scholarly journals Liquid-Phase Hydrodeoxygenation of Guaiacol over Mo2C Supported on Commercial CNF. Effects of Operating Conditions on Conversion and Product Selectivity

Catalysts ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 127 ◽  
Author(s):  
Rui Moreira ◽  
Elba Ochoa ◽  
José Pinilla ◽  
António Portugal ◽  
Isabel Suelves
Keyword(s):  
Xrd Analysis ◽  
Operating Conditions ◽  
Reaction Pathways ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Commercial Carbon ◽  
Major Reaction ◽  
Spent Catalysts ◽  
Temperature And Pressure ◽  
Mo2c Catalyst

In this work, a Mo2C catalyst that was supported on commercial carbon nanofibers (CNF) was synthetized and tested in the hydrodeoxygenation (HDO) of guaiacol. The effects of operating conditions (temperature and pressure) and reaction time (2 and 4 h) on the conversion of guaiacol and products selectivity were studied. The major reaction products were cresol and phenol, followed by xylenols and toluene. The use of more severe operating conditions during the HDO of guaiacol caused a diversification in the reaction pathways, and consequently in the selectivity to products. The formation of phenol may have occurred by demethylation of guaiacol, followed by dehydroxylation of catechol, together with other reaction pathways, including direct guaiacol demethoxylation, and demethylation of cresols. X-ray diffraction (XRD) analysis of spent catalysts did not reveal any significant changes as compared to the fresh catalyst.

Research on the Thermal Decomposition Process of K-Feldspar-CaSO4-CaO System

2013 ◽  
Vol 734-737 ◽  
pp. 916-920 ◽  
Author(s):  
Jing Xia Chao ◽  
Ju Pei Xia ◽  
Chao Qin Yang ◽  
Zhao Shu Zhang ◽  
Xue Jiao Ren
Keyword(s):  
Thermal Decomposition ◽  
Calcium Sulfate ◽  
Xrd Analysis ◽  
Operating Conditions ◽  
Decomposition Process ◽  
Complex Reaction ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray

The thermal decomposition process of K-feldspar-CaSO4-CaO system was studied by X-ray diffraction (XRD) analysis of the product which calcined at 1473K. The results show that KAlSi3O8 firstly is decomposed into KAlSi2O6 and released the SiO2, then has a complex reaction between KAlSi2O6 and CaO, which generated intermediates-K2SiO3 under the operating conditions. K2SiO3 is unstable and reacted with calcium sulfate to generate K2SO4. When the CaO amount is insufficient, the main products are KAlSi2O6 and 2CaOAl2O3SiO2, the potassium existed as K2S2O8; when n (CaO) / n (KAS6) 12:1, the products will further transfer into CaOSiO2 and 2CaO SiO2 and the potassium existed as K2SO4.

Aluminothermic Reduction of Niobium Pentoxide in a Hydrogen Plasma Furnace

2006 ◽  
Vol 514-516 ◽  
pp. 599-603
Author(s):  
Marcio W.D. Mendes ◽  
António Carlos P. Santos ◽  
Francisca de Fatima P. Medeiros ◽  
Clodomiro Alves Jr. ◽  
A.G.P. Silva ◽  
...  
Keyword(s):  
Hydrogen Plasma ◽  
Xrd Analysis ◽  
High Energy ◽  
Steel Tube ◽  
Aluminothermic Reduction ◽  
Powder Layer ◽  
Stainless Steel Tube ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
New Process

The aluminothermic reduction is a highly exothermal reaction between a metal oxide and aluminium. Conventionally this reaction is ignited by an electric resistance and the reaction products after cooling are in the form of a rigid block of mixed metal and aluminium oxide. In this work a new process of aluminothermic reduction is presented, in which the reaction is ignited by a hydrogen plasma. The niobium oxide and aluminium powders are high energy milled for six hours to form particles constituted of oxide and aluminum. Stoichiometric, substoichiometric and superstoichiometric mixtures were prepared. The mixture was placed in a stainless steel tube (the hollow cathode) inside the reactor chamber. The chamber was firstly evacuated. Then hydrogen at low pressure was introduced. In the following an electric discharge between the cathode and the anode localized just above the cathode ignites the plasma. The plasma heats the particles on the surface of the powder layer and starts the reaction that proceeds in each particle since the reactants are intimately mixed. The heat generated by the reaction propagates deeper in the layer until the whole mixture reacts. Substoichiometric mixtures can be used because hydrogen takes part of the reduction. The Nb2O5 – Al starting powder mixture and the products of the reaction are characterized by laser grain size measurement and X-Ray diffraction (XRD). The products are in form of powder or agglomerates of particles. Phases of reaction products was determined by XRD analysis and the particle size trough SEM.

