CHEMISTRY-A EUROPEAN JOURNAL
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2023
·Vol. 29
·期 18
·e202203152
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IF 4.3
Yan Long,Jie He,Hang Zhang,Yingkang Chen,Kang Liu,Junwei Fu,Hongmei Li,Li Zhu,Zhang Lin,Andrei Stefancu,Emiliano Cortes,Mingshan Zhu,Min Liu
Graphical Ag/Al 2 O 3 catalytic controllable synthesis of N-monomethylated amines by using CO 2 /H 2 as C 1 source has been demonstrated in a first example. The reactivity of methylated amines was reduced by the heterolytic dissociation of H 2 over the catalyst, and hence conversion of various amines to corresponding monomethylated amines was enabled with excellent selectivity. The selective synthesis of monomethylated amines with CO 2 is particularly challenging because the formation of tertiary amines is thermodynamically more favorable. Herein, a new strategy for the controllable synthesis of N-monomethylated amines from primary amines and CO 2 /H 2 is explored. First-principle calculations reveal that the dissociation of H 2 via an heterolytic route reduces the reactivity of methylated amines and thus inhibit successive methylation. In situ DRIFTS proves the process of formation and decomposition of ammonium salt by secondary amine reversible binding with H + on the Ag/Al 2 O 3 catalyst, thereby reducing its reactivity. Meanwhile, the energy barrier for the rate-determining step of monomethylation was much lower than that of overmethylation (0.34 eV vs. 0.58 eV) means amines monomethylation in preference to successive methylation. Under optimal reaction conditions, a variety of amines were converted to the corresponding monomethylated amines in good to excellent yields, and more than 90 % yield of product was obtained.
研究领域:
催化化学
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绿色化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2014
·
IF 6.007
Fredrik Gunnarsson,Moa Z. Granlund,Mattias Englund,Jazaer Dawody,Lars J. Pettersson,Hanna Härelind
We report on a high NO x reduction activity over Ag/Al 2 O 3 catalysts, using hydrogen produced in a fuel reformer. The focus of the study is to evaluate the performance of a hydrocarbon selective catalytic reduction (HC-SCR) catalyst in real conditions. Initially, the catalytic materials for the fuel reformer (Rh/CeO 2 -ZrO 2 ) and the HC-SCR (Ag/Al 2 O 3 ) were evaluated in separate bench-scale reactor setups. These two setups were subsequently joined into an integrated bench-scale reactor setup with the aim to evaluate the influence of the reformate on the HC-SCR activity in a controlled environment. In the final phase of the study a 4 wt.% Ag/Al 2 O 3 catalyst doped with 100 ppm(w) Pt was scaled up and tested in a pilot-scale reactor setup. The pilot-scale reactor setup enabled evaluation of the HC-SCR activity in real exhaust gases generated by a single cylinder engine (genset) together with a hydrogen-rich gas supplied from a fuel reformer. Commercial biodiesel (NExBTL) was used as reducing agent for the HC-SCR as well as fuel in the fuel reformer for both the bench-scale and pilot-scale experiments. This study gives an excellent link between evaluations of the catalytic materials, controlled bench-scale experiments and applied engine experiments, proving a viable concept for lean NO x reduction together with onboard hydrogen production. A NO x conversion of above 70% was reached at temperatures below 250 °C, in bench-scale experiments when hydrogen produced in the fuel reformer is added.
研究领域:
环境科学
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催化化学
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能源工程
✓ 已验证
DOI
高影响因子
SOLAR ENERGY
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2018
·
IF 4.374
Huajun Chen,Wenjie Tian,Wuxiu Ding
Metallic sliver-doped mesoporous Al 2 O 3 fibers (meso-Ag/Al 2 O 3 ) that can harvest visible light to speed up solar water purification, were synthesized by one-pot hydrothermal method. Insightful analyses of XRD, XRF and XPS of meso-Ag/ Al 2 O 3 verified that metallic silver occupied interstitial positions of Al 2 O 3 lattice forming interstitial solid solution. N 2 adsorption/desorption illustrated that meso-Ag/Al 2 O 3 exhibited significantly increases in the specific surface area, pore volume and average pore diameter after doping with silver. The UV–Vis diffuse reflectance spectra and disinfection performance indicated that meso-Ag/Al 2 O 3 can harvest visible light to promote the conversion of dioxygen to ROS for water disinfection compared with the widely used TiO 2 . With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 120 min with a small amount of material (8 mg/L) under simulated visible light.
