MATERIALS CHEMISTRY AND PHYSICS
·
2020
·
IF 3.408
Jiawei Wei,Bingqiang Han,Xuancheng Wang,Junfeng Chen,Yaowu Wei,Wen Yan,Nan Li
In this paper, CaO granules were prepared, using the slaked lime as the raw material as well as ZrO 2 , TiO 2 , and V 2 O 5 as additives, respectively. The influence of different additives on the sintering properties, microstructure and hydration resistance of CaO granules was investigated. The results indicated that the introduction of additives could obviously promote the densification and the hydration resistance of the specimens. Especially, the sintering mechanisms of the specimens with different additives were studied. For the specimens with ZrO 2 and TiO 2 as additives, the in-situ formed CaZrO 3 and Ca 3 Ti 2 O 7 between grain boundaries promoted the densification to enhance the properties of the granules. However, the adding of V 2 O 5 generated a coating on the surfaces of CaO granules which contributed to the best hydration resistance.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
Thermal Science and Engineering Progress
·
2023
·
IF 4.8
Shuai Guo,Guoliang Qi,Jialiang Gao,Deng Zhao,Kaixin Chen,Chenchen Zhao,Xingcan Li,Guangyu Li
Pyrolysis is an effective method for safely disposing of sewage sludge via conversion into a usable energy source. However, municipal sludge has a high protein content, which is a major source of NO x precursors. This study investigated the effect of CaO on NO x precursor formation during glutamate pyrolysis and demonstrated that CaO occupies the carbo x yl site of glutamic acid at 320 °C, which delays its decomposition and promotes the conversion of glutamic acid from a five- to a si x -membered ring. At 400 °C, heterocyclic nitrogen in the tar peaked from 4.87 to 53.87% after adding CaO. As the temperature increases to 480 °C, CaO might promote the conversion of heterocyclic nitrogen into tricyclic piperazine dione in the tar, which subsequently decomposed to produce HCN in large quantities. At 480 °C, CaO contributed to the decrease in pyrrole, pyridine, and quaternary nitrogen in the semi-coke from 24.81%, 12.93%, and 7.43% to 1.91%, 5.97%, and 1.43%, respectively and promoted HCN hydrolysis to form NH 3 . At 480–680 °C, CaO interacted with NH 3 to form CaCN 2 . The product of CaC x N y decomposition—CaC x —captured NH 3 . At high temperatures, CaO inhibited HCN release, which might be related to the reaction between CaO and HCN to form CaC x N y , subsequently reconverted into CaO at temperatures above 680 °C. These findings provide novel insights into the influence of CaO on amino acid pyrolysis to produce NO x precursors and the regulation of NO x precursor production.
研究领域:
环境科学
·
能源与燃料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Hui Li,Yongbo Wang,Xiaoling Ma,Zhongjie Wu,Ping Cui,Wanpeng Lu,Fengsheng Liu,Huijun Chu,Yangyang Wang
Calcium oxide (CaO) is recognized as a promising heterogeneous alkaline for transesterification. Nevertheless, equivalent catalytic activity to that of homogeneous alkaline and catalyst stability, especially, the Ca 2+ leaching are still great challenges for CaO used in biodiesel production. To address these problems, in this study, a typical metal organic framework, MIL-100(Fe) and calcium acetate are employed to synthesize the high effective, stable, and magnetic CaO-based catalyst. The preparation factors including calcium acetate addition and activation temperature are investigated to acquire the optimal conditions. Also, effects of transesterification parameters on oil conversion are concerned and the optimized parameters are further used for reusability test. In the meantime, extensive characterizations of TG/DTG/DSC, XRD, Raman spectroscopy, Hammett indicator titration, XPS, N 2 adsorption and desorption, SEM, TEM, VSM are conducted to elucidate the catalytic activity behavior. The as-synthesized catalyst (CAM750) with strong magnetism (112 emu/g) exhibits excellent catalytic activity of 95.09% with catalyst amount of 4 wt% and molar ratio of methanol to oil of 9 at 65 °C for 2 h, which could be easily separated from reaction system by a magnet. More importantly, Ca 2+ leaching is almost prohibited during the repeated cycle, where the leached Ca 2+ in biodiesel at the fourth cycle (1.4 mg/kg) is much less than the limit of EN 14214 standard. Furthermore, crystalline phase and magnetic property of the recovered catalyst are basically in accordance with the fresh catalyst. Therefore, this synthesis method is feasible to enhance and stabilize the catalytic activity of CaO for transesterification.
