Xn:Harmful;
827-52-1Relevant articles and documents
Schwartz et al.
, p. 2146 (1968)
Bulk hydrotreating MonW12-nS2 catalysts based on SiMonW12-n heteropolyacids prepared by alumina elimination method
Kokliukhin,Nikulshina,Mozhaev,Lancelot,Lamonier,Nuns,Blanchard,Bugaev,Nikulshin
, p. 26 - 37 (2021)
A series of unsupported mono- and bimetallic MonW12-nS2 catalysts were synthesized by alumina elimination from supported MonW12-nS2/Al2O3 samples using acid etching. Alumina supported catalysts have been in turn prepared by using monometallic H4SiMo12O40 and H4SiW12O40 heteropolyacids (HPAs), their mixture with Mo/W atomic ratio equal to 1/11 and 3/9, and mixed bimetallic H4SiMo1W11O40 and H4SiMo3W9O40 HPAs. All catalysts were characterized by N2 adsorption, temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), extended X-ray absorption fine structure (EXAFS) spectroscopy and powder X-ray diffraction (XRD) and their performance were evaluated in simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrogenation (HYD) of naphthalene. The etching process led to a successful removal of all the support and of the partially sulfided species, with sulfidation degrees of both Mo and W above 90 % on the final bulk solids. The active phase also underwent a rearrangement, as higher average length and stacking were measured on the bulk catalysts than on the original supported ones. Mixed MoWS2 phase was evidenced in all solids, prepared from mixed HPAs (MonW12-nS2) or from the mixture of monometallic HPAs (RefMonW12-nS2), by EXAFS and ToF-SIMS, with however a larger quantity on the MoW solids. It seems that the mixed MoWS2 phase observed on the supported MoW catalysts is maintained through the etching process, while on RefMonW12-nS2 the mixed phase, observed in a much lesser extent in the corresponding supported catalyst, could result from the aggregation of the monometallic slabs. MonW12-nS2 catalysts were found more effective than the monometallic catalysts and than the corresponding RefMonW12-nS2, in both dibenzothiophene hydrodesulfurization and naphthalene hydrogenation, which was related to the presence of the mixed phase maintained through the etching of the support.
Comparative activity of Ni-W and Co-Mo sulfides using transition metal oxides as precursors in HDS reaction of DBT
Quintana-Melgoza, Juan Manuel,Alonso-Nunez, Gabriel,Homero-Galvan, Donald,Avalos-Borja, Miguel
, p. 1082 - 1088,7 (2012)
Unsupported catalysts based on nickel, cobalt, tungsten, and molybdenum were prepared by sulphurization of Ni, Co, W, and Mo oxides. All catalysts were tested in hydrodesulphurization of dibenzothiophene reaction. The best activity was attained with a sample based on W (5.64 × 1016 molecules/s m2). The best selectivity for biphenyl (70.14 %) was achieved with Ni17S18. Materials were characterized by X-ray diffraction and surface area measurements. Graphical Abstract: Reaction network for hydrodesulphurization (HDS) of dibenzotiophene (DBT) by direct desulphurization pathway (DDS) and hydrogenating pathway (HYD) to produce biphenyl (BP) and cyclohexyl-benzene (CHB). nH2 = hydrogen excess at 3.378 MPa, dihydrodibenzotiophene (DHDBT), tetrahydrodibenzothiophene (THDBT), hexahydrodibenzothiophene (HHDBT), hydrogen sulphide (H2S). Ni 17S18 as a yield of 12.03 % THDBT, 17.83 % CHB, and 70.14 % BP.[Figure not available: see fulltext.]
Iron(II) bipyridine complexes for the cross-coupling reaction of bromocyclohexane with phenylmagnesium bromide
Matsubara, Yutaka,Yamaguchi, Takamichi,Hashimoto, Toru,Yamaguchi, Yoshitaka
, p. 198 - 202 (2017)
Three known iron(II) complexes bearing a bipyridine ligand, [FeCl2(bpy)2] (1), [FeCl2(bpy)]2 (2) and [FeCl2(dmbpy)] (3) (bpy?=?2,2′-bipyridine and dmbpy?=?6,6′-dimethyl-2,2′-bipyridine) were employed for the cross-coupling reaction of bromocyclohexane (4) with phenylmagnesium bromide (5). These complexes catalyzed the cross-coupling reaction. Among the three catalysts, complex 2 acted as an effective catalyst to afford the cross-coupled product phenylcyclohexane (6) in 92% yield. The X-ray crystal structure analyses of 2 and 3 were demonstrated.
