The Hydrolysis-Reduction of Arabinogalactan in the Presence of Ru/Cs3HSiW12O40 Catalyst

2020 ◽  
Vol 20 (4) ◽  
pp. 303-312
Author(s):  
N. V. Gromov ◽  
T. B. Medvedeva ◽  
V. N. Panchenko ◽  
M. N. Timofeeva ◽  
V. N. Parmon
Keyword(s):  
Metal Content ◽  
Nitrogen Adsorption ◽  
Bifunctional Catalyst ◽  
Effect Of Temperature ◽  
Cesium Salt ◽  
Highly Dispersed ◽  
Physicochemical Methods ◽  
Pharmaceutical Industries ◽  
Different Content ◽  
Xrd And Tem

The hydrolysis-reduction of hemicellulose arabinogalactan to arabitol and galactitol polyalcohols, which are widely used in the food and pharmaceutical industries, was studied. It was shown that the process could be performed with the bifunctional catalyst containing highly dispersed ruthenium deposited on the cesium salt of silicon-tungsten heteropolyacid, Ru/Cs3HSiW12O40. The catalysts with different content of ruthenium (0.3, 0.6 and 1 wt.%) were synthesized for the study. The catalysts and their Cs3HSiW12O40 support were examined by various physicochemical methods (low-temperature nitrogen adsorption, IR spectroscopy, XRD, and TEM). The effect of temperature, substrate/catalyst ratio and ruthenium content in the catalyst on the yields of target products was elucidated. The highest yields of target products were achieved at the metal content of 0.6 wt.% and equal weights of the loaded catalyst and substrate (the 1:1 ratio). At a temperature of 200 °C, arabitol and galactitol can be produced with the yields up to 12 and 48 % for 2 h of the reaction in the presence of catalyst with the composition 0.6%Ru/Cs3HSiW12O40.

Aqueous chemical grafting of modified-PEG onto maghemite nanoparticles: Influence of grafting conditions

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Claire-Hélène Brachais ◽  
Ling Hu ◽  
Diana Hach ◽  
Denis Chaumont ◽  
Aurélien Percheron ◽  
...  
Keyword(s):  
Covalent Bond ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
Size Exclusion ◽  
Maghemite Nanoparticles ◽  
Chemical Grafting ◽  
Exclusion Chromatography ◽  
One Step ◽  
Aqueous Conditions ◽  
Xrd And Tem

AbstractThe synthesis of maghemite nanoparticles coated with triethoxysilanemonomethylether- PEG (Si-mPEG), is presented in aqueous conditions, by the “grafting to” process. This procedure is performed in one step, starting from anchored polymer and native nanoparticles. The maghemite nanoparticles obtained were first identified by XRD and the average diameter is about 10 nm according to the Nitrogen adsorption, XRD and TEM techniques. The nature of the catalysts (acetic acid, triethylamine, NH4OH and dibutyl-tin-dilaurate) used for the establishment of the covalent bond between the γ-Fe2O3 particles and the SimPEG, as well as the influence of the temperature and the reaction time, were evaluated on the grafting rate of the particles in water by TGA and FTIR techniques. Using the size exclusion chromatography, SEC technique, we showed that the monomethoxy-PEG was resistant to mild acidic up to strong basic conditions. The best ratio “time/amount of polymer” for the highest grafting rate was the use of tinbased organometallic compound (DBTL) at 80 °C during 48 h. In these conditions, a grafting rate of 54 % is achieved.

The Effect of Temperature and Composition on Spinel Concentration and Crystal Size in High-Level Waste Glass

2001 ◽  
Author(s):  
Martin Mika ◽  
Milan Patek ◽  
Jaroslav Maixner ◽  
Simona Randakova ◽  
Pavel Hrma
Keyword(s):  
Crystal Size ◽  
Equilibrium Concentration ◽  
Effect Of Temperature ◽  
High Level Waste ◽  
Huge Number ◽  
Aluminoborosilicate Glass ◽  
High Level ◽  
The Cost ◽  
Different Content ◽  
The Mathematical Model

Abstract High-level radioactive wastes can be safely immobilized in alkali-aluminoborosilicate glass. To reduce the cost of the vitrification process, the waste loading should be maximized. This can be done by optimizing the process using mathematical modeling. The main objective of our work was to determine one of the necessary inputs for the mathematical model, which is the effect of temperature and composition on the concentration of spinel crystals and their size. We prepared six glasses with a different content of Li+, Na+, Mg2+, Ni2+, Cr3+, and SiIV and studied the effect of composition on the temperature dependence of spinel equilibrium concentration in glass by X-ray powder diffraction. The size of crystals was determined using optical microscopy. It was found that the temperature effect on spinel concentration significantly increased as the content of Ni2+ or Mg2+ in glass increased and slightly decreased as the content of Cr3+ increased and Li+ and Na+ content decreased. Both Ni2+ and Cr3+ acted as nucleating agents, producing a huge number of tiny spinel crystals (∼2 μm). In particular, Ni2+ seems to very significantly facilitate spinel crystallization.

