APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Yaming Fan,Yuqun Zhuo,Liangliang Li
SeO 2 adsorption mechanisms on CaO surface were firstly investigated by both density functional theory (DFT) calculations and adsorption experiments. Adsorption of multiple SeO 2 on the CaO (001) surface was investigated using slab model. Based on the results of adsorption energy and surface property, a double-layer adsorption mechanisms were proposed. In experiments, the SeO 2 adsorption products were prepared in a U-shaped quartz reactor at 200 °C. The surface morphology was investigated by field emission scanning electron microscopy (FE-SEM). The superficial and total SeO 2 mass fractions were measured by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. The surface valence state and bulk structure are determined by XPS and X-Ray Diffraction (XRD). The experimental results are in good agreement with the DFT results. In conclusion, the fundamental SeO 2 chemisorption mechanisms on CaO surface were suggested.
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
STEEL RESEARCH INTERNATIONAL
·
2024
·
IF 1.9
Li Zhang,Hang He,Lei Zhang,Yongqi Sun,Xu Gao,Jie Zeng,Wanlin Wang
Viscosity is an important property for CaO-SiO 2 -Al 2 O 3 -based slag systems, which showcases different scenarios in basic and acid slag systems with temperature change. This article elucidates the mechanism of their difference in viscosity–temperature property from melt structure. Results reveal that basic slag shows a low degree of polymerization (DOP) and a low viscosity of the melt due to an excessive O 2− ions depolymerizing the complex network structures, resulting in more low-polymerized Q 0 (Si) units and less high-polymerized Q 3 (Si) units. With the temperature decreases, the DOP and viscosity do not change significantly. However, the low DOP and viscosity favor crystal precipitation in the melt, leading to a solid–liquid mixed state of the slag, and thus a sharp increase in viscosity when the temperature decreases to 1275 °C. For acid slag, it undergoes a transformation into aluminosilicate structures with the introduction of numerous [AlO 4 ] 5− tetrahedra, accompanied by a significant increase in the relative mole fraction of high-polymerized Q 3 (Si) units. Consequently, the DOP and viscosity are obviously higher than that of the basic slag. Furthermore, the DOP and viscosity of the acid slag increase continuously with the temperature decreasing, thus impeding crystal precipitation and enhancing the glass transition tendency of the molten slag.
研究领域:
材料科学
·
冶金学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2018
·Vol. 102
·期 3
·1414-1424
·
IF 2.956
Yaowu Wei,Tao Zhang,Qi Zhang,Bingqiang Han,Nan Li
Improving the hydration resistance of CaO aggregates is the key to successful application of lime-based refractories in metallurgical industry. Additive Zr(OH) 4 and Al(OH) 3 were introduced in the preparation of CaO granules using granulation equipment and calcination method in this study. The results showed that the hydration resistance of CaO granules was improved significantly, especially for granules with 0.6 wt.% Zr(OH) 4 and 0.9 wt.% Al(OH) 3 , respectively. The shell of CaO granules was relatively dense after calcination and the volume of open pores of CaO granules decreased from 3.56 × 10 −2 to 1.80 × 10 −2 cm 3 /g when additive was introduced. Zr(OH) 4 and Al(OH) 3 have the opposite effect on the closed porosity of CaO granules, the closed porosity of CaO granules was decreased with Zr(OH) 4 addition, but increased with Al(OH) 3 addition.
