Mechanism of neopentane cracking over solid acids
Neopentane was used as a probe to test whether catalyst protons can attack the C-C and/or the C-H sigma-bonds in the cracking of alkanes. Over a variety of solid acids approximately one CH/sub 4/ molecule was formed for every neopentane reacted. Moreover, in most cases nearly as much isobutene was formed. With H-Y zeolite (H-Y) and particularly with H-mordenite (H-M), however, hydride transfer leading to paraffin formation became important or dominant. Generally, the results conformed to (CH/sub 3/)/sub 3/C-H/sup +/-CH/sub 3/ ..-->.. CH/sub 4/ + (CH/sub 3/)/sub 3/C/sup +/ with the t-butyl ion either decomposing to isobutene or else undergoing secondary reactions. The latter tended to increase with the intensive factor of the acidity, i.e., with the strength of the acid-base interaction. The fraction of neopentane converted to CH/sub 4/, when plotted in the Arrhenius fashion against T/sup -1/, produced straight lines from which apparent activation energies could be calculated. Values obtained fell between 30 kcal/mol for silica-alumina and 14 kcal/mol for H-M (the most acidic and active catalyst investigated). Controversial views found in current literature are discussed in light of the present results.
- Research Organization:
- Univ. of Pittsburgh, PA (USA)
- OSTI ID:
- 5259579
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 110:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020400* -- Petroleum-- Processing
ACTIVATION ENERGY
ALKANES
ALKENES
BUTENES
CATALYTIC CRACKING
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRACKING
DECOMPOSITION
ENERGY
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METHANE
MINERALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PETROLEUM
PH VALUE
PYROLYSIS
REACTION KINETICS
SOLIDS
SYNTHESIS
THERMOCHEMICAL PROCESSES
ZEOLITES