Abstract

Hierarchical ZSM-48, a one-dimensional pore system zeolite with the presence of mesopores, was obtained by post-synthesis alkaline and acid treatments. Hierarchical ZSM-48 exhibited excellent hexane cracking activity compared to parent ZSM-48, which can be attributed to better diffusion as a result of the created mesoporosity. Moreover, the post-synthesis treatment allowed for manipulation of the distribution of active sites. Consequently, better stability and higher propylene selectivity were accomplished. The spent catalyst was regenerated by removing the deposited coke from the pores, and the regenerated catalyst was characterized again to investigate the recyclability of the hierarchical structure achieved. Parent ZSM-48 showed the same textural and acidic properties after regeneration, while the structure of the post-treated sample suffered from serious defects. The defects severely decreased the number of active sites as measured by pyridine Fourier transform infrared spectroscopy and caused major s...

Highlights

  • One-dimensional zeolites, which have rarely been used because of their quick deactivation problem are given higher selectivity toward light olefins compared to three-dimensional zeolites.[6,10]

  • The durability and preservation of zeolite properties are highly required for the catalyst, which will be used in Fluid catalytic cracking (FCC) or any process because the calculations of material balance of separation units will be based on product selectivity

  • Successful extraction of some Si species from the framework of ZSM-48 was achieved as a result of the treatment with 0.2 M

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Summary

INTRODUCTION

The demand of light olefins, especially ethylene and propylene, is growing fast because they represent the raw materials for different petrochemical industries.[1−3] Naphtha cracking is the major process, which supplies the requested amounts of these olefins.[4,5] The catalytic cracking of naphtha is a more promising technology to boost the selectivity toward desired products.[6,7]. ZSM-48 (MRE) is one-dimensional zeolite with a 10membered ring pore system with a pore opening of 5.3 × 5.6 Å It is known as a high-silica zeolite with a disordered structural framework of ferrierite sheets connected together.[20,21] ZSM-48 showed interesting catalytic performance in different reactions, such as hexane hydrocracking,[21] hexane cracking,[6] and methanol to hydrocarbons.[22]. The durability and preservation of zeolite properties are highly required for the catalyst, which will be used in FCC or any process because the calculations of material balance of separation units will be based on product selectivity. Energy & Fuels a few drops of the suspension were placed onto a carbon-coated copper microgrid

EXPERIMENTAL SECTION
RESULTS AND DISCUSSION
Changes in Crystallinity as a Result of Catalyst
Changes in Acidity as a Result of Catalyst
CONCLUSION

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