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
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Chen Zhang,Benzheng Gao,Houyang Yu,Xin Wang,Jianliang Xie
CaO–B 2 O 3 –SiO 2 (CBS) is a promising lightweight, low-dielectric matrix material for high-temperature microwave-absorbing coatings. However, the comprehensive study of absorbent morphology evolution within such coatings and its influence on electromagnetic (EM) performance has not been conducted. In this work, a series of FeSiAl (FSA)/CBS composite coatings with various FSA contents were fabricated using atmospheric plasma spraying. The morphological evolution of the FSA phase and the resulting EM properties of the coatings were systematically analyzed. Experimental findings show that during the spraying process, when the size of FSA clusters in the composite powder exceeds the thickness of CBS splats, FSA clusters form a rigid contact with the underlying solidified coating, leading to the development of a lamellar structure. This lamellar FSA phase creates local conductive networks, which significantly increase the complex permittivity of the coating. These results provide valuable guidance for controlling absorbent morphology and optimizing the EM properties of CBS-based coatings.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Environmental Technology & Innovation
·
2025
·
IF 7.1
Yonglin Yang,Jiangyong He,Shuaige Shi,Long Yan,Jian Li,Xiaoyong Fan,Bi Chen,Guohui Dong,Hongrui Ma
There is a key issue about formation of highly toxic and easily dissoluble Cr(VI) during heat treatment of Cr-bearing solid waste, resulting in a prominent increase of environmental risk of incineration product. In this study, the effects of CaO and SiO 2 on formation and reduction of Cr(VI) were investigated during heating of Cr-bearing simulated sludge (Cr-SS) and Cr 2 O 3 , exploring Cr(III) oxidation mechanism. The findings indicates that doping CaO significantly promotes Cr(III) oxidation to Cr(VI), and chromium speciation vary with temperature. At 300℃, leaching amount of Cr(VI) in Cr-SS samples increases sharply to 9.3 % of total Cr. In contrast, no Cr(VI) was detected in Cr 2 O 3 samples. Above 300℃, oxidation rates of Cr(III) in different samples of Cr-SS and Cr 2 O 3 exhibit the same trend with temperature increasing. Above 1000℃, new Cr-containing crystalline phases were observed, like CaCr 2 O 4 and Ca 3 (CrO 4 ) 2 . The oxidation rate of Cr(III) is positively connected with the adding amount of CaO. Besides, doping SiO 2 to sludge prominently inhibits Cr(III) oxidation or facilitate Cr(VI) reduction at 600℃-1200℃, which is also confirmed by thermodynamic calculation, attributing to formation of Ca 5 Cr 2 SiO 12 and CaCr 2 O 4 . The number of holes in valence band will be changed through substitution of Cr(III) ions by cations of different valence states, thus facilitate or inhibit Cr(III) oxidation. The ions (III) can inhibit Cr(III) oxidation and promote Cr(VI) reduction. Introducing SiO 2 or Si-enriched materials to chromium-bearing wastes may be a promising alternative to solve the problem of highly toxic Cr(VI) formation during heat treatment.
研究领域:
环境科学
·
化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
·
2019
·Vol. 30
·期 2
·359-370
·
IF 1.335
Zheng Zhi,Lei Tong,Wang Jun,Wei Yi,Liu Xuejun,Yu Fengwen,Ji Jianbing
In this paper, we report the catalytic cracking of soybean oil for biofuel over γ-Al2O3/CaO composite catalysts. The influence of catalysts, cracking temperature and weight hourly space velocity (WHSV) on the products distribution were investigated. The maximum yield (70.0 wt.%) of biofuel with low acid value (6.7 mg KOH g-1) and oxygen content (5.6%), as well as high calorific value (44.2 MJ kg-1) was achieved over 35 wt.% γ-Al2O3/CaO at 480 ºC and 3.72 h-1. The paper focused on the variation of biofuel composition and cracking pathway caused by γ-Al2O3/CaO composite catalysts via gas chromatography-mass spectrometry (GC-MS) and thermogravimetric (TG) analysis. Calcium oxide would react with fatty acid to yield calcium carboxylates at 300-350 ºC, which were subsequently decomposed into hydrocarbons (57.9 wt.%) and ketones (22.6 wt.%) at 415-510 ºC. As for 35 wt.% γ-Al2O3/CaO, the addition of γ-Al2O3 was beneficial to generate alkenes (38.2 wt.%), arenes (10.6 wt.%) and alcohols (12.3 wt.%) with ketones decreasing (16.5 wt.%) via γ-hydrogen transfer reaction and disproportination.
