CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Chen Zeng,ZhiWei Jiang,Yongjian Zeng,Suyu Zhang,Rafael Luque,Kai Yan
H 2 -rich syngas production via microwave-assisted pyrolysis (MAP) of lignocellulosic biomass has recently gained significant attention in biorefineries. Herein, a novel pearl-like calcium oxide (P-CaO) was developed to investigate the dual roles of CaO in H 2 enhancement and CO 2 absorption during MAP of lignocellulosic biomass, dedicated to achieving high production of H 2 -rich syngas. Utilizing a self-constructed MAP system, the different catalytic performance between P-CaO and other metal oxides were examined, revealing that our P-CaO produced the highest H 2 yield (257 NmL/g corn stover , 7.6 times higher than no-catalyst group and 2.2 times higher than commercial CaO group), and lowest CO 2 production (44 NmL/g feedstock ), with syngas purity exceeding 72 vol% at 600°C. This increase in H 2 -rich syngas production demonstrated universal applicability across other biomass feedstocks. Finally, the study delved into the microstructural changes and phase transition mechanisms of P-CaO, shedding insights into gas formation pathways. The P-CaO nanoparticles, with abundant alkaline sites, excellent adsorption capacity and large specific surface area due to aggregate, facilitate the secondary cracking of organic intermediates like phenols, thus promoting the production of H 2 , while CO 2 adsorption derives a favorable shift in the water–gas shift equilibrium. These findings are expected to offer critical insights and serve as a reference for the development of efficient catalysts in the next-generation hydrogen industry.
研究领域:
能源科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS ES&T Engineering
·
2024
·
IF 7.4
Hanling Jiang,Jingwen Wang,Aijuan Zhou,Yong Liu
Advanced oxidation processes (AOPs) for removing ammonia nitrogen (NH4+-N) are of increasing interest in wastewater treatment. In this paper, the UV-activated persulfate (PS) process with CaO was applied to oxidize NH4+-N to nitrogen gas (N2). Nearly all of the NH4+-N (30 mg N/L) could be removed within 15 min, and the N2 selectivity was achieved at 95.0%. The addition of CaO made NH4+-N exist in the form of NH3, and HO• was the critical reactive species for NH4+-N oxidation. NO, N2H4, and NO2– were identified as oxidation intermediates and could be further removed. The reaction between N2H4 and NO2– with the assistance of UV/CaO promoted N2 generation during NH4+-N oxidation. The increased dosages of CaO (0.2 to 4.0 g/L) and PS (0.6 to 2.4 g/L) could enhance the NH4+-N oxidation, while the presence of CO32– (100 mM) significantly retarded the removal of NH4+-N. As high removal of NH4+-N (100%) and high N2 selectivity (>79.5%) could be achieved in lake water and secondary wastewater, the proposed UV/PS/CaO process could be potentially applied for the oxidation of NH4+-N in practical water treatment.
研究领域:
环境科学
·
废水处理
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yuchuan Feng,Jingwei Jia,Nana Wang,Suxia Ma
Hydration activation is an effective approach to improve the cyclic reactivity and mitigate the sintering of CaO sorbents. However, the interaction mechanism between sintering, hydration and reactivity remains unclear. In this study, we conducted hydration experiments using ex-situ water treatment in a separate hydrator to investigate the role of sintering degree in the activation reaction, complemented by ReaxFF molecular dynamics simulations (ReaxFF-MD) to elucidate the underlying mechanisms. The results revealed that high-temperature calcination causes apparent sintering of CaO, leading to a decline in CO 2 adsorption capacity. Hydration treatment greatly enriches the specific surface area and pore structure, providing more active sites and channels for CO 2 adsorption, thereby enhancing carbonation performance. The hydration degree of CaO was found to be negatively correlated with the degree of sintering, but positively correlated with the improvement of pore structure and property activation. Two types of hydroxyl groups (direct hydroxyl O w H and indirect hydroxyl O s H) were rapidly generated. O w H can convert to O s H through re-decomposition, involving O* radicals and proton diffusion. The hydroxylation gradually weakened as the sintering intensified. During the CaO hydration reaction, three types of water were generated: free H 2 O, adsorbed H 2 O and dissociated H 2 O. Free H 2 O and adsorbed H 2 O continued to increase with the degree of sintering, while the associated H 2 O decreased. Sintering significantly limited the diffusion of H atoms and hindered O s H formation, resulting in an overall decline in hydroxylation. For hydrated samples, the evaporation of free water, desorption of adsorbed water, and decomposition of dissociated water occurred simultaneously during heating. These phase transitions directly impacted on the evolution of pore structure.