scholarly journals Bi-Functional Catalyst/Sorbent for a H2-Rich Gas from Biomass Gasification

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1249
Author(s):  
Francesca Micheli ◽  
Enrica Mattucci ◽  
Claire Courson ◽  
Katia Gallucci
Keyword(s):  
High Temperature ◽  
Functional Materials ◽  
Active Phase ◽  
Biomass Gasification ◽  
X Ray Diffraction ◽  
Solid Sorbents ◽  
Co2 Sorbent ◽  
Mixing Method ◽  
Temperature Programmed ◽  
Sorption Study

The aim of this work is to identify the effect of the CaO phase as a CO2 sorbent and mayenite (Ca12Al14O33) as a stabilizing phase in a bi-functional material for CO2 capture in biomass syngas conditioning and cleaning at high temperature. The effect of different CaO weight contents is studied (0, 56, 85, 100 wt%) in sorbents synthesized by the wet mixing method. These high temperature solid sorbents are upgraded to bi-functional compounds by the addition of 3 or 6 wt% of nickel chosen as the metal active phase. N2 adsorption, X-ray diffraction, scanning electronic microscopy, temperature-programmed reduction analyses and CO2 sorption study were performed to characterize structural, textural, reducibility and sorption properties of bi-functional materials. Finally, sorption-enhanced reforming of toluene (chosen as tar model), of methane then of methane and toluene with bi-functional compounds were performed to study the best material to improve H2 content in a syngas, provided by steam biomass gasification. If the catalytic activity on the sorption enhanced reforming of methane exhibits a fast fall-down after 10–15 min of experimental test, the reforming of toluene reaches a constant conversion of 99.9% by using bi-functional materials.

scholarly journals Effect of High Pressure on the Reducibility and Dispersion of the Active Phase of Fischer–Tropsch Catalysts

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1915 ◽  
Author(s):  
Simón Yunes ◽  
Miguel Ángel Vicente ◽  
Sophia A. Korili ◽  
Antonio Gil
Keyword(s):  
High Pressure ◽  
Physicochemical Characterization ◽  
Active Phase ◽  
Incipient Wetness Impregnation ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

The effect of high pressure on the reducibility and dispersion of oxides of Co and Fe supported on γ-Al2O3, SiO2, and TiO2 has been studied. The catalysts, having a nominal metal content of 10 wt.%, were prepared by incipient wetness impregnation of previously calcined supports. After drying at 60 °C for 6 h and calcination at 500 °C for 4 h, the catalysts were reduced by hydrogen at two pressures, 1 and 25 bar. The metal reduction was studied by temperature-programmed reduction up to 750 °C at the two pressures, and the metal dispersion was measured by CO chemisorption at 25 °C, obtaining values between 1% and 8%. The physicochemical characterization of these materials was completed by means of chemical analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and scanning electron microscopy. The high pressure lowered the reduction temperature of the metal oxides, improving their reducibility and dispersion. The metal reducibility increased from 42%, in the case of Fe/Al2O3 (1 bar), to 100%, in the case of Fe/TiO2 (25 bar).

Basicity and Crystal Phase of Mesoporous K2O-MgO/ZrO2-La2O3 Catalyst

2014 ◽  
Vol 924 ◽  
pp. 269-274
Author(s):  
Yu Su ◽  
Guo Jun Dong ◽  
Cheng Yuan Wang ◽  
Jin Sheng Gao ◽  
Dong Sheng Ma ◽  
...  
Keyword(s):  
High Temperature ◽  
Monoclinic Phase ◽  
Dimethyl Carbonate ◽  
Catalyst Surface ◽  
Temperature Programmed Desorption ◽  
Solid Base ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

A new solid base, mesoporous K2O-MgO/ZrO2-La2O3, was prepared by hydrothermal and immersion process using a cationic surfactant C16H33(CH3)3NBr (CTAB) as template．The samples were characterized by N2 adsorption-desorption, X-ray diffraction(XRD), Raman spectroscope and CO2 temperature programmed desorption(CO2-TPD). XRD and Raman spectra indicated that the catalyst calcined at 600°C and 700 °C remained surface and bulk tetragonal phase and good mesoporous characteristics when the content of K2O is less than 0.5. While the monoclinic phase is appeared on catalyst surface when the content of K2O is more than 0.5 calcined at 700 °C. CO2-TPD proves that there are two adsorption states at high temperature corresponding to super alkaline sites of K2O and undecomposed KNO3. The catalyst with 0.4 mol ratio of K2O to ZrO2 calcined at 700 °C showed higher activity in the synthesis of di-2-ethylhexyl carbonate (DEHC) from dimethyl carbonate (DMC) and 2-ethylhexanol (EHOH).

scholarly journals Promotional Effect on Selective Catalytic Reduction of NOxwith NH3over Overloaded W and Ce on V2O5/TiO2Catalysts

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Seunghee Youn ◽  
Inhak Song ◽  
Do Heui Kim
Keyword(s):  
High Temperature ◽  
Selective Catalytic Reduction ◽  
Temperature Region ◽  
Catalytic Reduction ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
High Temperature Region ◽  
Promotional Effect ◽  
Temperature Programmed ◽  
Adsorption Desorption

W and Ce are known to be a good promoters to improve selective catalytic reduction (SCR) activity for V2O5/TiO2catalysts. This work aimed at finding the optimum ratio and loading of promoters (W and Ce) on V2O5/TiO2catalyst in order to improve SCR reactivity in low temperature region and to minimize N2O formation in high temperature region. In addition, we changed the order of impregnation between W and Ce precursors on V2O5/TiO2catalyst during the preparation and observed its effect on SCR activity and N2selectivity. We utilized various analytical techniques, such as N2adsorption-desorption, X-ray diffraction (XRD), and temperature-programmed reduction with hydrogen (H2TPR) to investigate the physicochemical properties of catalysts. It was found that W- and Ce-overloaded V2O5/TiO2catalyst such as W/Ce/V/TiO2(15 : 15 : 1 wt%) showed the most remarkable DeNOxproperties over the wide temperature region. Additionally, this catalyst significantly suppressed N2O formation during SCR reaction, especially in high temperature region (350–400°C). Based on the characterization results, it was found that such superior activity originated from the improved reducibility and morphology of W and Ce species on V2O5/TiO2catalyst when they are incorporated together at high loading.

High temperature X-ray diffraction investigation of an aluminium-silicon-corundum system

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 369-374 ◽  
Author(s):  
D. Garipoli ◽  
P. Bergese ◽  
E. Bontempi ◽  
M. Minicucci ◽  
A. Di Cicco ◽  
...  
Keyword(s):  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

scholarly journals Regenerable Sorbents for High‐Temperature Desulfurization of Syngas from Biomass Gasification

2021 ◽  
Author(s):  
Jianyu Ma ◽  
Mehdi Mahmoodinia ◽  
Kumar R. Rout ◽  
Edd A. Blekkan
Keyword(s):  
High Temperature ◽  
Biomass Gasification
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