Preparation of CuO/γ-Al2O3 Catalysts by Impregnationin Supercritical CO2

2011 ◽  
Vol 396-398 ◽  
pp. 1313-1317
Author(s):  
Li Min Li ◽  
San Kui Xu ◽  
Xiao Dong Wang ◽  
Nan Nan Guo ◽  
Yun Lai Su ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Xrd Analysis ◽  
Catalyst Preparation ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impregnation Time ◽  
Temperature And Pressure ◽  
Organometallic Precursors ◽  
Adsorption Quantity

CuO/γ-Al2O3 catalysts were prepared by supercritical CO2 (SC-CO2) impregnation method. The preparation was carried out in SC-CO2 with Cu(NO3)2 as precursor, methanol as assistant solvent, and γ-Al2O3 as support. The effects of impregnation parameters such as temperature and pressure of SC-CO2, impregnation time, ratio of precursor to support, and amount of assistant solvent on catalyst preparation were investigated. The as-prepared catalysts were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis and compared to that prepared by the conventional impregnation method. The SC-CO2 impregnation method provided higher adsorption rate, larger adsorption quantity, more homogeneous dispersion of precursor, and stronger interaction between precursor and support. The catalytic degradation of methylene blue (MB) was used as probe reaction to estimate the catalytic activity of two catalysts prepared by two methods. The catalyst prepared by SC-CO2 impregnation method exhibits significantly improved catalytic activity. These results show that the inorganic metallic reagents as precursor with assistant solvent can be used as an alternative for the organometallic precursors in SC-CO2 impregnation method.

Influences of thermal annealing and humidity exposure on surface structure of (100) single-crystal MgO substrate

1999 ◽  
Vol 14 (5) ◽  
pp. 2133-2137 ◽  
Author(s):  
M. P. Delplancke-Ogletree ◽  
M. Ye ◽  
R. Winand ◽  
J. F. de Marneffe ◽  
R. Deltour
Keyword(s):  
Surface Structure ◽  
Thermal Annealing ◽  
Substrate Surface ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Evaporation And Condensation ◽  
Atomic Force ◽  
Major Reaction Product ◽  
Major Reaction

We studied the influence of thermal annealing on the surface structure of (100) singlecrystal MgO substrates by atomic force microscopy (AFM). By annealing MgO substrates at various temperatures for 4 h in flowing oxygen, we showed that the surface reconstruction could be explained by considering surface diffusion, surface evaporation, and condensation. At an annealing temperature of 1473 K, a stepped structure was formed with screw dislocations acting as step sources. The influence of humidity on the surface morphology of MgO substrates was also studied by exposing them to a constant humidity of 40 and 80% for different times. After an exposure time of 1.5 h in 80% humidity, the substrate surface was already covered by reaction products. For the 40% humidity, the corresponding time is 10 h. The major reaction product was identified as Mg(OH)2 by x-ray diffraction.

Functionalized Silicate Supported TiO2-ZnO Nanocomposite Film and its Application in Simultaneous Photocatalytic Degradation of Toxic Molecules

2013 ◽  
Vol 764 ◽  
pp. 255-265 ◽  
Author(s):  
R. Dhanalakshmi ◽  
A. Pandikumar ◽  
R. Ramaraj
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Potential Candidate ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Molar Ratios ◽  
Amine Functionalized ◽  
Transmission Electron

The TiO2-ZnO nanocomposite materials ((TiO2-ZnO)NCM) with different molar ratios (Ti:Zn) was synthesized by chemical route and dispersed in functionalized silicate sol-gel matrix (Silicate/(TiO2-ZnO)NCM)). The as prepared Silicate/(TiO2-ZnO)NCM were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The dispersion of the small amount of (TiO2-ZnO)NCM in silicate sol-gel matrix paves the way for the preparation of solid-state thin film photocatalyst which is advantageous for the separation of the catalyst from solution, the substrates and the reaction products. The simultaneous photoinduced oxidation of methylene blue (MB) dye and reduction of Cr (VI) to Cr (III) was examined at different amine functionalized silicate sol-gel embedded (TiO2-ZnO)NCM films. The (TiO2-ZnO)NCM dispersed into the amine functionalized silicate sol-gel matrix (TPDT) exhibited enhanced photocatalytic activity when compared to the (TiO2-ZnO)NCM without the silicate sol-gel. The functionalized silicate sol-gel supported (TiO2-ZnO)NCM is a potential candidate for energy conversion and environment remediation and cleaning applications.

Preparation of Chrysotile Nanotubes under Hydrothermal Condition

2011 ◽  
Vol 284-286 ◽  
pp. 688-691 ◽  
Author(s):  
Yang Feng Huang ◽  
Ye Bin Cai ◽  
Hao Liu
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Condition ◽  
Xrd Analysis ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Inner Diameter ◽  
Temperature And Pressure

In a neutral environment, Chrysotile nanotubes have been synthesized by hydrothermal method, with MgO and SiO2powder as the starting materials. X-Ray Diffraction(XRD), Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM) are used to characterize the crystal structure and morphology of the as-prepared samples. We found that the diameter of Chrysotile is uniform. Their outer diameter is about 30~50 nm and the inner diameter is about 6~8 nm. The length of them is a few hundred nanometers. The XRD analysis indicates that the as-prepared Chrysotile is a Rhombohedral structures. The results of HRTEM and SAED showed that the {006} planes of serpentine roll up along the [600] direction to form the tubular structure. In addition, the curves of temperature and pressure with time showed that the water might participate in the reaction.

