Molecular Catalysis
·
2024
·
IF 3.9
Xingling Zhao,Xue Zhou,Wanyan Xing,Zhimin Yuan,Kaili Wang,Qihang Zhang,Yulong Shan,Jiani Liu,Lin Ju,Zaiyong Jiang,Hong He
CO is a ubiquitous air pollutant, frequently encountered in the fields of automotive exhaust purification, especial in the cold-start-emission stage. Pt based catalysts are widely used to purify CO into CO 2 owing to their exceptional performance. But they can be few excited to exhibit reasonable catalytic activity due to the low temperature at the cold-start-emission stage. In exhaust gas purification catalysts used by fossil fuel-based vehicles, Al 2 O 3 is used frequently. But there are rarely reports of Pt loaded Al 2 O 3 catalysts achieving feasible activity of CO oxidation at room temperature. Herein, we prepared Cu x Pt y alloy/Al 2 O 3 catalysts (with high penta-coordinated Al 3+ (Al V )), Al V centers as binding sites for Cu 3 Pt 1 alloys on Al 2 O 3 enable the high dispersion and stability of Cu 3 Pt 1 alloy. The adsorption capacity of O 2 and CO molecules on Cu 3 Pt 1 surface are stronger than the case on Pt surface, which may make O 2 and CO molecules more easily activated, making the CO oxidation reaction easier. In addition, the desorption of CO 2 from Cu x Pt y surface is easier compared to that on Pt surface, increasing the frequency of use of active sites there. Therefore, this Cu 3 Pt 1 /Al 2 O 3 catalyst exhibits 100 % conversion of CO with a GHSV of 6×10 3 mL·g −1 cat ·h −1 at room temperature. This work provides a feasible guideline for the design and synthesis of Pt loaded Al 2 O 3 catalysts toward room temperature CO oxidation.
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
Journal of Physical Chemistry C
·
2022
·
IF 4.177
Rui Wang,Zhenchao Zhao,Pan Gao,Kuizhi Chen,Zhehong Gan,Qiang Fu,Guangjin Hou
The dehydration of alcohols to value-added chemicals using alumina catalysts has been industrialized decades ago; however, despite years of fundamental research, the molecular-level understanding of the reaction process is still lacking. Herein, the dehydration reactions of ethanol on two representative aluminas, i.e., γ-Al2O3 and five-coordinated Al-rich Al2O3-nanosheet (Al2O3-NS), are comparatively investigated by a combination of solid-state NMR spectroscopy and reaction evaluations. NMR results reveal that the presence of hydroxyl groups nearby the Lewis acid sites (LASs) leads to different ethanol adsorption modes. The surface hydroxyls nearby LASs interfere with ethanol adsorption, which causes the methyl group to move away from the alumina surface and hinders the elimination of β-H, resulting in low reaction activity. In addition, the desorption property of surface hydroxyls will affect the dehydration reaction as they participate in the catalytic reaction cycles. Such effects may also explain the lower reaction activities for diethyl ether to ethylene compared with ethanol. Although both four- and five-coordinated Als are the possible active sites for ethanol dehydration, the reactivity of alcohol dehydration may also be substantially affected by the local environment of undercoordinated Als besides coordination numbers. These new insights demonstrate that the host–guest interaction regulated by the local environment of active sites plays an important role in the catalytic reaction.
