JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
·
2024
·
IF 3.1
Chen Yang,Li Zeng-yi,Tan Hao-bo,Fu Yu-ran,Ding Jun,Deng Cheng-ji,Yu Chao
To solve the problem of poor high-temperature service performance caused by low carbonization of MgO–C refractories, low-carbon MgO–C refractories with excellent thermal shock, oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al 2 O 3 powders as additives. The results indicated that the addition of micro-Al 2 O 3 powders optimized the internal structure of the material, like the columnar β-Si 3 N 4 with a stepped distribution and the mosaic structure formed between granular and flaky Mg 2 SiO 4 , which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance. Specifically, the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa, respectively. Moreover, the addition of micro-Al 2 O 3 powders promoted the formation of fine particles of Mg 2 SiO 4 , MgAl 2 O 4 and MgO, as well as a dense protective layer of Mg 2 SiO 4 in the material under high-temperature environment. Furthermore, spinel and high-temperature solid solution were formed in the corrosion environment. The oxidation and corrosion resistances were greatly improved by 41% and 15%, respectively.
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 11
·1-8
·
IF 2.8
Liu Juan,Liu Bing,Song Kai Xin
The effects of cold sintering assisted two-step sintering on the structural evolution and microwave dielectric properties of Al 2 O 3 ceramics are systematically investigated in this work. XRD analysis reveals that the crystal structure remains stable throughout the cold sintering and following high-temperature sintering processes. Rietveld refinement confirms the trigonal Al 2 O 3 configuration and the absence of impurities. Increasing cold sintering pressure results in improved relative density, reaching over 94% after post-sintering at 1575 °C. Additionally, the sintering temperature of Al 2 O 3 ceramics via cold-sintering assisted two-step sintering route is 100 °C lower than that via direct conventional sintering. The microwave dielectric properties, including ε r and Qf , exhibit enhancements with increasing cold sintering pressure and post-sintering temperature. The measured ε r closely aligns with the theoretical value, indicating a successful densification. Qf achieves its peak of 100,220 GHz at 1575 °C under 375 MPa, nearly 2 times higher than the value obtained at 125 MPa (53,280 GHz). The optimal microwave dielectric properties ( ε r = 9.67, Qf = 100,220 GHz, and τ f = − 54.5 ppm/°C) are achieved at a cold sintering pressure of 375 MPa and post sintering temperature of 1575 °C.
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FUEL
·
2024
·
IF 6.7
Shan Jiang,Qian Zhang,Xizi Lin,Wenjun Liu,Songbai Qiu,Riyang Shu
Hydrodeoxygenation (HDO) is an effective method for upgrading lignin-derived phenolic compounds into high-quality liquid fuels, and the support rational design of HDO catalysts is critical for boosting reaction efficiency. In this study, a series of Ni/Al 2 O 3 -C catalysts with different ratio of Al 2 O 3 and carbon components were proposed for the HDO of lignin-derived phenolic compounds. Ni/Al 2 O 3 -C-0.25 catalyst is screened for a superior HDO efficacy compared to the other catalysts, in which guaiacol can be completely converted at 220 °C, with 99.9 % cyclohexane selectivity produced at 4 h. Various characterizations for the catalysts were carried out, including BET, XRD, TEM, XPS and NH 3 -TPD. According to the characterization results, Ni/Al 2 O 3 -C-0.25 catalyst presents little dense Al 2 O 3 fiber structure, which favors the Ni metal dispersion and possesses the smallest Ni metal particle size (10.9 nm). This leads to the outstanding catalytic hydrogenation activity. Moreover, the specific interaction between Al 2 O 3 and carbon in Ni/Al 2 O 3 -C-0.25 catalyst results in the moderate acid property, which promotes the deoxygenation process of the intermediate products, as evidenced by the effective cleavage of C-O bond and the enhanced selectivity of cyclohexane products. The adaptation of Ni/Al 2 O 3 -C-0.25 catalyst to lignin-oil upgrade was also investigated, with a rise of hydrocarbon content from 6.1% to 47.5%. These results indicate that the catalysts with this composite support had the potential to upgrade lignin-derived phenolic compounds to superior grade hydrocarbon liquid fuels.
