FUEL
·
2021
·
IF 6.609
Pengcheng Wang,Jun Liu,Guo Liu,Peiwen Xu,Xinzhen Feng,Weijie Ji,Yulan Gao,Chak-Tong Au
In this work, we studied how the oxidic CoMoO x /Al 2 O 3 and sulphurated CoMoS x /Al 2 O 3 interfacial structures determine catalytic efficiency in selective hydrodesulfurization (HDS) of dibenzothiophene (DBT). To achieve this goal, we first synthesized the γ-Al 2 O 3 materials of unique morphologies through the ionic liquid-assisted hydrothermal process under different conditions. The resulting γ-Al 2 O 3 hexagonal plates (HP) and stacked hexagonal plates (SHP) are single crystallites with the dominant (1 1 0) and (1 1 1)/(1 0 0) facet structures, respectively; whereas the Al 2 O 3 rods show polycrystalline feature. Through impregnation of Mo/Co salts of different loadings, the various CoMoO x precursors were generated on the different Al 2 O 3 facets owing to the distinct interaction: mostly the two-dimensional (2D) poly-/mono-meric MoO x species together with the three-dimensional (3D) MoO 3 on the Al 2 O 3 (1 1 0) facet vs. the quasi 2D polymeric MoO x species on the Al 2 O 3 polycrystalline facet. Such structural difference further affected the sulfidation of the MoCoO x as well as the quantity of active MoCoS x entities on different γ-Al 2 O 3 supports: 10Mo3CoS x /Al 2 O 3 -HP had the highest level of MoCoO x sulfidation thus a much higher fraction of MoS 2 plus Co 9 S 8 /CoMoS species whereas less quantity of partially sulphurated CoMoO x S 2 /CoO x together with SO x 2- species. All the distinct interfacial domains of the sulphurated catalysts reasonably account for significantly different efficiency in HDS of DBT. Surface MoS 2 /CoMoS/Co 9 S 8 species of the highest content over the Al 2 O 3 (1 1 0) facet correspond to the highest DBT areal conversion rate and TOF value, owing to the enhanced MoS 2 -Co 9 S 8 and MoS 2 -CoMoS conjunction and synergism.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2023
·
IF 3.8
Jianhui Su,Yan Liu,Xiujing Peng,Guoxin Sun,Xuchuan Jiang
Due to the high activation energy barrier and the sporadic nature of nucleation, the temperature required for the transition from cubic dense γ-Al 2 O 3 to tripartite α-Al 2 O 3 is as high as 1100–1200 °C. In this work, a two-step strategy was employed to reduce the phase transformation temperature, and prepare α-Al 2 O 3 particles with good dispersion. As the first step, 10 nm sheet γ-Al 2 O 3 was obtained by ammonium aluminum carbonate (AACH) decomposition, which was more favorable to the crystal transformation in the next ball-milling processing. In the second step, γ-Al 2 O 3 powder with partial α-Al 2 O 3 produced in situ by ball-milling γ-Al 2 O 3 was calcined, and α-Al 2 O 3 nanoparticles were obtained at just 850 °C. The content of the α-Al 2 O 3 is determined by the Rietveld Refine method. The relationship between ball-milling time and α-Al 2 O 3 content was clarified, and the effect of α-Al 2 O 3 content on the transformation temperature and morphology of γ-Al 2 O 3 was discussed. The results showed that the α-Al 2 O 3 content rises with the increase of ball milling time, and spherical α-Al 2 O 3 nanoparticles can be obtained when the α-Al 2 O 3 content is 5 %. The addition of α-Al 2 O 3 seeds reduces the phase transition temperature but agglomeration exists. Our proposed two-step low-temperature calcination strategy is an important method for the preparation of alumina nanoparticles
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
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Shenglin Kang,Xuetong Zhao,Jing Guo,Jie Liang,Jianjie Sun,Yang Yang,Lijun Yang,Ruijin Liao,Clive A. Randall
Thermal-assisted cold sintering process (TA-CSP) has been applied to fabricate high dense α-Al 2 O 3 ceramics with submicron grain sizes. The α-Al 2 O 3 (80 wt%) and γ-Al 2 O 3 (20 wt%) powders are firstly mixed and then cold sintered at 300 °C to produce a green bulk with a relatively high density of ∼ 86.9 %, and then later a second heat treatment (800–1350 °C) is applied to finally fabricate (∼ 98 % dense) α-Al 2 O 3 ceramics with grain sizes of 720 nm. A microstructural analysis with XRD and TEM suggests that the TA-CSP samples not only complete the final densification but also drive a phase transition of γ-Al 2 O 3 to α-Al 2 O 3 . To put into perspective the Hardness and Young's modulus of TA-CSP samples reach ∼ 14 GPa and ∼ 335 GPa, respectively, which is comparable to conventional sintered samples processed at higher temperatures of 1500–1700 °C. Therefore, it is feasible to utilize TA-CSP to prepare α-Al 2 O 3 ceramics with small grain sizes at low sintering temperatures .
