Fischer–Tropsch synthesis: Effect of promoter type on alumina-supported Mo carbide catalysts
Vo, D-V.N., Nguyen, T-H, Kennedy, E.M., Dlugogorski, B.Z. and Adesina, A.A. (2011) Fischer–Tropsch synthesis: Effect of promoter type on alumina-supported Mo carbide catalysts. Catalysis Today, 175 (1). pp. 450-459.
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Molybdenum carbide catalysts promoted with K, Na, Co, and Ce have been synthesized by temperature-programmed carburization using a mixture of H 2/C3H8 and evaluated for the Fischer-Tropsch synthesis. Both α- and β-Mo carbide catalysts were produced during carburization via the formation of oxy-carbide intermediate phase. The two-stage Mo carbide synthesis appeared to be characterized by a compensation effect and isokinetic relationship for both promoted and undoped catalysts suggesting that the solid state transformation mechanism was similar across the promoters. The catalysts possessed relatively high BET area (177-210m2g cat -1) with finely dispersed Mo carbide particles (ca. 10nm) on the alumina support. The presence of weak and strong acid-base sites was also confirmed by NH3 and CO2-TPD runs. CO hydrogenation rate increased with H2 composition reaching optimal activity at yH2 between 0.67 and 0.75. FT activity improved with promoter addition in the order; K-MoC1-x/Al2O3 > Na-MoC1-x/Al2O3 > Ce-MoC 1-x/Al2O3 >Co-MoC1-x/Al 2O3 >MoC1-x/Al2O3 whilechain growth probability varied with feed composition and was enhanced by all promoters. The reaction rate data were adequately described by an Eley-Rideal model.
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|Copyright:||© 2011 Elsevier B.V.|
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