Highly dispersed molybdenum carbide nanoparticles supported on activated carbon as an efficient catalyst for the hydrodeoxygenation of vanillin

RSC Advances ◽  
2015 ◽  
Vol 5 (54) ◽  
pp. 43141-43147 ◽  
Author(s):  
Lili He ◽  
Yu Qin ◽  
Hui Lou ◽  
Ping Chen
Keyword(s):  
Activated Carbon ◽  
Molybdenum Carbide ◽  
Efficient Catalyst ◽  
Highly Dispersed ◽  
Xrd And Tem

Characterized by XRD and TEM, highly dispersed molybdenum carbide (Mo2C) nanoparticles with a diameter of 1–4 nm were effectively synthesized on activated carbon at 700 °C.

Direct Synthesis of Al-B-SBA-15 and its Application in Рreparing of Bifunctional Platinum Catalyst for Hydrogenation of Tetralin

2018 ◽  
Vol 18 (5) ◽  
pp. 31-36
Author(s):  
Ngo Thi Thanh Hien ◽  
Pham Trung Kien ◽  
Nguyen Anh Vu ◽  
Pham Thanh Huyen
Keyword(s):  
Mesoporous Material ◽  
Hydrogen Pressure ◽  
Platinum Catalyst ◽  
Direct Synthesis ◽  
Synthesis Method ◽  
Nitrogen Adsorption ◽  
Bifunctional Catalyst ◽  
Adsorption Desorption

In this work, the mesoporous material Al-B-SBA-15 has been obtained by direct synthesis method with Si : B : Al ratio of 10 : 0.5 : 0.5. Wetness impregnation (WI) method was used to load platinum on Al-B-SBA-15. The prepared support and catalyst were characterized by nitrogen adsorption-desorption measurement (BET), XRD, TEM, and TPD-NH3 to investigate the influence of aluminium and boron on characteristics of the catalyst. The activity of the bifunctional catalyst was tested for hydrogenation of tetralin at 180–220 °C, hydrogen pressure of 1.5–2.5 MPa for 3 h.

scholarly journals Kinetics of NiO and NiCl2Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3and Ni-Pd/Al2O3Catalysts

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Miroslav Sokić ◽  
Željko Kamberović ◽  
Vesna Nikolić ◽  
Branislav Marković ◽  
Marija Korać ◽  
...  
Keyword(s):  
Metal Content ◽  
Hydrogen Reduction ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Reduction Temperature ◽  
Time Intervals ◽  
Reduction Processes ◽  
Calcination Step ◽  
Before And After ◽  
Kinetics Of

The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3catalysts. The effect of temperature and time on NiO and NiCl2reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K.

Cu nanoclusters supported on nanocrystalline SiO2–MnO2: a bifunctional catalyst for the one-step conversion of glycerol to acrylic acid

2014 ◽  
Vol 50 (68) ◽  
pp. 9707-9710 ◽  
Author(s):  
Bipul Sarkar ◽  
Chandrashekar Pendem ◽  
L. N. Sivakumar Konathala ◽  
Ritesh Tiwari ◽  
Takehiko Sasaki ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Bifunctional Catalyst ◽  
Highly Dispersed ◽  
One Step ◽  
The One ◽  
Cu Nanoclusters

A material of highly dispersed Cu nanoclusters anchored on nanocrystalline SiO2–MnO2 has been prepared, and was found to act as a bifunctional catalyst for the one-step conversion of glycerol to acrylic acid using H2O2.

scholarly journals Combined synthesis and hydroprocessing on a cobalt catalyst on a cobalt-containing zeolite catalyst

2019 ◽  
Vol 80 (4) ◽  
pp. 304-311
Author(s):  
R. E. Yakovenko ◽  
I. N. Zubkov ◽  
S. V. Nekroenko ◽  
O. P. Papeta
Keyword(s):  
Synthesis Gas ◽  
Gas Flow ◽  
Bifunctional Catalyst ◽  
Gasoline Fraction ◽  
Chain Growth ◽  
Stable Operation ◽  
One Step ◽  
Physicochemical Methods ◽  
Branched Structure ◽  
Diesel Fractions