研究领域:
化学工程
·
可再生能源
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Fusheng Liu,Yaoyao Xiao,Xinxin Sun,Guohui Qin,Xiuyan Song,Yiyu Liu
Herein, CeO 2 -CaO nanoparticle coated on hollow ZrO 2 nanostructure (denoted as CeO 2 -CaO-ZrO 2 ) was prepared via a template impregnation method, which showed excellent catalytic performance for polycarbonate (PC) transesterification with methanol (named as methanolysis). The lattice oxygen (O 2− ) generated from the incorporation of CeO 2 and CaO to ZrO 2 , adsorbed atomic oxygen (O − ), or adsorbed molecular oxygen (O 2− ) generated from predominately via CeO 2 serve as the active species to promote PC methanolysis. In order to explore the detailed synergistic effect of different components and the influence of structure tailor, the mesoporous CaO-Al 2 O 3 was also investigated and compared with hollow CeO 2 -CaO-ZrO 2 . CeO 2 plays an important role in the storage and release of oxygen and forms stronger O 2− /O − /O 2 − basic sites. Notably, interfacial active species (electron-enriched O 2− /O − /O 2 − sites) participate in stripping protons from CH 3 OH which is the rate determination step for PC methanolysis. Such interfacial sites of CeO 2 -CaO-ZrO 2 catalyst serve as the optimal active site with the substantially declined activation energy barrier (∼0.31 eV) for stripping protons from CH 3 OH in contrast to that of 0.83 eV of CaO-Al 2 O 3 . The activation energy is considerably declined due to the interfacial synergistic component catalysis and abundant activation sites over hollow structure. The PC conversion over such hollow CeO 2 -CaO-ZrO 2 achieved almost 100% under the conditions of temperature 100 °C, m(cat):m(PC) = 0.05:1, n(methanol):n(PC) = 8:1 and time 2 h, while the conversion was only 13.4% over CaO-Al 2 O 3 under the same conditions. The hollow CeO 2 -CaO-ZrO 2 catalyst could be reused for 5 times without obvious decrease in PC conversion and BPA yield. This work supplies an extended understanding on interfacial synergistic catalysis toward PC methanolysis, which is important for efficient design and building of heterogeneous catalysts with higher activity.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Xingbo Wang,Yibo Pan,Weidong Fan,Hao Guo,Hai Zhang
Municipal solid waste incineration (MSWI), a promising technology for managing MSWI capacity, has a large amount of CO 2 in its flue gas emissions, but lacks effective means of carbon reduction. Modification of CaO-based sorbents using fly ash, a solid waste from coal-fired power plants, is a potential application to improve CO 2 capture capacity. In this study, a cost-effective fly ash-CaO sorbent was developed by combining high-calcium and high-magnesium fly ash with CaO by hydration. The CO 2 capture capacity and carbonation conversion of fly ash-CaO sorbents were investigated at different temperatures, CO 2 partial pressures and doping ratios in a calcination/carbonation reaction system. Optimum carbonation reaction temperature (760℃) for CaO and optimum calcination temperature (850℃) for fly ash were obtained. In the experiment of CaO doped with fly ash, the novel sorbents prepared by CaO doped with fly ash at a mass ratio of 3:1 had the highest carbonation conversion (98.88 %). The hydration reaction promoted the transformation of CaO to Ca(OH) 2 , which improved the CO 2 capture capacity of the sorbents. The inert materials (Al 2 O 3 , SiO 2 ) in the fly ash were uniformly distributed as structural skeleton in the sorbents, enhancing the structural stability and anti-sintering ability. The S element contained in the fly ash competes with CO 2 for adsorption sites and produces stable CaSO 4 , which reduces the carbon capture capacity of the sorbents. A unique mineralization sequestration process for MSWI carbon capture is proposed that is economical and industrially viable. A promising route to improve CO 2 capture performance with waste reutilization is emphasized.
研究领域:
环境科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
China Foundry
·
2025
·
IF 2.3
Hao Zong-dong,Tang Wei-zhe,Dou Rui,Wang Li
Alumina ceramics are crucial for high-performance applications, such as turbine blades, due to their excellent thermal stability and mechanical properties. However, existing fabrication methods often fail to balance strength, porosity, and dimensional precision. This study partially fills this research gap through a systematic investigation of calcium oxide (CaO) doping effects on alumina ceramic cores fabricated via ceramic stereolithography, with controlled doping ratios and sintering parameters. A ceramic paste was prepared using coarse and fine Al 2 O 3 particles mixed with CaO as a sintering aid, followed by debinding and sintering to achieve optimal mechanical properties. The results show that CaO doping significantly enhances the flexural strength of alumina cores while maintaining porosity levels between 20% and 30% and controlling the sintering shrinkage rate to about 5%. Additionally, CaO doping alters the microstructure by inhibiting the transformation of spherical fine particles into flaky grains, improving sintering activity. However, as the CaO doping content increases, the bending strength increases, while the shrinkage rate of the material also tends to increase, resulting in a reduction in the overall porosity. This has a negative impact on the control of the manufacturing precision of turbine blades. Thus, although CaO doping improves strength and microstructure, achieving necessary dimensional control requires further optimization of doping content and sintering conditions.
