scholarly journals CATALYTIC CONVERSION OF ETHYLENE ON SYSTEMS BASED ON THRICHLOROTRIS-(TETRAHYDROFURANATE)CHROMIUM(III) WITH SOS-TYPE LIGANDS IN COMBINATION WITH VARIOUS ORGANOALUMINUM COCATALYSTS

2021 ◽  
Vol 64 (4) ◽  
pp. 85-91
Author(s):  
Ilya A. Babenko ◽  
Viktor A. Bezborodov ◽  
Alexey I. Vilms
Keyword(s):  
Reaction Zone ◽  
Catalytic Conversion ◽  
Ethylene Oligomerization ◽  
Organoaluminum Compounds ◽  
Molar Ratio ◽  
Tridentate Ligands ◽  
Catalytic Systems ◽  
Ethylene Pressure ◽  
Ratio Of Components ◽  
Sulfur Containing

This work presents the results of studying the behavior of catalytic systems formed on the basis of trichlorotris-(tetrahydrofuranate)chromium(III) in the presence of sulfur-containing tridentate SOS-type ligands and activated by various organoaluminum compounds. In the formation of catalytic systems, the following compounds were used: SOS-type ligands - bis-(2-methylthioethyl) ether, bis-(2-ethylthioethyl) ether and bis-(2-phenylthioethyl) ether, organoaluminum compounds - triethylaluminum, triisobutylaluminum, tributylaluminum and methylaluminoxane. In the course of test experiments aimed at choosing an activator at a temperature of 40 °C and an ethylene pressure of 2 MPa, the best results were obtained for triethylaluminum. Therefore, further experiments on the catalytic conversion of ethylene were carried out only with this activator. To study the effect of the reaction temperature and ethylene pressure in the reaction zone, catalytic systems of the trichlorotris-(tetrahydrofuranate)chromium(III)/ligand/triethylaluminum composition were studied in the temperature range from 40 to 80 °C and an ethylene pressure of 2 - 3 MPa with a molar ratio of components Cr : L : AlEt3 = 1 : 1 : 20. As a result of studies, it was shown that in all cases when using tridentate ligands of the SOS type, the catalytic systems formed by us showed a tendency not only to polymerization, but also to oligomerization of ethylene. The best results in the field of ethylene oligomerization into hexenes were shown by the system of the composition trichlorotris-(tetrahydrofuranate)chromium(III) / bis-(2-methylthioethyl) ether/triethylaluminum, in which the content of the hexene fraction is 54 - 55 wt.%, while the selectivity to hexene-1 reaches 88 - 89%.

scholarly journals Catalytic Stereoselective Conversion of Biomass-Derived 4′-Methoxypropiophenone to Trans-Anethole with a Bifunctional and Recyclable Hf-Based Polymeric Nanocatalyst

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2808
Author(s):  
Yixuan Liu ◽  
Dandan Chen ◽  
Mingrui Li ◽  
Heng Zhang ◽  
Hu Li
Keyword(s):  
Raw Materials ◽  
Food Additives ◽  
Polymeric Materials ◽  
Catalytic Conversion ◽  
Economic Benefits ◽  
Molar Ratio ◽  
Catalytic Systems ◽  
Precious Metal Catalysts ◽  
Dehydration Reactions ◽  
Mpv Reduction

Anethole (AN) is widely used as an odor cleaner in daily necessities, and can also be applied in the fields of food additives, drug synthesis, natural preservatives, and polymeric materials’ preparation. Considering environmental and economic benefits, the use of biomass raw materials with non-precious metal catalysts to prepare high-value fine chemicals is a very promising route. Here, we developed an acid-base bifunctional polymeric material (PhP-Hf (1:1.5)) composed of hafnium and phenylphosphonate in a molar ratio of 1:1.5 for catalytic conversion of biomass-derived 4′-methoxypropiophenone (4-MOPP) to AN via cascade Meerwein–Pondorf–Verley (MPV) reduction and dehydration reactions in a single pot. Compared with the traditional catalytic systems that use high-pressure hydrogen as a hydrogen donor, alcohol can be used as a safer and more convenient hydrogen source and solvent. Among the tested alcohols, 2-pentanol was found to be the best candidate in terms of pronounced selectivity. A high AN yield of 98.1% at 99.8% 4-MOPP conversion (TOF: 8.5 h−1) could be achieved over PhP-Hf (1:1.5) at 220 °C for 2 h. Further exploration of the reaction mechanism revealed that the acid and base sites of PhP-Hf (1:1.5) catalyst synergistically promote the MPV reduction step, while the Brønsted acid species significantly contribute to the subsequent dehydration step. In addition, the PhP-Hf polymeric nanocatalyst can be recycled at least five times, showing great potential in the catalytic conversion of biomass.

