9002-91-9Relevant academic research and scientific papers
Ethanol Steam Reforming by Ni Catalysts for H2 Production: Evaluation of Gd Effect in CeO2 Support
Assaf, Elisabete M.,Ferreira, Gabriella R.,Lucrédio, Alessandra F.,Nogueira, Francisco G. E.
, (2022/01/19)
Abstract: Ni-based catalysts supported on CeO2 doped with Gd were prepared in this work to investigate the role of gadolinium on ethanol conversion, H2 selectivity, and carbon formation on ethanol steam reforming reaction. For this, catalysts containing 5 wt% of Ni impregnated on supports of ceria modified with different amounts of Gd (1, 5, and 10 wt%) were used. Ex-situ studies of XRPD suggest an increase of the lattice parameters, indicating a solid solution formation between Gd and Ce. Results of TPR showed an increase in metal-support interactions as the content of Gd increased. In situ XRPD studies indicated the formation of a GdNiO ternary phase for the catalysts containing Gd, which is in agreement with the results obtained by XANES. The catalysts were tested at three temperatures: 400?°C, 500?°C, and 600?°C. The conversion and productivity showed dependence with the Gd content and also with the temperature of the reaction. After the catalytic tests, catalysts containing Gd presented filamentous carbon possible due to a change in the reaction pathway. The highest ethanol conversion and H2 productivity were obtained at 600?°C for all catalysts and the best catalyst at this temperature was 5Ni_5GdCeO2. The promising performance of this catalyst may be associate with the lowest formation of GdNiO ternary phase, among the catalysts containing Gd, which means more Ni0 active species available to convert ethanol. Graphical Abstract: [Figure not available: see fulltext.]
Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis
Li, Han,Wenger, Oliver S.
supporting information, (2021/12/23)
The two-electron reduced forms of perylene diimides (PDIs) are luminescent closed-shell species whose photochemical properties seem underexplored. Our proof-of-concept study demonstrates that straightforward (single) excitation of PDI dianions with green
Binary Au–Cu Reaction Sites Decorated ZnO for Selective Methane Oxidation to C1 Oxygenates with Nearly 100% Selectivity at Room Temperature
Gong, Zhuyu,Liu, Huifen,Luo, Lei,Ma, Jiani,Tang, Junwang,Xing, Jialiang,Xu, Youxun
supporting information, p. 740 - 750 (2022/01/03)
Direct and efficient oxidation of methane to methanol and the related liquid oxygenates provides a promising pathway for sustainable chemical industry, while still remaining an ongoing challenge owing to the dilemma between methane activation and overoxidation. Here, ZnO with highly dispersed dual Au and Cu species as cocatalysts enables efficient and selective photocatalytic conversion of methane to methanol and one-carbon (C1) oxygenates using O2 as the oxidant operated at ambient temperature. The optimized AuCu–ZnO photocatalyst achieves up to 11225 μmol·g–1·h–1 of primary products (CH3OH and CH3OOH) and HCHO with a nearly 100% selectivity, resulting in a 14.1% apparent quantum yield at 365 nm, much higher than the previous best photocatalysts reported for methane conversion to oxygenates. In situ EPR and XPS disclose that Cu species serve as photoinduced electron mediators to promote O2 activation to ?OOH, and simultaneously that Au is an efficient hole acceptor to enhance H2O oxidation to ?OH, thus synergistically promoting charge separation and methane transformation. This work highlights the significances of co-modification with suitable dual cocatalysts on simultaneous regulation of activity and selectivity.
Catalytic Oxidation of Ethylene in Solutions of Palladium(II) Cationic Complexes in Binary and Ternary Aqueous Organic Solvents
Oshanina, I. V.,Pestunova, U. V.,Podtyagina, A. V.,Rusnak, I. N.,Temkin, O. N.
