scholarly journals Niobium on BEA Dealuminated Zeolite for High Selectivity Dehydration Reactions of Ethanol and Xylose into Diethyl Ether and Furfural

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1269
Author(s):  
Deborah S. Valadares ◽  
Maria Clara H. Clemente ◽  
Elon F. de Freitas ◽  
Gesley Alex V. Martins ◽  
José A. Dias ◽  
...  
Keyword(s):  
Solid State ◽  
Diethyl Ether ◽  
High Selectivity ◽  
Catalytic Properties ◽  
Good Activity ◽  
Green Solvent ◽  
Turnover Number ◽  
Dehydration Reactions ◽  
Leveling Effect

In this work, we investigated the role of solid-state dealumination by (NH4)2SiF6 (25% Al removal and 13% Si insertion), the impregnation of niobium (10, 18, and 25 wt. %) on dealuminated *BEA (DB) zeolite and their catalytic properties in ethanol and xylose transformations. Among all the studied catalysts, 18%Nb-DB showed increased mesoporosity and external areas. A leveling effect in the number and strength of the proposed two sites (Brønsted and Lewis) present in the catalyst (n1 = 0.24 mmol g−1, −ΔH1 = 49 kJ mol−1, and n2 = 0.20 mmol g−1, –ΔH2 = 42 kJ mol−1) in the catalyst 18%Nb-DB, might be responsible for its good activity. This catalyst presented the highest selectivity for diethyl ether, DEE (97%) with 61% conversion after 50 ethanol pulses at 230 °C (turnover number, TON DEE = 1.15). These features allowed catalytically fruitful bonding of the ethanol molecules to the neighboring sites on the channels, facilitating bimolecular ether formation through a possible SN2 mechanism. The same catalyst was active and selective for transformation of xylose at 180 °C, showing 64% conversion and 51% selectivity for furfural (TON Furfural = 24.7) using water as a green solvent.

scholarly journals OXIDATIVE AMMONOLYSIS OF 4-METHYLPYRIDINE ON OXIDE VANADIUM-TITANIUM-ZIRCONIUM CATALYST MODIFIED BY TIN AND TUNGSTEN OXIDES

2021 ◽  
Vol 73 (1) ◽  
pp. 196-203
Author(s):  
T. P MIKHAILOVSKAYA ◽  
◽  
R. KURMAKYZY ◽  
D.K. TOLEMISOVA ◽  
K. A. KADIRBEKOV ◽  
...  
Keyword(s):  
Structural Changes ◽  
High Selectivity ◽  
Catalytic Properties ◽  
Main Process ◽  
Contact Conditions ◽  
Oxidative Ammonolysis ◽  
Tungsten Oxides ◽  
Tio2 Anatase ◽  
Oxide Vanadium

Catalysts based on vanadium pentoxide modified by Ti, Sn, Zr and W oxides were tested in the oxidative ammonolysis of 4-methylpyridine. The role of the main process parameters such as temperature, the ratio of the initial components in the conversion of the methyl group to the nitrile one, and the optimal conditions for the oxidative ammonolysis of 4-methylpyridine were determined. It is determined that the V-Ti-Zr-O-catalyst and the sample containing 9% of tungsten oxide are superior in catalytic activity to the V-Ti-Zr-Sn-O contact. Conditions that ensure a high selectivity for the formation of 4-cyanopyridine were found. The highest yield of the target product (85-86%) was obtained on V-Ti-Zr-W-O at 270 °C, and the yield of 4-cyanopyridine was 87.5% at 310° C on the V-Ti-Zr-Sn-O catalyst. The phase composition and structural changes occurring in modified vanadium oxide catalysts have been studied. It is determined that mixed V-Ti-Zr-Sn-O and V-Ti-Zr-W-O catalysts contain ZrV2O7, the monoclinic modification of ZrO2 (baddeleyite), TiO2 (anatase), SnO2, WO3, and V2O5. In catalysts, it can exist in small amounts as a separate VO2 phase. The V-Ti-Zr-W-O catalyst showed the best catalytic properties. It has highactivity and selectivity towards 4-cyanopyridine.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

scholarly journals Understanding solid-state processing of pharmaceutical cocrystals via milling: Role of tablet excipients

