EFfect of alumina modification on the structure of cobalt-containing Fischer-Tropsch synthesis catalysts according to internal-field 59Co NMR data

An internal-field 59Co NMR study of cobalt-containing Fischer-Tropsch synthesis catalysts supported on different alumina modifications was reported. The Co/δ-Al2O3 sample was shown to contain single-domain fcc packing and stacking faults, whereas Co/γ-Al2O3 gave signals from the fcc domain walls, hcp and stacking faults, thus indicating differences in the particle size of the studied samples. T 2 relaxation times were measured; their distribution in a spectrum is non-uniform, which allows signals to be distinguished by their relaxation times. Quantitative measurements of the relative atoms content in different packings revealed that the catalysts have mostly a defect structure. A brief historical background was presented to characterize the internal-field 59Co NMR technique, the related problems, and different approaches to acquired data interpretation.