Visible-light-induced photocatalytic benzene/cyclohexane cross-coupling utilizing a ligand-to-metal charge transfer benzene complex adsorbed on titanium oxides
Yamamoto,Ohara,Yoshida
, p. 2046 - 2050 (2018)
The cross-coupling reaction of benzene and cyclohexane molecules proceeded selectively over Pd-modified titanium dioxide photocatalysts under visible light. A ligand-to-metal charge-transfer (LMCT) complex of benzene adsorbed on titanium oxide was proposed as the key species for the selective formation of the cross-coupling product.
The selectivity of sulfided NiW/Al2O3 catalyst in the hydrodesulfurization of dibenzothiophene
Nagai
, p. 3052 - 3054 (1989)
The hydrodesulfurization of petroleum residue is widely practiced and the need for a similar technology for coal-derived liquids is well recongnized. The selectivity of a sulfided NiW/Al2O3 catalyst for hydrodesulfurization has been studied at 300°C and 10.1 MPa total pressure. The presence of oxygen and sulfur compounds depressed the desulfurization of dibenzothiophene, but not the hydrogenation. The addition of large amounts of acridine improved the catalytic activity significantly for the desulfurization of dibenzothiophene to biphenyl while preventing hydrogenation.
Synthesis and Reactivity of Manganese(II) Complexes Containing N-Heterocyclic Carbene Ligands
Al-Afyouni, Malik H.,Krishnan, V. Mahesh,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 5088 - 5094 (2015)
A series of manganese(II) complexes containing aryl-substituted N-heterocyclic carbene (NHC) ligands have been synthesized and characterized. Chloride complexes of Mn(II) containing the NHC ligands 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and 1,3-dimesitylimidazol-2-ylidene (IMes) were prepared in straightforward fashion by direct carbene addition to MnCl2(THF)1.6. These complexes exist as chloride-bridged dimers in solution of formula [Mn2Cl2(μ-Cl)2(NHC)2]. The monomeric complex [MnCl2(IMes)2] has also been prepared and structurally characterized, although NMR studies are consistent with facile dissociation of one of the IMes ligands in solution. [Mn2Cl2(μ-Cl)2(IPr)2] serves as a precursor to dimeric alkyl and aryl compounds of Mn(II) including [Mn2R2(μ-Cl)2(NHC)2] (R = Bn, o-tolyl, and Ph) and the bridging methyl complex [Mn2Me2(μ-Me)2(IPr)2]. Stoichiometric reactions of these hydrocarbyl species with bromocyclohexane demonstrate that they are not chemically competent in C-C coupling reactions involving alkyl electrophiles.
One pot synthesis of NiMo-Al2O3 catalysts by solvent-free solid-state method for hydrodesulfurization
Yi, Xiaodong,Guo, Dongyun,Li, Pengyun,Lian, Xinyi,Xu, Yingrui,Dong, Yunyun,Lai, Weikun,Fang, Weiping
, p. 54468 - 54474 (2017)
A simple and solvent-free solid-state method was used to prepare NiMo-Al2O3 hydrodesulfurization (HDS) catalysts using Ni(NO3)2·6H2O, (NH4)6Mo7O24·4H2O, and AlCl3·6H2O as the solid raw materials and polyethylene glycol (PEG) as an additive. The effects of PEG addition on the precursor thermal decomposition, catalyst properties and dibenzothiophene (DBT) HDS activity were investigated. The as-prepared catalysts were characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that an increase in PEG addition dramatically increases specific surface area and pore volume of the catalyst, and improves Mo sulfidability and active MoS2 dispersion by blocking the aggregation of metals, and consequently increases the number of HDS active sites. However, excess PEG leads to the decrease in specific surface area and pore volume attributed to the metal sintering caused by the strong heat release during thermal decomposition. As a result, dibenzothiophene HDS activity enhanced with increasing PEG addition and peaked at NiMoAl-15 (15% weight ratio of PEG to alumina), which exhibited a significantly higher activity as compared to the NiMo/Al2O3 catalyst prepared by wetness co-impregnation.
