1194-65-6Relevant articles and documents
Investigation of BiVO4 structure variations on the dichlorotoluene ammoxidation performance
Li, Xiongjian,Huang, Chi
, p. 866 - 870 (2021)
In this study, BiVO4 synthesized by hydrothermal and calcination methods were explored as catalysts in the ammoxidation of dichlorotoluenes to shed light on the structure-reactivity correlations. The BiVO4 samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), Brunauer–Emmett–Teller (BET), and UV–Vis spectrophotometry. The results showed that the catalytic activity of BiVO4 greatly relied on the structure variations. The hydrothermal prepared BiVO4 exhibited better catalytic activities as a consequence of its greater structure deformation, with maximum yields of 73.1, 72.2, and 70.8% for 3,4-, 2,4- and 2,6- dichlorobenzonitrles, respectively.
Hydrothermal Synthesis of Urchin-like W-V-O Nanostructures with Excellent Catalytic Performance
Li, Xiongjian,Sun, Li,Hu, Mingjie,Huang, Ronghua,Huang, Chi
, p. 14758 - 14763 (2018)
Urchinlike W-V-O microspheres have been successfully synthesized for the first time by a one-pot hydrothermal approach. The as-synthesized W-V-O material was characterized by several techniques such as XRD, SEM, TEM, FTIR, EDS, BET, and Raman spectroscopy. The characterization results have revealed that the W-V-O microspheres consist of numerous one-dimensional nanobelts radially grown from the center. The typical nanobelts display rectangular cross sections with lengths of several micrometers, widths of about 50 nm, and thicknesses of approximately 10-20 nm. Vanadium oxides are dispersed highly either on the external surface or inside the channel surface of the hexagonal WO3 structure. In addition, the as-obtained urchin-like W-V-O material was explored as a catalyst for the ammoxidation of 2,4- and 2,6-dichlorotoluene to the corresponding nitriles. The catalytic results have indicated that the W-V-O nanostructures show excellent performance with yields of 2,4- and 2,6-dichlorobenzonitrile respectively reaching up to 77.3 and 75.1%, which are the highest among the previously reported catalysts with two components. The formation process of the urchinlike W-V-O microspheres was simply investigated.
Effect of nitrogen-containing compounds on polychlorinated dibenzo-p-dioxin/dibenzofuran formation through de novo synthesis
Kuzuhara, Shunsuke,Sato, Hiroshi,Tsubouchi, Naoto,Ohtsuka, Yasuo,Kasai, Eiki
, p. 795 - 799 (2005)
An experimental study was conducted to clarify the suppression effect of nitrogen-containing compounds, that is, ammonia and urea, on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) through the de novo synthesis reaction. In the experiment, graphite and copper chloride contained in a mixture were used as sources of carbon and chlorine, respectively. The granulated sample mixture was charged as a packed-bed in the glass tube and heated at 300 °C in the flow of Ar-O 2 gas mixture. In some cases, urea was added as aqueous solution to the sample, while ammonia was added to the gas flowed through the sample bed. The amount of PCDD/Fs formed decreases significantly by the addition of both ammonia and urea. Particularly, the addition of urea reduces the amount of PCDD/Fs discharged in the outlet gas by approximately 90%. The oxidation rate of carbon in the early stage of the experiment, that is, the heating period, is promoted by the addition of nitrogen-containing compounds. However, soon after the temperature reaches 300 °C, the formation rate becomes lower than that of the case without the addition of nitrogen-containing compounds. On the other hand, organic compounds containing amino (-NH2) or cyanide (-CN) groups and those containing nitrogen within the carbon ring frame were detected in the outlet gas in the case of urea addition. Typically observed aromatic compounds are chlorobenzonitriles, chlorobenzeneamines, and chloropyridines. This suggests a possibility that hydrogen and/or chlorine combined with PCDD/Fs are also substituted by such nitrogen-containing groups, and this decreases the formation rate of their frame of carbon rings. This phenomenon was also consistent with the fact that a significant reduction was observed in the amount of PCDD/Fs released to the outlet gas when urea was added.
Ammoxidation of 2,6-dichloro toluene - From first trials to pilot plant studies
Martin,Kalevaru,Smejkal
, p. 275 - 279 (2010)
The scaling-up of the gas phase catalytic ammoxidation of 2,6-dichloro toluene (DCT) to 2,6-dichloro benzonitrile (DCBN) over a promoted vanadium phosphate (VPO) catalyst from first lab-scale experiments to pilot plant runs is reported. First experiments in a row of conversions of isomeric dichloro toluenes using simple, non-promoted VPO catalysts only show poor yield and selectivity. In particular, DCT ammoxidation is hindered due to bulky chlorine substituents probably preventing a sufficient interaction of the methyl group and lattice oxygen and/or N-containing surface species. Improved synthesis of VPO catalyst with the addition of promoters and γ-alumina or titania leads to significant increase in DCT conversion and DCBN yield. A Cr containing vanadyl pyrophosphate catalyst admixed with titania (anatase) showed conversion up to 97% with DCBN yields of ca. 80%. The same catalyst was also used for pilot plant runs, usually in the form of 5 mm × 3.5 mm shaped tablets that were prepared from a larger batch of solid synthesis. The scaling-up of the process using 100 ml of catalyst was investigated both by catalytic experiments and reactor simulations. The results showed that the temperature control will be crucial in scaling-up. Validation of simulation results with that of experimental results was also checked and a good agreement between measured and simulated results is observed.
Highly Modular Flow Cell for Electroorganic Synthesis
Gütz, Christoph,Stenglein, Andreas,Waldvogel, Siegfried R.
, p. 771 - 778 (2017)
A highly modular electrochemical flow cell and its application in electroorganic synthesis is reported. This innovative setup facilitates many aspects: an easy adjustment of electrode distance, quick exchange of electrode material, and the possibility to easily switch between a divided or undivided cell. However, the major benefit of the cell is the exact thermal positioning of the electrode material into a Teflon piece. Thereby, the application of expensive and nonmachinable electrode materials like boron-doped diamond or glassy carbon can easily be realized in flow cells. By this geometry, the maximum surface of such valuable electrode materials is exploited. The cell size can compete with classical preparative approaches in terms of performance and productivity. The optimization of reaction parameters and an easy up-scaling to larger flow cells is possible. By using this cell, the starting material can be saved in the development of the electroorganic transformations. To demonstrate the utility of this particular cell, two transformations of important building blocks for the fine chemical and pharmaceutical industry were established including an efficient and simple workup protocol.
Synthesis of nanoparticle-built FeVO4 microspheres with improved low temperature catalytic activity in ammoxidation
Chen, Fang,Chen, Piao,Hu, Hao,Li, Xiongjian,Yang, Shuijin
, (2021/10/12)
FeVO4 microspheres were successfully fabricated by a hydrothermal approach. Characterization results revealed that the FeVO4 microspheres are composed of numerous nanoparticles. In the ammoxidation of 2,6-dichlorotoluene (DCT) to 2,6-dichlorobenzonitrile (DCBN) catalyzed by FeVO4 microspheres, the conversion of DCT reaches up to 87% at a much lower temperature of 320 °C in comparison to previously reported catalysts (380–420 °C). The reason for this is that irons greatly improve the electron transport, leading to well reduction redox properties of vanadium species which are important to enhance the initial activation efficiency of C-H bond in methyl group.
