In:
New Journal of Chemistry, Royal Society of Chemistry (RSC), Vol. 46, No. 8 ( 2022), p. 3916-3924
Abstract:
In this work, the effects of ethanol on n -heptane catalytic cracking over HZSM-5 zeolites were explored at 550 °C for 6 h on stream. Particular attention was paid to the measurement of product distribution, especially alkene and aromatic products. Due to the unique structure, ethanol easily interacts with the acid sites over HZSM-5 zeolites. It favored the dehydration to ethene formation and prevented alkene secondary reaction to aromatic formation. Thus, ethanol addition promoted alkene selectivity while reducing aromatic selectivity in n -heptane catalytic cracking. However, ethanol addition accelerated the deactivation of HZSM-5 zeolites. XRD, 27 Al MAS NMR, TG-DSC, N 2 adsorption–desorption, and NH 3 -TPD were employed to characterize the fresh and spent HZSM-5 zeolites and elucidate the roles of ethanol in coke formation and HZSM-5 deactivation during n -heptane catalytic cracking. It was found that alkene promotion caused by ethanol addition enhanced coke formation and its migration from the micropores to the external surface of HZSM-5 zeolites. The formation and accumulation of external coke sharply blocked the pore openings and reduced the accessibility of the acidic site, accelerating HZSM-5 deactivation. Moreover, ethanol was more harmful to the framework of HZSM-5 zeolites compared to n -heptane. It accelerated the collapse of HZSM-5 crystallite, which was negative to the catalytic performance.
Type of Medium:
Online Resource
ISSN:
1144-0546
,
1369-9261
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
1472933-7
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