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The activation of Phillips Cr/silica catalysts: VI. Influence of hold time

Paper ID Volume ID Publish Year Pages File Format Full-Text
43678 45982 2008 7 PDF Available
Title
The activation of Phillips Cr/silica catalysts: VI. Influence of hold time
Abstract

This report attempts to further define the underlying principles governing activation of the Phillips Cr/silica catalyst. Calcining the catalyst causes dehydroxylation or annealing of the silica surface that generates the active site population, and thereby the catalyst activity and polymer character. The extent of dehydroxylation during activation depends not only on the calcining temperature, but also on the calcining time, making the two variables seemingly inter-convertible in their effect on catalyst and polymer behavior. However, the rate of surface annealing also depends on temperature, so that the degree of time dependence can vary with the choice of activation temperature. These facts can be used to explain commercial behavior and to design more efficient activation recipes.

Graphical abstractThe temperature used to activate Cr/silica catalyst determines its activity and polymer character, such as MW distribution. In this paper, activation time is shown to be equally important, affecting the catalyst much as temperature does. Commercial dehydroxylation of the silica is a time-dependent process in which both time and temperature can be considered as inter-convertible.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Phillips chromium catalyst; Ethylene polymerization; Polyethylene; Catalyst activation
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The activation of Phillips Cr/silica catalysts: VI. Influence of hold time
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 335, Issue 2, 8 February 2008, Pages 180–186
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
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