RARE METALS
·
2018
·Vol. 38
·期 1
·1-13
·
IF 1.5
Liu Qi,Wang Wen-Qiang,Yang Yue,Liu Xue-Gang,Xu Sheng-Ming
Aluminum recovery is a key issue for the overall recycling of valuable metals from spent catalysts. This paper focuses on the recovery and regeneration of alumina with high additional value from the spent hydrodesulfurization catalyst CoMo/Al 2 O 3 . The results indicate that 98.13% alumina is successfully leached from the treated spent catalysts by an alkaline leaching process under the conditions of 5 mol·L −1 sodium hydroxide, a liquid/solid ratio of 20 ml·g −1 , a temperature of 160 °C and a reaction time of 4 h. In the leaching residue, no difficult leaching compound is found and cobalt and nickel are enriched, both of which are conducive to the subsequent metal recovery step. The reaction order of aluminum leaching is 0.99. This reaction fits well with the interfacial chemical reaction model, and its apparent activation energy is calculated as 45.50 kJ·mol −1 . Subsequently, γ-Al 2 O 3 with a high specific surface area of 278.3 m 2 ·g −1 , a mean size of 2.2 μm and an average pore size of 3.10 nm is then regenerated from the lixivium, indicating its suitability for use as a catalyst carrier. The recovery and regeneration of alumina from spent catalysts can not only significantly contribute to the total recycling of such hazardous spent catalysts but also provide a new approach for the preparation of γ-Al 2 O 3 with a high specific surface area using spent catalysts as the aluminum sources.
研究领域:
化学工程
·
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
·
2023
·
IF 4.5
Zhao-wang DONG,Xue-yi GUO,Yang XIA,Pei-dong LIU,Jin-xi QIAO,Zhong-chen LI,Han-ning LIU
Silicon in two types of upgraded titania slag (UGS) containing different components was removed using a low-temperature alkali solution and melt leaching. The effects of temperature, time, and NaOH solution concentration on desilication rate were investigated. Desilication in melt can lead to the loss of titanium in upgraded titania slag. After agitating at a speed of 600 r/min and 80 °C for 300 min, the silicon content in domestic slag decreased from 0.96 wt.% to 0.29 wt.%, and the leaching rate was 69.8% after leaching in 4 mol/L sodium hydroxide solution. Under the same conditions, the silicon content in imported slag decreased from 1.11 wt.% to 0.12 wt.%, and the desilication rate was up to 89.2%. The alloy powders obtained from the reduction of upgraded titania slag with magnesium were sintered to produce titanium alloy, and the alloy was characterized. It was determined that the Ti 5 Si 3 phase in the titanium alloy product was successfully eliminated. In addition, the two UGS materials and the chemical principle of desiliconization were analyzed using a thermodynamic software.
研究领域:
材料科学
·
冶金工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2023
·
IF 5.2
Zhang Lei,Wang Hengliang,Lei Zhang,Jia Yang,Liu Jianwei,Wang Jingli
Using fly ash acid leaching residue as the silicon source, sodium silicate solution was produced by alkali leaching and the wet gel was obtained by the sol-gel method. Hexamethyldisiloxane (HMDSO) was used to modify the surface of the wet gel, thereby reducing the capillary tension during the atmospheric pressure drying process, and finally preparing a silica aerogel material with hydrophobic properties. The effects of different alkali leaching conditions, different sol pH, HMDSO dosage on the aerogel density and the changes of aerogel material properties and composition during the preparation process were investigated, and the reaction mechanism of silica aerogel preparation by atmospheric pressure drying was described. The results showed that the optimum conditions for alkali leaching were 20 wt% NaOH concentration, 2 h reaction time and 100 °C, and the desilication rate was 81.72%; the lowest Silica aerogel density of 108 mg/cm 3 at pH 5 to 6; the lowest density of silica aerogel was 110 mg/cm 3 at a modifier to wet gel volume ratio of 1:1.4.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Ying Gao,Jiafeng Zhang,Yanan Tu,Weidong Wang,Ziqi Zhu,Zhiqiang Xu
The preparation of hierarchical porous silica aerogels from coal gasification fine slag (CGFS) offers an effective approach to achieving high-value utilization of solid waste and reducing the production cost of solid adsorbent matrix materials. However, the main challenges involve overcoming technical barriers to efficiently and value-added conversion of CGFS into silica aerogels with CO₂ adsorption properties, as well as elucidating the phase transformation mechanisms during the synthesis process. In this study, CGFS was used as the raw material to obtain a silicon-containing precursor through pre-decarbonization (with ash content as high as 99.82 %) and alkali dissolution treatment. A hierarchical porous silica aerogel was then synthesized using an efficient hydrothermal process. The effect of alkali dissolution on silicon extraction and the phase transformation mechanisms were thoroughly discussed, and the leaching mechanism was analyzed through thermodynamic and kinetic models. The results showed that the high leaching rate of silicon was attributed to the presence of a large amount of amorphous SiO₂ in the decarbonized fine slag (DCFS), while the formation of zeolite Na-P1 and hydroxysodalite during the alkali dissolution process affected the efficiency of silicon extraction. Then, the structural formation mechanism and CO₂ adsorption properties of the hierarchical porous silica aerogels were analyzed using N₂ adsorption-desorption and CO₂-TPD. The SiO₂-1-30-0.5 exhibited a high CO₂ adsorption ability of 1.53 mmol g −1 , and the CO₂ adsorption capacity maintained 94.78 % of the original value and after 5 adsorption-desorption cycles.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Bo Li,Haijun Guo,Zhen Xiong,Lian Xiong,Shimiao Yao,Mengkun Wang,Hairong Zhang,Xinde Chen
γ-valerolactone (GVL) is a sustainable chemical, which can be obtained by hydrogenation of levulinic acid (LA) and levulinate. Herein, we reported a solvent-free hydrogenation of butyl levulinate (BL) to GVL and 1,4-pentanediol (1,4-PDO) over a skeletal Cu-Al-Zn catalyst. The skeletal Cu-Al-Zn catalyst was prepared from Devarda's alloy by alkali leaching and the catalyst was characterized by different analysis methods. The aluminum in the Devarda's alloy was dissolved by sodium hydroxide in the leaching process and many active Cu atoms were generated on the catalyst surface and the skeletal Cu-Al-Zn exhibited many micrometer-scale irregular particles with rough surface. The skeletal Cu-Al-Zn catalyst showed the excellent performance in the solvent-free hydrogenation of BL to GVL under constant hydrogen pressure (5 wt% catalyst loading, 180°C, 6 MPa of H 2 , 6 h): the LA conversion was 100%, the GVL yield was 74.75% and the 1,4-PDO yield was 25.63%. Moreover, the catalyst showed stable performance and it was reusable up to 5 times without apparent loss of activity. A stable hydrogen pressure with Zn would suppressed the dehydration of 1,4-PDO.
研究领域:
催化
·
绿色化学
·
可持续化学
✓ 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）