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 21
·13036-13042
·
IF 3.269
Fenfen Lu,Yan Xu,Xia Jiang,Yang Liu,Jiale Huang,Daohua Sun
Low temperature 1,3-butadiene hydrogenation over biosynthesized Pd/γ-Al2O3 catalysts annealed under different atmospheres (H2 and air) was compared in a fixed bed reactor, and the catalysts were prepared using a facile sol-immobilization method. The structural properties of the Pd/γ-Al2O3 catalysts in relation to their activities in 1,3-butadiene hydrogenation were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, hydrogen temperature-programmed reduction, thermogravimetry, transmission electron microscopy, CO chemisorption measurement techniques and Fourier transform infrared spectroscopy. The results of characterization revealed that the calcination atmosphere (H2 and air) exhibited a remarkable impact on the chemical state of Pd species and catalytic activity, and the coexistence of the metallic state and oxidation state of Pd was a key factor for higher catalytic activity and butene selectivity, while the catalyst with the existence of the metallic state only (H2–Pd/γ-Al2O3) showed lower butene selectivity, and the catalyst with the oxidation state alone (air–Pd/γ-Al2O3) hardly showed any activity in 1,3-butadiene hydrogenation. Therefore, the chemical state of Pd played an important role in the 1,3-butadiene hydrogenation reaction.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·Vol. 107
·期 10
·6764-6773
·
IF 3.5
Huihui Yan,Kun Wang,Liping Zhao,Peng Zhang,Han Chen,Jing Liu,Lian Gao
A new type of Ni/Al 2 O 3 self-supporting catalysts, with high specific surface area, was fabricated by blow-spinning technology. These Ni/Al 2 O 3 self-supporting catalysts are hollow flexible fibers and were utilized for the dry reforming of methane. The Ni/Al 2 O 3 catalysts exhibited exceptional catalytic performance, maintaining their activity for over 150-h at a high temperature of 800°C. The Ni nanoparticles disputed on the hollow fibers demonstrated remarkable resistance to sintering and coking during high-temperature catalysis. This was a noteworthy feature, as sintering and coking are common challenges faced by catalysts during high-temperature reactions. Furthermore, the catalysts retained its activity even after a rigorous 150-h test at 800°C, indicating its durability and stability. Importantly, the Ni/Al 2 O 3 self-supporting could be successfully reactivated after the test, further highlighting its reusable nature. This study offers promising new avenues for the development of high-temperature, self-supporting, and reactivatable catalysts.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Manyu Zhang,Zhijian Fu,Hui Chen,Jia Yu,Liwen Zhang,Chenghan Yang,Yubo Zhou,Yingjie Hua,Xuyu Wang,Hongbing Ji
The catalytic oxidation of formaldehyde (HCHO) at ambient temperature is a highly efficient, cost-effective and environmentally friendly approach for formaldehyde removal. Reactive oxygen (O*) and reactive hydroxyl groups (OH*) are the main active species in the catalytic oxidation reaction of HCHO. Therefore, it is crucial to design catalysts that can simultaneously enhance the surface concentrations of O* and OH*, thereby improving their overall catalytic performance. The present study aimed to design an Al 2 O 3 /CoNC catalyst featuring layered carbon nitride coupled with metal oxides possessing domain-limited cobalt (Co) metal active sites, to efficiently remove HCHO (≈100 %, 100 ppm, RH=50 %, GSHV=20,000 mL/(g h)) and ensure stability (more than 90 % formaldehyde removal within 450 h) at ambient temperature. The characterization revealed that the interaction between Al 2 O 3 -supported metal and CoNC resulted in enhanced confinement of Co, leading to a higher abundance of edge structures exposing more active sites. Additionally, the presence of highly dispersed Co-N X active sites and increased oxygen vacancies effectively facilitated the adsorption and activation processes of HCHO and O 2 , as well as the adsorption and desorption dynamics of intermediates during the reaction. These factors collectively contributed to an improved catalytic activity. The results of in situ infrared spectroscopy revealed that the catalyst improved the adsorption and activation of O 2 and H 2 O, leading to the rapid generation of substantial amounts of O* and OH*. This synergistic interaction between Al 2 O 3 and CoNC plays a crucial role in the sustained production of O* and OH*, promoting efficient of intermediate decomposition, and ensuring excellent catalytic activity and stability for HCHO.
