Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

Huang, Yeying; Li, Tingcheng; You, Qingliang; You, Xiangqian; Zhang, Qian; Zhang, Daohong; Xie, Guangyong

doi:10.1016/s1872-2067(18)63119-5

Cited by 17 publications

(8 citation statements)

References 32 publications

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“…The X-ray diffraction (XRD) pattern of the V–Cr catalyst is shown in Figure a, a monoclinic CrVO 4 phase (PDF 83–0761) can be observed, and V–Cr–O mixed oxide is believed to perform ideal ammoxidation reactivity. , The Raman spectra in Figure b confirms the existing of CrVO 4 phase, as the strongest peak at 923 cm –1 is assigned to the stretch of V–O–Cr bond of crystalline CrVO 4 , while the 785 cm –1 peak is assigned to the vibration of dichromates, both peaks can be observed in a CrVO 4 sample. , The transmission electron microscope (TEM) image is shown in Figure c, the d -spacing of the observed planes is measured to be 0.330 nm, which is similar to the estimated values of (2 2 0) plane of CrVO 4 obtained by XRD pattern. The surface area of the catalyst determined by Brunauer–Emmett–Teller (BET) model based on N 2 physisorptionis is 57.0 m 2 g –1 , which is suitable for the oxidation reaction.…”

Section: Resultsmentioning

confidence: 78%

Kinetic Study of Meta-Xylene Ammoxidation Reaction over a Commercial V–Cr Mixed Oxide Catalyst

Feng

et al. 2021

Ind. Eng. Chem. Res.

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The reaction behavior of meta-xylene ammoxidation on a commercial V−Cr mixed oxide catalyst (NC-IV) were studied in a fixed bed reactor, by kinetic modeling of experimental data of designed conditions. Specially, the oxidation of NH 3 to N 2 was also involved in the kinetic model, which is vital in the ammoxidation reaction. The catalyst showed monoclinic CrVO 4 phase and spherical morphology with an average particle diameter of 45 μm. Nonlinear regression analysis of the evaluation data has been employed to determine the rate constant and the order of reaction. The results indicated that m-xylene, oxygen, and ammonia share similar kinetic reaction orders for the production of isophthalonitrile (IPN) and m-tolunitrile (MTN), while the NH 3 oxidation reaction shows the highest reaction order, indicating that the partial pressure of ammonia and O 2 requires a precise control. The calculation of activation energies implies that selective ammoxidation to IPN has the highest activation energy (170.6 kJ mol −1 ), which is higher than MTN formation (117.5 kJ mol −1 ). The oxidation of m-xylene to CO 2 has slightly higher activation energy (122.9 kJ mol −1 ) than MTN production, implying the production of mtolunitrile is the dominant reaction under high reaction WHSV. The NH 3 oxidation shows the lowest activation energy (58.2 kJ mol −1 ) than the m-xylene participated reactions demonstrating a relatively easy NH 3 oxidation. These kinetic analyses are useful for a better understanding of the catalytic ammoxidation reaction of alkyl substituted aromatics over V−Cr mixed oxide catalysts.

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Section: Resultsmentioning

confidence: 78%

Kinetic Study of Meta-Xylene Ammoxidation Reaction over a Commercial V–Cr Mixed Oxide Catalyst

Feng

et al. 2021

Ind. Eng. Chem. Res.

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“…The catalytic tests were performed in fix-bed mode and the reaction conditions were fixed as follows: 400 °C, 0.13g/gCat•h -1 , ammonia ratio of 3, and air ratio of 15. The conversion of p-chlorotoluene over Cat-VCr0.5 was much lower than that over Cat-VCr1, Cat-VCr1.5 and Cat-VCr2, due to the low catalytic activity of orthorhombic-CrVO 4 [41] and monoclinic-Cr 2 V 4 O 13 [42] in Cat-VCr0.5. The ratio of V 4+ /V 5+ in the catalyst increased with an increase of Cr/V ratio, thus the redox process in the catalyst was accelerated and the catalytic activity was improved.…”

Section: Catalytic Performancementioning

confidence: 86%

“…Many methods, including hydrothermal, solvothermal, sol-gel [39], and spray drying methods [40], have been developed for the design and synthesis of nano-or micro-sized catalysts. We have prepared a series of VCrO nanoparticles [41][42][43] and VMoO [43] micro-cuboids by hydrothermal method, and found they exhibited excellent performance for the ammoxidation of chlorotoluenes. Huang and Li also produced some VCrO [26], VWO [22] and VTiO [24] micro-or nano-structures through hydrothermal synthesis and investigated their catalytic performance for ammoxidation of dichlorotoluenes.…”

