Comparison of MgO-supported Ni-Mo hydrodesulfurization catalysts prepared by impregnation and by precipitation-adsorption in emulsion

1991 ◽  
Vol 56 (3) ◽  
pp. 580-589 ◽  
Author(s):  
Vladimír Koloušek ◽  
Pavel Pálka ◽  
Eva Hillerová ◽  
Miroslav Zdražil
Keyword(s):  
Surface Area ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Indirect Evidence ◽  
Active Phase ◽  
Impregnation Method ◽  
Base Interaction ◽  
Chemical Surface ◽  
Supported Ni

Magnesia-supported Ni-Mo sulfide catalysts were prepared by several versions of aqueous impregnation method and by the unconventional method of precipitation-adsorption of sulfides in emulsion water-toluene. The activity of catalysts was tested in hydrodesulfurization of thiophene at pressure of 1.6 Mpa. The samples of Ni-Mo/MgO prepared by impregnation exhibited only 15 – 30% of the activity of Ni-Mo/Al2O3 catalysts Shell 324; the principle obstacle was found to be chemical and hydrothermal instability of MgO with high surface area. The activity of samples prepared by precipitation-adsorption was not much lower than that of the impregnated catalysts; this was taken as an indirect evidence of the acid-base interaction between sulfides and MgO surface. It was concluded that the course of low activity of Ni-Mo/MgO catalysts was textural and not chemical; surface area of Ni-Mo active phase in MgO-supported catalysts was supposed to be lower than in Al2O3-supported catalysts.

Metal Oxides (such as Al2O3 and TiO2) as Catalyst Supports for Hydrogen Release by Hydrolysis of Sodium Borohydride NaBH4

2010 ◽  
Vol 65 ◽  
pp. 209-214
Author(s):  
Ouardia Akdim ◽  
Umit Bilge Demirci ◽  
Philippe Miele
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Active Phase ◽  
Hydrogen Release ◽  
Catalytic Systems ◽  
Hydrolysis Of

Hydrolysis of NaBH4 to release molecular hydrogen is today an intensely investigated reaction and most of the studies focus on the material used as catalyst. Among the various metals tested up to now, cobalt has soon showed to be the most attractive in terms of reactivity and cost. Nevertheless, in order to further decrease its cost by decreasing its amount as well as to increase its reactivity, cobalt has been dispersed over supports. The as-formed supported catalysts have showed to be more efficient. This is the topic of the present study. Herein it is showed that CoCl2 supported over an Al2O3 support with a specific surface area of 180 m2 g-1 is more reactive than CoCl2 supported over a high-surface-area activated carbon (780 m2 g-1), CoCl2 being in-situ reduced into the Co-based active phase. CoCl2-Al2O3 is besides as reactive as another CoCl2-Al2O3 catalyst, the latter support having a higher specific surface area (i.e. 250 m2 g-1). In fact, CoCl2-Al2O3 is more performing than neat CoCl2 whereas the latter has been often showed as being one of the best catalytic systems. To further gain in reactivity, a new, alternative strategy has been envisaged. The Al2O3 was mixed together with a controlled amount of another oxide, namely TiO2. The CoCl2- Al2O3-TiO2(20 wt%) was found to be more reactive than CoCl2-Al2O3. All of these reactivity data are reported and briefly discussed hereafter. Further studies are in progress to highlight the reasons of such improved reactivity.

scholarly journals Multifunctional and Environmentally Friendly TiO2–SiO2 Mesoporous Materials for Sustainable Green Buildings

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4226
Author(s):  
Ghedini ◽  
Menegazzo ◽  
Manzoli ◽  
Di Michele ◽  
Puglia ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Environmentally Friendly ◽  
Green Building ◽  
Structural Features ◽  
Modulated Dsc ◽  
Synthetic Approach ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method

This work deals with the formulation of environmentally friendly, cheap, and readily-available materials for green building applications, providing the function of air purificator by improving the safety and the comfort of an indoor environment. High surface area TiO2–SiO2 samples, prepared by a simple, cost effective, and scalable synthetic approach, proved to be effective in maximizing the properties of each component, i.e., the photocatalytic properties of titania and the high surface area of silica. TiO2 was introduced onto an ordered mesoporous silica Santa Barbara Amorphous-15 (SBA-15), that is featured by interesting insulating features, by using an incipient wetness impregnation method. The photocatalytic activity was evaluated in gas phase oxidation of ethylbenzene, which was selected as model volatile organic compound (VOC) molecule. The morphological, textural and structural features along with the electronic properties, the hydrophilicity and heat capacity of the materials were investigated in depth by scanning electron microscopy, powder X-ray diffraction, N2 physisorption, diffuse reflectance UV-Vis, FT-IR spectroscopies, and modulated DSC (MDSC) dynamic scan. Outstanding performances in the ethylbenzene abatement results are promising for further application in the green building sector.

