Low severity upgrading of F-T waxes with solid superacids. Quarterly report
In the past year, we synthesized a Pt/ZrO{sub 2}/SO{sub 4} catalyst which exhibits high conversions and selectivity for desirable products from long-chain paraffins, such as n-hexadecane, n-dotriacontane(n-C{sub 32}) and a SASOL wax(C{sub 58}-C{sub 64}). The catalyst preparation procedure has been carefully worked out and is reproducible. Isomerization and hydrocracking activities of long-chain paraffins and selectivities to various products were examined under mild conditions: 443 K and 2.5 MPa initial hydrogen pressure. Effects of temperature, pressure, catalyst loading, Pt concentration on n-alkane conversions were studied to understand the mechanism on the acid catalyst surface. Upgrading of the alkanes proceeds through initial isomerization followed by {beta}-scission reactions and further isomerizations. Isomerization is favored at low temperature and short reaction times, whereas cracking is favored at higher temperatures or pressures. The hydrogen pressure has a considerable influence on the product distribution. Hydrogen transfer probably proceeds through dissociation of molecular hydrogen to generate pretonic acid sites which cause C-C cleavage. Effect of increasing Pt loadings shows a trend similar to increasing hydrogen pressure. Characterization of the present catalyst demonstrates that catalytic activity depends to a large extent on proper coordination of finely dispersed platinum to strong acid sites as well as on pore size distribution.
- Research Organization:
- Pittsburgh Univ., PA (United States). Dept. of Chemical and Petroleum Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91304
- OSTI ID:
- 10124861
- Report Number(s):
- DOE/PC/91304-T4; ON: DE93008123
- Resource Relation:
- Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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