Catalytic Activity of High-Surface-Area Amorphous MgO Obtained from Upsalite

The first aim of the research was to synthesize a pure Upsalite, which is an amorphous form of MgCO3, by modifying a procedure described in the literature, so that it would be the precursor of a high-surface, amorphous magnesium oxide. The results indicate that within the studied reaction conditions, the type of alcohol used as the reactant has the most pronounced effect on the yield of reaction. From the two alcohols that led to the highest yield of Upsalite, methanol gave a substantially larger surface area (794 vs. 191 m2 g−1). The optimized synthesis conditions of Upsalite were used to obtain MgO via thermolysis, whose activity in the transfer hydrogenation reaction (THR) from ethanol, 2-propanol and 2-pentanol to various carbonyl compounds was determined. The optimal conditions for the thermolysis were as follows: vacuum, T = 673 K as the final temperature, and a heating rate of 2 deg min−1. The high-surface, amorphous magnesia (SBET = 488 m2 g−1) was found to be a very selective catalyst to 4-t-butylcyclohexanone in THR, which led to a diastereoselectivity of over 94% to the E-isomer of 4-t-butylcyclohexanol for more than 3 h, with conversions of up to 97% with either 2-propanol or 2-pentanol as the hydrogen donor. In the case of acrolein and 2-n-propylacrolein being used as the hydrogen acceptors, the unsaturated alcohol (UOL) was the main product of the reaction, with higher UOL yields noted for ethanol than 2-propanol.

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Ce–Zr materials with a high surface area as catalyst supports for hydrogenation of CO2

Functional Materials Letters ◽

10.1142/s1793604720400044 ◽

2020 ◽

Vol 13 (04) ◽

pp. 2040004

Author(s):

Nikolay D. Evdokimenko ◽

Alexander L. Kustov ◽

Konstantin O. Kim ◽

Igor V. Mishin ◽

Vera D. Nissenbaum ◽

...

Keyword(s):

Surface Area ◽

Heterogeneous Catalysts ◽

High Surface ◽

High Surface Area ◽

Oxygen Storage Capacity ◽

Hydrogenation Reaction ◽

Oxygen Storage ◽

Hexadecyltrimethylammonium Bromide ◽

Developed Surface ◽

Direct Hydrogenation

The most promising way of CO2 utilization is its catalytic conversion into valuable products, in particular, the direct hydrogenation of CO2 on heterogeneous catalysts to obtain such products as synthesis gas, hydrocarbons, alcohols, esters, carboxylic acids, and some other organic molecules. Heterogeneous iron-based catalysts possess a special position among the promising candidates for the synthesis of CO2-based hydrocarbons. However, individual iron oxide catalysts have a fairly low surface area, which requires their deposition on the support or modification. CeO2 is rather attractive in catalysis because of its high oxygen storage capacity. The most effective thermal stabilizer of CeO2 is ZrO2. In this work, cerium–zirconium systems with various Ce to Zr ratios were synthesized by the method of coprecipitation in the absence and presence of the hexadecyltrimethylammonium bromide template. These systems were characterized by adsorption of N2, XRD, and DTA-TG-DTG and used as supports for 5% Fe catalysts. The activity of synthesized Fe-containing catalysts was investigated in the reaction of CO2 hydrogenation. The developed surface and the presence of cerium in the supports are the possible reasons for the high activity of Fe-containing catalysts in the hydrogenation reaction of CO2.

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TiO2 nanofibers resembling ‘yellow bristle grass’ in morphology by a soft chemical transformation

Dalton Transactions ◽

10.1039/c5dt01027f ◽

2015 ◽

Vol 44 (20) ◽

pp. 9637-9645 ◽

Cited By ~ 9

Author(s):

Sandeep Nandan ◽

T. G. Deepak ◽

Shantikumar V. Nair ◽

A. Sreekumaran Nair

Keyword(s):

Surface Area ◽

Chemical Transformation ◽

High Surface ◽

High Surface Area ◽

Reaction Conditions ◽

Tio2 Nanofibers ◽

One Dimensional

We synthesized a uniquely shaped one-dimensional (1-D) TiO2 nanostructure having the morphology of yellow bristle grass with high surface area by the titanate route under mild reaction conditions.