Hydrogenation of Biphenyl Using a Hydrogen Storage Alloy as a Hydrogenation Reagent
Nakagawa, Shin-Ichi,Murata, Satoru,Nomura, Masakatsu,Sakai, Tetsuo
, p. 1599 - 1603 (1996)
A detailed investigation of the hydrogenation reaction of biphenyl with MmNi3.5Co0.7Al0.8H4.2 [Mm: mixture of La, Ce, Pr, and Nd (30 : 52 : 5 : 13 wt ratio)] to give either cyclohexylbenzene or bicyclohexyl was performed. Time profiles of the amounts of hydrogen evolved from the alloy and that introduced into biphenyl during the reaction were measured; it was suggested that the hydrogen absorbed by the alloy could predominantly react with the substrate, and the hydrogen released into the gas phase played only a minor role in the reaction. The deuteration of biphenyl with the deuterated alloy, MmNi3.5Co0.8Al0.8D3.5, was also examined; a GC-MS analysis of the reaction mixture indicated that a H-D exchange between the hydrogen in the substrate and the deuterium in the alloy took place as a parallel reaction to hydrogenation of the aromatic rings, and, as a result, the product cyclohexylbenzene appeared to contain 3-9 deuterium atoms.
Phosphotungstic acid encapsulated in USY zeolite as catalysts for the synthesis of cyclohexylbenzene
Yang, Yufei,You, Yue,Wu, Junyan,Feng, Junbo,Zhang, Yadong
, p. 573 - 580 (2021)
Abstract: In this work, a new type of catalyst, USY-HPW, was successfully prepared by encapsulating phosphotungstic acid (HPW) into ultra-stable Y zeolite (USY). The obtained catalyst USY-HPW was characterized by various techniques including N2 adsorption/desorption isotherms, XRD, SEM, TG-DSC, XPS, NH3-TPD, FT-IR, Py-IR. The catalytic properties of USY-HPW were evaluated by using a model alkylation reaction of benzene with cyclohexene to form cyclohexylbenzene. The conversion rate of cyclohexene can reach as high as 99.99%. Compared with USY alone, USY-HPW displayed markedly improved selectivity and yield for the target product of cyclohexylbenzene, ca. 5.41% and 8.73%, respectively. Besides, reusability tests indicated the high durability USY-HPW as the yield of cyclohexylbenzene can still reach to 83.50% after eight runs. All these results demonstrate that USY-HPW catalyst has good performances and holds good potential in acid catalyzed organic chemistry. Graphical abstract: [Figure not available: see fulltext.].
Organic reaction in water. Part 2. A new method for dechlorination of chlorobiphenyls using a Raney Ni-Al alloy in dilute aqueous alkaline solution
Liu, Guo-Bin,Tsukinoki, Takehito,Kanda, Tadashige,Mitoma, Yoshiharu,Tashiro, Masashi
, p. 5991 - 5994 (1998)
Use of a Raney Ni-Al alloy in dilute aqueous alkaline gave rise to strong reducing power and chlorobiphenyls were reduced easily to biphenyl and/or phenylcyclohexane, respectively, without any organic solvents.
Streiff et al.
, p. 361,364 (1957)
Influence of Oxygen-Containing Compounds on Conversion and Selectivity of Dibenzotiophene and Naphthaline on Bulk and Supplied Co(Ni)MoS2 Catalysts
Nikulshin, P. A.,Pimersin, A. A.,Salnikov, V. A.,Varakin, A. N.
, p. 1761 - 1771 (2019)
The supported CoMoS2/Al2O3 and NiMoS2/Al2O3 catalysts were synthesized by impregnating of alumina to incipient wetness with aqueous solutions of 12-molybdophosphoric heteropoly acid and nickel or cobalt citrates. A bulk Ref-MoS2 catalyst was synthesized by thermal decomposition of ammonium tetratiomolybdate. The synthesized catalysts were examined by low temperature nitrogen adsorption and high resolution transmission electron microscopy. The catalytic properties were studied in the dibenzothiophene hydrodesulfurization and naphthalene hydrogenation in the presence of dodecanoic acid or guaiacol in a flow unit with a microreactor under hydrogen pressure. The bulk catalyst Ref-MoS2 had minimal sensitivity to dodecanoic acid and guaiacol during the combined hydrotreatment of dibenzothiophene and naphthalene. The effective adsorption constants of dodecanoic acid and guaiacol were calculated using the Langmuir-Hinshelwood model.