研究领域:
催化化学
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材料科学
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物理化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Wenming Liu,Shenyou Yang,Qiuli Zhang,Tianyao He,Yiwei Luo,Jinxiong Tao,Daishe Wu,Honggen Peng
Herein, a series of nano-flower sheet-like alumina spheres (NF-Al 2 O 3 ) with rich unsaturated pentacoordinate Al 3+ sites stabilizing Ru-CeO x catalysts were designed and synthesized for catalytic total oxidation of one typical light alkanes (propane, C 3 H 8 ). The 90 % conversion temperature (T 90 ) and the apparent activation energy (Ea) of Ru-Ce 7 /NF-Al 2 O 3 modified by 7 wt.% of CeO 2 were as low as 207 °C and 56.7 kJ mol −1 , respectively. In addition, it also exhibited superior water, sulfur and carbon dioxide resistance and recycling performance. The excellent catalytic performance of propane total oxidation over Ru-CeO x /NF-Al 2 O 3 is mainly attributed to NF-Al 2 O 3 has rich unsaturated pentacoordinate Al 3+ sites can anchor the Ru-CeO x active species. The anchoring effect of Al 3+ penta on the metal active unit can effectively promote the dispersion of Ru-CeO x active species and stabilize the electronic valence state of Ru 0 . The degradation of C 3 H 8 over Ru-CeO x /NF-Al 2 O 3 conformed to the Mars-van-Krevelen mechanism through two different pathways as revealed by the in situ DRIFTS.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2022
·
IF 3.898
Zhenyu Wu,Zengxi Li,Chunshan Li
The bare amorphous Al 2 O 3 -AlPO 4 and Cs/Al 2 O 3 -AlPO 4 catalysts were developed for the aldol condensation of methyl acetate with formaldehyde to methyl acrylate. The structure and property of catalyst were characterized by XRD, XPS, BET, Pyridine-IR, FT-IR, 27 Al-MASNMR, NH 3 -/CO 2 -TPD and SEM. The correlation between structural features and acid-base properties was established, and the loading effect of the cesium species was investigated. Due to cooperative catalytic effects between the penta-coordinated Al and Al 2 O 3 , the weak-II acid and medium acid site densities and the product selectivity were improved. While the basic site densities of these catalysts were almost in proportion to the conversion of methyl acetate. The loaded Cs could form new basic sites and change the distribution of acid sites which further enhance the catalytic performance. As a result, the 10Cs/8AlP was proved to be an optimal catalyst with the yield and selectivity of 21.2% and 85% for methyl acrylate respectively. During the reaction, a deactivation behavior was observed on 10Cs/8AlP catalyst due to the carbon deposition, however, it could be regenerated by thermal treatment in the air atmosphere at 400 °C.
研究领域:
化学工程
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催化材料科学
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2015
·Vol. 44
·期 20
·9382-9390
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IF 4.197
Qiang Yu,Yanhong Liu,Diansheng Liu,Jianfeng Li
Three five-coordinate, high spin manganese(II) “picket fence” porphyrin complexes, [Mn(TpivPP)(L)] (TpivPP = α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinato; L = 1-MeIm (1-methylimidazole), 1-EtIm (1-ethylimidazole) and 2-MeHIm (2-methylimidazole)), are synthesized and studied by single-crystal X-ray, UV-vis and electronic paramagnetic resonance (EPR) spectroscopy. Structural parameters are investigated and compared with analogues. Low temperature (90 K), high field EPR studies of [Mn(TpivPP)(1-MeIm)] and [Mn(TpivPP)(2-MeHIm)] showed five resonances including characteristic signals at ∼5.9 and ∼2.0. The simulations of the EPR spectra give the zero field splitting (zfs) parameters (D, E and λ) and the hyperfine coupling constant (A).
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2021
·Vol. 47
·期 19
·26869-26876
·
IF 4.527
Shao-Min Lin,Ya-Ling Yu,Ming-Feng Zhong,Huan Yang,Chen-Yang Zhang,Zhi-Jie Zhang,Wei Xu,Jiong-Yan Xie,Yu-Chun Qiu
Converting the γ phase into the α phase completely is necessary in the presintering stage of industrial alumina (Al 2 O 3 ), which requires high temperature and energy consumption. To reduce the presintering temperature, γ-Al 2 O 3 was activated by oxalic acid . XRD , 27 Al-MAS-NMR and TG-DSC were used to characterize the γ - alumina before and after activation, and the phase transformation was studied. The formation temperature of α-Al 2 O 3 decreased to 1029 °C for oxalic acid activated γ-Al 2 O 3 , and the α-fraction was 100% for activated γ-Al 2 O 3 at 1300 °C. After oxalic acid activation , the diffraction peak intensity of γ-Al 2 O 3 decreased significantly; the results of 27 Al-MAS-NMR suggested that octahedral [AlO 6 ] in γ-Al 2 O 3 was easier than tetrahedral [AlO 4 ] to be attacked by oxalic acid , and the formation of pentavalent [AlO 5 ] with higher reaction activity, which was in favour of the lowering formation temperature of α-Al 2 O 3 . The dissolution concentration of Al increased after oxalic acid activation, and the dissolution process was controlled by surface reactions. Oxalic acid mainly attacked the octahedral aluminium in γ-Al 2 O 3 and extracted Al as three complexes of [Al(C 2 O 4 )] + , [Al(C 2 O 4 ) 2 ] - and [Al(C 2 O 4 ) 3 ] 3- . Oxalic acid activated γ - Al 2 O 3 with a lower phase transformation temperature has broad application prospects in the alumina industry.
