Journal of Magnesium and Alloys
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2023
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IF 17.6
Xiang Zhou,Haotian Guan,Heng Lu,Yangfan Lu,Jianbo Li,Jingfeng Wang,Yu'an Chen,Qian Li,Fusheng Pan
While early transition metal-based materials, such as MXene, has emerged as an efficient catalyst for the Mg-based hydrogen storage materials, their strong interaction with hydrogen resulted in the high hydrogen diffusion barrier, hindering further improvement of catalytic activity. A MXene is characterized by rich anionic groups on its surface, significantly affecting electronic and catalytic functionalities. Using Nb 2 C T x as an example, we herein illustrate the critical role of anionic T x defects on controlling hydrogen dissociation and diffusion processes in Mg-based hydrogen storage materials. The hydrogen desorption properties of MgH 2 can be significantly enhanced by utilizing T x controllable Nb 2 C T x , and it can release 3.57 wt.% hydrogen within 10 min under 240 °C with the reduced dehydrogenation activation barrier. It also realized stable de/hydrogenation reactions for at least 50 cycles. DFT studies combined with kinetic analysis revealed that the catalyst‒hydrogen interaction could be systematically controlled by optimizing surface T x defect density, accelerating the hydrogen dissociation and diffusion processes at the same time. These results demonstrate that the T x defects serve as the effective catalytically active centers of Nb 2 C T x , offering a flexible catalyst design guideline.
研究领域:
材料科学
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能源化学
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纳米技术
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表面科学
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催化化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2023
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IF 16.5
Wanjun Guo,Zhi-Qiang Wang,Shuang Xiang,Yaxuan Jing,Xiaohui Liu,Yong Guo,Xue-Qing Gong,Yanqin Wang
ABSTRACT Owing to the wide application of primary amines, their selective production via reductive amination has become a crucial research topic. Various metal-supported catalysts (Pt, Ru, Rh, Ir, Co, Ni, etc. ) have been investigated, and metallic species have been recognized as active sites in recent years. Herein, we reveal for the first time that CoO species containing oxygen vacancies within a core-shell-structured Co@CoO catalyst accelerate the ammonolysis of Schiff bases, key intermediates in reductive amination, through NH 3 dissociation to hydride-like NH 2 δ – species, delivering an excellent reductive amination performance. The catalyst is highly stable and was utilized in 10 catalytic cycles for the amination of biomass-derived cyclopentanone (CPO) to cyclopentylamine (CPA) without deactivation. Various computational models in combination with spectroscopic measurements indicated that this catalyst not only drives the dissociation of H 2 to the active H δ – species, but also enables the homolytic cleavage of NH 3 to NH 2 δ – . D 2 isotopic tracing experiments provided further evidence of the direct involvement of hydride-like NH 2 δ – species in Schiff base ammonolysis. Theoretical calculations verified the stable co-adsorption of H δ – and NH 2 δ – , which allows the Schiff base to move freely on the surface of the CoO shell and participate extensively in molecular collisions, resulting in exceptional catalytic activity. This is the first study that demonstrates the potential of metal oxide catalysts for the production of primary amines via reductive amination.
研究领域:
催化
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化学工程
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材料科学
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物理化学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
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2023
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IF 9.8
Tan Li,Jing Su,Linjia Yin,Xiangkun Zhang,Cong Wang,Xinbao Li,Jing Zhang,Kaige Wang
A Cu-based catalyst was developed for one-step solvent-free synthesis of aviation biofuel from biomass-derived ketones, including acetone, cyclopentanone, cyclohexanone, and 2-pentanone. Under the optimal working conditions, the conversion rate of acetone, cyclopentanone, cyclohexanone and 2-pentanone of 100% can be achieved by using Cu/Al2O3. 79.7 c% maximum carbon yield of liquid hydrocarbons with 89.5% selectivity of aviation biofuel was obtained under the conditions of 1.0 MPa H2, 280 °C, and 2 h−1 WHSV. The effects of the calcination temperature on the acidity and basicity of the catalyst, as well as the valence and dispersion of Cu species, were investigated. Based on DFT calculations and in situ DRIFTS results, the preferred adsorption of carbonyl groups and efficient dissociation of hydrogen on Cu+ increased the local concentration of H and feedstock on the catalyst surface, accelerating the rate-determining step that predominated on Cu0. The synergistic effect of Cu0 and Cu+ enhanced the formation of aviation biofuel.
研究领域:
催化
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化学工程
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可再生能源
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
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2024
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IF 4.4
Yajie Luan,Huaqi Wang,Changfeng Han,Xiuying Zhao,Youping Wu
The aging degradation process is significantly accelerated in unsaturated natural rubbers (NR) due to their susceptibility to α-H bond dissociation caused by exposure to heat and oxygen. Recently, the European Union has listed widely used antioxidant N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) as the restricted category of compounds, sparking a growing desire to find environmentally friendly alternatives. Through a combination of molecular simulation and experimental methods, this study aims to investigate the protection mechanism and conformational relationship of the natural antioxidant gallic acid (GA) and its ester derivatives within the NR matrix. The ultimate objective is to identify natural antioxidants that possess the capability to effectively substitute 6PPD. Simulation results of the chemical aging factor suggest that the phenolic hydroxyl hydrogen dissociation energy of GA is lower than that of the α-H bond of NR, thereby delaying the aging process. Based on the influence of physical aging factors, the polarity of GA derivatives decreases as the modified alkyl chain lengthens, improving the compatibility and migration resistance with NR, strengthening interaction force, and lowering oxygen permeability. Additionally, comprehensive simulation results indicate that octyl gallate derivatives exhibit notable antioxidant properties. Subsequent DPPH radical scavenging experiments, microstructural characterizations, and macroscopic mechanical property tests have confirmed the optimal antiaging properties of octyl gallate in NR, which these ester derivatives are expected to be a nontoxic, nonhazardous, and safe natural antioxidant alternative to 6PPD.
研究领域:
材料科学
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高分子化学
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环境科学
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化工工程
✓ 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）