The effect of surface oxygenated groups of carbon nanotubes on liquid phase catalytic oxidation of cumene

Chi, Yumei; Zhu, Maguang; Li, Yuhang; Yu, Hao; Wang, Hongjuan; Peng, Feng

doi:10.1039/c5cy01631b

Cited by 16 publications

(11 citation statements)

References 42 publications

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“…The chaotic relationships between the specific activities on different O species were found (Figures S10 and S11), indicating that the inhibition effect in this reaction catalyzed by o-NCNTs did not just result from the surface oxygen functionality, which is different from our previous work. 56 Different solvents and aldehydes for the production of ε-CL were examined (Table 4). Solvents with different polarities, such as acetonitrile, acetone, and ethyl alcohol, exhibited low efficiency (entries 2−4).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Huang

Bai

Feng

et al. 2022

ACS Sustainable Chem. Eng.

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The catalytic synthesis of lactones from alkanes is a novel strategy from the viewpoint of environmentally benign technology. In this work, we propose a new protocol of using a typical alkane (cyclohexane, CyH) as a substrate to produce lactone (ε-caprolactone, ε-CL) in the presence of carbon nanotubes (CNTs) and aldehydes. The results demonstrated that CNTs could be used as an efficient catalyst for the production of ε-CL. Nitrogen doping would greatly enhance the activity, with 26.2% conversion of CyH and 87% selectivity of ε-CL. The specific N dopants served as complex active sites for improving the catalytic efficiency of NCNTs with an optimum content of N (3.38 atom %). Further investigations revealed that the ratio of pyridine N/ quaternary N probably played a significant role in the facilitation of this reaction, which displayed a linear relationship with the specific activity of NCNTs. A mechanistic study demonstrated that the activation of benzaldehyde for the production of carbonyl radicals was considered as the initial reaction, which activated CyH molecules to produce alkyl radicals, thus promoting the oxidation of CyH. The intermediate product CyO was found to be the main precursor of ε-CL, and during the reaction, cyclohexanol (Cy−OH) would likely be transformed into CyO.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Huang

Bai

Feng

et al. 2022

ACS Sustainable Chem. Eng.

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“…Because metallic impurities and structural defects in the hollow core or at the tips of the CNTs may block the penetrant molecules through the CNT channels (Figure S2), the annealing method was used to improve the quality of the CNTs. , As expected, the performance of the aligned CNT (open-ended)/PDMS membrane being annealed is 1.5 times higher than that of the unannealed membrane, which is 3.7 times higher than that of the “closed CNT” membrane in the VSVP process, respectively (Figure S8). A similar performance improvement was also observed for bioethanol recovery (Figure S8), indicating that the annealing treatment could make CNT channels more permeable for alcohols and water by reducing metal catalyst nanoparticles and structural defects in the CNT channels.…”

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confidence: 77%

“…Thus, our CNT composite membrane could block biological threats and facilitate molecular particles permeation. Because some of the CNTs may have typical defects, such as kinks, metallic impurities and “bamboo-type” inner structures, the annealing treatment was used to reduce the metal catalyst nanoparticles and the structural defects. , As shown in Figure S2, the annealing treatment can efficiently remove metal particles and lower defects in the hollow core or at the tips of the CNTs. The annealed CNTs form a better hollow tubular structure than the untreated CNTs (Figures S2 and S3a).…”