scholarly journals Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of Zr,Zr- and Zr,Al-Hydride Intermediates in Alkene Dimerization and Oligomerization

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 39
Author(s):  
Lyudmila V. Parfenova ◽  
Pavel V. Kovyazin ◽  
Almira Kh. Bikmeeva ◽  
Eldar R. Palatov
Keyword(s):  
Diffusion Coefficients ◽  
Organoaluminum Compounds ◽  
Zirconium Hydride ◽  
Nmr Studies ◽  
Catalytic Systems ◽  
Selective Formation

The activity and chemoselectivity of the Cp2ZrCl2-XAlBui2 (X = H, Bui) and [Cp2ZrH2]2-ClAlEt2 catalytic systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 were studied in reactions with 1-hexene. The activation of the systems by B(C6F5)3 resulted in the selective formation of head-to-tail alkene dimers in up to 93% yields. NMR studies of the reactions of Zr complexes with organoaluminum compounds (OACs) and boron activators showed the formation of Zr,Zr- and Zr,Al-hydride intermediates, for which diffusion coefficients, hydrodynamic radii, and volumes were estimated using the diffusion ordered spectroscopy DOSY. Bis-zirconium hydride clusters of type x[Cp2ZrH2∙Cp2ZrHCl∙ClAlR2]∙yRnAl(C6F5)3−n were found to be the key intermediates of alkene dimerization, whereas cationic Zr,Al-hydrides led to the formation of oligomers.

Isomorphous rare-earth tris[bis(2,6-diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3-diene polymerization and in the inhibited oxidation of polydimethylsiloxane

2018 ◽  
Vol 74 (5) ◽  
pp. 590-598 ◽  
Author(s):  
Mikhail E. Minyaev ◽  
Alexander N. Tavtorkin ◽  
Sof'ya A. Korchagina ◽  
Galina N. Bondarenko ◽  
Andrei V. Churakov ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Catalytic Properties ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Neodymium Complex ◽  
Butadiene Polymerization ◽  
Bond Network ◽  
Phosphate Ligands ◽  
Monodentate Coordination

Crystals of mononuclear tris[bis(2,6-diisopropylphenyl) phosphato-κO]pentakis(methanol-κO)lanthanide methanol monosolvates of lanthanum, [La(C24H34O4P)3(CH3OH)5]·CH3OH, (1), cerium, [Ce(C24H34O4P)3(CH3OH)5]·CH3OH, (2), and neodymium, [Nd(C24H34O4P)3(CH3OH)5]·CH3OH, (3), have been obtained by reactions between LnCl3(H2O) n (n = 6 or 7) and lithium bis(2,6-diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds (1)–(3) crystallize in the monoclinic P21/c space group and have isomorphous crystal structures. All three bis(2,6-diisopropylphenyl) phosphate ligands display a κO-monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O2P(O-2,6-iPr2C6H3)2}3(CH3OH)5] molecular unit exhibits four intramolecular O—H...O hydrogen bonds, forming six-membered rings. The unit forms two intermolecular O—H...O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O2P(O-2,6-iPr2C6H3)2}3(CH3OH)5]·CH3OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen-bond network. Complexes (1)–(3) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound (2) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6-diisopropylphenyl) phosphato-κO]neodymium, (3′), which was obtained as a dry powder of (3) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.

