科研之友
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摘要
Transition metals (V, Mn, Fe, Co and Ni) were mixed with bituminous coal and carbonized at 600 degrees C to obtain activated carbons (AC) with different catalytic and physical properties. A variety of analytical techniques - XRD, SEM, FTIR and BET surface area were used to characterize the samples. The presence of different proportions of crystalline structures and surface functional groups were observed depending on the metal added in the carbon matrix. The samples surface areas changed from 140.9 to 296.0 m(2)/g for V- and Ni-AC, with corresponding increase in pore volumes and diameters. There are graphitic and metalcarbon phases as evidenced by XRD. The aromatic stacking appears to decrease from V- to Co-AC. V-AC exhibited fewer occurrences of turbostratic carbon interlayers. In the FTIR spectra, region assigned to aromatic C=C stretching and CH-bending have been observed. Their relative proportions diminish based on the nature of the transition metal used. The samples were tested as catalysts at 450-550 degrees C using a feed mixture of propane and argon - in the presence or absence of CO2 in the feed stream. Propylene selectivities per unit area increase along the groups of the metals. Ni-AC exhibited the best performance per gram in terms of propane conversions (1.5-17.7%) and selectivities to propylene (39.9-49.0%) in the temperature range. Partial substitution of argon with CO2 in the feed exhibited general increase in propane conversion with no significant change in propylene selectivities.
- 出版日期2011-5
