Effect of boron on the sulfur poisoning of Co/TiO2 Fischer-Tropsch catalysts

TiO2 was treated with boron (0.05, 0.1%: boric acid source) to give B/TiO2. CO(NO3)(2).6H(2)O(10% Co) was then added to both TiO2 and B/TiO2 (incipient wetness) and the materials were then sulfided with 100, 200 and 500 ppm (N H4)(2)S. The sulfided Co/TiO2 catalysts with and without boron were charact erised by TPR and O-2 titration and evaluated for Fischer-Tropsch synthesis . Low-level sulfur addition (100, 200 ppm S) did not significantly influenc e the activity and selectivity of the catalysts. The addition of a higher-l evel loading of sulfur (500 ppm S) resulted in severe sulfur poisoning of c atalysts (80% decrease in reaction rate), but the modification of Co/TiO2 b y boron retarded this poisoning (35% decrease in reaction rate). A shift in the product distribution to light molecular weight hydrocarbons (alpha = 0 .32) was observed for the 500 ppm S loaded catalyst (no boron addition) whi le boron addition retarded this shift (alpha = 0.47). The effect of boron o n the sulfur poisoning resistance of the Co/TiO2 catalysts is discussed. (C ) 2001 Elsevier Science B.V. All rights reserved.