Catalysts
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2021
·Vol. 11
·期 10
·1187
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IF 4.146
Qiuyue Zhou,Zhi-Qiang Wang,Wei Hong,Baohui Lou,Shihui Zou
Oxidative dehydrogenation of KA-oil (a mixture of cyclohexanone and cyclohexanol) is an economically attractive process to produce cyclohexanone because it provides a chance to avoid the energy-intensive alcohol-ketone separation process. The application of this process, however, is hampered by the low cyclohexanone selectivity which results from the competitive adsorption of cyclohexanol and cyclohexanone on the catalyst surface. Herein, by engineering Pt-Bi2O3interface to tune the geometric and electronic structure of Pt, we successfully weaken the cyclohexanone adsorption without compromising the oxidation of cyclohexanol. As a result, Bi2O3-Pt/SiO2with Bi-to-Pd ratio of 0.2 exhibits a 5 times higher cyclohexanone selectivity than Pt/SiO2at the same conversion of KA oil. Long term test suggests that the Pt-Bi2O3interface is stable in the oxidative dehydrogenation of KA-oil.Keywords:KA-oil;oxidative dehydrogenation;bismuth;Pt;electronic effect
研究领域:
化学工程
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催化科学
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2023
·
IF 6.2
Gao-yu Zhao,Shan Hu,Shu-chang Luo,Juan Lei,Yanfen Wei
To examine the electronic effect of substituents on the photocatalytic performance of PhC 2 Cu, two organometallic photocatalysts with either an F-atom (4F-P) or a CH 3 -group (4CH 3 -P) substituent at the phenyl ring para position were prepared by a facile one-step aqueous-phase method. Density functional theory calculations of the three organometallic photocatalysts (4F-P, P and 4CH 3 -P) revealed the substituent electronic effect on the frontier orbital energies and on the charge density at the Cu + ion. This study indicates that the introduction of the strongly electron-withdrawing F atom facilitates the effective separation of the photo-generated charge carriers, while the introduction of the electron-donating CH 3 group inhibits it. Consequently, the 4F-P photocatalyst exhibits greater photo-degradation activity compared to 4CH 3 -P and unsubstituted P. This investigation has shown that the introduction of a strongly electron-withdrawing substituent group is an effective strategy to improve the photocatalytic activity.
研究领域:
化学
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材料科学
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高影响因子
MOLECULES
·
2023
·Vol. 28
·期 10
·4136
·
IF 4.6
Yongwang Ren,Huizhong Xu,Beibei Han,Jing Xu
At present, the selective hydrogenation of α, β-unsaturated aldehydes remains a challenge due to competition between unsaturated functional groups (C=C and C=O). In this study, N-doped carbon deposited on silica-supported nickel Mott–Schottky type catalysts (Ni/SiO2@NxC) was prepared for the selective hydrogenation of cinnamaldehyde (CAL) by using the respective hydrothermal method and high-temperature carbonization method. The prepared optimal Ni/SiO2@N7C catalyst achieved 98.9% conversion and 83.1% selectivity for 3-phenylpropionaldehyde (HCAL) in the selective hydrogenation reaction of CAL. By constructing the Mott–Schottky effect, the electron transfer from metallic Ni to N-doped carbon at their contact interface was promoted, and the electron transfer was demonstrated by XPS and UPS. Experimental results indicated that by modulating the electron density of metallic Ni, the catalytic hydrogenation of C=C bonds was preferentially performed to obtain higher HCAL selectivity. Meanwhile, this work also provides an effective way to design electronically adjustable type catalysts for more selective hydrogenation reactions.Keywords:Ni catalyst;N-doped carbon;electronic effect;cinnamaldehyde hydrogenation
研究领域:
催化化学
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材料科学
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PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2020
·Vol. 22
·期 5
·2849-2857
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IF 3.43
Chaoyue Zhao,Xianliang Qiao,Zenghuimin Yi,Qingxin Guan,Wei Li
A green catalyst for acetylene hydrochlorination yielding a VCM is presented using imidazole as a single component metal-free catalyst. The mechanisms and reactivities of imidazole-catalyzed acetylene hydrochlorination have been investigated by combined computational and experimental studies. The electronic effects of ortho-substituents on the reactivities have also been investigated. Through theoretical calculations and experimental studies, the nitrogen-atom including a lone pair active site of single component imidazole for metal-free acetylene hydrochlorination is proposed. It is suggested that the nitrogen-atom including a lone pair of imidazole adsorbs an HCl molecule to form an imidazole-HCl complex, which serves as the active catalyst to participate in the reaction process of acetylene hydrochlorination. Besides, the results show that C2H2 assists in the electrophilic addition of HCl, undergoing an almost planar six-membered ring transition state. Computational studies on the ortho-substitution of the active sites will have an important impact on the catalytic efficiency.
