9002-91-9Relevant articles and documents
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.
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
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.]
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.
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.
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.
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.
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.
Selective Butene Formation in Direct Ethanol-to-C3+-Olefin Valorization over Zn-Y/Beta and Single-Atom Alloy Composite Catalysts Using in Situ-Generated Hydrogen
Allard, Lawrence F.,Assary, Rajeev S.,Cordon, Michael J.,Krause, Theodore R.,Kropf, A. Jeremy,Li, Zhenglong,Lin, Fan,Liu, Dongxia,Miller, Jeffrey T.,Purdy, Stephen C.,Unocic, Kinga A.,Wang, Huamin,Wegener, Evan C.,Yang, Ce,Zhang, Junyan,Zhou, Mingxia
, p. 7193 - 7209 (2021/06/30)
The selective production of C3+olefins from renewable feedstocks, especially via C1and C2platform chemicals, is a critical challenge for obtaining economically viable low-carbon middle-distillate transportation fuels (i.e., jet and diesel). Here, we report a multifunctional catalyst system composed of Zn-Y/Beta and “single-atom” alloy (SAA) Pt-Cu/Al2O3, which selectively catalyzes ethanol-to-olefin (C3+, ETO) valorization in the absence of cofed hydrogen, forming butenes as the primary olefin products. Beta zeolites containing predominately isolated Zn and Y metal sites catalyze ethanol upgrading steps (588 K, 3.1 kPa ethanol, ambient pressure) regardless of cofed hydrogen partial pressure (0-98.3 kPa H2), forming butadiene as the primary product (60% selectivity at an 87% conversion). The Zn-Y/Beta catalyst possesses site-isolated Zn and Y Lewis acid sites (at ～7 wt % Y) and Br?nsted acidic Y sites, the latter of which have been previously uncharacterized. A secondary bed of SAA Pt-Cu/Al2O3selectively hydrogenates butadiene to butene isomers at a consistent reaction temperature using hydrogen generatedin situfrom ethanol to butadiene (ETB) conversion. This unique hydrogenation reactivity at near-stoichiometric hydrogen and butadiene partial pressures is not observed over monometallic Pt or Cu catalysts, highlighting these operating conditions as a critical SAA catalyst application area for conjugated diene selective hydrogenation at high reaction temperatures (>573 K) and low H2/diene ratios (e.g., 1:1). Single-bed steady-state selective hydrogenation rates, associated apparent hydrogen and butadiene reaction orders, and density functional theory (DFT) calculations of the Horiuti-Polanyi reaction mechanisms indicate that the unique butadiene selective hydrogenation reactivity over SAA Pt-Cu/Al2O3reflects lower hydrogen scission barriers relative to monometallic Cu surfaces and limited butene binding energies relative to monometallic Pt surfaces. DFT calculations further indicate the preferential desorption of butene isomers over SAA Pt-Cu(111) and Cu(111) surfaces, while Pt(111) surfaces favor subsequent butene hydrogenation reactions to form butane over butene desorption events. Under operating conditions without hydrogen cofeeding, this combination of Zn-Y/Beta and SAA Pt-Cu catalysts can selectively form butenes (65% butenes, 78% C3+selectivity at 94% conversion) and avoid butane formation using onlyin situ-generated hydrogen, avoiding costly hydrogen cofeeding requirements that hinder many renewable energy processes.
Study of Cu modified Zr and Al mixed oxides in ethanol conversion: The structure-catalytic activity relationship
Zhukova,Chuklina,Maslenkova
, p. 159 - 165 (2021/03/17)
Here, we study the influence of the Cu modified (Zr + Ce)O2-Al2O3 systems composition and synthesis conditions on their catalytic properties in the ethanol conversion. First, we obtained varios ratios mixed Al-Zr supports at different synthesis temperatures using a sol-gel method. Then we modified the surface of the oxides by Cu, reduced in hydrogen flow. All obtained systems demonstrated а high alcohol conversion and selectivity to acetaldehyde. The surface area (SBET), the pore volume, and the pore distribution were measured by the nitrogen adsorption method. The structure of the samples have been investigated by XRD and XAS-spectroscopy. A correlation between the synthesis temperature and contents of mixed oxide support and textural properties were observed. The results show that Al-Zr mixed oxide support structure plays a crucial role in forming a Cu active site for ethanol dehydrogenation to acetaldehyde.
