Conversion of Ethanol to n-Butanol over NiCeO2 Based Catalysts: Effects of Metal Dispersion and NiCe Interactions

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

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Ultrasound-Assisted Preparation of Mo/ZSM-5 Zeolite Catalyst for Non-Oxidative Methane Dehydroaromatization

Catalysts ◽

10.3390/catal11030313 ◽

2021 ◽

Vol 11 (3) ◽

pp. 313

Author(s):

Heidy Ramirez-Mendoza ◽

Mafalda Valdez Lancinha Pereira ◽

Tom Van Gerven ◽

Cécile Lutz ◽

Ignacio Julian

Keyword(s):

Catalytic Activity ◽

Ion Exchange ◽

Active Sites ◽

Chemical Properties ◽

Successful Implementation ◽

Metal Dispersion ◽

Zeolite Framework ◽

Dispersed Catalysts ◽

Methane Dehydroaromatization ◽

Ultrasound Assisted

The activity and selectivity of Mo/ZSM-5, benchmarking catalyst for the non-oxidative dehydroaromatization of methane, strongly depend on the cluster size, spatial distribution, and chemical environment of the Mo-based active sites. This study discloses the use of an ultrasound-assisted ion-exchange (US-IE) technique as an alternative Mo/ZSM-5 synthesis procedure in order to promote metal dispersion along the zeolite framework. For this purpose, a plate transducer (91.8 kHz) is employed to transmit the ultrasonic irradiation (US) into the ion-exchange reactor. The physico-chemical properties and catalytic activity of samples prepared under the said irradiation procedure and traditional impregnation (IWI) method are critically evaluated. Characterization results suggest that US neither affects the crystalline structure nor the particle size of the parent zeolite. However, US-IE promotes molybdenum species dispersion, avoids clustering at the external fresh zeolite surface and enhances molybdate species anchoring to the zeolite framework with respect to IWI. Despite the improved metal dispersion, the catalytic activity between catalysts synthesized by US-IE and IWI is comparable. This suggests that the sole initial dispersion enhancement does not suffice to boost the catalyst productivity and further actions such ZSM-5 support and catalyst pre-conditioning are required. Nevertheless, the successful implementation of US-IE and the resulting metal dispersion enhancement pave the way toward the application of this technique to the synthesis of other dispersed catalysts and materials of interest.

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Factors influencing the determination of metal dispersion on supported platinum catalysts by the gas chromatographic pulse technique

Journal of Catalysis ◽

10.1016/0021-9517(76)90402-4 ◽

1976 ◽

Vol 44 (2) ◽

pp. 314-317 ◽

Cited By ~ 11

Author(s):

J PRASAD

Keyword(s):

Platinum Catalysts ◽

Metal Dispersion ◽

Pulse Technique ◽

Factors Influencing ◽

Supported Platinum ◽

Supported Platinum Catalysts

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Effect of metal dispersion on CO hydrogenation over Pd/HZSM-5 catalysts

Catalysis Letters ◽

10.1007/bf00808598 ◽

1995 ◽

Vol 31 (4) ◽

pp. 341-350 ◽

Cited By ~ 4

Author(s):

Jong-Ki Jeon ◽

Son-Ki Ihm

Keyword(s):

Co Hydrogenation ◽

Metal Dispersion

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Hydrogen Adsorption Capacity Investigation of Ni-Co-Al Mixed Oxides

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.917.360 ◽

2014 ◽

Vol 917 ◽

pp. 360-364 ◽

Cited By ~ 4

Author(s):

M. Abdus Salam ◽

Suriati Sufian

Keyword(s):

Hydrogen Adsorption ◽

Mixed Oxides ◽

Textural Properties ◽

Metal Dispersion ◽

Temperature Programmed Reduction ◽

Oxide Formation ◽

Nickel Cobalt ◽

Icp Ms ◽

Temperature Programmed ◽

Adsorption Desorption

Micro-mesoporous mixed oxides containing nickel, cobalt and aluminum have been synthesized using conventional coprecipitation method. FESEM and HRTEM analyses demonstrated the flower and hexagonal plate-like nanostructured of mixed oxides. Different mixed oxide formation, homogenous metal dispersion, textural properties were investigated using XRD, ICP-MS and BET (N2 adsorption-desorption) techniques. nanostructured mixed oxides exhibited 2.6 wt% hydrogen adsorption that were studied using temperature programmed reduction-adsorption-desorption (H2-TPR/TPD) and thermogravimetric and differential thermal analysis (TGA-DTA) techniques. Investigation corresponds that morphologies, textural properties and surface energy of mixed oxides are important in hydrogen adsorption.

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