Green synthesis of low-carbon chain nitroalkanes via a novel tandem reaction of ketones catalyzed by TS-1

Chu, Qingyan; He, Guangke; Yang, Xi; Wang, Ping; Yu, Haoxuan; Li, Rui

doi:10.1016/j.catcom.2018.01.022

Cited by 11 publications

(7 citation statements)

References 31 publications

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“…Indeed, the Si-OH groups are difficult to release free H protons interacting with pyridine, which represent the Brønsted acid sites. In contrast, ZrO 2 -modified SiO 2 exhibits clear IR adsorption bands located at 1606 and 1447 cm –1 , which can be assigned to Lewis acid sites . Also, another relatively weaker adsorption band located at 1489 cm –1 represents the combined effect of L-acid sites and B-acid sites.…”

Section: Resultsmentioning

confidence: 93%

“…In contrast, ZrO 2 -modified SiO 2 exhibits clear IR adsorption bands located at 1606 and 1447 cm −1 , which can be assigned to Lewis acid sites. 77 Also, another relatively weaker adsorption band located at 1489 cm −1 represents the combined effect of L-acid sites and B-acid sites. As seen from Py-IR spectra, it is well confirmed that ZrO 2 has more L-acid sites but fewer B-acid sites.…”

Section: Resultsmentioning

confidence: 99%

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Particle-Size-Dependent Methane Selectivity Evolution in Cobalt-Based Fischer–Tropsch Synthesis

et al. 2020

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The effects of the cobalt particle size in the range of 6.5−26.3 nm on the catalyst structural transformation and methane selectivity evolution in Fischer−Tropsch synthesis (FTS) have been investigated. In situ X-ray diffraction experiments revealed that cobalt was maintained as CoO under a reaction environment when initial Co 3 O 4 particles on SiO 2 were below 8.4 nm. The large metallic Co particles can keep a stable size and phase state, indicating almost unchanged catalytic activity and methane selectivity. In contrast, small metallic Co or CoO particles show a gradual increase in methane selectivity with time on stream. Stable large metallic Co particles can be explained as the dominant surface high-coordinated Co atoms having a weak binding ability for H 2 O molecules, which are more difficult to be oxidized into CoO. It is believed that CoO rather than metallic Co atoms could interact with Si-OH groups to form inactive cobalt silicate (Co 2 SiO 4 ), which leads to a higher methane selectivity and drives a decrease in the particle size during the FTS reaction. ZrO 2 as a structural promoter highly dispersed on SiO 2 was found to give a milder increase in methane selectivity due to fewer chances of Si-OH interacting with CoO species. Density functional theory (DFT) calculations combined with CO temperature-programmed desorption (CO-TPD), NH 3 -TPD, CO 2 -TPD, and Py-IR demonstrate that Co/ZrO 2 interfacial sites play a crucial role in enhancing the catalytic activity as the electron accumulation in the interface region not only increases the CO adsorption amount but also promotes the CO dissociation on cobalt sites. At the same time, a higher surface C*/H concentration benefits a lower methane selectivity. ZrO 2 , which acts as a Lewis acid, can adsorb CO molecules abundantly but weakly by the interaction between Zr 4+ cations and O atoms in CO. Especially, for the 15Co(C)/Q15 catalyst with initial CoO particles on SiO 2 , methane selectivity rapidly increases at an early reaction stage, which originates from easier accessible CoO reacting with Si-OH groups. In addition, both 15Co(C)/Q15 and 15Co(C)/10Zr(I)-Q15 catalysts show the dominant CoO phase, which is active in the FTS reaction. Indeed, the DFT calculations demonstrate that CO activation on the CoO(200) surface via the H-assisted CH 2 O dissociation pathway exhibits a lower activation energy of 1.21 eV compared to that on the face-centered cubic (fcc) Co(111) surface with an activation energy of 1.42 eV, despite that direct CO dissociation, CHO dissociation, and CHOH dissociation on CoO(200) show higher activation energies. This study provides a prime scientific understanding about regulating catalytic activity and methane selectivity.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Particle-Size-Dependent Methane Selectivity Evolution in Cobalt-Based Fischer–Tropsch Synthesis

et al. 2020

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“…Then titanium peroxide reacts with NH 3 •H 2 O to form ammonium peroxide, which would easily release NH 2 OH. Eventually, NH 2 OH would react with MEK to produce MEKO by non-catalytic oxidation [37]. The addition of Ni reduced the electron cloud density of the titanium active center, improved its electrophilicity, enhanced the adsorption capacity for H 2 O 2 , and thus increased the reaction rate of the control step of ketoammoximation, i.e., the formation rate of hydroxylamine.…”

