Fischer-Tropsch Synthesis:Kinetics and Effect of Water for a Co/SiO_2 Catalyst

摘要

The addition of water during Fischer-Tropsch synthesis over a 12.4 wt % Co/SiO_2 catalyst led to a significant increase in CO conversion.A positive reversible impact of water on catalyst activity was observed at partial pressures of water of <25 vol % added H_2O.The CO conversion recovered to the reference activity after the termination of water addition.Therefore,this enhanced reversible activity for Co/SiO_2 catalysts seems to be due to a kinetic effect of water.The catalyst was characterized using different techniques,including temperature-programmed reduction(TPR),Brunauer-Emmett-Teller(BET)surface area analysis,and H_2 chemisorption.The rate expression has been obtained over the catalyst,using a 1-L continuously stirred tank reactor(CSTR)that was operated at a temperature of 483 K,a pressure of 2.21 MPa(21.42 atm),IVCO feed ratios of 1.0-2.4,and 10%-70% CO conversion over a range of reactant partial pressures.The data of this study are fitted by a power-law expression of the form r_(CO)= kP_(CO_~(-0.25)P_(H_2)~(-0.5)/(1 +,where k = 0.89 mol h~(-1)gcat~(-1)and m =-0.155.