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Updated: Jul 29, 2026

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
Published on: November 27, 2015
Enhanced para-xylene selectivity in the toluene alkylation reaction at ultralow contact time
John Breen1, Robbie Burch, Manisha Kulkarni
1CenTAcat, School of Chemistry, Queen's University Belfast, David Keir Building, Belfast BT9 5AG, UK.
Abstract:
Dramatic improvements in the para-xylene selectivity of the toluene alkylation reaction can be effected by operating the catalytic reaction at ultralow contact time. Unexpectedly, the rate of alkylation is sustained, while unwanted side reactions are suppressed. By demonstrating that contact time directly influences the fate of para-xylene, which is known to form and diffuse preferentially within the zeolite catalyst, we conclude that external mass transfer is a key parameter in controlling selectivity. Even non-optimized catalysts can be made to achieve near-perfect selectivity, without sacrificing conversion.
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