ABSTRACT
Anderson-Schulz-Flory Plots ..........................................................290 15.4.2 Arrhenius Plot and Activation Energy Calculations
by the Power Law Model ..................................................................290 15.5 Conclusions ...................................................................................................292 Acknowledgments .................................................................................................. 293 References .............................................................................................................. 293
In the present investigation, the novel one-pot synthesis approach has been employed to synthesize large-pore ordered mesoporous carbon (OMC) support using Pluronic F127 as the starting template. A series of OMC-and multiwalled carbon nanotube (MWCNT)-supported catalysts composed of 9% K, 4.5% Co, 15% Mo, and 1.5 wt.% Rh metal species were then prepared and evaluated at similar catalytic reaction conditions for the conversion of syngas to higher alcohols. The catalysts were thoroughly characterized by N2 adsorption analysis, XRD, Raman spectroscopy, and SEM and TEM techniques. Results from SEM images evidenced that the MWCNT material is composed of arrays of interwoven nanotubules, whereas the OMC exhibited a composite of aggregated nanoparticles. Nonetheless, TEM and N2 adsorption-desorption isotherms confirmed the presence of high mesoporosity in both materials. At this similar metal loading, CO hydrogenation experiments conducted at temperatures of 300°C-340°C, pressure 8.3 MPa, gas hourly space velocity (GHSV) of 3600 mL (STP)/h gcat, and an H2/CO ratio of 1.25 revealed a superior alcohol productivity over the MWCNT-supported catalyst as compared to its OMC counterpart, probably due to the differences in their pore structure and morphology. Though the OMC-supported KCoMoRh catalyst showed overall better textural properties, the MWCNT-supported catalyst showed the maximum (38.4%) total amount of higher alcohol produced as compared to its OMC counterpart (36.5%). That notwithstanding, the apparent activation energies (Ea) of the OMCand MWCNT-supported catalysts were calculated as 76.2 and 66.4 kJ/mol, respectively, which is quite dissimilar, suggesting that at this metal loading, the supports might have affected the major reaction pathway for the CO hydrogenation reaction for higher alcohol synthesis.
