Yoo, KS Gopal, S Smirniotis, PG 2024-01-21T04:41:59Z 2024-01-21T04:41:59Z 2021-09-03 2005-06-22 0888-5885 https://pubs.kist.re.kr/handle/201004/136351 A series of ZSM-12 samples were prepared by calcining them at different temperatures that are much higher than what is normally used. The catalytic activities of these samples were tested using cracking of n-hexane at 400 degrees C. It was found that the cracking activities of samples calcined at certain temperatures were unusually high: 3-4 times greater than that of the regular sample, which was calcined at 550 degrees C. Interestingly, this enhanced activity was observed at two separate, relatively narrow, ranges of temperatures: one around 650 degrees C and the other around 800 degrees C. Bronsted and Lewis acid sites attributed to extraframework cationic aluminum were quantified with Fourier transform infrared of adsorbed pyridine. The Lewis/Bronsted ratios of the enhanced-activity samples were high compared those of the low-activity samples; the trend in variation of the Lewis/Bronsted ratios of the samples with calcination temperature closely mirrored the trend observed for the catalytic activities. This is an indication that there is a synergistic interaction between the Bronsted and Lewis acid sites that is responsible for the enhanced cracking activity. English AMER CHEMICAL SOC ACID PROPERTIES Y ZEOLITES CATALYSTS STEAM NMR IR HYDROISOMERIZATION ISOMERIZATION MORDENITE SITES Enhancement of n-hexane cracking activity over modified ZSM-12 zeolites Article 10.1021/ie0488602 1 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, v.44, no.13, pp.4562 - 4568 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 44 13 4562 4568 scie scopus 000229870000010 2-s2.0-22444436014 Engineering, Chemical Engineering Article ACID PROPERTIES Y ZEOLITES CATALYSTS STEAM NMR IR HYDROISOMERIZATION ISOMERIZATION MORDENITE SITES