Methanol-to-olefin conversion over ZSM-5: influence of zeolite chemical composition and experimental conditions on propylene formation

Abstract

The transformation of methanol into light olefins over ZSM-5 zeolites with different SiO₂/Al₂O₃ molar ratios (SAR) and phosphorus contents was investigated. An increase in the SAR and amount of incorporated phosphorus reduced the acid-site strength and density, which favored catalytic stability and the production of light olefins, mainly propylene. Under an isoconversion of 91%, high propylene/ethylene molar ratios were observed using the zeolite with the highest SAR (i.e., HZ(280)) and the one containing 4 wt.% P (i.e., 4PHZ(30)). However, the latter was less stable when used in a long-term reaction. An experimental design was employed to investigate how the reaction temperature and methanol partial pressure affect the propylene (C₃⁼) yield in the reaction catalyzed by the HZ(280) zeolite, which led to a temperature of 475 °C and a methanol partial pressure of 0.04 atm using the proposed model within the experimental design space.

Keywords:

• Experimental design
• HZSM-5
• light olefins
• methanol conversion
• propylene
• zeolite

Acknowledgments

The authors thank CENPES/PETROBRAS – the Brazilian Petroleum Company – for technical and financial support and NUCAT/COPPE/UFRJ for FTIR and XRF analyses.

1. This is a note. The style name is Footnotes, but it can also be applied to endnotes.

Conflicts of interest

There are no conflicts of interest.

Additional information

Funding

This work was supported by CENPES/PETROBRAS – the Brazilian Petroleum Company and NUCAT/COPPE/UFRJ.