Protection of rhodium/alumina catalysts by potassium functionalization of the alumina support

1991 ◽  
Vol 95 (10) ◽  
pp. 4028-4033 ◽  
Author(s):  
Mohamed I. Zaki ◽  
Todd H. Ballinger ◽  
John T. Yates
Keyword(s):  
Alumina Support ◽  
Alumina Catalysts

Vapor Phase Catalytic Transformations of Terpene Hydrocarbons in the C10H16 Series. II. Aromatization of α-Pinene over Chromia–Alumina

1972 ◽  
Vol 50 (1) ◽  
pp. 113-118 ◽  
Author(s):  
A. Stanislaus ◽  
L. M. Yeddanapalli
Keyword(s):  
Vapor Phase ◽  
Alumina Support ◽  
Pure Alumina ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The aromatization of α-pinene in the vapor phase over chromia gel and chromia–alumina catalysts prepared from aluminas of different acidity has been studied. The acidity of alumina support has a remarkable influence on the composition of the aromatics resulting from the dehydrogenation of α-pinene. Over weakly acidic chromia–alumina doped with 1% sodium catalyst, α-pinene is aromatized to p-cymene, 1,2,4- and 1,2,3-trimethylbenzenes with traces of toluene and xylenes, whereas over the strongly acidic chromia – pure alumina and chromia–alumina containing 5% HF catalysts it gives considerable amount of m-cymene, toluene, and tetramethylbenzenes. A satisfactory mechanism to explain the formation of these compounds is offered.

Hydrogen production via surrogate biomass gasification using 5% Ni and low loading of lanthanum co-impregnated on fluidizable γ-alumina catalysts

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Adriana Sánchez Enríquez ◽  
Daniel G. González Castañeda ◽  
Alan R. Calzada Hernández ◽  
Ivan Cruz Reyes ◽  
Benito Serrano Rosales
Keyword(s):  
Hydrogen Production ◽  
Reaction Time Data ◽  
Favorable Effect ◽  
Time Data ◽  
Alumina Support ◽  
Recent Contribution ◽  
Catalytic Gasification ◽  
Crystallite Sizes ◽  
Analysis Package ◽  
Alumina Catalysts

AbstractNickel on alumina support offers opportunity for gasification of biomass for hydrogen production. In a recent contribution from our research team, (González Castañeda, D. G., et al. 2019) showed that cerium or lanthanum co-impregnation at 2 wt% with nickel may have a favorable effect for biomass catalytic gasification. However, and given an observed influence of lanthanum on the formation of small Ni crystallite sizes, five Ni/γ-Al2O3 based fluidizable La promoted catalysts were studied. Nickel-alumina catalysts promotion was effected varying La in the 0.5 and 1.0 wt% range. Once impregnation precursors loaded, they were reduced at 480 °C via an activation step. Catalysts were characterized using BET, XRD, AA, TPR, TPD, H2-chemisorption, TEM-EDX and FTIR. Catalyst performance was established in a fluidized CREC Riser Simulator, using: a) glucose as surrogate biomass, b) 600 °C, c) steam/biomass (S/B) ratio of 1, d) catalyst /biomass (C/B) ratio of 3.2 and e) 20 s reaction time. Data obtained was analyzed using an ANOVA statistical data analysis package with the 5 wt% Ni and 0.5–1 wt% La and Ce on γ-Al2O3 catalysts, prepared using a pH of 1 of impregnating solution were the best yielding 0.53–0.56 hydrogen molar fractions. These catalysts also gave a 39% reduced coke, and this while compared with the coke formed on the 2% Ce – 5 wt%Ni/γ-Al2O3 (González Castañeda, D. G., et al. 2019). This promising performance was assigned to the dominant NH3-TPD medium acidity, the high catalyst specific surface (∼140 m2/g), and the good 9% metal dispersion with 9–10 nm nickel crystallites.

The role of alumina support in the deoxygenation of rapeseed oil over NiMo–alumina catalysts

2011 ◽  
Vol 176 (1) ◽  
pp. 409-412 ◽  
Author(s):  
Peter Priecel ◽  
Libor Čapek ◽  
David Kubička ◽  
František Homola ◽  
Petr Ryšánek ◽  
...  
Keyword(s):  
Rapeseed Oil ◽  
Alumina Support ◽  
Alumina Catalysts

The effect of composition of cobalt-molybdenum catalysts on their surface acidity and isomerisation activity

1980 ◽  
Vol 45 (3) ◽  
pp. 697-702 ◽  
Author(s):  
Vlastimil Vyskočil ◽  
Miroslav Zdražil
Keyword(s):  
Chromatographic Method ◽  
Surface Acidity ◽  
Parallel Reaction ◽  
Molybdenum Catalysts ◽  
The Difference ◽  
Kinetics Of ◽  
Alumina Catalysts

Kinetics of isomerisation of cyclohexene to methylcyclopentene proceeding as parallel reaction to hydrogenation of cyclohexene to cyclohexane on cobalt-molybdenum catalysts of different composition has been measured. The surface acidity of these catalysts was estimated from the difference in the adsorption of toluene and heptane which was measured by chromatographic method. In a series of catalysts containing molybdenum the acidity parallels isomerisation activity. Cobalt on alumina catalysts and alumina itself have greater acidity but exhibit lower isomerisation activity compared to the catalysts containing molybdenum.