研究领域:
化学
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催化科学
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DOI
PubMed
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 21
·4994
·
IF 4.2
Fan Ma,Hong-Wei Lin,Zizi Li,Wen-Jing Li,Jia-Wei Wang,Gangfeng Ouyang
Noble-metal-free CO2reduction systems based on cobalt phthalocyanine (CoPc) and its derivatives have demonstrated remarkable photocatalytic performances; however, their structure-activity relationship with electronic tuning remains unexplored. Herein, we now provide a systematic study to investigate the electron effects of substituents on theCoPcfamily in photocatalytic CO2reduction, where a Cu(I) heteroleptic photosensitizer is utilized. The highest performance can be achieved using cobalt tetracarboxylphthalocyanine in light-driven CO2-to-CO reduction, with a maximum turnover number of 2950 at 450 nm and an outstanding apparent quantum yield of 63.5% at 425 nm, over ten times the activity with the tetra-dimethylamino-substitutedCoPcderivative. The favorable electron-withdrawing effects have been further verified by DFT calculations and cyclic voltammetry, which reduces the overpotential required for CO2reduction and decreases the Gibbs free energy of the catalyst active intermediates, particularly the CO-desorption energetics.
研究领域:
材料科学
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催化化学
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环境科学
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DOI
PubMed
高影响因子
JOURNAL OF POWER SOURCES
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2025
·
IF 7.9
Lingling Li,Yingliang Feng,An Pei,Lihua Zhu,Weizhen Wang,Guang Li,Chengxiu Huang,Zhiqing Yang,Hengqiang Ye
Different atomic ratios of PtPd alloy nanoparticles (NPs) supported on carbon doping with nitrogen-NC (Pt x Pd y /NC) are successfully prepared to simultaneously enhance hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR), in which Pt 5 Pd 5 /NC with an atomic ratio of 5:5 has the best performance. Pt 5 Pd 5 /NC exhibits a significantly reduced HER overpotential (12 mV@10 mA cm −2 ) and the mass activity (MA) for MOR is up to 6.85 A mg −1 PtPd , 11.61 and 34.25 times higher than that of commercial Pt/C (Pt/C-JM) and commercial Pd/C (Pd/C-JM), respectively. Remarkably, coupling boosted HER on the cathode with accelerated MOR on the anode, efficient H 2 generation is achieved. This two-electrode flow cell only requires a cell voltage of 1.100 V at 100 mA cm −2 and can be stably operated for >300 h at 1.960 V with impressive long-life stability. Such performance even outperforms that of (IrO 2 ) OER‖HER (Pt/C-JM) cell. Electrochemical in-situ Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis show that electronic effect is formed between N and PtPd and can oxidize the intermediate HCOO - at a lower potential (0.300 V), promote the desorption of the toxic intermediates and improve the catalytic property.
研究领域:
材料科学
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电化学
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Qi Yang,Pengfei Wang,Chen Li,Benlei Wang,Ying Zheng,Yi Feng,Zidi Miao,Maoshuai Li,Mei-Yan Wang,Shouying Huang,Xinbin Ma
Delineating the geometrical and electronic structure of supported metal is significant for developing heterogeneous hydroformylation catalysts. This study modulated the configuration and charge distribution of Rh to construct highly efficient Rh@SiO 2 catalysts for formaldehyde hydroformylation. The structure sensitivity of Rh species reveals that single-atom Rh can solely catalyze hydrogenation, while Rh aggregates are active for hydroformylation. Moderate Rh nanoclusters (0.98 nm) offered the highest TOF (183 h −1 ) and selectivity (90.8 %) of glycolaldehyde. Electronic effects demonstrate that synergy between Rh 0 and Rh + sites on the cluster is essential to enhancing the reaction. The Rh 0 species function as the adsorption/activation sites for H 2 and formaldehyde, and the Rh + sites act to coordinate PPh 3 and CO to form Rh δ+ (CO) x (PPh 3 ) y active species. This study provides new insights into the design of heterogeneous catalysts and guidance for understanding the structure sensitivity of active metal and hydroformylation mechanism.
