تاثير زيركونيم روي مشخصات فيزيكي و عملكرد كاتاليست كبالت در سنتز فيشر- تروپش

The Effect of Zirconium on Cobalt Catalyst in Fischer-Tropsch Synthesis

A series of 10 wt% Co/SiO2 catalysts with different loading ratios of zirconia (0, 5, 10, 15, 20) has been prepared through an original pesudo sol-gel method. All catalysts were characterized by BET; XRD, SEM and TPR experiments. The catalytic performance of the catalysts for the so-called Fischer-Tropsch Synthesis was examined under H2/CO=2 at 230°C and 8 bar in a fixed bed microreactor. By increasing Zirconia, the Co-SiO2 interaction decreases and is replaced by Co-Zr interaction which favours reduction of the catalyst at lower temperatures. While it leads to a higher degree of reduction and as increase in the metallic cobalt atoms on the surface. The activity of the promoted catalysts increases with the addition of zirconia (max. by a factor 2.5). The C1 ` selectivity increased with the addition of zirconia (from 42.3% in unpromoted catalyst to 69.8% in the 20% ZrO2 promoted). This can be attributed to the higher amount of the surface cobalt metal present and to the larger cobalt particle size.