研究领域:
化学工程
·
能源科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2021
·
IF 6.789
Xiao Xia,Liqiang Zhang,Zhanyao Li,Xueliang Yuan,Chunyuan Ma,Zhanlong Song,Guifang Chen
CaSO 4 reduction decomposition for CaO preparation provides a theoretical basis for the utilization of the industrial byproduct, gypsum. In this study, the effects of temperature (950 °C–1150 °C), CO 2 /CO partial-pressure ratio (1–15), CO concentration (1%–5%), and O 2 concentration (1%–7%) on the preparation of CaO from CaSO 4 by CO reduction decomposition under different reaction atmospheres were investigated. The physical properties of CaO prepared by the decomposition of CaSO 4 and CaCO 3 were analyzed and compared. Finally, the reaction mechanism of the reduction decomposition of CaSO 4 to CaO by CO was studied. The findings reveal that CaSO 4 can be completely decomposed into CaO when the reaction temperature exceeds 1000 °C, CO% ≥ 2%, and P(CO 2 )/P(CO) ≥ 8. Furthermore, the addition of an appropriate amount of O 2 can improve the yield of CaO in the products. In an O 2 –CO–N 2 atmosphere, where O 2 % = 7% and CO% = 16%, CaSO 4 can be completely decomposed into CaO without the addition of CO 2 . The physical properties of CaO prepared by the reduction and decomposition of CaSO 4 are better than those prepared by the calcination of CaCO 3 . An analysis of the reaction mechanism of the reduction decomposition of CaSO 4 by CO reveals that CaSO 4 generates CaO and CaS simultaneously. In addition, CaS can react with unreacted CaSO 4 to form CaO. Furthermore, it can react with CO 2 to produce CaO if an appropriate amount of CO 2 is added to the reaction atmosphere. The secondary interactions of CaS with CaSO 4 and CO 2 can significantly improve the yield of CaO in the product.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yi Fang,Yingjie Li,Jigang Zhang,Youhao Zhang,Zhiwei Chu,Kuihua Han
CaO/CaCO 3 heat storage is considered a promising technology to solve the intermittency of solar energy. Fluidized-bed reactor is commonly used as calciner/carbonator to efficiently achieve heat storage. In the fluidized-bed reactor, the particle cohesion impedes fluidization of CaO/CaCO 3 particles, adversely impacting heat storage. However, the current research rarely focuses on the cohesive behavior of CaO-based particles in fluidization during CaO/CaCO 3 heat storage process. Furthermore, current research on cohesive behavior primarily focuses on experimental studies, lacking an explanation of the underlying mechanisms at the molecular level. In this work, the cohesive behavior of CaO-based particles in CaO/CaCO 3 heat storage process was studied on a fluidized-bed reactor. The particle cohesion is reflected by the tensile yield strength during the transition from static state to fluidization state. The results indicate that the cohesive behavior of CaCO 3 particles gradually is strengthened with increasing temperature. The tensile yield strength of CaCO 3 particles at 800 °C is 1770 Pa, which is 200 % higher than that at 500 °C. Additionally, the carbonation enhances the cohesive behavior of CaO particles. The tensile yield strength of CaO particles after the carbonation is 55 % higher than that of before the carbonation. The enhanced cohesive behavior of CaO particles during the carbonation results in the defluidization. Molecular dynamics simulation shows that the formation of sintering necks at above 650 °C in the carbonation stage results in cohesive behavior of CaO particles. The introduction of 5 % Al 2 O 3 fines (50–75 μm) as lubricant effectively improves the fluidization quality of CaO particles in the carbonation stage, thereby enhancing the exothermic performance of CaO particles. These findings provide valuable insights for the industrial application of CaO/CaCO 3 heat storage in fluidization.
