Volume 238, 2022

The merit of pressure dependent kinetic modelling in steam cracking

Abstract

Renewable cracking feedstocks from plastic waste and the need for novel reactor designs related to electrification of steam crackers drives the development of accurate and fundamental kinetic models for this process, despite its large scale implementation for more than half a century. Pressure dependent kinetics have mostly been omitted in fundamental steam cracking models, while they are crucial in combustion models. Therefore, we have assessed the importance of pressure dependent kinetics for steam cracking via in-depth modelling and experimental studies. In particular we have studied the influence of considering fall-off on the product yields for ethane and propane steam cracking. A high-pressure limit fundamental kinetic model is generated, based on quantum chemical data and group additive values, and supplemented with literature values for pressure dependent kinetic parameters for β-scission reactions and homolytic bond scissions of C2 and C3 species. Model simulations with high-pressure limit rate coefficients and pressure dependent kinetics are compared to new experimental measurements. Steam cracking experiments for pure ethane and propane feeds are performed on a tubular bench-scale reactor at 0.17 MPa and temperatures ranging from 1058 to 1178 K. All important product species are identified using a comprehensive GC × GC-FID/q-MS. For homolytic bond scissions, the inclusion of pressure dependent kinetics has a significant effect on the conversion profile for ethane steam cracking. On the other hand, pressure dependence of C2 β-scissions significantly influences conversion and product species profiles for both ethane and propane steam cracking. The C3 β-scissions pressure dependence has a negligible effect in ethane steam cracking, while for propane steam cracking the effect is non-negligible on the product species profiles.

Graphical abstract: The merit of pressure dependent kinetic modelling in steam cracking

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
03 feb 2022
Accepted
11 mar 2022
First published
25 mar 2022

Faraday Discuss., 2022,238, 491-511

The merit of pressure dependent kinetic modelling in steam cracking

J. Aerssens, F. Vermeire, S. U. Aravindakshan, R. Van de Vijver and Kevin M. Van Geem, Faraday Discuss., 2022, 238, 491 DOI: 10.1039/D2FD00032F

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