, p. 734 - 743 (2022/01/13)
Abstract: The effect of organic solvents on the rate of ethylene oxidation with p-benzoquinone to acetaldehyde in aqueous organic solutions of palladium cationic complexes has been studied. It was found that the reaction rate increased when the acceptor number of the solvent increased and the donor number decreased. The oxidation of ethylene and cyclohexene in binary (N-methylpyrrolidone–H2O) and ternary (acetonitrile–N-methylpyrrolidone–H2O) solvents was studied in more detail. In contrast to the acetonitrile–Н2О system, in the N-methylpyrrolidone–Н2О binary solvent hydrogen peroxide oxidizes ethylene to acetaldehyde in the presence of Pd(II) cationic complexes. The use of a solvent N-methylpyrrolidone acceptable for cyclohexene (CH) oxidation technology leads to a decrease in the rate and selectivity of cyclohexanone synthesis.
Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
Mukherjee, Aparajita,Bhattacharya, Samaresh
, p. 15617 - 15631 (2021/05/19)
The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
Synthesis and characterization of Merrifield resin and graphene oxide supported air stable oxidovanadium(IV) radical complexes for the catalytic oxidation of light aliphatic alcohols
Chaudhary, Nikita,Haldar, Chanchal,Kesharwani, Neha
, (2021/07/26)
Imidazole modified Merrifield resin and (3-Aminopropyl)trimethoxysilane-modified graphene oxide supported oxidovanadium(IV) radical complexes PS-im-[VIVO(tbnC[rad])(acac)] (1) and GO-ATPMS-[VIVO(tbnO[rad])(acac)] (2) were synthesized and characterized by various spectroscopic, thermal and chemical techniques. The radical nature of 1 and 2 was established by trapping experiments in addition to EPR spectroscopy. In EPR analysis, complex 2 shows a prominent signal with g = 2.005, characteristic of an oxygen-centered radical. The neat complex [VIVO(tbnC[rad])(acac)] (A) displays an EPR signal at g = 2.0025, typical of carbon-centered radical. On the contrary, such characteristic EPR signal of a radical is absent in complex 1, presumably due to spin pairing. XPS analysis confirms the +4 oxidation state of vanadium in fresh as well as recycled catalysts 1 and 2. Both the supported complexes show excellent catalytic activity towards a variety of aliphatic alcohols. Comparatively, the polymer-supported complex displays better substrate conversion than the graphene oxide-supported complex. However, 2 shows better selectivity towards aldehydes, whereas carboxylic acids are obtained as major products in the presence of 1. Interestingly, catalyst 1 is almost equally effective towards all the examined alcohols, but its effectiveness reduces slightly for longer carbon chain alcohols. On the other hand, catalyst 2 shows better substrate conversion for the alcohols with a longer carbon chain. During the catalytic oxidation of alcohols, the active intermediate species oxidoperoxidovanadium(V) complex ([VO(O2)(tbn)(acac-H)]?) was detected by FT-IR, UV–vis, and LC–MS analysis.
Effect of Nitro Derivatives of 1,2,4-Triazole on the Radiation-Induced Oxidation of Ethanol
Brinkevich,Maliborskii, A. Ya.,Kapusto,Sverdlov,Grigor’ev, Yu. V.,Shadyro
, p. 59 - 64 (2021/02/27)
Abstract: The effect of 1,2,4-triazole and its nitro derivatives on the formation of final molecular products of radiation-induced transformations of oxygen-saturated ethanol has been studied. It has been found that the test compounds are almost not decomposed in the course of radiolysis, whereas they insignificantly decrease or do not affect the radiation-chemical yields of H2O2 and acetaldehyde. The experimental data indicate that the nitro derivatives of 1,2,4-triazole cannot compete with oxygen for α-hydroxyethyl radicals, and they do not interact with oxygen-centered radicals formed in the system. The reaction rate constant of the oxidation of α-hydroxyethyl radicals by the nitro derivatives of 1,2,4-triazole was found to be k ≤ 4.6 × 109 L mol?1 s?1 by calculation using the method of competing reactions.