研究领域:
材料科学
·
陶瓷工程
·
机械性能优化
✓ 已验证
产品关联
DOI
高影响因子
Energies
·
2024
·Vol. 17
·期 13
·3172
·
IF 3
Maierhaba Abudoureheman,Lanzhen He,Kunpeng Liu,Bo Wei,Jia Lv,Jianjiang Wang,Quan Zhu
The contents of alkali and alkaline earth metals are higher in Zhundong coal, and there are serious problems of slagging and fouling during the combustion process. Therefore, it is of great significance to reveal the mechanism of slagging and fouling in the boiler of Zhundong coal. In this paper, first-principle calculations based on density functional theory are used to study the competition mechanism of alkaline metal oxides during the combustion process in Zhundong coal by establishing the Na2O(110)/CaO(100)-SiO2(100) double-layer interface model. The results show that the bond lengths of the surface of Na2O(110) and CaO(100) with SiO2(100) after adsorption were generally lengthened and the value of bond population became smaller, which formed a stable binding energy during the reaction. The electron loss of Na is 0.05 e, the electron loss of Ca is 0.03 e, and the electron loss of Na2O is greater than that of CaO. The charge transfer on the surface of Na2O with SiO2is obviously higher than that of CaO and the orbital hybridization on the surface of CaO with SiO2is weaker than that on the surfaces of Na2O with SiO2. Na2O is easier to react with SiO2than CaO. The adsorption energies on the surface of Na2O and CaO with SiO2are −5.56 eV and −0.72 eV, respectively. The adsorption energy of Na2O is higher than that of CaO, indicating that Na2O is more prone to adsorption reactions and formation of Na-containing minerals and other minerals, resulting in more serious slagging. In addition, the XRD analyses at different temperatures showed that Na-containing compounds appeared before Ca-containing ones, and the reaction activity of Na2O is stronger than that of CaO in the reaction process. The experimental results have good agreement with the calculation results. This provides strong evidence to reveal the slagging and fouling of Zhundong coal.
研究领域:
能源科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2024
·
IF 6.3
Wenjie Li,Erfei Xiao,Chenguang Li,Chaopeng Zhang,Xin Guo
The calcium looping (CaL) technique, renowned for its exceptional ability to withstand high temperatures and remarkable heat storage capacity, perfectly complements 3rd generation concentrated solar power (CSP) plants. However, the poor cycling stability and low spectrum absorption rate of CaO obstruct system efficiency. In order to tackle these problems, we impregnated steel slag with acetic acid and doped Mn to create a novel CaO-based energy storage material. Thermogravimetric analysis (TGA) and fixed-bed cycling of the material revealed that the material has outstanding cyclic heat storage properties. Compared to CaO, the material has an 85 % higher initial adsorption rate, 73 % higher 30-cycle energy storage density, and 9.5 times higher average light absorption. Spherical pellets were prepared for industrial applications through the extrusion-spheronization method. The energy storage density for 30 cycles was reduced by 10.26 % for the pellets compared to the powder material, but the average light absorption rate was improved. The compressive strength of the composite pellets was 8.4 times higher than the dolomite pellets. It was found that the light absorption capacity of the material increased with the number of cycles, which was attributed to the migration of Mn and Mg from the interior to the surface. Finally, the excellent photothermal conversion capability of the new composite material was verified by the photothermal conversion test. Therefore, Mn-doped CaO-based composite material derived from steel slag is promising for application in the next-generation CaL-CSP system.
研究领域:
材料科学
·
能源工程
·
太阳能技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Yu Fan,Bowen Lu,Xinyu Zhi,Cong Luo,Liqi Zhang
NiFe 2 O 4 exhibits excellent redox properties and is widely applied in CaO-NiFe 2 O 4 chemical looping processes. However, rapid sintering of Ni-Fe alloy under reaction conditions limited its industrial applications. The CeO 2 -NiFe-CaO were synthesized through a physical mixing method with NiFe 2 O 4 as a precursor, and its CO 2 capture capacity and in-situ hydrogenation performance were conducted on ICCC-RWGS reaction under different conditions. 20CeO 2 -NiFe-CaO exhibited a CO yielding of 9.35 mmol/g at 650 °C. During the carbon capture stage, CO 2 was adsorbed by CaO, leading to the formation of CaCO 3 . In the hydrogenation conversion stage, hydroxyl groups were generated on the surface, combining with CaCO 3 to produce formate species, further generating H 2 O and CO. 15CNF-CaO exhibited superior cyclic ICCC-RWGS reaction performance compared to 15NF-CaO, with a CO yield of 1.88 mmol/g after 40 cycles. CeO 2 inhibited the sintering of catalytic components, preserving a higher specific surface area and smaller particle size. Furthermore, CeO 2 in 15CNF-CaO inhibited carbon deposition and enhanced in-situ hydrogenation performance, exhibiting better CaO regeneration capability and better cyclic stability. These results could provide insight for designing the DFMs for the ICCC-RWGS process.
研究领域:
化学工程
·
材料科学
·
环境科学
✓ 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）