scholarly journals Ruthenium particle size and cesium promotion effects in Fischer–Tropsch synthesis over high-surface-area graphite supported catalysts

2017 ◽  
Vol 7 (5) ◽  
pp. 1235-1244 ◽  
Author(s):  
José L. Eslava ◽  
Xiaohui Sun ◽  
Jorge Gascon ◽  
Freek Kapteijn ◽  
Inmaculada Rodríguez-Ramos
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Tropsch Synthesis ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis

The effect of ruthenium particle size on Fischer–Tropsch synthesis has been studied at 513 K, H2/CO = 2 and 15 bar.

scholarly journals Synthesis of heterogeneous catalysts with well shaped platinum particles to control reaction selectivity

2008 ◽  
Vol 105 (40) ◽  
pp. 15241-15246 ◽  
Author(s):  
Ilkeun Lee ◽  
Ricardo Morales ◽  
Manuel A. Albiter ◽  
Francisco Zaera
Keyword(s):  
Surface Area ◽  
Heterogeneous Catalysts ◽  
Colloidal Particles ◽  
Supported Catalysts ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Metal Particles ◽  
Platinum Particles

Colloidal and sol-gel procedures have been used to prepare heterogeneous catalysts consisting of platinum metal particles with narrow size distributions and well defined shapes dispersed on high-surface-area silica supports. The overall procedure was developed in three stages. First, tetrahedral and cubic colloidal metal particles were prepared in solution by using a procedure derived from that reported by El-Sayed and coworkers [Ahmadi TS, Wang ZL, Green TC, Henglein A, El-Sayed MA (1996) Science 272:1924–1926]. This method allowed size and shape to be controlled independently. Next, the colloidal particles were dispersed onto high-surface-area solids. Three approaches were attempted: (i) in situ reduction of the colloidal mixture in the presence of the support, (ii) in situ sol-gel synthesis of the support in the presence of the colloidal particles, and (iii) direct impregnation of the particles onto the support. Finally, the resulting catalysts were activated and tested for the promotion of carbon–carbon double-bond cis-trans isomerization reactions in olefins. Our results indicate that the selectivity of the reaction may be controlled by using supported catalysts with appropriate metal particle shapes.

scholarly journals Co3O4Catalysts on CeO2-ZrO2Supports and Co3O4-CeO2Catalysts on Al2O3/SiO2Supports for the Oxidation of Propylene

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Tien The Nguyen ◽  
Phuong Thi Mai Pham ◽  
Thang Minh Le ◽  
Isabel Van Driessche
Keyword(s):  
Solid Solution ◽  
Surface Area ◽  
Minimum Temperature ◽  
High Surface ◽  
High Surface Area ◽  
Active Phase ◽  
Optimal Composition ◽  
Catalytic Activities

Different compositions of Co3O4catalysts on CeO2-ZrO2solid solution (Ce0.9Zr0.1O2and Ce0.8Zr0.2O2) have been studied for the oxidation of propylene. The optional amount of Co3O4active phase on CeO2-ZrO2support of 30 wt% was found. The mixed Co3O4-CeO2-ZrO2with the same composition of the optimal supported ones showed approximately the same activity, which was not higher than the activity of the mixed Co3O4-CeO2catalyst. Catalytic activities of mixed Co3O4-CeO2with different loading contents supported on high surface area supports (Al2O3, SiO2) were then measured. The optimal composition of active phase was still 30 wt% but the minimum temperature of the highest activity increased to above 300°C due to the inert nature influence of the support.

scholarly journals Oxidative Desulfurization Catalyzed by Phosphotungstic Acid Supported on Hierarchical Porous Carbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2369
Author(s):  
Bao Wang ◽  
Lihua Kang ◽  
Mingyuan Zhu
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Oxidative Desulfurization ◽  
Sisal Fiber ◽  
Porous Carbon Material ◽  
Impregnation Method ◽  
Desulfurization Rate ◽  
Hierarchical Porous ◽  
Hierarchical Porous Carbons

A hierarchical porous carbon material (HPC) with an ultra-high specific surface area was synthesized with sisal fiber (SF) as a precursor, and then H3PW12O40•24H2O (HPW) was immobilized on the support of SF−HPC by a simple impregnation method. A series characterization technology approved that the obtained SF−HPC had a high surface area of 3152.46 m2g−1 with micropores and macropores. HPW was well-dispersed on the surface of the SF−HPC support, which reduced the loading of HPW to as low as 5%. HPW/SF-HPW showed excellent catalytic performance for oxidative desulfurization, and the desulfurization rate reached almost 100% under the optimal reaction conditions. The desulfurization rate of HPW/SF-HPW could be maintained at above 94% after four recycles.

scholarly journals Understanding Pore Surface Modification of Sucrose-Modified Iron Oxide/Silica Mesoporous Composite for Degradation of Methylene Blue

