TITLE: Particle size dependence in Fischer-Tropsch synthesis.

AUTHOR: D. Mahajan;   E. Zuckerman;   A. Kobayashi.

INST.  AUTHOR: Brookhaven National Lab., Upton, NY.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1994,  17p.

NTIS ORDER NO.: DE95003124INW

NOTES: Coal liquefaction and gas conversion contractors' review conference, Pittsburgh, PA (United States), 7-8 Sep 1994. Sponsored by Department of Energy, Washington, DC.

ABSTRACT:

The use of ultrafine particle (UFP) iron catalysts in slurry-phase Fischer-Tropsch (F-T) synthesis was investigated. Two systems were selected: (1) NANOCAT(trademark) or MACH-1, a commercially available unsupported Fe(sub 2)O(sub 3) material with mean particle diameter (MPD) of 3 nm (surface area (SA) = 255 m(sup 2)(center dot)g(sup (minus)1); density (d) = 0.05 g(center dot)mL(sup (minus)1)), and (2) an unsupported Fe(sub 2)O(sub 3) material from BASF with MPD of 20-80 nm (SA = 16-20 m(sup 2)(center dot)g(sup (minus)1); d = 5.25 g(center dot)mL(sup (minus)1)). For reference, the UCI catalyst with MPD of 32.5 (mu)m SA = 232 m(sup 2)(center dot)g(sup (minus)1); d = 0.80 g(center dot)mL(sup (minus)1); composition (wt%): Fe(sub 2)O(sub 3) = 69.6, K(sub 2)O = 5.1 SiO(sub 2) = 8.3, CuO = 2.6; loss on ignition (LOI) = 14.8 was also included. After slurried catalyst reduction with CO at 280(degrees)C, F-T activity data were collected at 240(degrees)C and 0.78 MPa with balanced gas (H(sub 2)/CO (approximately) 2/1). A run was also completed with MACH-1 at 260(degrees)C and 2.77 MPa. At 240(degrees)C, 0.78 MPa, and gas-hourly-space-velocity (GHSV) of 4.5-4.7 NL(center dot)gFe(sup (minus)1)(center dot)h(sup (minus)1), space-time-yields (STY) of hydrocarbon products were 0.36, 0.26, and 0.54 kg(center dot)kgFe(sup (minus)1)(center dot)h(sup (minus)1) for BASF, MACH-1, and UCI respectively. The corresponding (alpha) values obtained from Anderson-Schulz-Flory (ASF) plots (in the C(sub 3)-C(sub 7) range) were 0.60, 0.57, and 0.50. A Moessbauer study on a MACH-1 sample, quenched after 199 hours at 260(degrees)C, indicated that MACH-1 was in the magnetic phase. EXAFS and Moessbauer measurements on several unreduced, freshly reduced, and quenched UFP samples are in progress. The H(sub 2)/CO stoichiometry used is relevant to natural gas-derived syngas. Future runs will utilize these data for development of UFP catalysts for oxygenates synthesis with CO(sub 2)-rich syngas.

REPORT  NUMBER: BNL-60794;   CONF-9409168-9

CONTRACT  NUMBER: AC02-76CH00016