Design and Implementation of an Intensified Coprecipitation Reactor for the Treatment of Liquid Radioactive Wastes

2013 ◽  
Author(s):  
Julie Flouret ◽  
Yves Barré ◽  
Hervé Muhr ◽  
Edouard Plasari
Keyword(s):  
Reaction Zone ◽  
Residence Time ◽  
Flow Rate ◽  
High Efficiency ◽  
Solid Phase ◽  
Continuous Process ◽  
Decontamination Factor ◽  
Barium Nitrate ◽  
Molar Ratio ◽  
Experimental Conditions

The coprecipitation is a robust and inexpensive process for the treatment of important volumes of low and intermediate radioactive level liquid wastes. Its major inconvenient is the huge volume of sludge generated. The purpose of this work is to optimize the industrial coprecipitation continuous process by achieving the following objectives: - maximize the decontamination efficiency; - minimize the volume of sludge generated by the process; - reduce the treatment cost decreasing the installation volume. An innovative reactor with an infinite recycling ratio was therefore designed. It is a multifunctional reactor composed of two zones: a perfectly mixed precipitation zone and a classifier to perform liquid-solid separation. The experiments are focused on the coprecipitation of strontium by barium sulphate. The effluent containing sulphate ions and the barium nitrate solution are injected in the reaction zone where strontium and barium coprecipitate as sulphates. The produced solid phase is returned into the reaction zone by the classifier and goes out slowly from the reactor bottom with a residence time much higher than the liquid phase. This creates both a high concentration of solid phase in the reaction zone and a high efficiency of decontamination. The experimental conditions simulate the industrial effluents. The total treatment flow rate is 17 L/h, with an effluent flow rate of 16 L/h and a reactive flow rate of 1 L/h, hence a mean residence time of 10 minutes. In these experimental conditions, the molar ratio sulphate/barium after mixing corresponds to 4.9. These conditions are used in the reprocessing plant of La Hague. The decontamination factor reached in these experimental conditions is excellent: DF = 1500. The decontamination factor obtained with the classical continuous process is only equal to 60. Different process parameters are studied in order to optimize the reactor/classifier: residence time, barium nitrate flow rate and racking flow rate. The decrease of barium nitrate flow rate reduces the volume of sludge generated by the process keeping a high efficiency of strontium decontamination: DF = 400. An excess of sulphate is necessary to perform an efficient decontamination, but the molar ratio sulphate/barium can be reduced to 3 instead of 4.9 used industrially. The reactor/classifier also represents an efficient device for the coprecipitation process intensification. Indeed, it can sensibly reduce the final installation size while treating important volume of effluents. This innovative reactor optimizes both the decontamination efficiency of radioactive liquid wastes and the reduction of sludge volume. A reduction of sulphate ions in the discharge is also possible, which is environmentally friendly.

L-Argininium phosphite – a new candidate for NLO materials

2015 ◽  
Vol 71 (5) ◽  
pp. 415-421 ◽  
Author(s):  
Vahram V. Ghazaryan ◽  
Boris A. Zakharov ◽  
Aram M. Petrosyan ◽  
Elena V. Boldyreva
Keyword(s):  
Phosphorous Acid ◽  
Molar Ratio ◽  
Asymmetric Unit ◽  
Salt Formation ◽  
Nlo Properties ◽  
Carboxylate Groups ◽  
Protonated Amine ◽  
Nlo Materials ◽  
Ir And Raman ◽  
Ratio Of Components

In order to investigate the possibility of salt formation in the L-Arg–H3PO3–H2O system, single crystals of L-argininium phosphite, C6H15N4O2+·H2PO3−, were prepared by evaporation of an aqueous solution containing equimolar quantities of L-arginine and phosphorous acid. The asymmetric unit contains one L-argininium(+) cation and one phosphite [HPO2(OH)]−anion. The phosphite anions form chains parallel to [010] by O—H...O hydrogen bonding, with an O...O distance of 2.630 (3) Å. The protonated amine and guanidyl groups of the L-argininium(+) cations form N—H...O hydrogen bonds with the carboxylate groups and anions. The IR and Raman spectra are discussed in relation to the crystal structure. The salt displays nonlinear optical (NLO) properties. Another salt was obtained from a solution with a 1:2 molar ratio of components, but was characterized by vibrational spectra only.

