Acid-catalyzed cracking of paraffinic hydrocarbons. 3. Evidence for the protonated cyclopropane mechanism from hydrocracking/hydroisomerization experiments

Journal Article · Mon Mar 01 00:00:00 EST 1993 · Industrial and Engineering Chemistry Research; (United States)

OSTI ID:6561011

Tiong Sie, S ^[1]

---

1. Koninklijke/Shell-Lab., Amsterdam (Netherlands)

The mechanism for acid-catalyzed cracking proposed in the first paper of this series, which assumes a protonated dialkylcyclopropane carbonium ion as intermediate instead of a classical carbenium ion, has been applied to rationalize experimental results obtained in the hydrocracking/hydroisomerization of normal paraffins. The new mechanism is shown to be capable of explaining many characteristics of the hydrocracking process which cannot be understood via the classical theory, such as the virtual absence of methane and ethane as cracked products, the relatively low production of propane as compared to the higher hydrocarbons, and characteristic patterns in the branching of the cracked fragments. The new mechanism also makes it clear why crackability increases so rapidly with increasing number of carbon atoms above n-heptane and why n-hexane and lower hydrocarbons are so difficult to crack. An explanation is also offered for the ease with which high selectivities can be achieved in the isomerization of C[sub 5]/C[sub 6], as contrasted with the difficulty of isomerizing C[sub 7+] without significant cracking.

• OSTI ID: 6561011
• Journal Information: Industrial and Engineering Chemistry Research; (United States), Vol. 32:3; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ALKANES
CATALYTIC CRACKING
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CYCLOALKANES
HEPTANE
HEXANE
HYDROCRACKING
ISOMERIZATION
MOLECULAR WEIGHT
REACTION INTERMEDIATES
CHEMICAL REACTIONS
CRACKING
DECOMPOSITION
HYDROCARBONS
KINETICS
ORGANIC COMPOUNDS
PYROLYSIS
REACTION KINETICS
THERMOCHEMICAL PROCESSES
YIELDS
020400* - Petroleum- Processing