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 THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Haonan Cui,Hongcheng Yang,Hua Wang,Yixuan Zheng,Yuchen Wang,Hongyu Yang,Enzhu Li
CaO-Al 2 O 3 -B 2 O 3 (CAB) glass-ceramics with varying Al 2 O 3 content were fabricated using the melting method including melting and quenching of mixture of raw materials. The obtained glass powder was pressed into the desired shape and sintered for measurement. At 900 °C, the crystallinity initially increased and then decreased with increasing Al 2 O 3 content. The highest crystallinity of 62.29 % was obtained when the Al 2 O 3 content was 0.5 mol%, and exhibited excellent dielectric properties : ε r = 4.35, Q × f = 53,085 GHz, and τ f = –33.95 ppm/°C. The variation of dielectric properties with increasing Al 2 O 3 content is attributed to the crystallinity process. The crystallization process of CAB system was determined by crystallization activation energy , the lowest value of 302.085 kJ/mol corresponds to the highest crystallinity. The crystallization, dielectric properties and sintering behavior of CAB system indicate that CAB system prepared by melting method have promising prospect as new LTCC glass-ceramics.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2020
·
IF 3.687
Ning Xiang,Xiaojin Han,Yarong Bai,Qiaoyan Li,Jianfeng Zheng,Yulin Li,Yaqin Hou,Zhanggen Huang
Supported noble metal catalysts have been widely utilized for HCHO catalytic oxidation. When the active components are fixed, the altering and regulation of the supports would have a huge effect on catalytic performance. Here, two types of Pd/γ-Al 2 O 3 catalysts with different support size (micro-γ-Al 2 O 3 and nano-γ-Al 2 O 3 , respectively) were fabricated and used for HCHO oxidation. Compared with the micro-sized counterpart, the Pd/nano-γ-Al 2 O 3 catalyst exhibited much superior HCHO oxidation performance which could totally oxidize 160 ppm of HCHO into harmless CO 2 under a WHSV of 100,000 mL g cat −1 h −1 at room temperature. Multiple characterizations including XRD, BET, TEM, CO chemisorption, FT-IR, O 2 -TPD, XPS and in situ DRIFTS were implemented to study the effect of γ-Al 2 O 3 support size on physicochemical properties of Pd/γ-Al 2 O 3 catalysts and elucidate the structure-activity relationship. The results revealed that large specific surface area, rich surface OH groups as well as high curvature of nano-γ-Al 2 O 3 not only facilitated HCHO adsorption, but also stabilized highly dispersed Pd species which then promoted the activation of oxygen and boosted formate species decomposition, and consequently leading to the enhanced HCHO oxidation performance of Pd/nano-γ-Al 2 O 3 . This work deepens the comprehension of support size-dependent activity of Pd/γ-Al 2 O 3 catalysts for HCHO oxidation and provides an alternative method to prepare high-performance Pd catalysts for HCHO oxidation.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Xiaoyu Yang,Xuanxuan Lei,Shaokun Tang
A simple hydrothermal method is utilized to fabricate hierarchically olive-like γ -Al 2 O 3 using ionic liquid [Bmim]BF 4 as the structure directing agent . The olive-like γ -Al 2 O 3 presents uniform morphology with the average diameter of 500 nm and rich mesopores. As template, ionic liquid [Bmim]BF 4 plays a crucial role in the controllable morphology of the product. [Bmim]BF 4 is absorbed on the AlOOH nanoparticles surface via the H-bond interaction and induces crystalline oriented growth. Then the forming AlOOH nanosheets self-assemble into olive-like hierarchical structure through π–π stack interaction. Given that the structure advantage of the olive-like γ-Al 2 O 3 and the limited study concerning cerium-based catalysts in Fenton-like reaction, nano-CeO 2 / γ -Al 2 O 3 supported catalyst is prepared and used in Fenton-like degradation for the first time. The result suggests that the olive-like γ -Al 2 O 3 support not only reduces the surface energy with more uniform CeO 2 (ca. 4–5 nm) dispersion but also improve the concentration of Ce 3+ active sites. The CeO 2 / γ -Al 2 O 3 catalyst displays superior catalytic activity for the degradation of Orange II (AO7) compared with pure CeO 2 nanoparticles.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Wenjie Zhang,Jing Zhao,Linfeng Wang,Guofu Liu,Dekui Shen,Huiyan Zhang