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confidence: 99%

Tuned Fabrication of the Aligned and Opened CNT Membrane with Exceptionally High Permeability and Selectivity for Bioalcohol Recovery

et al. 2018

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Synthetic membranes usually suffer from a ubiquitous trade-off between permeability and selectivity. Carbon nanotube (CNT)-based hybrid materials have shown attractive properties in high-performance membrane preparation; however, the aggregation of random CNTs in polymer remains a great challenge. Herein, the aligned and open-ended CNT/(polydimethylsiloxane) PDMS membranes are controllably fabricated to form a hamburger-like structure that possesses nanochannels (∼10 nm) in the intermediate layer as well as angstrom cavities in the embedded PDMS. These aligned CNT membranes surpass the filling content limitation of the nonaligned CNT/PDMS membrane (37.4 wt % versus ∼10 wt %), leading to excellent mechanical properties and a multiplying performance increase of mass flux and selectivity for the separation of alcohols. The membranes break the permeability-selectivity trade-off with both parameters remarkably increasing (maximum 9 times) for bioalcohol separation. The established pervaporative-ultrafiltration mechanism indicates that the penetrant molecules preferentially pass through CNT internal nanochannels with increasing membrane permeability, thereby paving a way to nanoscale design of highly efficient channeled membranes for separation application.

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“…The nonmetallic, excellent catalytic performance and high stability of carbon nanotubes (CNTs) made them an excellent catalyst for selective oxidation [10–12]. Based on our previous research, we found that CNTs possess excellent catalytic performance for the oxidation of cumene [11, 13–15]. The advantage of CNTs is that oxygen can be activated on the surface of CNTs to generate active oxygen species (ROS), which has been reported [16, 17].…”

Section: Introductionmentioning

confidence: 99%

“…Because doping nitrogen would cause the strong interaction between CHP and CNTs [15]. The main oxidation product of cumene catalyzed by CNTs is CHP [11, 13, 19]. In that way, cumene and CHP are able to react continuously on the surface of CNTs.…”

Section: Introductionmentioning

confidence: 99%

Inhibitory effect of Zn²⁺ on the chain‐initiation process of cumene oxidation

Chen

Cao

et al. 2021

Int J of Quantum Chemistry

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Carbon nanotubes (CNTs) have excellent catalytic activity in liquid phase reaction, especially in aerobic oxidation of cumene. In previous work, the conversion of cumene was 41.8% and the selectivity of cumene hydroperoxide was 71.5%, which was catalyzed by CNTs. But a small amount of impurity Zn2+ totally blocked up the aerobic oxidation of cumene that catalyzed by CNTs, which is an unexpected discovery. By analyzing the catalytic mechanism of CNTs, the inhibition effect of Zn2+ is locked on the abstraction of H atom from cumene. The inhibition of Zn2+ is confirmed in two effects by density functional theory calculations. First, due to the strongly coordination of active oxygen species (ROS) by Zn2+, the energy barrier of initial reaction increases to 1.90 eV, which is nearly 4 times higher than that of the only ROS promoted‐process. Second, the interaction of Zn2+ and RO· or ROO· to inhibits the chain propagation reaction of free radicals. This work precisely demonstrates that the inhibition effect of Zn2+ on initial reaction of cumene. The most significant thing is that the effect of metallic heteroatoms is not negligible in organic oxidation reaction.

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The effect of surface oxygenated groups of carbon nanotubes on liquid phase catalytic oxidation of cumene

Abstract: Surface oxygenated groups, instead of surface defects, play a negative role in the liquid phase radical oxidation reaction catalyzed by carbons.

Cited by 16 publications

References 42 publications

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Tuned Fabrication of the Aligned and Opened CNT Membrane with Exceptionally High Permeability and Selectivity for Bioalcohol Recovery

Inhibitory effect of Zn²⁺ on the chain‐initiation process of cumene oxidation

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The effect of surface oxygenated groups of carbon nanotubes on liquid phase catalytic oxidation of cumene

Abstract: Surface oxygenated groups, instead of surface defects, play a negative role in the liquid phase radical oxidation reaction catalyzed by carbons.

Cited by 16 publications

References 42 publications

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Tuned Fabrication of the Aligned and Opened CNT Membrane with Exceptionally High Permeability and Selectivity for Bioalcohol Recovery

Inhibitory effect of Zn2+ on the chain‐initiation process of cumene oxidation

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Inhibitory effect of Zn²⁺ on the chain‐initiation process of cumene oxidation