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A statistically designed set of experiments was run in a continuous downflow fixed-bed reactor to evaluate the intrinsic kinetics of the formation of methanol, higher alcohols, total hydrocarbon, and carbon dioxide from synthesis gas under a range of experimental conditions. To eliminate mass-transfer resistance, a multiwalled carbon nanotube (MWCNT)-supported K-promoted trimetallic sulfided Co-Rh-Mo catalyst was used in the particle size range of 147-210 μm. To predict the reaction rate for higher alcohol synthesis, the power law model was used for the reaction between CO and H 2 on the catalyst surface. The operating conditions, such as reactor temperature (T), pressure (P), gas hourly space velocity (GHSV), and H 2 /CO molar ratio, were varied in the ranges of 275-350 °C, 800-1400 psig (5.52-9.65 MPa), 2.4-4.2 m 3 standard temperature and pressure (STP) (kg of catalyst) -1 h -1 , and 0.5-2.0, respectively. The data of this study are well-fitted by the power law model. The activation energies of ethanol and higher alcohols obtained over Co-Rh-Mo-K/MWCNT were low compared to those values reported in the literature.

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Multiwalled carbon nanotubes (MWCNTs) and activated carbon were used as supports for the Co (4.5 and 6 wt %) promoted K (9 wt %) modified Rh-Mo catalysts (1.5 wt % Rh and 15 wt % Mo). The catalysts were extensively characterized in both oxide and sulfide phases. A drastic fall in surface area over the activated carbon-supported catalysts was observed after impregnating with metal species. Diffraction peaks were observed in the X-ray diffraction (XRD) patterns of the sulfided alkali-modified trimetallic catalysts, due to the characteristic reflections of the K-Mo-S mixed phase. H 2 -temperature programmed reduction (TPR) profiles showed that the reduction behavior of metal species was improved with the addition of Co. The activated carbon-supported trimetallic catalysts showed less activity and selectivity compared to the MWCNT-supported catalyst, and metal dispersions were higher on the MWCNT-supported catalysts. The MWCNT-supported, alkali-promoted trimetallic catalyst with 4.5 wt % Co showed the highest total alcohols yield of 0.244 g/(g cat h), ethanol selectivity of 20.1%, and higher alcohols selectivity of 31.4% at 320 °C and 8.28 MPa using a gas hourly space velocity (GHSV) of 3.6 m 3 (STP)/(kg catalyst h). A maximum total alcohol yield of 0.261 g/(g cat h) and a selectivity of 42.9% were obtained on the 4.5 wt % Co-Rh-Mo-K/MWCNT catalyst, at a temperature of 330 °C. The total alcohol yield increased from 0.163 to 0.256 g/(g cat h) with increased pressure from 5.52 MPa (800 psig) to 9.65 MPa (1400 psig) over the 4.5 wt % Co-Rh-Mo-K/MWCNT catalyst.

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