The pyrolytic reforming of toluene to hydrogen and CNTs over the commercial and self-prepared Al 2 O 3 loaded with Fe through the impregnation method is investigated in a fixed bed reactor under the temperature from 600 °C to 800 °C. The physicochemical properties of Fe–Al 2 O 3 catalysts and Al 2 O 3 supports were characterized by XPS, H 2 -TPR, HRTEM and H 2 -pulse chemisorption . The reforming process over the catalyst of Fe loaded on self-prepared Al 2 O 3 gives the excellent H 2 yield of 27.8 mmol/(g-Fe) and graphite yield of 82.6 wt%, which is much higher than those from that over the catalyst of Fe loaded on the commercial Al 2 O 3 . It is evidenced by H 2 -pulse chemisorption that 5.1 % of Fe 0+ dispersion over the commercial Al 2 O 3 with mainly-exposed (110) facet while 11.2 % of Fe 0+ dispersion over self-prepared Al 2 O 3 with mainly-exposed (111) facet were obtained. The adsorption energy of iron cluster (Fe 4 ) with Al 2 O 3 (111) facet was estimated to be −14.5 eV through the DFT simulation, which is notably higher than that of iron cluster (Fe 4 ) with Al 2 O 3 (110) facet as −9.1 eV. With regard to the MD simulation along with XRD analysis of the Fe 3 C crystallite , Fe 0+ particles can be prominently molten at the high Fe 0+ dispersion over Al 2 O 3 facet, promoting the carbon solubility for the assembly of multi-wall CNTs without the deposition of unwanted amorphous carbon .
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Jia Shen,Chen Chen,Lichuan Song,Liding Zhong,Kai Shan,Yanglong Guo,Wangcheng Zhan,Yun Guo,Haifeng Wang,Li Wang
The anchoring effect between surface hydroxyls (–OH) and metal species has been extensively utilized to enhance catalyst stability. Nevertheless, few studies have investigated the impact of alloying process involving different types of –OH species. In this research, we discovered that the formation of the alloy particles Pt 3 Co was significantly influenced by the presence of distinct –OH species on Al 2 O 3 . Intriguingly, those Pt 3 Co alloy particles exclusively formed on α-Al 2 O 3 owing to the weak interaction between both Pt and Co species and the triply bridging hydroxyls (µ 3 -OH). In contrast, Pt and Co species were found to be separately dispersed on γ-Al 2 O 3 because of the strong anchoring effect of terminal hydroxyls (µ 1 -OH), especially for Co atoms. Density functional theory (DFT) calculations highlighted the difference in adsorption energies of the two metals on different hydroxyl groups, providing a theoretical rationale for the influence of hydroxyl groups on alloy formation. The presence of Pt 3 Co alloy resulted in a fourfold increase in the specific catalytic rate of Pt 3 Co/α-Al 2 O 3 in CO-PROX compared to Pt 3 Co/γ-Al 2 O 3 . Arguably for the first time, this study demonstrates the association between alloy formation and –OH groups, providing a unique perspective on the design of alloy catalysts.
研究领域:
催化化学
·
材料科学
·
理论计算化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Jialiang Zhao,Jinlian Li,Xiaofang Zhang,Xudong Luo,JiJia Li,Xin Qi,Yiran Man,Rui Lin,Zhipeng Xie
Currently, porous Al 2 O 3 ceramics have attracted extensive attention because of their unique properties. However, the low strength of porous Al 2 O 3 ceramics constrains their practical application. Herein, the porous Al 2 TiO 5 –Al 2 O 3 ceramics with higher strength were prepared through the Al 2 O 3 hollow spheres (HSs) coated with TiO 2 sol using co-precipitation method. The present work is to study the effects of Al 2 TiO 5 solution content on the sintering behavior and mechanical properties of porous Al 2 O 3 ceramics. Then, the enhancement mechanism was analyzed by comparison of the bulk density, porous, shrinkage, compressive strength , and the resultant microstructure. With Ti(SO 4 ) 2 solution content as the primary parameter to control the Al 2 TiO 5 content, it was found that when Ti(SO 4 ) 2 solution content was 15 mL, the minimum value of porosity reached 30.4%, while the maximum values of bulk density and shrinkage reached 2.52 g/cm 3 and 9.4%, respectively. Furthermore, the compressive strength of porous Al 2 O 3 ceramics containing 15 mL Ti(SO 4 ) 2 solution reached a maximum of 53.1 MPa, which is attributed to the formation of the liquid phase and the presence of elongated Al 2 TiO 5 grains. This results from the improvement of bonding strength between Al 2 O 3 HSs.