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PubMed
高影响因子
FUEL
·
2024
·
IF 6.7
Yan Liu,Lei Li,Junfeng Zhang,Bo Hou
Optimizing metal nanoparticle size, dispersion, accessibility, and metal-support interaction has proven impactful for Fischer-Tropsch synthesis (FTS) activity, selectivity of long-chain hydrocarbons and stability. Herein, the Co/Al 2 O 3 -CAI catalyst was successfully prepared by a coordination-assisted impregnation strategy. Compared with Co/Al 2 O 3 -EWI catalyst prepared by traditional impregnation method, the Co/Al 2 O 3 -CAI catalyst displayed superior FTS performance with a low methane selectivity (3.2 %) and surprisingly high C 5+ hydrocarbons selectivity (94.0 %) within 200 h reaction time. The catalyst remained excellent stability with ca. 40 % CO conversion even after 1600 h on stream. It revealed that the high dispersion of cobalt species as well as reduced CoAl 2 O 4 spinel could be achieved via a coordination-assisted impregnation strategy, which provide the increased number of surface-exposed Co sites. Meanwhile, the relatively strong metal-support interaction facilitated surface confinement of cobalt species and electron transfer, guarantying catalyst stability under long-term FTS process. This work provides a new insight into the design of highly efficient and stable catalysts for FTS reaction.
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SURFACE & COATINGS TECHNOLOGY
·
2025
·
IF 6.1
Chi Yan,Jialin Li,Yuhao Dai,ZhiJiang Lan,Haobo Wang,Hua Tong,Xiaojun Ye,Xiao Yuan,Cui Liu,Hongbo Li
Polyimide (PI), commonly used in space applications, is vulnerable to atomic oxygen (AO) erosion in low Earth orbit, causing performance degradation. Atomic layer deposition (ALD) of ultrathin films has great potential as AO protective coatings for aerospace materials. In this study, nanometer-thick plasma-enhanced atomic layer deposition (PEALD) SiO 2 films were deposited on in-situ oxygen plasma-activated PI surfaces. The nucleation and growth process of SiO 2 was systematically analyzed. A uniform and dense SiO 2 film was formed, providing limited resistance to AO erosion, but not sufficient for extreme environmental conditions. To further enhance AO resistance, we introduced thermal ALD-Al 2 O 3 interlayers within the same processing window and alternately deposited conformal, continuous Al 2 O 3 /SiO 2 nanolaminates on the PI surface. The Al 2 O 3 interlayer effectively reduced the film deposition roughness, forming a smoother, denser barrier layer and minimizing growth defects. This dense ALD-Al 2 O 3 /SiO 2 nanolaminate, with its inert Si-O-Al bonds, effectively prevents AO from penetrating the substrate, showing superior protection under long-term AO exposure. After AO irradiation, the surface remained smooth with no obvious defects or voids, effectively avoiding undercutting caused by AO. The synergistic effect of alumina and silica provides excellent AO protection while maintaining good optical transmittance.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Nan Shi,Hengxi Zhu,Jiamin Qi,Bin Li,Jin Zhang
Carbonyl sulfur (COS) was difficult to be removed by conventional desulfurization technologies because of its stable chemical properties. Mesoporous γ-Al 2 O 3 (MA) showed excellent potential for hydrolysis of COS, but the catalyst life was greatly shortened with the progress of the reaction. Therefore, improving the catalyst life is the key to MA which can apply to hydrolysis of COS. In this study, P123 modified mesoporous γ-Al 2 O 3 (P-MA) catalyst was prepared by sol–gel method, and it was regulated by template agent and acidity regulator. These preparation conditions of P-MA were optimized to improve the hydrolysis efficiency of COS. The effects of temperature, space velocity, relative humidity and oxygen concentration for the hydrolysis efficiency of COS were studied. The results show that the optimized P-MA catalyst is suitable for COS low-temperature hydrolysis reaction, and it can maintain 99 % for 10 h under the tough reaction conditions. The only crystal of P-MA was γ-Al 2 O 3 with large specific surface area and uniform distribution pore, which are beneficial to the COS hydrolysis. In addition, the hydrolysis efficiency of COS can also remain 97 % for 10 h in the O 2 and CO 2 atmosphere, indicating that the P-MA catalyst has a specific anti-poisoning ability. The kinetics and reaction mechanism of COS catalytic hydrolysis were studied, which showed that the adsorption of H 2 S was the key to hindering the continuous reaction. The P-MA can effectively inhibit the adsorption of H 2 S, which greatly improved COS hydrolysis life of P-MA. This study provided a theoretical basis for the application of Al 2 O 3 catalyst in the COS hydrolysis.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Saibei Zhang,Xiaohan Qu,Hui Lv,Jingbo Mao,Jinxia Zhou