2021 ◽  
Vol 601 ◽  
pp. 120514 ◽  
Author(s):  
Rahamatullah Shaikh ◽  
Saeed Shirazian ◽  
Sarah Guerin ◽  
Eoin Sheehan ◽  
Damien Thompson ◽  
...  
Keyword(s):  
Solid State ◽  
Pharmaceutical Cocrystals ◽  
Tablet Excipients ◽  
State Processing

A monovacant heteropolytungstate-incorporated trimeric carbonyl rhenium cluster, [(AsW11O39){Re(CO)3}3(μ3-OH)(μ2-OH)]6−: synthesis, structure and catalytic properties

RSC Advances ◽  
2014 ◽  
Vol 4 (55) ◽  
pp. 28848-28851 ◽  
Author(s):  
Yanhui Zhang ◽  
Dongdi Zhang ◽  
Zhiyuan Huo ◽  
Pengtao Ma ◽  
Jingyang Niu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Selectivity ◽  
Catalytic Properties ◽  
The Novel ◽  
Rhenium Cluster

The novel undecatungstoarsenate-supported carbonyl rhenium derivative exhibits prominent catalytic activity and high selectivity in the cycloaddition of epoxides.

The Role of Protons and Formation Cu(NH3)2+ During Ammonia-Assisted Solid-State Ion Exchange of Copper(I) Oxide into Zeolites

2018 ◽  
Vol 62 (1-4) ◽  
pp. 100-107 ◽  
Author(s):  
Peter N. R. Vennestrøm ◽  
Lars F. Lundegaard ◽  
Christoffer Tyrsted ◽  
Dmitriy A. Bokarev ◽  
Alina I. Mytareva ◽  
...  
Keyword(s):  
Solid State ◽  
Ion Exchange

Role of solid-state structure in propene hydrogenation with nickel catalysts

1990 ◽  
Vol 86 (4) ◽  
pp. 739 ◽  
Author(s):  
Giovanni Carturan ◽  
Stefano Enzo ◽  
Renzo Ganzerla ◽  
Maurizio Lenarda ◽  
Roberto Zanoni
Keyword(s):  
Solid State ◽  
Nickel Catalysts ◽  
State Structure ◽  
Solid State Structure

scholarly journals Electrochemiluminescence Study of Europium (III) Complex with Coumarin3-Carboxylic Acid

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Stefan Lis ◽  
Krzysztof Staninski ◽  
Tomasz Grzyb
Keyword(s):  
Aqueous Solution ◽  
Spectral Analysis ◽  
Energy Transfer ◽  
Solid State ◽  
Carboxylic Acid ◽  
Elemental Analysis ◽  
Aluminium Electrode ◽  
The Eu

The europium (III) complex of coumarin-3-carboxylic acid (C3CA) has been prepared and characterized on the basis of elemental analysis, IR, and emission (photoluminescence and electrochemiluminescence) spectroscopy. The synthesised complex having a formula Eu was photophysically characterized in solution and in the solid state. Electrochemiluminescence, ECL, of the system containing the Eu(III)/C3CA complex was studied using an oxide-covered aluminium electrode. The goal of these studies was to show the possibility of the use of electrochemical excitation of the Eu(III) ion in aqueous solution for emission generation. The generated ECL emission was very weak, and therefore its measurements and spectral analysis were carried out with the use of cut-off filters method. The studies proved a predominate role of the ligand-to-metal energy transfer (LMET) in the generated ECL.

Facile Solid State Method Route Synthesis and Enhance Visible Light Activities of BiVO4 by Doping Co

2016 ◽  
Vol 703 ◽  
pp. 316-320
Author(s):  
Hai Feng Chen ◽  
Jing Ling Hu ◽  
Bing Xu
Keyword(s):  
Solid State ◽  
Visible Light ◽  
Catalytic Effect ◽  
Catalytic Properties ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Illumination Time ◽  
X Ray ◽  
State Method

Using NH4VO3, Bi (NO3)3•5H2O and Co (NO3)2•6H2O as raw materials, Co doped BiVO4 (Co/BiVO4) photocatalysts were successfully prepared by solid state method. And the photo catalytic properties were test in this work. Crystal structures of these samples were characterized by X-ray diffraction (XRD). The Methyl Orange (MO) was simulated as the sewage under the visible light to explorer the influence of the illumination time and the mass of photocatalyst. The visible-light absorption spectrum of BiVO4 was broadening with doping Co. It was found that the Co/BiVO4 had higher photocatalytic activity than pure BiVO4 .The reason of enhanced catalytic effect also had been analyzed and discussed in the article.

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