A composite Co-Al2O3/SiO2/HZSM-5 catalyst has been developed for one-step synthesis of fuel series hydrocarbons from CO and H2. The catalyst was obtained by mixing and forming powders with a Co-Al2O3/SiO2 catalyst, zeolite HZSM-5, and boehmite Al(O)OH?H2O. The physicochemical methods XRD, PEM, BET established the phase composition of the catalyst, the particle size of cobalt (8.2 ± 1 nm), its specific surface area (286 m2/g). Tests were carried out in the synthesis of hydrocarbons from CO and H2 for 60 hours at a temperature of 240 ° C, a pressure of 2.0 MPa, and a gas flow rate of 1000 h-1. It is shown that synthesis gas diluted by 40% with nitrogen can produce liquid C5+ hydrocarbons with a selectivity of 69% and a productivity of 81 kg/(m3?h). The yield of С5+ hydrocarbons was 70 g/m3 of the leaked synthesis gas and 135 g/m3 of the converted synthesis gas. Synthetic oil has a molecular mass distribution close to monomodal (the probability of chain growth is 0.81), 88% consists of gasoline and diesel fractions and 12% of long-chain C19+ hydrocarbons. The ratio of isomeric hydrocarbons to normal hydrocarbons (iso/n) is 1,26, and the ratio of olefinic hydrocarbons to paraffinic hydrocarbons is 0,97. In the gasoline fraction of hydrocarbons (C5-C10), a high content of alkenes of normal and branched structure (76,3%) is noted, the proportion of iso-alkanes and n-alkanes is 10,8 and 12,9%, respectively. The catalyst showed stable operation, the rate of its deactivation is comparable to the rate of deactivation of a commercial bifunctional catalyst.

Modified Vermiculites Study by Various Physicochemical Methods

2015 ◽  
Vol 752-753 ◽  
pp. 257-262 ◽  
Author(s):  
N.P. Shapkin ◽  
V.I. Razov ◽  
I.G. Khalchenko ◽  
V.I. Mayorov ◽  
A.L. Shkuratov ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Acid Concentration ◽  
Apparent Density ◽  
Brilliant Green ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Positron Annihilation Lifetime ◽  
Maximum Sorption ◽  
Physicochemical Methods ◽  
Internal Volume

Kovdor (Karelia) deposite vermiculites modified by acid of different concentrations and chitosan were studied using positron annihilation lifetime spectroscopy, measuring apparent density, dye adsorption, nitrogen adsorption by BET and porometry. It has been shown that after acidizing vermiculite density changes comparing to the samples’ density depending on the acid concentration. The density increases with the increasing acid concentration. Internal volume of the micropores and the value of maximum sorption of brilliant green change directly proportional to the density of the modified vermiculite.

scholarly journals Structure, Texture and Catalytic Properties of Pd/SiO2 Catalysts

1996 ◽  
Vol 13 (5) ◽  
pp. 423-431 ◽  
Author(s):  
S.A. El-Hakam ◽  
Awad I. Ahmed ◽  
S.M. Hassan ◽  
H.M. Farage
Keyword(s):  
Active Site ◽  
Metal Content ◽  
Catalytic Properties ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
X Ray ◽  
Surface Areas ◽  
Dehydrogenation Of Cyclohexane ◽  
Adsorption Surface ◽  
Kinetics Of

The structural properties of Pd/silica catalysts have been investigated by means of DTA and X-ray techniques. The X-ray results indicate that Pd metal is the only phase formed. The textural properties were determined using low-temperature nitrogen adsorption. Surface areas were calculated and the dependence of the surface area on the metal content has been discussed. Pore structure analyses indicate the presence of both micro-and meso-pores. The dehydrogenation of cyclohexane was found to be affected by the metal content. The active site for the dehydrogenation process on Pd/silica catalysts consists of one Pd atom. The kinetics of the dehydrogenation exhibit a fractional order.

Thermo-Decomposition Process of Preparation of Nanometer Cobalt Ferrite Oxides and their Doped into Peg-20000

2010 ◽  
Vol 148-149 ◽  
pp. 1254-1257
Author(s):  
Li Xiao ◽  
Guan Zhou Qiu ◽  
Le Xian Xia ◽  
Han Chen
Keyword(s):  
Magnetic Particles ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Average Diameter ◽  
Decomposition Process ◽  
Effect Of Temperature ◽  
Decomposition Stage ◽  
Oxide Powders ◽  
The Difference ◽  
Xrd And Tem

The sol-gel method was used to prepare three kinds of nanometer magnetic particles, the nano-cobalt ferrite oxide powders and those doped by LaCl3.nH2O with different ratio. In the thermo-decomposition process of the precursors to get these magnetic particles, TG/DTG was applied for investigating their character. It has been showed that the difference of the activation energies of these particles in different thermo-decomposition stage, even not in the same stage for different sample. XRD was used to analysis the effect of temperature on precursor of CoFe2O4. It has been showed that the prepared magnetic particles with the average diameter less than 100nm were characterized by XRD and TEM. To study nano-magnetic particles and polymer electrolyte compounds, the three kinds of nanometer magnetic particles were doped into polyethylene glycol-20000 (peg-20000) with different rations respectively to obtain the compound substance with optimal conductivity, 0.686 S.m-1.

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