Section: Introductionmentioning

confidence: 99%

Spray dried VCrO/SiO2 micro-spheroidal catalyst for the ammoxidation of p-chlorotoluene

Du,

Huang,

Tang

et al. 2023

Res Chem Intermed

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Formulation and shaping of heterogeneous catalysts are vital in the successful industrial application. Here micro-sized vanadium chromium composite oxides catalysts with the spherical shape were prepared via spray drying with colloidal silica as a binder material. The structural properties of catalysts with different Cr/V molar ratios were characterized by XRD, XPS, FT-IR, TPR, and particle size distribution analysis. It was revealed that the addition of Cr inhibited the formation of the crystalline phase V2O5 and decreased the reduction temperature of pentavalent vanadium species, and also resulted in the formation of monoclinic CrVO4 and a highly dispersed state of vanadia species. VCrO/SiO2 particles with various Cr/V atomic ratio were studied as catalysts for p-chlorotoluene ammoxidation to p-chlorobenzonitrile, in which the catalyst with Cr/V ratio of 1 exhibited the best catalytic performance. When the Cr/V ratio was less than 1, mixed phases of orthorhombic CrVO4 and monoclinic Cr2V4O13 were formed and resulted in a low catalytic activity. With the increase of Cr/V ratio, the ratio of V 4+ /V 5+ in the catalysts increased, thus the activation energy required for V reduction decreased, resulting in the catalytic activity of the catalysts improved. However, too large an amount of Cr led to the formation of highly oxidizing hexagonal-Cr2O3 phase, which reduced the selectivity of the catalytic reaction.

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“…Cr, Ti, Mo or P) on carriers (e.g. silica or alumina) or as bulk systems [5][6][7][8][9][10][11][12][13][14][15]. V-Cr-O based composite oxides are known to be highly e cient for selective gas-phase ammoxidation of various chloro-substituted toluenes.…”

Section: Introductionmentioning

confidence: 99%

“…V-Cr-O based composite oxides are known to be highly e cient for selective gas-phase ammoxidation of various chloro-substituted toluenes. Nano-or micro-sized V-Cr-O catalysts have been prepared by several methods such as solid-state reaction [5], co-precipitation [6], hydrothermal [7][8][9] and solvothermal routes [10]. Spray drying method has the characteristics of fast heat transfer, large evaporation rate, short drying time and low equipment cost [16].…”

Section: Introductionmentioning

confidence: 99%

Effect of metal oxide contents on the structure and performance of spray dried CrVO4/SiO2 catalysts for the ammoxidation of chlorotoluenes

Tong,

Huang,

Tang

et al. 2024

Preprint

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This work aims at developing a customized ammoxidation catalyst through optimizing the metal oxide content in CrVO4/SiO2 catalysts. Various amounts of Cr-V-O with 1:1 molar ratio of Cr/V were successfully loaded on SiO2 via spray drying method with colloidal silica as the binder. Polarized light microscope (PLM) illustrated that the CrVO4/SiO2 particles presented as well dispersed microspheres in the micro size (20-80 μm). X-ray diffraction spectroscopy (XRD) confirmed the formation of monoclinic CrVO4 phase wherein the metal oxide content was ranged from 30 to 70 weight percent. FT-IR spectra indicated that the introduction of metal oxide had no obvious effects on the skeletal structure of SiO2. X-ray photoelectron spectroscopy (XPS) analysis revealed that the valence state of V and Cr was hardly affected with increasing the metal oxide content. Performances of the obtained CrVO4/SiO2 catalysts with different metal oxide contents were investigated via the ammoxidation of a model compound namely; para-chlorotoluene. As a result of catalytic test, the CrVO4/SiO2 catalyst with 60% metal oxide content exhibited the best catalytic performance. In addition, this catalyst was an efficient and selective catalyst toward ammoxidation reactions of toluene, ortho- and meta-chlorotoluenes.

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Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

Cited by 17 publications

References 32 publications

Kinetic Study of Meta-Xylene Ammoxidation Reaction over a Commercial V–Cr Mixed Oxide Catalyst

Kinetic Study of Meta-Xylene Ammoxidation Reaction over a Commercial V–Cr Mixed Oxide Catalyst

Spray dried VCrO/SiO2 micro-spheroidal catalyst for the ammoxidation of p-chlorotoluene

Effect of metal oxide contents on the structure and performance of spray dried CrVO4/SiO2 catalysts for the ammoxidation of chlorotoluenes

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