研究领域:
环境科学
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材料科学
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水处理
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Houlin Wang,Shuting Luo,Xinghao Li,Wei Liu,Xiaodong Wu,Duan Weng,Shuang Liu
Developing catalysts with high cost-efficiency, good oxidation activities and strong thermal resistance is an ongoing task. Herein, we present the design and synthesis of confined catalysts with Ag protected by alumina. Thermal treatment at 800 °C for 10 h caused neither silver loss nor deactivation of this catalyst. Instead, nano-particles of Ag formed because of the heat/O 2 -derived ripening. These highly dispersed silver species and the catalyst’s mesoporous structure worked in tandem to achieve good catalytic performance for oxidation reactions, which made the aged sample a good candidate as CO elimination and gasoline particulate filter catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
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.
研究领域:
化学工程
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催化科学
·
能源材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2018
·
IF 4.484
Xueyan Chen,Min Chen,Guangzhi He,Fei Wang,Guangyan Xu,Yaobin Li,Changbin Zhang,Hong He
Ag-based catalysts are efficient materials for formaldehyde (HCHO) oxidation in the low-temperature range. It has been reported that K addition can increase the catalytic performance of Ag-based catalysts, whereas the specific role of K doping remains ambiguous. In this work, Ag/Al2O3 and K–Ag/Al2O3 catalysts with different K doping levels were prepared and subsequently tested for catalytic HCHO oxidation. It was observed that K doping has a dramatic promotion effect on the activity of the Ag/Al2O3 catalyst. The 2K–Ag/Al2O3 sample was the most active catalyst, over which HCHO could be completely converted into CO2 and H2O in a gas hourly space velocity of 100 000 mL/(gcat h) at 65 °C. The catalysts were next characterized by X-ray powder diffraction, Brunauer–Emmett–Teller, transmission electron microscopy, H2-temperature-programmed reduction, UV–vis, X-ray absorption fine structure, and in situ diffuse reflectance infrared Fourier transform spectroscopy methods. The characterization results show that addition of K species increased the content of metallic Ag species in Ag/Al2O3 catalysts and promoted the adsorption and activation of oxygen species, whereas excessive doping with K+ resulted in the agglomeration of Ag particles and loss of some metallic sites. Therefore, the 2K–Ag/Al2O3 catalyst demonstrated the best performance among the series of K-doped catalysts. Promotion of O2 activation by K doping, rather than enhanced Ag dispersion or surface OH activation or exposure of more Ag(111) facets, was found to be the key factor in the improved catalytic performance of K–Ag/Al2O3 catalysts.
研究领域:
环境催化
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材料化学
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大气污染控制
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纳米催化
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表面科学
✓ 已验证
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2021
·
IF 7.664
Mingli Han,Zhicheng Shi,Wenqiang Zhang,Kun Zhang,Huanlei Wang,Davoud Dastan,Runhua Fan
High dielectric permittivity materials are widely employed in various electronic devices. To satisfy the ongoing miniaturization of electronic devices, materials with further enhanced dielectric permittivities are strongly desired. In this work, a novel design of epoxy composites based on Ag/Al 2 O 3 /3D-BaTiO 3 foams with hierarchical heterogeneous microstructures are prepared. It is found that, the spatial distribution of the Ag particles can be easily controlled via adjusting the Ag + /Al 3+ mole ratios, yielding highly tailorable dielectric properties. When the Ag + /Al 3+ mole ratios are low, the Ag particles are well isolated by surrounding Al 2 O 3 , yielding the formation of numerous equivalent micro-capacitors and substantially enhanced dielectric permittivity. Moreover, the dielectric permittivities of the composites increase with higher Ag + /Al 3+ mole ratios. Consequently, a high dielectric permittivity of 160 @10 kHz, which is about 35 times that of the epoxy matrix, is achieved in the composite with a Ag + /Al 3+ mole ratio of 1.8. Meanwhile, a low tangent of about 0.062 is maintained. As the Ag + /Al 3+ mole ratio increases, the Ag particles become interconnected, forming Ag networks. Consequently, a plasma-like negative phenomenon which should be attributed to the plasma oscillation of free electrons in the percolative Ag networks, is observed. This work offers an effective route to design polymer composites with tailorable high permittivity and negative permittivity.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
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