Transient X-ray Diffraction Reveals Global and Major Reaction Pathways for the Photolysis of Iodoform in Solution

2008 ◽  
Vol 120 (6) ◽  
pp. 1063-1066 ◽  
Author(s):  
Jae Hyuk Lee ◽  
Joonghan Kim ◽  
Marco Cammarata ◽  
Qingyu Kong ◽  
Kyung Hwan Kim ◽  
...  
Keyword(s):  
Reaction Pathways ◽  
X Ray Diffraction ◽  
X Ray ◽  
Major Reaction

scholarly journals Characterization and Comparative Performance of TiO2 Photocatalysts on 6-Mercaptopurine Degradation by Solar Heterogeneous Photocatalysis

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 118 ◽  
Author(s):  
Luis A. González-Burciaga ◽  
Cynthia M. Núñez-Núñez ◽  
Miriam M. Morones-Esquivel ◽  
Manuel Avila-Santos ◽  
Adela Lemus-Santana ◽  
...  
Keyword(s):  
Band Gap ◽  
Anatase Phase ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Heterogeneous Photocatalysis ◽  
Operating Conditions ◽  
X Ray Diffraction ◽  
Comparative Performance ◽  
Tio2 Photocatalysts ◽  
Ph Conditions

The crystallographic properties of two titanium dioxide (TiO2) photocatalysts, P25, and commercial C1-TiO2 reactive grade, were analyzed by X-ray diffraction (XRD) and the band-gap was calculated with UV–Vis spectrometry with integration sphere. Then, their performance was tested in the degradation of 6-mercaptopurine (6-MP) by heterogeneous photocatalysis with solar radiation under different pH conditions and the addition of hydrogen peroxide (H2O2); the degradation efficiency was monitored by UV–Vis spectrophotometry. The XRD analysis showed that both photocatalysts studied have anatase phase, while only P25 contains rutile; the band gap values were lower, in both catalysts, than those reported for catalysts obtained by the sol-gel method. With both photocatalysts, degradation experiments showed efficiency greater than 98% in experiments in the presence of H2O2 regardless of pH. The properties of the photocatalysts, along with the data obtained from the experimentation, helped determine the best semiconductor for the degradation of 6-MP with these operating conditions in this work.

Transient X-ray Diffraction Reveals Global and Major Reaction Pathways for the Photolysis of Iodoform in Solution

2008 ◽  
Vol 47 (6) ◽  
pp. 1047-1050 ◽  
Author(s):  
Jae Hyuk Lee ◽  
Joonghan Kim ◽  
Marco Cammarata ◽  
Qingyu Kong ◽  
Kyung Hwan Kim ◽  
...  
Keyword(s):  
Reaction Pathways ◽  
X Ray Diffraction ◽  
X Ray ◽  
Major Reaction

Sphalerite oxidation by Thiobacillus fertooxidans and Thiobacillus thiooxidans

1995 ◽  
Vol 41 (7) ◽  
pp. 578-584 ◽  
Author(s):  
Oswaldo Garcia Jr. ◽  
Jerry M. Bigham ◽  
Olii H. Tuovinen
Keyword(s):  
Thiobacillus Ferrooxidans ◽  
Solid Phase ◽  
Sulfide Oxidation ◽  
Xrd Analysis ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Thiobacillus Thiooxidans ◽  
X Ray

Sphalerite (ZnS) oxidation was monitored in Thiobacillus ferrooxidans and Thiobacillus thiooxidans cultures and in abiotic controls by X-ray diffraction (XRD) analysis of solid phases and by chemical analysis of solution composition. X-ray diffraction data revealed no solid-phase reaction products in unsupplemented sphalerite media, whereas minor amounts of S0 accumulated in FeSC4-amended sphalerite media with or without T. ferrooxidans inoculum. Jarosite ((K,Na,H3O,NH4)Fe3(SO4)2(OH)6) also precipitated in the amended T. ferrooxidans cultures. When sphalerite media inoculated with T. thiooxidans were amended with S0, acid production was enhanced, decreasing the pH to 1.1, but Zn dissolution was not accelerated. By comparison with T. thiooxidans, T. ferrooxidans was more efficient in the oxidation of sphalerite.Key words: bioleaching of sphalerite, sphalerite oxidation, Thiobacillus ferrooxidans, Thiobacillus thiooxidans, zinc sulfide oxidation.

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