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
iScience
·
2025
·
IF 4.1
Fanfan Liang,Yungen Liu,Silin Yang,Yan Wang,Yiyang Peng
High-concentration refractory coffee wastewater containing about 2000 mg/L of biotoxic lactic acid is treated by microwave technology. At a microwave power of 900 W, a large amount of activated carbon (AC) reduces the number of hot spots. After microwave radiation, the lactic acid concentration drops to 200 mg/L, with a removal rate of 90 %. CaO promotes the process. In the microwave-AC-CaO method, “hotspots” on AC generate free radicals. The effects of microwaves degrade lactic acid into CO 2 and H 2 O. The microwave-AC-CaO method can rapidly degrade lactic acid. And the degradation rate of lactic acid can be further improved by adding transition-metal oxides to modify AC.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2020
·
IF 4.419
Woo Sung Yum,Jung-Il Suh,Do Hoon Kim,Jae Eun Oh
Recently, the combined use of calcium oxide (CaO) and calcium formate (Ca(HCOO) 2 ) has been proposed as an alternative activator for ground granulated blast furnace slag (GGBFS) (referred to as CaO-Ca(HCOO) 2 -activated GGBFS system). However, this clinker-free binder system produces calcium aluminate hydrate (C 2 AH 8 ), generally leading to the degradation of cementitious binder systems by its conversion to other phases. Thus, in this study, attempts to remove C 2 AH 8 from this system without losing the strength are suggested by the use of two additives (i.e., calcium sulfate (CaSO 4 ) and calcium nitrate (Ca(NO 3 ) 2 ), respectively). Results revealed that the above-mentioned additives completely remove C 2 AH 8 in the initial curing stage via its conversion to ettringite or NO 3 - and NO 2 -AFm, respectively. In addition, the additives reduced the extent of the total shrinkage and the standard deviation of strength results of triplicate samples. However, CaSO 4 exerted a beneficial effect on the strength, while Ca(NO 3 ) 2 exerted a marginal or detrimental effect on the strength. Therefore, this study suggested a new mixture form of an activator, comprising CaO , Ca(HCOO) 2 , and CaSO 4 , to activate GGBFS for maintaining strength without the conversion issue of C 2 AH 8 .
研究领域:
建筑材料学
·
材料科学
✓ 已验证
DOI
高影响因子
RENEWABLE ENERGY
·
2020
·
IF 6.274
Tongxin Qu,Shengli Niu,Zhiqiang Gong,Kuihua Han,Yongzheng Wang,Chunmei Lu
CaO is efficient in catalyzing transesterification for biodiesel production , but its industrial application is inherently restricted by active sites leaching. To address this drawback, CaO is decorated into wollastonite to prepare the stable Ca/wollastonite catalyst. Microwave-assisted transesterification is used to produce biodiesel from palm oil, which effectively accelerates the reaction rate and improves the conversion efficiency. The Ca/wollastonite-0.8 catalyst with the mass ratio of CaO to wollastonite of 0.8 performs well with the fatty acid methyl ester (FAME) yield of 97.59%. Also, this catalyst is highly stable, where the FAME yield of 87.30% could be obtained for the fifth reused cycle. CaO is evenly dispersed on the wollastonite surface and the total basicity is high to 0.281 mmol g −1 . Meanwhile, transesterification parameters are optimized by response surface methodology with central composite design (RSM-CCD) and the maximum FAME yield of 98.46% is achieved at reaction temperature of 64.2 °C, molar ratio of methanol to palm oil of 15.54 and mass ratio of catalyst to palm oil of 9.21 wt % for 3 h. Besides, the mass ratio of catalyst to palm oil is the primary variable. Wollastonite is demonstrated to be feasible to enhance the stability of CaO in catalyzing transesterification.
