Effect of magnesium modification over H-ZSM-5 in methanol to propylene reaction

Chen Chen,Zhe Meng,Qiang Zhang,Honghong Shan,Chunyi Li

doi:10.1007/s13203-015-0129-7

Chen Chen, Zhe Meng + Show 3 more

Open Access

https://doi.org/10.1007/s13203-015-0129-7

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Abstract

H-ZSM-5-based catalyst is a recognized catalyst which is particularly selective towards the formations of light olefins in the methanol reaction. A series of H-ZSM-5 (SiO2/Al2O3 = 38) modified with different amounts of magnesium have been investigated. All the samples were characterized by X-ray diffraction instrument (XRD), temperature-programmed desorption of NH3 (NH3-TPD) and Fourier Transform Infrared Spectoscopy (FT-IR). The results indicated that the impregnation of H-ZSM-5 (SiO2/Al2O3 = 38) zeolite with various magnesium loading amount significantly affected the strength of acid sites and decreased the concentration of both weak and strong acid sites. As a result of modification, magnesium mainly interacted with strong Bronsted acid sites, thus generated new medium strong acid sites and enhanced the yield of propylene. The optimum acid property for methanol to propylene (MTP) reaction was gotten over 4.0 Mg-ZSM-5 (4.0 wt% Mg) zeolite catalyst. The maximum yield of propylene was 10.62 wt% over 4.0 Mg-ZSM-5 zeolite catalyst by the 30 min on stream. Coke which was mostly formed on strong Bronsted acid sites, would cause the catalysts deactivation, so the reduction of strong Bronsted acid sites could enhance the catalytic stability.

Highlights

Propylene is one of the most important organic raw materials for the synthesis of a variety of important downstream chemical materials, such as polypropylene, acrylonitrile, epoxy propane, etc
The results indicated that the impregnation of H-ZSM5 (SiO2/Al2O3 = 38) zeolite with various magnesium loading amount significantly affected the strength of acid sites and decreased the concentration of both weak and strong acid sites
In order to explore the role of acid character in methanol to propylene (MTP) reaction and to enhance propylene selectivity, we imported Mg onto H-ZSM-5(SiO2/Al2O3 = 38) to adjust the acid property and find optimum acidity for MTP reaction

Summary

Introduction

Propylene is one of the most important organic raw materials for the synthesis of a variety of important downstream chemical materials, such as polypropylene, acrylonitrile, epoxy propane, etc. The results indicated that the impregnation of H-ZSM5 (SiO2/Al2O3 = 38) zeolite with various magnesium loading amount significantly affected the strength of acid sites and decreased the concentration of both weak and strong acid sites. The optimum acid property for methanol to propylene (MTP) reaction was gotten over 4.0 Mg-ZSM-5 (4.0 wt% Mg) zeolite catalyst.

Results

Conclusion