Superacid catalysis of light hydrocarbon conversion. Fifth quarterly report, August 25, 1994--December 31, 1994
- Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
Fe- and Mn-promoted sulfated zirconia (psZ) was used to catalyze the conversion of n-butane at atmospheric pressure, 225--450 C, and n-butane partial pressures in the range of 0.0025--0.01 atm. At temperatures < 225 C, the significant reactions were isomerization and disproportionation; in the range of 225--300 C, these reactions were accompanied by cracking; at temperatures > 350 C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part from coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 is consistent with cracking occurring by the Haag-Dessau mechanism. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-psZ at 450 C was about 3 {times} 10{sup {minus}8} mol/(g of catalyst {times} s); for comparison, the rate of cracking of n-butane catalyzed by HZSM-5 under these conditions was estimated to be 1 {times} 10{sup {minus}8} mol/(g of catalyst {times} s). This comparison suggests that the catalytic activity of the psZ at 450 C is about the same as that of the zeolite, although its activity for n-butane isomerization and disproportionation at temperatures < 100 C is orders of magnitude greater than those of zeolites. Thus the indication of superacidity of the psZ does not extend to high temperatures. The results raise questions about the nature of the presumed superacidity: perhaps the acidic sites responsible for the low-temperature catalytic performance of psZ do not exist at the higher temperatures; alternatively, the low-temperature reactions may involve catalyst functions other than the acidic function.
- Research Organization:
- California Univ., Davis, CA (United States); Delaware Univ., Newark, DE (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC22-93PC92116
- OSTI ID:
- 10119129
- Report Number(s):
- DOE/PC/92116-T5; ON: DE95007558; TRN: AHC29508%%100
- Resource Relation:
- Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cracking of n-butane catalyzed by iron- and maganese-promoted sulfated zirconia
Superacid catalysis of light hydrocarbon conversion. DOE PETC fourth quarterly report, May 25, 1994--August 24, 1994
Related Subjects
BUTANE
ISOMERIZATION
OXIDATION
REDUCTION
CRACKING
IRON
CATALYTIC EFFECTS
MANGANESE
ZIRCONIUM OXIDES
PROGRESS REPORT
METHANE
ETHYLENE
PROPYLENE
CHEMICAL REACTION KINETICS
ZEOLITES
PROMOTERS
PH VALUE
SURFACE PROPERTIES
CATALYSTS
TEMPERATURE DEPENDENCE
EXPERIMENTAL DATA
020500
PRODUCTS AND BY-PRODUCTS