研究领域:
化学工程
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2013
·
IF 3.258
Ruikun Wang,Jianzhong Liu,Yujie Yu,Junhu Zhou,Kefa Cen
Urbanization has generated large volumes of municipal wastewater sludge (sludge for short) that threaten the environment and human health. As such, utilization of the sludge in a cost-effective manner is an important concern. The sludge, as a carbon-containing material, can be made into coal-sludge slurry (CSS) by mixing it with pulverized coal. However, the slurryability of the raw sludge is relatively poor due to the abundance of hydrophilic groups in the sludge and its loose floc structure. In this study, modification of the sludge with calcium oxide (CaO) showed positive effects on the sludge slurryability. The characteristic viscosity of the coal raw-sludge slurry (R-CSS) was 1635.3 mPa s. After modification of the sludge with 2 wt.% CaO for 24 h, the CSS viscosity decreased to 1184.4 mPa s. The hydrophobic group (C C and C H) content of the sludge increased from 61.5% to 74.9% as the CaO dosage increased from 0% to 4%, and the zeta potential increased from –55.1 eV to –36.2 eV. The optimum CaO dosage for improved slurryability was found to be 2 wt.%. Compared with R-CSS, the coal modified-sludge slurry (M-CSS) showed lower yield stress, weaker pseudoplastic and thixotropic behaviors, and poorer static stability.
研究领域:
环境科学
·
能源工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2023
·
IF 8.9
Tao Huang,Lulu Zhou,Chun-Hai Yang,Shu-wen Zhang
The alkalinity of CaO is commonly insufficient in alkali-activating raw soils or minerals for the formation of cementation or geopolymerization. In this study, nonthermal plasma (NTP) irradiation was employed to activate traditional CaO to enhance its efficacy in alkali activation and further intensify the self-cementation of gold tailings. The solidification/stabilization (S/S) of the gold tailings-based matrix activated by NTP-CaO was better than that of CaO. The NTP irradiation enhanced the surface hydroxyl groups and oxygen atoms, decreased the binding energy, formed nanoparticles , and significantly changed the morphologies of the calcium activator. The dosage of the NTP-irradiated CaO (NTP-CaO) directly affected the self-cemented solidification/stabilization of gold tailings. The Johnson-Mehl-Avrami–Kolmogorov model was appropriate for analysing the NTP-CaO-activated geopolymerization kinetics of gold tailings. Three-dimensional (3D) structural minerals covered with small pores were determined in the NTP-CaO-activated cemented samples. The employment of NTP-CaO facilitated the formation of aluminosilicate geopolymers during the self-cementation of gold tailings according to comprehensive characterization strategies. The study achieves the efficient self-remediation of gold tailings by activating calcium precursors, which further solves the contradiction between salinization and alkali activation in the field of noncalcined cementitious materials.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·Vol. 108
·期 4
·e20286
·
IF 3.5
Shu Li,Wenjie Wei,Guangyu Wang,Zemeng Weng,Boya Zhang,Zhanmin Cao
The phase equilibria information of the CaO–SbO x system in the range of 700–1580°C in air was obtained for the first time using quenching method and thermal analysis. The equilibrium phase compositions were determined using x-ray diffraction and Scanning Electron Microscopy-Energy Dispersion Spectrum. The invariant reaction temperatures were determined using thermogravimetry-differential scanning calorimetry. A perovskite solid solution between Ca 2 Sb 2 O 7 and CaO, designated as (Ca 6 Sb 2 O 11 ) s.s , was observed. Within this solid solution, three polymorphic forms were identified: orthorhombic, tetragonal, and cubic. The transition temperatures between these polymorphic forms vary with compositional changes. Additionally, the crystal structure of cubic Ca 6 Sb 2 O 11 was analyzed. CaSb 2 O 6 was observed to decompose into Ca 2 Sb 2 O 7 , Sb 4 O 6 , and O 2 above 1336 ± 5°C. The eutectic temperature of α-Sb 2 O 4 and CaSb 2 O 6 was found to be 1220 ± 5°C.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2025
·
IF 6.6
Zhenyun Tian,Weichao Zheng,Liu Yang,ChuanMing Wu,Jialong Kang,Jiawen Chen,Guibao Qiu
The recovery of valuable metals from spent SCR catalysts currently centers on chromium and tungsten oxides. However, this approach demands substantial consumption of acids and bases, and due to the low vanadium and tungsten content, its economic output is minimal. In contrast, titanium dioxide, which exists in significantly higher proportions within the catalyst, is largely overlooked, aggravating environmental issues and leading to considerable resource wastage. This research proposes utilizing spent SCR catalysts as raw materials to directly synthesize titanium alloys, thereby increasing the recovery value of these discarded materials. The findings reveal that aluminum, employed as a reducing agent, efficiently reduces the majority of valuable metals in the catalyst, resulting in the formation of titanium alloys. Furthermore, the addition of calcium oxide markedly enhances the reduction process and improves slag-metal separation. When the CaO content reaches 50 wt%, titanium recovery achieves an impressive rate of 93.34 wt%. The produced alloy comprises primarily a Ti–Al alloy matrix, with a Ti–Si alloy as a dispersed reinforcing phase uniformly distributed within the matrix, demonstrating significant potential for practical applications.