研究领域:
催化化学
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材料科学
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高影响因子
RSC Advances
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2018
·Vol. 8
·期 63
·36298-36312
·
IF 2.936
Xiaohui He,Guangshui Tu,Feng Zhang,Shengmei Huang,Changwen Cheng,Chuanyi Zhu,Yapeng Duan,Suli Wang,Defu Chen
Eight bis-(salicylaldehyde-benzhydrylimino)nickel complexes with different electron groups (Ni1–Ni8), Ni{(3-R1)(5-R2)C6H2(O)CHNCH(C6H5)2}2, (R1 = H, R2 = H, Ni1; R1 = H, R2 = CH3, Ni2; R1 = H, R2 = OCH3, Ni3; R1 = H, R2 = Br, Ni4; R1 = CH3, R2 = H, Ni5; R1 = OCH3, R2 = H, Ni6; R1 = Br, R2 = Br, Ni7; R1 = Cl, R2 = Cl, Ni8), were synthesized and their crystal structures were characterized using single crystal X-ray diffraction. The results revealed that Ni1–Ni6 belong to the monoclinic system (space group P2(1)/n), Ni7 belongs to the monoclinic system (space group C2/c) and Ni8 belongs to the triclinic system (space group P). All nickel complexes exhibited high activities (0.46–2.07 × 106 gpolymer molNi−1 h−1) toward norbornene homopolymerization, and a strong electron-withdrawing group on the salicylaldimino aromatic ring can enhance the catalytic activity and favor polymerization. Ni1 and Ni2 exhibited high activities (0.55–2.40 × 105 gpolymer molNi−1 h−1) toward copolymerization of norbornene and 1-hexene in the presence of B(C6F5)3. The 1-hexene content in the copolymers could be controlled up to 7.98–12.50% by varying the comonomer feed ratio of 1-hexene from 10 to 50%. It is observed that when the 5-position of the salicylaldimino aromatic ring has a substituent (–CH3), the 1-hexene insertion rate is lower than that without a substituent. In addition, the polymers showed high molecular weights (1.5–2.4 × 105 g mol−1) and narrow molecular weight distributions (1.62–1.89). The obtained polymers were also verified to be amorphous copolymers and had high thermal stability, good solubility and optical transparency.
研究领域:
化学
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材料科学
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PubMed
高影响因子
DALTON TRANSACTIONS
·
2015
·Vol. 45
·期 4
·1496-1503
·
IF 4.197
Xiaohui Hu,Shengyu Dai,Changle Chen
The synthesis, characterization and ethylene polymerization properties of a series of salicylaldimine Ni(II) complexes with a dibenzhydryl moiety are described. These Ni complexes are designed to bear systematically varied electron donating and withdrawing substituents. These complexes are among the most active salicylaldimine Ni(II) catalysts in ethylene polymerization. Moreover, these complexes demonstrate good thermal stability, maintaining high activity at 80 °C. The polyethylene generated possesses a high molecular weight, moderate branching density and high melting temperature. Surprisingly, the electronic perturbations only exert moderate influence on the ethylene polymerization process despite the covalently close proximity of the electron donating or withdrawing substituents to the metal center. Comparing with the traditional iso-propyl substituted nickel analogue, these new complexes show up to an order of magnitude higher activity, generating polyethylene with much higher molecular weight, similar or slightly lower branching density and much higher melting temperature.
研究领域:
材料化学
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催化化学
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PubMed
高影响因子
ORGANOMETALLICS
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2022
·
IF 3.837
Shu Jiang,Yuting Zheng,Ming Liu,Zhixin Yu,Yanping Ma,Gregory A. Solan,Wenjuan Zhang,Tongling Liang,Wen-Hua Sun
Ten examples of nickel(II) halide complexes [8-{N(2,4-(C15H13)2-6-RC6H2N)}C9H8N]NiBr2 [R = Me (Ni1), Et (Ni2), iPr (Ni3), Cl (Ni4), or F (Ni5)] and [8-{N(2,4-(C15H13)2-6-RC6H2N)}C9H8N]NiCl2 [R = Me (Ni6), Et (Ni7), iPr (Ni8), Cl (Ni9), or F (Ni10)], each incorporating a sterically encumbered N,N-chelating 8-[2,4-bis(dibenzocycloheptyl)-6-R-phenylimino]-5,6,7-trihydroquinoline ligand, are disclosed. Full details for the preparation of these complexes as well as the zinc-mediated synthesis of precursor ligands L1–L5 are given. Structural characterization of Ni3(H2O), Ni6, Ni7(H2O), and Ni8(H2O) reveals halide-bridged dinuclear structures of the type (N,N)NiX(μ-X)2NiX(N,N) with the ortho-substituted dibenzocycloheptyl groups providing steric protection to each metal center. In the presence of ethylaluminum dichloride (EtAlCl2) or methylaluminoxane (MAO), Ni1–Ni10 displayed high activities for ethylene polymerization [≤6.17 × 