研究领域:
材料化学
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无机化学
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固态化学
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工业催化
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陶瓷材料
✓ 已验证
DOI
高影响因子
ACS Nano
·
2024
·
IF 15.8
Guoqiang Zhao,Xiaoyu Tao,Tongsen Guo,Liangjie Fu,Huaming Yang
Solution-phase epitaxy is a versatile method to synthesize functional nanomaterials with customized properties, where supports play a central role as they not only serve as nucleation templates but also greatly affect the local electronic structures. However, developing functional supports remains a great challenge. Herein, inspired by the commonly observed epitaxy of minerals in the natural environment, we report using calcination-modified kaolinite as the support for the epitaxial growth of hexagonal CoO nanoparticles (h-CoO NPs), which enables over 40 times higher mass-specific activity toward H2O2 electrochemical activation than the counterpart without the support. High-resolution electron microscopy, magic-angle spinning nuclear magnetic resonance, and X-ray absorption fine structure results prove that the Al sites in kaolinite play a crucial role in the formation of h-CoO NPs. Moreover, the five-coordinate Al (AlV) sites produced by the dehydration of kaolinite are indispensable for forming the epitaxial interface. Theoretical calculations reveal that the local electron densities around AlV sites are lower than those of general six-coordinate Al sites, which render AlV sites with strong adsorption capability that facilitates the nucleation of h-CoO NPs. Also, the AlV sites induce the electron transfer from h-CoO to the kaolinite support that results in the upshift of the Co 3d band center and hence improve the H2O2 activation kinetics. Our results demonstrate the superiority of nanoclay as functional supports and could offer a more benign strategy to the solution-phase epitaxy production of functional nanomaterials for diverse applications.
研究领域:
材料科学
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电化学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2023
·
IF 3.6
Huanhuan Song,Jingwen Li,Yinbin Zhang,Ke Chen,Le Liu,Junjie Zhang,Xin-Hua Duan,Mingyou Hu
Difluoromethylated heterocyclic compounds have found broad applications in numerous bioactive molecules. Herein, we report photoredox catalysis-induced direct C–H difluoromethylation of heterocycles by using bis(difluoromethyl) pentacoordinate phosphorane (PPh3(CF2H)2, 1) as the reagent. A variety of heterocycles, such as quinoxalin-2(1H)-one, thiophene, indole, and coumarin, are readily tailored with a difluoromethyl group. The method is featured as transition-metal-free by using an organic compound Erythrosin B as the catalyst and O2 as the oxidant.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2021
·
IF 7.92
Wenfeng Han,Bing Liu,Yanjun Chen,Zhongsheng Jia,Xiaoli Wei,Weiyu Song
The design and synthesis of highly dispersed metal catalyst have attracted increasing attention, and it is still challenging to generate stable metal clusters with high metal loadings. Support plays a crucial role in determining particle morphology and dispersion. Herein, we demonstrate a strategy for synthesizing an amorphous alumina with 62% Al 3+ penta sites (penta-coordinated Al 3+ ) via solution combustion synthesis. It provides sufficient oxygen defects to anchor Ru species. For benzene hydrogenation reaction, the catalyst displays the high TOF (18833 h −1 ), which is about 2 times higher than that of catalysts supported on commercial alumina. The DFT calculations also confirm that the high catalytic performance is closely correlated with the special configuration of Ru active sites over coordinatively unsaturated alumina. The penta-coordinated Al 3+ was also applied to prepare Pd catalyst with high dispersion. This work provides a superior support which possesses abundant Al 3+ penta sites and affords a possibility for the generation of high and stable dispersion for the preparation of supported metal catalysts.
研究领域:
催化化学
·
材料科学
·
理论计算
✓ 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）