研究领域:
化学工程
·
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Shuo Zhang,Shihao Zhang,Shuran Li,Rongwei Ma,Anyu Wang,Zhen Liu,Keping Yan
In this study, the planetary ball milling with CaO addition was used to remediate lindane-contaminated soil. Based on Hertzian theory, a mathematical model was proposed to simulate the trajectory of grinding ball and the local energy transfer during a planetary operation at the disk rotation velocities of 150–250 rpm. Besides, the influence of different parameters on lindane removal in soil was investigated, whose results showed that disk rotation velocity and reagent-to-soil ratio had a positive effect, while soil moisture, initial concentration of lindane , and mass of polluted soil demonstrated a negative influence. The mechanochemical method exhibited a higher degradation performance at 3 wt% CaO addition, and a disk rotation velocity of 250 rpm. Active species generated by ball collisions in the presence of CaO, especially superoxide (·O 2 − ) demonstrated a significant role in participating in the lindane conversion. In combination with GCMS and XPS analysis , the proposed model provides insight into mechanochemical remediation process from physical and chemical perspectives, which mainly includes four main steps: mixing, inducing, chemical reaction, and structure destruction.
研究领域:
环境科学
·
土壤修复
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ISIJ INTERNATIONAL
·
2017
·Vol. 57
·期 1
·62-67
·
IF 1.11
Zijian Su,Yuanbo Zhang,Yingming Chen,Guanghui Li,Tao Jiang
A considerable amount of works were focused on the formation mechanism of calcium ferrite phases during the iron ore sintering process, especially under various O2 content atmospheres at temperatures higher than 1100°C. But little attention has been paid on reactions between CaO and iron oxides in CO–CO2 atmospheres at lower temperatures. In this study, the solid state reaction mechanisms between CaO and Fe3O4 under CO–CO2 atmospheres at 800°C–1100°C were revealed by using XRD, VSM, etc. The results indicated that Ca2Fe2O5 was easily formed under 5–50 vol% CO/(CO+CO2) atmosphere above 850°C via the reaction of 6CaO + 2Fe3O4 +CO2 = 3Ca2Fe2O5 + CO and the reaction would be promoted with increasing the roasting temperature. In the CO–CO2 atmosphere, Fe3O4 is easily oxidized to Fe2O3 in the presence of CaO because CO2 components act as oxidative medium for the oxidation of Fe2+ to Fe3+.
研究领域:
冶金学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2019
·
IF 1.911
Junqiang Zhang,Shu Zhang,Mei Zhong,Zhi Wang,Guoyu Qian,Junhao Liu,Xuzhong Gong
CaO needs to show high activity to be used as Ca-sorbent and slagging agent. Hydration activity is an important characteristic to evaluate the activity of CaO. In this study, carbide slag from polyvinyl chloride (PVC) industry was utilized as precursor for preparing high activity CaO. The roles of crystallite grain, average pore diameter (APD) and volume fraction of pore < 200 nm in diameter (VF200) in hydration activity of CaO from carbide slag (CS-CaO) were respectively investigated. The hydrolysis kinetics model of CaO shows a three-dimensional spherically symmetric diffusion model (D4), which suggests that hydration activity was mainly associated with APD and VF200 of CS-CaO with limited correlation to the crystal size. Specifically, the hydration activity of CS-CaO is increased with increasing VF200, while decreased with increasing APD. Under the invariable calcination temperature, the core–shell structure formed by the addition of graphite or CaCO 3 to CS effectively inhibits the sintering of CS-CaO and improves VF200. Consequently, the hydration activity of CS-CaO increased from 22.79 °C·min −1 to 27.19 °C·min −1 and to 29.27 °C·min −1 , with addition of 5% graphite or 5% CaCO 3 into carbide slag, respectively.
