Low severity upgrading of F-T waxes with solid superacids
In the last quarters a new class of solid superacids, including sulfated zirconium-hafnium oxides and ZrO[sub 2]/SO[sub 4] modified by Mn and Fe, were synthesized and shown to be active for isomerization and hydrocracking of hexadecane (n-C[sub 16]H[sub 34]). The reaction was carried out in a tubing bomb under mild conditions: 2.5 MPa and 433 K. Pt/HfO[sub 2]S0[sub 4] catalyst exhibited a low activity for hydrocracking of n-C[sub 16], but the addition of ZrO[sub 2] to the sulfated hafnium improved its activity considerably. An 85 wt % conversion level was achieved when the molar ratio of ZrO[sub 2] to HfO[sub 2] reached 1:1, indicating the possibility of a synergistic effect between zirconium and hafnium. It has recently been reported that Mn,Fe/ZrO[sub 2]/SO[sub 4] is about three orders of magnitude more active than ZrO[sub 2]/SO[sub 4] for isomerizing n-butane. As a result, an 0.5%Mn1.5%Fe/ZrO[sub 2]/SO[sub 4] catalyst was prepared according to a procedure given in a patent. It was found that, without Pt, the catalyst was inactive for hydrocracking of n-C[sub 16], possibly by deactivation due to coking. It is interesting that a 68 wt % conversion level was achieved after incorporation of Pt along with a product distribution that was shifted towards longer chain paraffins. ZrO[sub 2]/SO[sub 4]has been reported to be a superacid with H[sub 0] < [minus]16 as measured by the Hammett indicator method. However, the acid strength of some ZrO[sub 2]/SO[sub 4] based catalysts, such as the mentioned catalysts, could not be measured by using Hammett indicators because the catalysts are colored gray. We successfully modified an in situ FT-IR analytical system to characterize the acidity of these catalysts. We have applied the method using pyridine as adsorbate to demonstrate their acid strength. Preliminary results indicated a level of acidity of our catalysts which is consistent with their performance in hydrocracking of n-C[sub 16].
- Research Organization:
- Pittsburgh Univ., PA (United States). Dept. of Chemical and Petroleum Engineering
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91304
- OSTI ID:
- 6704063
- Report Number(s):
- DOE/PC/91304-T5; ON: DE93011453
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FISCHER-TROPSCH SYNTHESIS
WAXES
REFINING
CATALYSTS
HAFNIUM OXIDES
HEXADECANE
HYDROCRACKING
ISOMERIZATION
PH VALUE
PLATINUM
PROGRESS REPORT
SULFATES
ZIRCONIUM OXIDES
ALKANES
CHALCOGENIDES
CHEMICAL REACTIONS
CRACKING
DECOMPOSITION
DOCUMENT TYPES
ELEMENTS
HAFNIUM COMPOUNDS
HYDROCARBONS
METALS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
PROCESSING
PYROLYSIS
REFRACTORY METAL COMPOUNDS
SULFUR COMPOUNDS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM COMPOUNDS
010408* - Coal
Lignite
& Peat- C1 Processes- (1987-)