SOME ZSM-5, NU-1, ALUMINA SUPPORTED METAL CATALYSTS FOR THE FISCHER-TROPSCH REACTION.

摘要

Some new supported metal catalysts for the Fischer-Tropsch reaction have been prepared from the metal cluster carbonyls Ir(,4)(CO)(,12) and Os(,3)(CO)(,12) with alumina as the support, and from Co(,2)(CO)(,8) and Fe(,3)(CO)(,12) with the synthetic zeolites ZSM-5 and NU-1 as the supports. These catalysts were prepared by using an extraction technique with cyclohexane as the solvent. The extraction technique is a new method of preparing supported metal catalysts which was developed during the course of this research. The catalysts were characterized by using a variety of bulk and surface techniques in the as prepared state, after calcination in air, and after catalytic evaluation. The bulk techniques used for this characterization include X-ray powder diffraction, infrared spectroscopy, Raman spectroscopy, uv-visible spectroscopy, atomic absorption spectroscopy, magnetic studies, and Mossbauer spectroscopy, while the surface techniques include X-ray photoelectron spectroscopy, ion scattering spectrometry, and secondary ion mass spectrometry. It was concluded from the characterization data obtained for the as prepared samples that the catalysts consist of small particle-sized, less than 50 (ANGSTROM), iridium and osmium carbonyls, or iron and cobalt oxides on the support.; The supported iron and cobalt catalysts prepared by the extraction technique were found to be significantly different from catalysts prepared by the conventional wet impregnation technique, where metal salts are used in aqueous solution as the source of the metal. The zeolite supported iron and cobalt catalysts were tested for the Fischer-Tropsch reaction, i.e., their ability to convert synthesis gas, a mixture of carbon monoxide and hydrogen in a 1:1 ratio, to hydrocarbon products. These catalysts were found to be active for this conversion at temperatures of 280(DEGREES)C and 300(DEGREES)C and a pressure of 300 psig. In addition, it was found that the catalysts limited the hydrocarbon chain length in the products. The ZSM-5 supported iron catalysts were found to yield the most gasoline range hydrocarbons (C(,5)-C(,11)) in the product distributions obtained from the Fischer-Tropsch reaction; therefore, the iron on ZSM-5 (Fe/ZSM-5) catalysts were studied in more detail.