Section: Mechanism Analysismentioning

confidence: 99%

Nickel-Modified TS-1 Catalyzed the Ammoximation of Methyl Ethyl Ketone

Yang

Wang

et al. 2019

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In this paper, five kinds of transition metal-modified titanium silicalite-1 (M-TS-1) were prepared by an ultrasonic impregnation method. We studied their catalytic performances in the ammoximation of methyl ethyl ketone (MEK). The various M-TS-1 catalysts revealed distinct differences in their MEK ammoximation activity. The nickel-modified TS-1 (Ni-TS-1), especially 3 wt % Ni-TS-1, exhibited a satisfactory conversion of MEK (99%) associated with a high selectivity of methyl ethyl ketoxime (MEKO) (99.3%), which was 6% higher than that of TS-1 under the same conditions. Moreover, the catalyst showed excellent recyclability and the reactivity could be completely recovered after regeneration. The catalysts were characterized by Powder X-ray Diffraction (XRD), Fourier Transformed Infrared Spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), and so on. It was demonstrated that the skeleton structure of TS-1 was basically maintained and the electron environment of the Ti active site was changed after the nickel modification, which can optimize the adsorption capacity and the activation for H2O2. Meanwhile, the surface nickel species reduced the surface acidity of the catalyst, which provided an appropriate pH and inhibited the deep oxidation of oxime.

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“…It is due to the ability of deep oxime oxidation to produce nitroalkanes that we successfully applied it to the reaction of ketone green synthesis of nitroalkanes through a series of experiments. [11] However, the micropores of TS-1 restrict the diffusion of molecules in the pore channel, which limits its catalytic activity on the one hand and causes the accumulation of some molecules in the pore channel on the other hand, accelerating the deactivation of the catalyst. To solve this problem, researchers have carried out a large number of basic and theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Green Synthesis of 2‐Nitropropane via Ammoximation‐Oxidation over Organic Base Modified TS‐1 Catalysts

et al. 2022

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Modified TS-1 catalysts for the acetone ammoximation-oxidation reaction were prepared by post-treating TS-1 with different concentrations of TPAOH/TIPA, and the effects of alkali treatment on the catalytic performance were systematically investigated. The techniques such as XRD, SEM, TEM and N 2 sorption were used to characterize the catalyst samples, which exhibited that the introduction of alkali increased the volume and quantity of mesopores, while there was no obvious influence on the framework structure and titanium content in the framework. And the improvement in catalyst performance after alkali treatment was attributed to the increase of mesopores and the decrease in diffusion limitation. In addition, three common ammoximation catalysts (Ti-MOR, Ti-MWW and TS-1) were systematically investigated in this reaction. Ti-MOR showed superiority in the ammoximation to oxime, while TS-1 displayed the best catalytic performance in the ammoximation oxidation of ketones to nitroalkanes. It was indicated that modified TS-1 could be a promising catalyst for the ammoximation-oxidation reaction of acetone.

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Green synthesis of low-carbon chain nitroalkanes via a novel tandem reaction of ketones catalyzed by TS-1

Cited by 11 publications

References 31 publications

Particle-Size-Dependent Methane Selectivity Evolution in Cobalt-Based Fischer–Tropsch Synthesis

Particle-Size-Dependent Methane Selectivity Evolution in Cobalt-Based Fischer–Tropsch Synthesis

Nickel-Modified TS-1 Catalyzed the Ammoximation of Methyl Ethyl Ketone

Green Synthesis of 2‐Nitropropane via Ammoximation‐Oxidation over Organic Base Modified TS‐1 Catalysts

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