scholarly journals Influence of Alumina Precursor Properties on Cu-Fe Alumina Supported Catalysts for Total Toluene Oxidation as a Model Volatile Organic Air Pollutant

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 252
Author(s):  
Tadej Žumbar ◽  
Alenka Ristić ◽  
Goran Dražić ◽  
Hristina Lazarova ◽  
Janez Volavšek ◽  
...  
Keyword(s):  
Surface Characterization ◽  
Iron Concentration ◽  
Catalytic Performance ◽  
Air Pollutant ◽  
Molar Ratio ◽  
Homogeneous Distribution ◽  
Total Oxidation ◽  
Alumina Support ◽  
Determining Factors ◽  
Volatile Organic

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al2O3 catalysts used for the total oxidation of toluene as a model volatile organic air pollutant is elucidated. Surface characterization of the catalysts revealed that the surface area, pore volume and acid site concentration of the alumina supports are important but not the determining factors for the catalytic activity of the studied catalysts for this type of reaction. The determining factors are the structural order of the support precursor, the homogeneous distribution of the catalytic sites and reducibility, which were elucidated by XRD, NMR, TEM and temperature programed reduction (TPR). Cu–Fe/Al2O3 prepared from bayerite and pseudoboehmite as highly ordered precursors showed better catalytic performance compared to Cu-Fe/Al2O3 derived from the amorphous alumina precursor and dawsonite. Homogeneous distribution of FexOy and CuOx with defined Cu/Fe molar ratio on the Al2O3 support is required for the efficient catalytic performance of the material. The study showed a beneficial effect of low iron concentration introduced into the alumina precursor during the alumina support synthesis procedure, which resulted in a homogeneous metal oxide distribution on the support.

ChemInform Abstract: RAMAN SPECTROSCOPIC STUDY OF COBALT-MOLYBDENUM Γ-ALUMINA CATALYSTS

1978 ◽  
Vol 9 (40) ◽  
Author(s):  
J. MEDEMA ◽  
C. VAN STAM ◽  
V. H. J. DE BEER ◽  
A. J. A. KONINGS ◽  
D. C. KONINGSBERGER
Keyword(s):  
Spectroscopic Study ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Alumina Catalysts

Effect of Fe and Co promoters on CO methanation activity of nickel catalyst prepared by impregnation – co-precipitation method

2020 ◽  
Vol 18 (5-6) ◽  
Author(s):  
Buyan-Ulzii Battulga ◽  
Tungalagtamir Bold ◽  
Enkhsaruul Byambajav
Keyword(s):  
Synergetic Effect ◽  
Space Velocity ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Alumina Support ◽  
Co Methanation ◽  
Temperature Range ◽  
Co Precipitation ◽  
Catalyst Distribution

AbstractNi based catalysts supported on γ-Al2O3 that was unpromoted (Ni/γAl2O3) or promoted (Ni–Fe/γAl2O3, Ni–Co/γAl2O3, and Ni–Fe–Co/γAl2O3) were prepared using by the impregnation – co-precipitation method. Their catalytic performances for CO methanation were studied at 3 atm with a weight hourly space velocity (WHSV) of 3000 ml/g/h of syngas with a molar ratio of H2/CO = 3 and in the temperature range between 130 and 350 °C. All promoters could improve nickel distribution, and decreased its particle sizes. It was found that the Ni–Co/γAl2O3 catalyst showed the highest catalytic performance for CO methanation in a low temperature range (<250 °C). The temperatures for the 20% CO conversion over Ni–Co/γAl2O3, Ni–Fe/γAl2O3, Ni–Fe–Co/γAl2O3 and Ni/γAl2O3 catalysts were 205, 253, 263 and 270 °C, respectively. The improved catalyst distribution by the addition of cobalt promoter caused the formation of β type nickel species which had an appropriate interacting strength with alumina support in the Ni–Co/γAl2O3. Though an addition of iron promoter improved catalyst distribution, the methane selectivity was lowered due to acceleration of both CO methanation and WGS reaction with the Ni–Fe/γAl2O3. Moreover, it was found that there was no synergetic effect from the binary Fe–Co promotors in the Ni–Fe–Co/γAl2O3 on catalytic activity for CO methanation.

Dimerization of Hexadecene with Acid Mesoporous Silica‐Alumina Catalysts

2021 ◽  
Author(s):  
Narendra Kumar ◽  
Marina Lindblad ◽  
Jaana Makkonen ◽  
Väinö Sippola ◽  
Heidi Österholm ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Silica Alumina ◽  
Alumina Catalysts

scholarly journals Template-free ZSM-5 membrane preparation on alumina support by secondary hydrothermal synthesis

2020 ◽  
pp. 100049
Author(s):  
Helena Schneider ◽  
Lucas K. Schindel ◽  
Lucas B. Gomes ◽  
Isabel C. Tessaro ◽  
Nilson R. Marcilio
Keyword(s):  
Hydrothermal Synthesis ◽  
Membrane Preparation ◽  
Alumina Support ◽  
Template Free
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