106 g of PE (mol of Ni)−1 h–1 for Ni6/EtAlCl2 at 20 °C], generating low-molecular weight polyethylene waxes. Notably, catalysts incorporating a 6-alkyl group (Me, Et, or iPr) as the N-aryl substituent proved to be more active than their 6-halide (Cl or F) counterparts and formed relatively higher-molecular weight polymers (Mw range of 9.1–22.9 kg mol–1) with a narrow dispersity. Moreover, analysis of these waxes by 13C nuclear magnetic resonance spectroscopy showed that they typically possessed short chain branching (>83% methyl) with branching densities of 79–90 branches per 1000 Cs. In addition, chain end analysis revealed the presence of both vinyl (−CH═CH2) and internal vinylene (−CH═CH−) functional groups, highlighting the role of both β-H elimination and isomerization.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Qinghua Qu,Yuqiao Jiang,Linyan Cheng,Qingyuan Xue,Ranran Li,Cheng Fang,Hongping Li,Jing Ding,Hui Wan,Guofeng Guan
Covalent organic frameworks (COFs) with high specific surface area, ordered pore wall, modified porous surface and customizable chemical structure have been widely used in CO 2 capture. However, the screening of functionalized COFs suitable for CO 2 capture still relies on experiments, which will require a long experimental period with blindness and randomness. Herein, we chosed three electron withdrawing groups (–NO 2 , –CN and −Br) and three electron donating groups (–CH 2 NH 2 , –CH 3 , –OCH 3 ) to explore the effect of electron withdrawing ability of functional groups on the CO 2 adsorption capacity. Grand canonical Monte Carlo (GCMC) method was used to simulate the adsorption capacity of CO 2 over X-TpBD-COFs (X=–NO 2 , –CN, −Br, –CH 2 NH 2 , –CH 3 , –OCH 3 ). As the result, NO 2 -TpBD-COF had the highest adsorption capacity among the six functionalized X-TpBD-COFs at 100 kPa and 25 ℃ (49.37 cm 3 /g), while OCH 3 -TpBD-COF had the lowest adsorption capacity among them (23.51 cm 3 /g at 25 ℃ and 100 kPa). The order of binding energy was basically the same as the order of adsorption capacity when the synergistic interactions between functional groups and oxygen atoms in Tp were considered according to density functional theory (DFT). Molecular dynamics (MD) showed that the diffusion and distribution of CO 2 were mainly effected by pore structures. To verify the simulation results, NO 2 -TpBD-COF and OCH 3 -TpBD-COF were successfully prepared by solvothermal method. The CO 2 adsorption capacities of these two COFs were basically consistent with the conclusion obtained by the simulations. This study provided a way for simulation to guide accurate and rapid experimental design of COF materials for CO 2 capture.
研究领域:
材料科学
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环境科学
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化学工程
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DOI
高影响因子
ACS Catalysis
·
2021
·
IF 13.084
Boyang Liu,Ning Huang,Yu Wang,Xiaocheng Lan,Tiefeng Wang
Rh-based homogeneous catalysts with phosphine ligands are highly active in hydroformylation reactions. Using DFT calculations, we found a similar electronic effect of inorganic phosphorus in the Rh2P structure. The energy profiles demonstrated that Rh2P would significantly enhance the styrene hydroformylation activity in comparison with Rh, which was further confirmed by experiments. Triphenylphosphine (PPh3) was used as the phosphorus source, and Rh2P supported on silica was prepared by impregnation at a relatively low temperature (550 °C). The turnover frequency (TOF) of styrene hydroformylation was increased to 1496 h–1, which was comparable with some single atom catalysts (SACs). Recycling tests showed a good stability in five runs. Furthermore, HAADF-STEM, XPS, and other characterizations confirmed the synthesis of the Rh2P structure. The promotion effect of P was bifunctional. On the one hand, the doped P separated the surface Rh atoms, which eliminated the surface hollow sites and prevented excessively strong adsorption of the reactants. On the other hand, electrons transferred from Rh to P, causing the surface Rh atoms to be positively charged, which was favorable for hydroformylation reactions. The geometric effects improved the dispersion and the electronic effects changed the rate-determining step from CO insertion to phenylpropionyl hydrogenation, both leading to a higher hydroformylation activity.
研究领域:
化学
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材料科学
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高影响因子
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