Cu-based catalysts featured with high activity at low temperatures and suppressed CO generation are expected to attract significant attention in the methanol steam reforming (MSR) reaction for on-board hydrogen production for proton exchange membrane fuel cells. Herein, we demonstrate that Ag incorporation into a CuO/ZnO/Al 2 O 3 catalyst leads to enhanced hydrogen production activity and suppressed CO selectivity in MSR reactions at low temperatures (200–220 °C). The characterization results revealed that incorporation of a small amount of Ag in the catalyst not only improves the dispersion of the polymetallic components and diversifies the Cu species, but also lowers Cu reduction temperature and brings more oxygen vacancies , thereby leading to improved catalytic performance. The preparation conditions, structure-activity relationship, and stability of the Ag-promoted catalyst were investigated in detail based on time-on-steam tests and characterizations. This finding paves a new possible way for the optimization of the Cu-based catalysts for MSR.
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高影响因子
Journal of Materiomics
·
2024
·
IF 8.4
Li Tan,Jiufeng Dong,Li Li,Chengyuan Wang,Yuqi Liu,Yujuan Niu,Zizhao Pan,Liang Sun,Hong Wang
High-temperature polymer nanocomposites with high energy storage density ( U e ) are promising dielectrics for capacitors used in electric vehicles, aerospace, etc. However, filler agglomeration and interface defects at high filler loadings significantly limit the enhancement of U e and hamper the large-scale production of the nanocomposites. Here, polyetherimide (PEI) nanocomposites with nanoscale alumina (AO) at ultra-low contents were prepared via in situ polymerization from PEI monomers. We compared two composite dielectric preparation methods ( in situ polymerization and ordinary solution blending) under the same conditions. In contrast to the nanocomposites obtained by blending PEI polymers with AO, the in situ nanocomposites exhibit substantially improved filler dispersion, together with largely suppressed conduction loss at high fields and high temperatures, leading to comprehensive enhancements of breakdown strength ( E b ), charge-discharge efficiency ( η ) and U e , simultaneously. The 0.3%(in volume) AO filled PEI nanocomposite film exhibits a superior U e of 4.8 J/cm 3 with η of 90% at 150 °C, which is 128% and 218% higher than those of pristine PEI and the ex situ PEI/AO nanocomposite film under the same conditions, respectively. This work provides a scalable strategy for the preparation of dielectrics with both good processability and excellent high-temperature energy storage performance.
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Membranes
·
2024
·Vol. 14
·期 5
·117
·
IF 3.3
Yuqi Song,Kai Miao,Jinxin Liu,Yutang Kang,Dong Zou,Zhaoxiang Zhong
Membrane distillation (MD) is considered a promising technology for desalination. In the MD process, membrane pores are easily contaminated and wetted, which will degrade the permeate flux and salt rejection of the membrane. In this work, SiC ceramic membranes were used as the supports, and an Al2O3micro-nano structure was constructed on its surface. The surface energy of Al2O3@SiC micro-nano composite membranes was reduced by organosilane grafting modification. The effective deposition of Al2O3nanoflowers on the membrane surface increased membrane roughness and enhanced the anti-fouling and anti-wetting properties of the membranes. Simultaneously, the presence of nanoflowers also regulated the pore structures and thus decreased the membrane pore size. In addition, the effects of Al2(SO4)3concentration and sintering temperature on the surface morphology and performance of the membranes were investigated in detail. It was demonstrated that the water contact angle of the resulting membrane was 152.4°, which was higher than that of the pristine membrane (138.8°). In the treatment of saline water containing 35 g/L of NaCl, the permeate flux was about 11.1 kg⋅m−2⋅h−1and the salt rejection was above 99.9%. Note that the pristine ceramic membrane cannot be employed for MD due to its larger membrane pore size. This work provides a new method for preparing superhydrophobic ceramic membranes for MD.
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