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
Solid Fuel Chemistry
·
2022
·Vol. 56
·期 1
·37-44
·
IF 0.829
Wang Ruiyu,Sun Bingkang,Zhu Jiliang,Fan Xing
Abstract Nano γ-Al 2 O 3 support was prepared by sol-gel method, and the Mg 2 Si/γ-Al 2 O 3 catalyst was prepared by impregnation method from Mg 2 Si and the γ-Al 2 O 3 support. The catalyst was characterized by X-ray diffraction, N 2 adsorption-desorption, scanning electron microscopy and CO 2 temperature-programmed desorption analysis. The catalytic hydrocracking of lignite-related modelcompounds, 1-methoxynaphthalene (1-MON) and bibenzyl ether (BE), was investigated. Mg 2 Si was well distributed on the surface and in the voids of γ-Al 2 O 3 support. The Mg 2 Si/γ-Al 2 O 3 catalyst had high specific surface area, large amount of mesopores, strong basicity, and exhibited high catalytic efficiency in hydrocracking of 1-MON and BE due to the synergic effect between Mg 2 Si and γ-Al 2 O 3 . Under an initial hydrogen pressure of 3 MPa and reaction time of 60 min, the conversion of 1-MON and BE reached 100% when the reaction temperatures were 225 and 175°C, respectively. The selectivities for naphthalene and toluene were close to 100%, only traces of the hydrogenated products were detected. After 4 cycle tests, the catalytic activity of Mg 2 Si/γ-Al 2 O 3 catalystdropped to 50%.
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2018
·
IF 11.698
Suqian Xu,Hanxu Zhu,Wenrui Cao,Zhibin Wen,Jinnan Wang,Corvini Philippe François-Xavier,Thomas Wintgens
Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots were synthesized for the first time to enhance the catalytic activity and utilization of H 2 O 2 . SEM, TEM, XPS, FT-IR, XRD, TPR and solid-state EPR were used to characterize the catalysts. In the Cu-Al 2 O 3 -g-C 3 N 4 system, the electron-rich centre of Cu and electron-deficient site of Al were formed due to the higher electronegativity of Cu. Moreover, Cu ions could coordinate with the hydroxyl on the tri-s-triazine ring of g-C 3 N 4 or the graphene conjugated π-domains of C-dots via the Cu O C linkage so that the orbital interactions involving electron transport from π → Cu also induced the formation of an electron-rich Cu centre and an electron-deficient π-electron conjugated system, resulting in the strengthening of the dual-reaction centres. This mechanism was validated by Roman, EPR and XPS spectra. In addition, EPR experiments demonstrated that two electron-transfer processes formed OH in the presence of H 2 O 2 . The first electron transfer was from the electron-rich Cu centres to H 2 O 2 , and the other was from H 2 O to the electron-deficient site. Thus, more OH were generated and high H 2 O 2 utilization was achieved in the Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots suspension. Furthermore, the turnover frequency (TOF) for the Cu-Al 2 O 3 -C-dots and Cu-Al 2 O 3 -g-C 3 N 4 dispersions were determined and were found to be much higher than those of the classic homogeneous Fenton reaction. Thus, Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots showed high activity and stability for the catalytic degradation of organic pollutants under mild conditions.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Xin Song,Wenjie Pan,Fangjun Shao,Zijiang Zhao,Xiaonian Li,Zhongzhe Wei,Jianguo Wang
The development of alkyne semihydrogenation catalysts with high conversion and selectivity under mild conditions is extremely challenging. Here, the modulation of Pd by different crystalline aluminas was investigated to improve the reaction performance. XPS confirmed that different crystalline aluminas modified the electronic structure of palladium. The Pd0.5/γ-Al2O3 catalyst with a Pd loading of 0.48 wt % attained 98% conversion and 91% selectivity. Stronger interaction of the γ-Al2O3 support with the loaded Pd nanoparticles resulted in electron deflection toward the support. The electronic structure of Pd was altered by modulating the crystallographic shape of the support, resulting in metal nanoparticles containing more Pd2+. Electron-deficient Pd2+ adsorbs more strongly on an electron-rich C≡C, which in turn modulates the competitive adsorption of alkenes and alkynes. Finally, the effective semihydrogenation of phenylacetylene was realized at low temperature and pressure.
研究领域:
化学工程
·
催化
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）