Exploring the reasons for Zr-improved performance of alumina supported cobalt fischer-tropsch synthesis

In order to investigate the enhancement of Zr in FTS performance, a series of Zr-modified 20 wt% Co/Al2O3 catalysts has been prepared by regulating the Zr and Co impregnation order and Zr amount and then the catalytic performance were evaluated in a fixed reactor. The Zr addition leads to a significant increase in activity, olefin/paraffin ratio for C3 and C4 at a similar CO conversion, and selectivity to C5+ compared with the Co/Al2O3 catalysts. The co-impregnation of Zr and Co shows the most attractive catalytic performance. This can be attributed to the higher reducibility of the catalyst as well as the formation of Co–Zr interface. The introduction of Zr can enhance the interaction between C∗ and cobalt active sites and weaken the CO bond, making CO easier to be dissociated and the selectivity of C5+ is improved.