2021 ◽  
Vol 16 (3) ◽  
pp. 459-471
Author(s):  
Yuvita Eka Pertiwi ◽  
Maria Ulfa ◽  
Teguh Endah Saraswati ◽  
Didik Prasetyoko ◽  
Wega Trisunaryanti
Keyword(s):  
Methylene Blue ◽  
Iron Oxide ◽  
Surface Area ◽  
Heterogeneous Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Impregnation Method ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Wide Range

Santa Barbara Amorphous (SBA-15) containing iron oxide with a sucrose-modified in a heterogeneous reaction for degradation methylene blue (MB) successful synthesized used hydrothermal, ultrasonication, and wet impregnation method. SBA-15 is mesoporous silica that can easily serve as external and internal surfaces making it suitable for a wide range of applications. The structure and morphology of materials were characterized using Surface Area Analyzer (SAA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Transmission Electron Microscopy (TEM). Iron oxide impregnated as a maghemite phase has an average size of 12 nm and well distributed on the SBA-15. After modified with sucrose the materials remaining stable, which has a two-dimensional hexagonal (p6mm) structure, high specific surface area, and large pore volume (up to 1.82 cm3.g−1). The degradation of MB was evaluated under visible light irradiation using UV-Vis spectroscopy. Catalytic activity showed efficiencies of 52.9; 70.2; and 21.1% for SBA-15, Fe2O3/SBA-15, and sucrose-modified Fe2O3/SBA-15 respectively. Sucrose-modified Fe2O3/SBA-15 has the lowest efficiency, which probably occurs due to the presence of pore-blocking and the formation of micropores on the external pore. The modification with sucrose has the advantage of producing a high surface area even though there is a catalytic center due to partial decomposition which causes a decrease in the efficiency of degradation of MB. All materials provide a high micro surface area so that they can be further adapted and can be widely applied to many potential applications as both catalyst support and an adsorbent. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Effects of Ultrasound Irradiation on Synthesis of Solid Acid Catalysts

2016 ◽  
Vol 701 ◽  
pp. 67-72 ◽  
Author(s):  
Mariam Ameen ◽  
Mohammad Tazli Azizan ◽  
Suzana Yusup ◽  
Anita Ramli ◽  
Madiha Yasir ◽  
...  
Keyword(s):  
Surface Area ◽  
Solid Acid ◽  
High Surface ◽  
High Surface Area ◽  
Ultrasound Irradiation ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Impregnation Method ◽  
Wet Impregnation ◽  
Wet Impregnation Method

The studies based on morphological characterization to assess the effects of ultrasound irradiation on synthesis of solid acid catalysts. Three sets of catalyst formulation were synthesized by both wet impregnation method and ultrasound assisted methods with different wt. % of Ni loading on γ-Al2O3. The XRD, BET, TEM and FESEM techniques were used to characterize the nano-particles. Physicochemical characterization revealed that the synthesized catalysts particles using ultrasound irradiation were in nano size range (1-24.5 nm) with equal dispersion of metal oxide, high surface area with increase of metal loading and high phase purity than the catalysts synthesized conventional method. These catalysts were also found in various crystal structures like cubic, monoclinic and tetrahedral. The use of ultrasound irradiation has great significance over the wet impregnation method in relation to the rate of synthesis of nanocatalysts. The high surface area, high thermal stability and small particle size (up to 1 nm) are the basic elements for high activity of solid acid catalysts in hydrocracking and hydrodeoxygenation of various feedstock in petroleum industries.

scholarly journals Rational Design of High Surface Area Mesoporous Ni/CeO2 for Partial Oxidation of Propane

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 388 ◽  
Author(s):  
Mohammad Peymani ◽  
Seyed Alavi ◽  
Hamidreza Arandiyan ◽  
Mehran Rezaei
Keyword(s):  
Surface Area ◽  
Partial Oxidation ◽  
Active Sites ◽  
Rational Design ◽  
High Surface ◽  
High Surface Area ◽  
High Dispersion ◽  
Propane Conversion ◽  
Impregnation Method ◽  
Efficient Catalyst

A Ni loaded catalyst on mesoporous ceria, with a large surface area, prepared through the surfactant-assisted precipitation and impregnation method was investigated as an efficient catalyst for propane partial oxidation to produce synthesis gas. The results show that 2.5 wt% Ni/CeO2 had the optimum Ni loading, exhibiting the highest catalytic propane conversion. It also showed excellent stability, with no obvious activity drop after a 10 h time-on-stream reaction and slightly decreased in H2 and CO yields. The investigation of the reactant composition effect on carbon formation showed that by decreasing the C/O2 ratio the content of accumulated carbon decreased and propane conversion increased. The good activity of the Ni/CeO2 can be ascribed to the high surface area and rich surface defects of the ceria support and a high dispersion of active sites (Ni nanoparticles).

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