Type of Document	Dissertation
Author	Hong, Suk Bong
URN	etd-10132005-152545
Title	Aromatization of n-hexane by platinum containing molecular sieves and distribution and motion of organic guest molecules in zeolites
Degree	PhD
Department	Chemical Engineering
Advisory Committee	Advisor Name Title Davis, Mark E. Committee Chair Conger, William L. Committee Member Cox, David F. Committee Member Hanson, Brian E. Committee Member Wills, George B. Committee Member
Keywords	Molecular sieves Zeolites Hexane
Date of Defense	1992-04-05
Availability	restricted
Abstract A vapor phase impregnation technique with Pt(acac)2 has been developed and used to load Pt into aluminosilicate (KL, BaKL, KBaKL, NaY, CsNaY, FAU, EMT, ZSM-12 and SSZ-24) and aluminophosphate (AIP04-5 and VPI-5) molecular sieves. 13C MAS NMR, TEM and H2 chemisorption measurements reveal that Pt can be loaded into the micropores of molecular sieves with both charged and neutral frameworks. Pt containing molecular sieves were tested as catalysts for the aromatization of n-hexane at 460 - 510°C and atmospheric total pressure in order to study the influence of Pt cluster size and support acidity/basicity, microstructure and chemical composition on activity and selectivity. High selectivity to benzene over most of the zeolite samples demonstrates that support acidity/basicity and microstructure do not contribute directly to the aromatization selectivity over Pt catalysts. A clear trend of increasing benzene selectivity with decreasing Pt cluster size is found. These observations suggest that the exceptional reactivity of Pt/KL for the aromatization of n-hexane results from the lack of any acidity in the support and the ability of zeolite L to stabilize the formation of extremely small Pt clusters. Pt/AIP04-5 and PWPI-5 show high selectivity to n-hexane with little formation of benzene while opposite is observed for Pt/SSZ-24. The differences in catalytic behavior are attributed to variations in the environment of Pt clusters which are situated in either an aluminophosphate or silicate micropore.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access  LD5655.V856_1992.H663.pdf 4.07 Mb 00:18:49 00:09:40 00:08:28 00:04:14 00:00:21 next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.

If you have questions or technical problems, please Contact DLA.