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
JOM
·
2024
·Vol. 76
·期 5
·2403-2413
·
IF 2.1
Zhang Jie,Li Detian,Zhang Yuankun,He Chengdan,Feng Sen,Wang Jin,Li Chengfang,Wang Yongjun,Liu Aimin,Shi Zhongning
The lunar regolith can be utilized as raw materials for constructing lunar bases through the fabrication of lunar cement. However, the low CaO content in lunar regolith presents a challenge for producing silicate cement. This study explores enriching CaO in NEU-1 lunar soil simulant by calciothermic reduction. Non-isothermal differential scanning calorimetry analysis indicated that calcium reacted with Fe 2 O 3 , SiO 2 , and Al 2 O 3 at approximately 808°C, 816°C, and 826°C, respectively. The reaction ratios were 1.1, 1.6, and 0.8, with apparent activation energies of 941.6 kJ/mol, 965.17 kJ/mol, and 547.28 kJ/mol. The products obtained from the calciothermic reduction of lunar soil simulant were CaO, Ca 2 Si, and AlFe, as analyzed by X-ray diffraction. Increasing the temperature was found to be beneficial to the reaction process, and a suitable reaction temperature of 850°C was determined. X-ray photoelectron spectroscopy analysis showed that the reduction percentages of SiO 2 and Al 2 O 3 were 93.01% and 91.04%, respectively, at 850°C for 30 min. The CaO content in the product obtained by calciothermic reduction was 50.65%, which could be further increased to 81.16% after crude purification, and the CaO yield was 82.57%. These results demonstrated that the process has a significant CaO enrichment effect.
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
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Yingchao Hu,Wenqiang Liu,Jian Sun,Mingkui Li,Xinwei Yang,Yang Zhang,Minghou Xu
A novel inert solid support of Nd 2 O 3 was introduced to enhance the cyclic carbonation/calcination performance of CaO-based sorbents. CaO particles were incorporated into Nd 2 O 3 by a wet-mixing method, using three organometallic precursors (OMPs) as calcium precursors and neodymium(III) acetate hydrate as inert support precursor. For comparison, CaO-based sorbents directly produced from precursors and the naturally occurring sorbent (limestone) were also investigated. FSEM and EDAX results revealed that the ultrafine active specie of CaO particles were homogeneously dispersed into Nd 2 O 3 inert support. As a result, an improved durability and higher carbonation conversion were observed owing to the retarded sintering and the delayed diffusion controlled stage respectively for the sorbents investigated. The performance of the synthetic sorbents also relies on the precursor. When calcium dl -lactate pentahydrate (CaL) was used to incorporate CaO into the inert support Nd 2 O 3 , the highest conversion and best durability were obtained. The effect of calcination temperatures on the sorbent durability was also investigated. Under a relatively severe calcination temperature of 900 °C, a high conversion of about 67% were obtained after 100 carbonation/calcination cycles for a sorbent synthesized from calcium dl -lactate pentahydrate (CaL) and neodymium(III) acetate hydrate. When the calcination temperature was changed to a mild one of 800 °C, a significantly high conversion (>92.5%) was maintained over 100 carbonation/calcination cycles. Besides, no apparent capacity decline was observed for the sorbents after granulation.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
W.Z. Sun,J.G. Cheng,Z.K. Huang,Y. Jiang,L.E. Wu,L.M. Liu
During investigation of the phase relations in the SiC–ZrO 2 –CaO ternary system, it was revealed that ZrO 2 reacted with SiC and CaO to form ZrC and calcium silicate via a series of solid-state reactions. Because these reactions may provide a new route to reaction-sintering of ZrC ceramics, ZrC/SiC and ZrC/salt composites, the formation process of the ZrC phase was analyzed. Subsolidus phase diagram of the related SiC–SiO 2 –ZrC–ZrO 2 –CaO (Si–Zr–Ca–O–C) quinary system at 1400 °C was presented.
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
Journal of Materials Research and Technology-JMR&T
·
2022
·
IF 6.267
Funian Han,Liang Yu,Guanghua Wen,Jun Guo,Chunhua Ran,Shaopeng Gu
In this study, the effect of Na 2 O on the sintering and melting behavior of representative CaO-SiO 2 -CaF 2 slag were synthetically investigated by TG-DSC, DIL, XRD, SEM, XPS, and BET. As expected, most shrinkage of CaO-SiO 2 -CaF 2 slags with and without Na 2 O during the sintering process originated from solid-phase sintering, and the formation temperature of cuspidine as the sintering phase was reduced by Na 2 O to 550 °C. While Na 2 O also transformed Ca 4 Si 2 O 7 F 2 to Ca 2 NaSiO 4 F at 650 °C–880 °C and caused unexpected volume expansion, owing to increased cell volume and corresponding pore expansion. Moreover, Na 2 O reduced the melting point of CaO-SiO 2 -CaF 2 slag and promoted the volatilization of fluoride by changing the final phase before melting.
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
危险品化学品经营许可证（带存储）