Chromium-Based Catalyst for Ethylene Tetramerization to 1-Octene

2011 ◽  
Vol 347-353 ◽  
pp. 3392-3395
Author(s):  
Bao Jun Zhang ◽  
Bu Wei Yu ◽  
Gang Wang ◽  
Jian Zhong Li ◽  
Si Han Wang ◽  
...  
Keyword(s):  
Catalyst System ◽  
Ethylene Oligomerization ◽  
Steric Effects ◽  
Molar Ratio ◽  
Ethylene Tetramerization ◽  
Electric Effects

Novel diphoshinoamine(PNRNP) ligands have been used in ethylene oligomerization with Cr(III) compounds and cocatalyst. The results indicate that the catalyst system can yield 1-octene in selectivities up to 80%. Another novel diphoshinoamine ligands (((Ar2P)2N)2R)(R=cyclopropylamine) also were synthesized and characterized. Factors which affect the result of ethylene tetramerisation, such as cocatalyst, temperature, pressure and the molar ratio of Al/Cr were examined. Steric effects and electric effects were also considered in this report.

scholarly journals Trapping the Short-Chain Odd Carbon Number Olefins Using Nickel(II)-catalyzed Tandem Ethylene Oligomerization and Friedel-Crafts Alkylation of Toluene

2020 ◽  
Author(s):  
Sergey Zubkevich ◽  
Vladislav Tuskaev ◽  
Svetlana Gagieva ◽  
Alexander Pavlov ◽  
Viktor N. Khrustalev ◽  
...  
Keyword(s):  
Elemental Analysis ◽  
Carbon Number ◽  
Ethylene Oligomerization ◽  
Short Chain ◽  
X Ray Diffraction ◽  
Catalytic Systems ◽  
X Ray ◽  
H Nmr ◽  
Maldi Tof

<div>Nickel(II) complexes with pyrazole-based ligands are widely employed in catalysis of ethylene</div><div>oligomerization and subsequent Friedel-Crafts alkylation of toluene. We have prepared ten new</div><div>nickel(II) dibromide complexes with various substituted bis(azolyl)methanes. They have been</div><div>characterized using <sup>1</sup>H NMR, IR, MALDI-TOF and elemental analysis. The structures of three</div><div>complexes have been unambiguously established using X-ray diffraction. It was found that these</div><div>complexes in the presence of Et<sub>2</sub>AlCl or Et<sub>3</sub>Al<sub>2</sub>Cl<sub>3</sub> are active both in ethylene oligomerization and</div><div>Friedel-Crafts alkylation processes (activity up to 3720 kgoligomer·mol[Ni]<sup>−1</sup>·h<sup>−1</sup>). The use of Et<sub>3</sub>Al<sub>2</sub>Cl<sub>3</sub></div><div>results in the higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with</div><div>Et<sub>3</sub>Al<sub>2</sub>Cl<sub>3</sub> produced small amounts of odd carbon number olefins (up to 0.8%). The Friedel-Crafts</div><div>alkylation was used as a trap for previously undetected short-chain odd carbon number olefins (C<sub>3</sub> and</div><div>C<sub>5</sub>).</div>

scholarly journals SYNTHESIS OF In-CONTAINING HIGH-SILICA ZEOLITE OF ZSM-5 TYPE

2017 ◽  
Vol 60 (8) ◽  
pp. 84
Author(s):  
Khasay R. Samedov ◽  
Ulviya A. Mamedova ◽  
Kerim G. Ragimov ◽  
Zarema A. Jabbarova
Keyword(s):  
Degree Of Crystallinity ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Solid Product ◽  
X Ray ◽  
Type Zeolite ◽  
High Silica ◽  
Tetrabutylammonium Iodide ◽  
High Degree ◽  
Ratio Of Components