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Some Research on the Magnetic X Zeolite Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.2040 ◽

2011 ◽

Vol 311-313 ◽

pp. 2040-2047 ◽

Cited By ~ 1

Author(s):

Ming Liang Yuan ◽

Cong Song ◽

Guan Jie Yan

Keyword(s):

Surface Area ◽

Molecular Sieves ◽

High Surface ◽

High Surface Area ◽

Weight Ratio ◽

Scanning Calorimetry ◽

Synthesis Conditions ◽

Magnetic Zeolite ◽

X Zeolite ◽

Zeolite Composite

X zeolite behaves excellent properties of shape selective catalysis, molecular sieves and iron-exchange for its unique tunnel structure and large specific surface area. In this paper magnetic core has been introduced into the zeolite structure and magnetic zeolite with high stability and adsorption properties have been prepared. Synthesis conditions and adsorption of Pb2+ also have been studied. Magnetic zeolite composite was hydrothermally synthesized with a traditional hydrothermal method by adding magnetic Fe3O4 suspension in the zeolite synthesis system. Synthesis conditions and adsorption of Pb2+ also have been studied. The products were characterized with X Ray diffraction (XRD), IR spectrometer (IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Thermogravimetric (TGA) and differential scanning calorimetry (DSC) instruments. The results show that the products have an X zeolite crystal structure and present super paramagnetic properties. The saturation magnetization value of the product is about 3.7 emu•g-1. The weight ratio of magnetic Fe3O4 in the magnetic zeolite composite is calculated to be about 5%. The magnetic zeolite composites have high surface area and the absorption capability of the products is 196.8mg/g.

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Organic-Silica Hybrid Materials Consisting of the Double Four-Ring Silicate Structure as a Building Block

MRS Proceedings ◽

10.1557/proc-346-163 ◽

1994 ◽

Vol 346 ◽

Cited By ~ 6

Author(s):

Isao Hasegawa ◽

Masanori Ishida ◽

Seijl Motojima ◽

Shigeo Satokawa

Keyword(s):

Surface Area ◽

Hybrid Materials ◽

Building Block ◽

High Surface ◽

High Surface Area ◽

Bet Surface Area ◽

Reaction Conditions ◽

Silicate Structure ◽

Organic Silica ◽

Silica Hybrid

ABSTRACTCopolymerization of the cubic octameric silicate anion (Si8O208-) with dimethyldichlorosilane in 2, 2-dimethoxypropane has yielded organic-silica hybrid materials consisting of the S13O20 structure as a building block. The hybrid materials have shown high surface area by calcination in air. The reaction conditions have been optimized to produce the materials with higher specific surface area. As a result, the hybrid materials with BET surface area of 406 m2 g-1 have been obtained.

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Synthesis, characterization, and reactivity of tungsten oxynitride

Journal of Materials Research ◽

10.1557/jmr.1998.0324 ◽

1998 ◽

Vol 13 (8) ◽

pp. 2321-2327 ◽

Cited By ~ 21

Author(s):

Toby E. Lucy ◽

Todd P. St. Clair ◽

S. Ted Oyama

Keyword(s):

Surface Area ◽

High Surface ◽

High Surface Area ◽

X Ray Diffraction ◽

Heating Rates ◽

Continuous Transformation ◽

X Ray ◽

Synthesis Conditions ◽

Temperature Programmed ◽

Temperature Programmed Reaction

High surface area tungsten oxynitride has been prepared by the temperature programmed reaction (TPR) of WO3 with NH3. All samples were characterized by x-ray diffraction (XRD), nitrogen physisorption, CO chemisorption, and elemental analysis. Samples were prepared at different heating rates (β), and a Redhead analysis yielded an activation energy for nitridation of 109 kJ mol−1. A heating rate of 0.016 K s−1 gave optimal synthesis conditions. Solid state intermediates were studied by interrupting the temperature program at various stages. No distinct suboxide phases were found using XRD. The nitridation step was determined to be a continuous transformation from oxide to oxynitride. Surface area, CO uptake, and nitrogen weight % were all found to increase as the reaction progressed. Reactivity experiments showed reasonable hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) activity, but little hydrogenation (HYD) or hydrodesulfurization (HDS) activity.

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Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

10.26434/chemrxiv.7770338.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Kailun Yang ◽

Recep Kas ◽

Wilson A. Smith

Keyword(s):

Surface Area ◽

High Surface ◽

High Surface Area ◽

Catalyst Layer ◽

Active Surface ◽

Active Surface Area ◽

High Concentration ◽

Copper Electrodes ◽

Surface Enhanced ◽

Local Current

This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO2 electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO2 electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO2 electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer.

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Rugae-like FeP nanocrystal assembly on a carbon cloth: an exceptionally efficient and stable cathode for hydrogen evolution

Nanoscale ◽

10.1039/c5nr02375k ◽

2015 ◽

Vol 7 (25) ◽

pp. 10974-10981 ◽

Cited By ~ 95

Author(s):

Xiulin Yang ◽

Ang-Yu Lu ◽

Yihan Zhu ◽

Shixiong Min ◽

Mohamed Nejib Hedhili ◽

...

Keyword(s):

Gas Phase ◽

Surface Area ◽

Hydrogen Evolution ◽

Hydrogen Generation ◽

High Surface ◽

High Surface Area ◽

Catalytic Efficiency ◽

Carbon Cloth ◽

Nanocrystal Assembly

High surface area FeP nanosheets on a carbon cloth were prepared by gas phase phosphidation of electroplated FeOOH, which exhibit exceptionally high catalytic efficiency and stability for hydrogen generation.

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