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
MINERALS ENGINEERING
·
2022
·
IF 5.479
Xianping Luo,Xianqiang Yuan,Kunzhong He,Yongbing Zhang,Caigui Luo,Zishuai Liu,Hepeng Zhou
Impurity metal ions in ionic rare earth ores are similar to rare earth ions in terms of occurrences and similarities in properties. During the leaching operation, a large number of impurity ions enter the rare earth leaching solution, which makes the crystal form of the rare earth unstable or forms an amorphous flocculent precipitate. The commonly used ammonium bicarbonate (NH 4 HCO 3 ) precipitation crystallization process has low rare earth precipitation rate, long precipitation crystallization period, and high ammonia nitrogen content in precipitation wastewater. In this paper, the leaching solution obtained by ionic rare earth ore magnesium salt leaching-combined impurity removal process was taken as the research object, and the effects of precipitants, such as NH 4 HCO 3 , calcium oxide, sodium carbonate, and oxalic acid, on the preparation of crystalline rare earth precipitation were investigated through comparison. On the premise of determining the best rare earth precipitant, the effects of dosage, stirring speed, stirring time, and aging time on the preparation of crystalline rare earth precipitate were investigated further. The precipitation effects of different precipitation processes were studied systematically combined with SEM-EDS, laser particle size analysis, and other means to characterize the morphology of crystalline products. Results showed that when calcium oxide was used as a precipitant, the molar ratio was 2.5. After stirring at a constant speed of 200 r/min for 4 h and aging for 4 h, precipitates with good crystal appearance, smooth crystal surface and easy filtration were obtained. This process promoted crystal growth of rare earth precipitates, and the crystal grain size, which was beneficial to the improvement of the quality of rare earth products, increases significantly.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 94
·91968-91980
·
IF 3.289
Fu Yang,Bangbang Wang,Shijian Zhou,Xiaoning Yang,Yan Kong
Catalytic performance of heterogeneous catalysis is strongly dependent on the dispersity of catalytic active sites, and especially a high exposure of the unit active phase is promising for the overall catalytic process. In this study, a novel strategy was developed to fabricate an unprecedented CaO-based mesoporous solid strong base catalyst. Relying on the physicochemical assembly of Ca2+ in the interface between a micelle and siliceous wall, thin-layer-like calcium oxide species were formed in situ and dispersed in the mesochannels of silica. Wherein, the gradual coverage of CaO on the mesoporous wall was controlled by adjusting the amounts of Ca2+ on alkylamine micelles. Interestingly, a novel sponge-like microscale structure of silica was discovered in the CaO-based mesoporous-composites for the first time, which completely differs from the reported mesoporous silica. More importantly, the introducing of a CaO solid base on the pore wall is nearly non-destructive for the textural properties of the mesoporous matrix. The direct template-induced mesoporous solid strong base not only received extremely dispersed and unexpected enhanced strong basic sites (CO2-desorption temperature ≥718 °C), but also avoided repeated thermal processes for the degradation of the basic resource, and saved energy and time. This heterogeneous alkaline catalyst shows excellent catalytic activity for the synthesis of dimethyl carbonate under a milder reaction condition (30 °C, 25 min) and holds stability and reusability beyond comparison with the conventional catalysts. The dispersed and enhanced strong basic sites, combined with excellent mesoporous properties, are demonstrated to be responsible for such a high catalytic performance.
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
危险品化学品经营许可证（带存储）