High silicate zeolite ZSM-5 on the basis of SiO2–In2O3–NaOH with an organic structure forming agent tetrabutylammonium iodide (TBAI) was synthesized in the temperature range of T = 150–220°C, pH = 9-12, τ = 48-240 h. As initial components, silica gel MSKO containing 86% SiO2, tetrabutylammonium iodide (TBAI), chemically pure NaOH and metallic indium (In) were used which mixed by hydrothermal synthesis. At the end of the synthesis, the solid product was separated from the mother liquor, washed on the filter with distilled water from an excess of alkali and dried at 120 °C, calcined at 550 °C (16 h). The products of hydrothermal crystallization were determined by X-ray (RFA – on the device D2-Phaser "Bruker"), differential thermal (DTA- STA-449 F3 Jupiter NETZSCH), by X-ray diffraction (XRD of brand SRM-18) and infrared spectroscopy (IR on FTIR spectroscopy, Nicolefisio VSA) analysis methods. During the synthesis, it was experimentally established that at T = 200 °C; τ = 240 h; pH≈9-10 molar ratio of components 5.78SiO2∙0.058In2O3∙0.625Na2O∙0.11H2O∙0.95 ((C4H9) 4NJ) – MFI-type zeolite is crystallized. When comparing XRF data with literature data, they were referred to a type zeolite of ZSM-5 differing in high degree of crystallinity. The following chemical composition of the synthesized zeolite (wt.%) was established by the X-ray diffraction (SRM-18) method: SiO2 – 94.01; In2O3 – 4.92; Na2O – 1.06 corresponding to the formula 0.96Na2O:In2O3:88SiO2:10H2O.Forcitation:Samedov Kh.R., Mamedova U.A., Ragimov K.G., Jabbarova Z.A. Synthesis of In-containing high-silica zeolite of ZSM-5 type.Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 84-87.

Determination of Composition of Reaction Mixtures from Alkylation of Toluene on Phosphorus-Modified H-ZSM-5 Zeolite

1993 ◽  
Vol 58 (8) ◽  
pp. 1832-1838
Author(s):  
Dušan Mravec ◽  
Jiří Herain ◽  
Štefan Holotík
Keyword(s):  
Gas Chromatography ◽  
Space Velocity ◽  
Ethylene Oligomerization ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Alkylation Reaction ◽  
Cyclization Reactions ◽  
Subsequent Cyclization ◽  
High Resolution Gas Chromatography

Determination of analytical composition of reaction mixtures formed by alkylation of toluene with ethylene on a phosphorus-modified H-ZSM-5 zeolite was made by a capillary high resolution gas chromatography. Identification of individual components of these reaction mixtures was performed by GS-MS method, using the samples obtained at 320 and 400 °C on H-ZSM-5 catalyst (modul 43.6) modified with 3.4 wt.% phosphorus at toluene to ethylene molar ratio 4.5 : 1 and the catalyst loading expressed as weight hour space velocity WHSV (for toluene) = 6.9 h-1. The reaction mixtures contained a total of 86 hydrocarbons. It was confirmed that in the addition to the main alkylation reaction, there proceeds also ethylene oligomerization with subsequent cyclization and aromatization, disproportionation, alkylation and cyclization reactions of alkylaromatic hydrocarbons to give alkylnaphthalenes and alkylindanes.

scholarly journals An Investigation of the Organoborane/Lewis Base Pairs on the Copolymerization of Propylene Oxide with Succinic Anhydride

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 253 ◽  
Author(s):  
Lan-Fang Hu ◽  
Dan-Jing Chen ◽  
Jia-Liang Yang ◽  
Xing-Hong Zhang
Keyword(s):  
Propylene Oxide ◽  
Succinic Anhydride ◽  
Lewis Base ◽  
Molar Ratio ◽  
Base Pairs ◽  
Catalytic Systems ◽  
Aliphatic Polyesters ◽  
Lewis Bases ◽  
Molecular Weights ◽  
High Ester

The copolymerization of biorenewable succinic anhydride (SA) with propylene oxide (PO) is a promising way to synthesize biodegradable aliphatic polyesters. However, the catalytic systems for this reaction still deserve to be explored because the catalytic activity of the reported catalysts and the molecular weights of produced polyesters are unsatisfied. Herein, we investigate the copolymerization of SA with PO catalyzed by the organoborane/base pairs. The types of Lewis bases, organoboranes, and their loadings all have a large impact on the activity and selectivity of the copolymerization. High ester content of >99% was achieved when performed the PO/SA copolymerization using triethyl borane (TEB)/phosphazene base P1-t-Bu (t-BuP1) pair with a molar ratio of 1/1 at 30–80 °C. Using TEB/t-BuP1 pair with the molar ratio of 4/1 at 80 °C, the turnover of frequency (TOF) was up to 128 h−1 and clearly higher than the known TOF values (0.5–34 h−1) of the PO/SA copolymerization by previously reported catalysts. The number-average molecular weights (Mns) of the resultant polyesters reached up to 20.4 kg/mol when copolymerization was carried out using TEB/t-BuP1 (1/1, in molar ratio) at 30 °C.

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