Reactivity of vanadyl pyrophosphate catalyst in ethanol ammoxidation and β-picoline oxidation: Advantages and limitations of bi-functionality
Tabanelli, Tommaso,Mari, Massimiliano,Folco, Federico,Tanganelli, Federico,Puzzo, Francesco,Setti, Laura,Cavani, Fabrizio
, (2021/04/23)
This study investigates the catalytic activity of vanadyl pyrophosphate (VPP) for both gas-phase ethanol ammoxidation to acetonitrile and β-picoline oxidation to nicotinic acid. Both reactions may be alternative processes to the industrial technologies used to produce these two chemicals. The reaction networks were investigated, also by feeding possible intermediates; in-situ DRIFT spectroscopy was used to monitor the interaction of ethanol and ammonia with the catalyst. VPP bi-functionality features played an important role in the two reactions; specifically, acidity was detrimental either because it catalyzed undesired reactions, such as ethanol dehydration to ethylene during ethanol ammoxidation, or because it caused a strong interaction with reactants – especially those containing N atoms, ammonia and β-picoline – thus giving rise to some surface saturation phenomena which inhibited the consecutive reactions leading to the final desired compounds, acetonitrile and nicotinic acid. The co-feeding of steam helped product desorption, thus enhancing selectivity in β-picoline oxidation.
Selective Preparation of Olefins through Conversion of C2 and C3 Alcohols on NASICON-Type Phosphates
Ermilova, M. M.,Il’in, A. B.,Orekhova, N. V.,Yaroslavtsev, A. B.
, p. 693 - 700 (2021/07/26)
Abstract—: We have studied the catalytic activity of LiZr2(PO4)3-based NASICON-type phosphates for conversion of C2 and C3 aliphatic alcohols with the aim of selectively preparing C2–C4 olefins. Selectivity has been controlled via partial heterovalent substitutions of In3+ or Nb5+ for Zr4+ or Mo for phosphorus. We have investigated the structure and morphology of the synthesized catalysts. The nature of the dopants has been shown to play a key role in determining the selectivity of the catalysts studied. Partial In3+ substitution for Zr4+ improves the dehydrogenating properties of the materials, whereas partial substitutions of Nb5+ for Zr4+ and Mo6+ for P5+ improve their dehydrating properties. We have demonstrated the possibility of highly selective preparation of ethylene and butylenes from ethanol and of propylene from propanol-1 and propanol-2.
Kinetically Controlled Synthesis of Rhodium Nanocrystals with Different Shapes and a Comparison Study of Their Thermal and Catalytic Properties
Zhao, Ming,Chen, Zitao,Shi, Yifeng,Hood, Zachary D.,Lyu, Zhiheng,Xie, Minghao,Chi, Miaofang,Xia, Younan
, p. 6293 - 6302 (2021/05/07)
We report the synthesis of Rh nanocrystals with different shapes by controlling the kinetics involved in the growth of preformed Rh cubic seeds. Specifically, Rh nanocrystals with cubic, cuboctahedral, and octahedral shapes can all be obtained from the same cubic seeds under suitable reduction kinetics for the precursor. The success of such a synthesis also relies on the use of a halide-free precursor to avoid oxidative etching, as well as the involvement of a sufficiently high temperature to remove Br- ions from the seeds while ensuring adequate surface diffusion. The availability of Rh nanocrystals with cubic and octahedral shapes allows for an evaluation of the facet dependences of their thermal and catalytic properties. The data from in situ electron microscopy studies indicate that the cubic and octahedral Rh nanocrystals can keep their original shapes up to 700 and 500 °C, respectively. When tested as catalysts for hydrazine decomposition, the octahedral nanocrystals exhibit almost 4-fold enhancement in terms of H2 selectivity relative to the cubic counterpart. As for ethanol oxidation, the order is reversed, with the cubic nanocrystals being about three times more active than the octahedral sample.
