A comparison of the reactivities of propanal and propylene on HZSM-5

• Published in: Journal of catalysis Vol. 271; no. 2; pp. 201 - 208
• Main Authors: Hoang, Trung Q., Zhu, Xinli, Sooknoi, Tawan, Resasco, Daniel E., Mallinson, Richard G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 04.05.2010; Elsevier; Elsevier BV
• Subjects: Aldehyde conversion; Aldol condensation; Aromatization; Biofuels; Catalysis; Chemistry; Deoxygenation; Exact sciences and technology; General and physical chemistry; HZSM-5; Ion-exchange; Oxygenates conversion; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zeolites: preparations and properties; Aromatization; Deoxygenation; Oxygenates conversion; Aldehyde conversion; HZSM-5; Biofuels; Aldol condensation; Trimer; Catalytic reaction; Oligomerization; Hydrocarbon; Biofuel; Aldehyde; Condensation; Conversion; Aldol; Heterogeneous catalysis; Propene; Olefin; Acids; Dimer; Chemical reactivity; Propanal; Ethylenic compound
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2010.01.017

Propanal is found to be much more reactive than propylene and to form mostly 2-methyl-2-pentenal and C 9 aromatics as early products in the reaction network through the aldol pathway. The reactivities of propanal and propylene have been compared over HSZM-5 zeolites (Si/Al = 45 and 25). Propanal is found to be much more reactive than propylene and to form mostly 2-methyl-2-pentenal and C 9 aromatics as early products in the reaction network. Propylene, in contrast, requires more severe conditions to form C 6 and C 7 aromatics. It is proposed that propanal undergoes acid-catalyzed aldol condensation to form 2-methyl-2-pentenal. This dimer undergoes further condensation to form the aldol trimer, which subsequently dehydrates and cyclizes into C 9 aromatics. In contrast, it is well known that propylene, like other olefins, undergoes aromatization via oligomerization and formation of a hydrocarbon pool. While in the conversion of propanal, propylene is also produced, it appears that it does not play a major role in the formation of aromatics under conditions of shorter space times and lower temperatures, at which propanal produces aromatics in significant amounts.