Molecular approach to prepare mixed MoW alumina supported hydrotreatment catalysts using H4SiMo: NW12- nO40 heteropolyacids
Nikulshina,Blanchard,Mozhaev,Lancelot,Griboval-Constant,Fournier,Payen,Mentré,Briois,Nikulshin,Lamonier
, p. 5557 - 5572 (2018)
H4[SiMonW12-nO40] heteropolyacids (HPAs) are interesting precursors for the preparation of alumina-supported hydrotreatment catalysts to introduce both metals simultaneously while maintaining a Mo-W nanoscale proximity. Two heteropolyacids (n = 1 and 3) have been synthesized and used for the first time to prepare hydrotreatment catalysts. Crystal structure refinement has been performed and evidenced the formation of β-H4[SiMo3W9O40] with three ordered Mo sites forming a face. The purity of the samples in aqueous solution has been determined by Raman spectroscopy and polarographic characterization. These heteropolyacids were then impregnated on alumina to prepare supported MoW-based catalysts. As references, catalysts with the same Mo/W ratios have been prepared using monometallic H4SiMo12O40 and H4SiW12O40 HPAs (mixture of these 2 HPAs in the impregnating solution). EXAFS characterization after drying performed simultaneously at the Mo K and W LIII edges indicates preservation of the mixed heteropolyanion SiMonW12-nO404- at the alumina surface even if partial decomposition to Keggin lacunary species could not be excluded and evidences the mixed MoW-S2 slab formation after sulfidation. Better catalytic hydrogenation properties for dibenzothiophene hydrodesulfurization and naphthalene hydrogenation have been obtained when using β-H4[SiMo3W9O40], which is explained by the formation of the mixed MoW-S2 active phase.
Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
, p. 208 - 218 (2021/12/29)
A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
Metallic Barium: A Versatile and Efficient Hydrogenation Catalyst
Stegner, Philipp,F?rber, Christian,Zenneck, Ulrich,Knüpfer, Christian,Eyselein, Jonathan,Wiesinger, Michael,Harder, Sjoerd
supporting information, p. 4252 - 4258 (2020/12/22)
Ba metal was activated by evaporation and cocondensation with heptane. This black powder is a highly active hydrogenation catalyst for the reduction of a variety of unactivated (non-conjugated) mono-, di- and tri-substituted alkenes, tetraphenylethylene, benzene, a number of polycyclic aromatic hydrocarbons, aldimines, ketimines and various pyridines. The performance of metallic Ba in hydrogenation catalysis tops that of the hitherto most active molecular group 2 metal catalysts. Depending on the substrate, two different catalytic cycles are proposed. A: a classical metal hydride cycle and B: the Ba metal cycle. The latter is proposed for substrates that are easily reduced by Ba0, that is, conjugated alkenes, alkynes, annulated rings, imines and pyridines. In addition, a mechanism in which Ba0 and BaH2 are both essential is discussed. DFT calculations on benzene hydrogenation with a simple model system (Ba/BaH2) confirm that the presence of metallic Ba has an accelerating effect.
Ligand-enabled and magnesium-activated hydrogenation with earth-abundant cobalt catalysts
Han, Bo,Jiao, Hongmei,Ma, Haojie,Wang, Jijiang,Zhang, Miaomiao,Zhang, Yuqi
, p. 39934 - 39939 (2021/12/31)
Replacing expensive noble metals like Pt, Pd, Ir, Ru, and Rh with inexpensive earth-abundant metals like cobalt (Co) is attracting wider research interest in catalysis. Cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. Herein, we describe a hydrogenation method for polycyclic aromatic hydrocarbons (PAHs) and olefins with a magnesium-activated earth-abundant Co catalyst. When diketimine was used as a ligand, simple and inexpensive metal salts of CoBr2in combination with magnesium showed high catalytic activity in the site-selective hydrogenation of challenging PAHs under mild conditions. Co-catalyzed hydrogenation enabled the reduction of two side aromatics of PAHs. A wide range of PAHs can be hydrogenated in a site-selective manner, which provides a cost-effective, clean, and selective strategy to prepare partially reduced polycyclic hydrocarbon motifs that are otherwise difficult to prepare by common methods. The use of well-defined diketimine-ligated Co complexes as precatalysts for selective hydrogenation of PAHs and olefins is also demonstrated.
