![]() The formation and accumulation of external coke sharply blocked the pore openings and reduced the accessibility of the acidic site, accelerating HZSM-5 deactivation. 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. XRD, 27Al 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. However, ethanol addition accelerated the deactivation of HZSM-5 zeolites. Thus, ethanol addition promoted alkene selectivity while reducing aromatic selectivity in n-heptane catalytic cracking. It favored the dehydration to ethene formation and prevented alkene secondary reaction to aromatic formation. Due to the unique structure, ethanol easily interacts with the acid sites over HZSM-5 zeolites. ![]() Particular attention was paid to the measurement of product distribution, especially alkene and aromatic products. In this work, the effects of ethanol on n-heptane catalytic cracking over HZSM-5 zeolites were explored at 550 ☌ for 6 h on stream.
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June 2023
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