What question did this study set out to answer?

This research aims to optimize the production of light olefins from n-dodecane using modified ZSM-5 catalysts.

April 16, 2026

Regenerable Light Olefin Production via Steam-Enhanced Catalytic Cracking of n-Dodecane on P-ZSM-5 Extrudate

Key Points

This research aims to optimize the production of light olefins from n-dodecane using modified ZSM-5 catalysts.
Evaluated different H-ZSM-5 zeolites under dry catalytic cracking (DCC) and steam catalytic cracking (SCC).
Tested various silica-to-alumina ratios (SAR) for their impact on light olefin yield.
Modified zeolite with phosphorus to enhance catalytic performance.
Shaped optimal catalysts into cylindrical extrudates for improved mechanical strength.
High-SAR ZSM-5 showed better results under DCC, while low-SAR ZSM-5 excelled under SCC conditions.
The optimal phosphorus-modified extrudates achieved over 60% light olefin yield after 100 hours on stream.
These extrudates demonstrated excellent regenerability and minimal acidity loss, making them suitable for industrial use.

Abstract

To address the growing demand for light olefins and the declining use of middle-distillate transportation fuels, this study investigated steam catalytic cracking (SCC) of n-dodecane (n-C12) over ZSM-5-based catalysts as a model system for heavier hydrocarbon feeds. Commercial H-ZSM-5 zeolites with different SiO2/Al2O3 molar ratios (SAR) were first evaluated under dry catalytic cracking (DCC) and SCC conditions. In DCC, high-SAR ZSM-5 provided the highest light olefin yield, whereas in SCC, the low-SAR ZSM-5 achieved the highest light olefin yield with strongly suppressed coke deposition. On the optimal zeolite ZSM-5, an intermediate P loading (1–2.5 wt %) increased the n-C12 conversion without sacrificing olefin selectivity, owing to suppression of the strong acidity, decreased concentrations of Bro̷nsted and Lewis acid sites, and improved hydrothermal stability. The optimal 1.5P-ZSM-5 (30) was shaped into cylindrical extrudates by using colloidal silica as an Al-free binder, giving sufficient mechanical strength while preserving the catalytic performance of the powder catalyst. Under optimized SCC conditions, the optimal catalyst extrudate retained a light olefin yield of >60% after 100 h on stream and showed excellent regenerability with minimal loss of acidity. These results demonstrate that phosphorus-modified ZSM-5 extrudates are promising industrial catalysts for the SCC of long-chain hydrocarbons.

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