xiaohong Sun,Ruisong Guo,Xinqi Zhao
Spherical α-alumina powder has been widely used in advanced alumina ceramics manufacturing due to its excellent sphericity, uniform particle size distribution and good dispersion. However, the small size and fast growth rate of α-alumina precursor particles lead to strong agglomeration during grain growth, making it difficult to obtain uniformly dispersed α-alumina particles with good sphericity. In this study, polyethylene glycol 2000 (PEG2000) and poly (ammonium acrylate) (PAA-NH 4 ) were used as composite dispersants to decrease agglomeration during the preparation of alumina precursors. When the contents of PEG2000 and PAA-NH 4 were 0.5 g L −1 and 0.06 g L −1 (S4), respectively, uniformly dispersed alumina precursor particles with good sphericity and a particle size of about 506 nm were obtained, and the morphology remained stable after calcination. After molding and sintering the calcined powders, alumina ceramics with superior mechanical properties were produced. Compared to commercial α-alumina ceramics, flexural strength is increased by approximately 28.9 %, while fracture toughness is increased by approximately 29.2 %. This study offers a new foundation for the development of high-performance alumina powders and ceramics, supporting their engineering applications.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·Vol. 47
·期 19
·26869-26876
·
IF 4.527
Shao-Min Lin,Ya-Ling Yu,Ming-Feng Zhong,Huan Yang,Chen-Yang Zhang,Zhi-Jie Zhang,Wei Xu,Jiong-Yan Xie,Yu-Chun Qiu
Converting the γ phase into the α phase completely is necessary in the presintering stage of industrial alumina (Al 2 O 3 ), which requires high temperature and energy consumption. To reduce the presintering temperature, γ-Al 2 O 3 was activated by oxalic acid . XRD , 27 Al-MAS-NMR and TG-DSC were used to characterize the γ - alumina before and after activation, and the phase transformation was studied. The formation temperature of α-Al 2 O 3 decreased to 1029 °C for oxalic acid activated γ-Al 2 O 3 , and the α-fraction was 100% for activated γ-Al 2 O 3 at 1300 °C. After oxalic acid activation , the diffraction peak intensity of γ-Al 2 O 3 decreased significantly; the results of 27 Al-MAS-NMR suggested that octahedral [AlO 6 ] in γ-Al 2 O 3 was easier than tetrahedral [AlO 4 ] to be attacked by oxalic acid , and the formation of pentavalent [AlO 5 ] with higher reaction activity, which was in favour of the lowering formation temperature of α-Al 2 O 3 . The dissolution concentration of Al increased after oxalic acid activation, and the dissolution process was controlled by surface reactions. Oxalic acid mainly attacked the octahedral aluminium in γ-Al 2 O 3 and extracted Al as three complexes of [Al(C 2 O 4 )] + , [Al(C 2 O 4 ) 2 ] - and [Al(C 2 O 4 ) 3 ] 3- . Oxalic acid activated γ - Al 2 O 3 with a lower phase transformation temperature has broad application prospects in the alumina industry.
研究领域:
材料化学
·
无机化学
·
固态化学
·
工业催化
·
陶瓷材料
✓ 已验证
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2019
·
IF 1.479
Wei Zhang,Yee-Kwong Leong,Chunbao Sun,Hong Fan,Xianwei Zhang
The yield stress and zeta potential of washed spherical α-Al2O3 suspensions with two to four layers of critic acid(CA) and polyethyleneimine(PEI_Mw1.8and 70 kDa) adsorbed sequentially were characterized. With CA adsorbed as the first layer, pHξ=0 was shifted to a lower pH and the maximum yield stress (τymax) was reduced. With PEI adsorbed as the first layer, the pHξ=0 was moved slightly higher. With the introduction of the second layer, the CA/PEI additive was formed which functioned as a bridging agent. The pH range of yield stress was broadened significantly and increased with the number of layers. This pH ranged from 2.5 to 11. The CA/PEI multilayer additive loses its positive charge at pH >11. There was less adsorption in layer3 and layer4 when lower Mw PEI is applied to the suspension. The CA/PEI multilayer additive formed by PEI of Mw70000 and CA was larger in size than that formed by PEI of Mw 1800 and CA. Lower Mw PEI produced a stronger flocculated network or higher τymax suspension due to a higher concentration of multilayer additive. CA/PEI multilayer additive was participating in bridging and particle bridging interaction was not affected by the adsorption order of CA and PEI.GRAPHICAL
研究领域:
材料科学
·
化学工程
·
胶体科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Weida Shi,Xiaoyu Hu,Minghui Qiu,Zhihao Jin,Xianfu Chen,Yiqun Fan
A high-efficiency α-alumina ultrafiltration membrane was proposed and fabricated by co-sintering a gel layer with a pre-sintered interlayer. A pre-sintered interlayer with rigidity and low roughness was used, which was conducive to the preparation of a defect-free and ultra-thin separation layer. In the process of co-sintering, the crystal phase of the separation layer was completely transformed to α-alumina at 950 °C, and permeation of pre-sintered interlayer increase with calcination temperature. The prepared α-alumina ultrafiltration membrane had an ultrathin thickness of only ∼140 nm, pure water permeability as high as 230 L m −2 h −1 bar −1 , and average pore size approximately ∼7 nm. In the separation of polyvinyl alcohol (PVA) wastewater, the membrane had a rejection rate of 99 % and permeability of 60 L m −2 h −1 bar −1 . In the removal of Congo red dye, it showed a high rejection rate of >99 % and permeability of 212 L m −2 h −1 bar −1 .
研究领域:
材料科学
·
化学工程
·
环境工程
✓ 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）