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Coke analysis by temperature-programmed oxidation: Morphology characterization

Paper ID Volume ID Publish Year Pages File Format Full-Text
42859 45944 2009 7 PDF Available
Title
Coke analysis by temperature-programmed oxidation: Morphology characterization
Abstract

Temperature-programmed oxidation (TPO) profiles obtained using high final temperature are usually very similar in shape and it is not possible to easily distinguish among different kinetic models. Typically, statistical criteria are used to select the one that best fits the experimental TPO profile. In this work, we show that using final temperatures selected in such a way that the coke is still reacting with oxygen, relevant information can be obtained from the experimental profile. Coked naphtha reforming catalysts, obtained from an industrial reactor, are characterized by running TPO analyses using intermediate temperatures. Results clearly show that the coke reaction order changes as the coke conversion increases. When the initial coke content is approximately 5 wt% or higher, coke has a tridimensional structure that leads to a low reaction order, close to 0.2. At high conversion levels, approximately 80%, the coke reaction order starts increasing until reaching a value of 1 at conversion close to 1. This information is easily obtained by plotting the experimental coke reaction order using the data at constant temperature. In this way, it is possible to easily distinguish among different models, and to replicate the experimental results.

Graphical abstractTemperature-programmed oxidation technique may provide useful and unique information regarding coke morphology and kinetics parameters, as long as the experiment is carried out up to intermediate final temperature. This experimental design makes it possible to distinguish how the coke reaction order changes as a function of coke conversion, and replicate complex kinetics behavior such as those found in catalyst with high level of coke, e.g. 14 wt%, as shown in the figure.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Temperature-programmed-oxidation; Coke characterization; Coke morphology
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 364, Issues 1–2, 31 July 2009, Pages 35–41
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us