The conversions of 1,3,5-trimethylbenzene over beta zeolite: Effect of SiO2/Al2O3 ratio

✍ Scribed by Shiao-Jung Chu; Yu-Wen Chen

• Publisher: Wiley (John Wiley & Sons)
• Year: 1998
• Tongue: English
• Weight: 217 KB
• Volume: 72
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/(sici)1097-4660(199805)72:1<1::aid-jctb861>3.0.co;2-h

✦ Synopsis

A series of beta zeolites with various ratios has been syn-SiO 2 /Al 2 O 3 thesized. These samples were characterized with respect to crystallinity, particle size, acidity and sorption capacities of water, n-hexane and cyclohexane. The conversion of 1,3,5-trimethylbenzene (TrMB) was conducted in a Ðxed bed reactor at 493È743 K and atmospheric pressure. The conversion of 1,3,5-TrMB decreased with an increase in the ratio of the zeolite. The zeolites SiO 2 /Al 2 O 3 with low ratio favored the disproportionation and the zeolites with SiO 2 /Al 2 O 3 high ratio favored the isomerization. These can be interpreted by the SiO 2 /Al 2 O 3 acid concentration of zeolite.

In the isomerization, all zeolites produced more 1,2, 4-TrMB than 1,2,3-TrMB. In the disproportionation, the selectivity of tetramethylbenzene (TeMB) was in the order of 1,2,3,5 The concentration of 1,2,4,5-TeMB is greater than that at equilibrium. The results show that shape selectivity comes into e †ect. The reaction temperature and the reaction time on stream also a †ect the selectivity signiÐcantly due to coke formation in the zeolites.