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Oxidation of asphaltenes adsorbed onto NiO nanoparticles

Paper ID Volume ID Publish Year Pages File Format Full-Text
40712 45863 2012 6 PDF Available
Title
Oxidation of asphaltenes adsorbed onto NiO nanoparticles
Abstract

Differential thermogravimetry (DTG) and differential scanning calorimetry (DSC) plots help identifying reaction zones and enable activation energy calculations. Recently, Nassar et al. [1] and [2] reported major shifts in the DTG combustion peaks and reaction zones between virgin and adsorbed asphaltenes onto commercial metal oxide nanoparticles. They attributed the accompanying reduction in activation energy to a significant catalytic role played by the nanoparticles, especially for NiO nanoparticles. It should be noted that in these experiments only monolayer adsorption from toluene model solutions was encountered. More recently, our group reported multilayer adsorption of asphaltenes from heavy oils onto in situ prepared and commercial NiO nanoparticles [3]. Contrary to the previous literature, the thermal behavior of these asphaltenes revealed a surface role entailing an enhanced exposure of adsorbed asphaltenes to the oxidant stream. In this work, we critically re-evaluated the claim of catalytic effect of nanoparticles [1], [2], [4] and [5] and provide an experimental protocol which demonstrates a surface effect.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (155 K)Download as PowerPoint slideHighlights► In situ prepared NiO nanoparticles show high potency as adsorbent and additive. ► Sequential combustion of adsorbed layers model is more founded. ► Activation energy, Ea, calculations reflect lower values for physically adsorbed species. ► Chemically adsorbed species react at high T with higher Ea. ► Role of NiO nanoparticles is surface exposure not catalytic.

Keywords
Asphaltenes; Nanoparticle; Heavy oil; Oxidation; Activation energy; NiO
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 445–446, 28 November 2012, Pages 166–171
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
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Price was $35.95
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