Fabrication of enhanced core-shell CO-ZIF-67@MOX (M = ZN, MN and K) nanocomposites via intermediate pyrolysis and plasma treatment for fischer tropsch synthesis

Abstract

In this work, catalyst performance was evaluated with product selectivity, deactivation, and CO conversion values. Among the low-temperature pyrolysis catalysts, CoZ@600 showed the highest overall average CO conversion with a value of 31,3%. Plasma-treated catalysts showed higher initial CO conversion but they were deactivated fast which means non-plasma-treated catalysts were more stable than the plasma-treated ones. For all group II catalysts, initially, high CO conversions were observed. As in the case of group I catalysts, the highest CO conversions were achieved over plasma-treated catalysts. Among the group II catalysts, P_CoZ@900 has shown the highest overall average CO conversion with 26,1% in 40h time on stream. Moreover, last but not least, a stepwise decrease in CO conversion was observed for P_CoZ@900. When the product selectivities were evaluated, whatever the pyrolysis temperature is, plasma-treated samples have shown higher olefin selectivity. Among all the 12 catalysts, CoZ@500 and CoZ@600 showed the highest overall average C2-C4 paraffin and C5+ selectivities. After deductions from not only CO and H2 conversions but also product selectivity, CoZ@600 gave the most promising results. Due to this outcome, coating with Zn, Mn and K was applied to CoZ@600. Among the coated catalysts, CoZ@600-ZnOx has shown promising results not only with 34,9% CO and 38,4% H2 conversion but also with 21,4% C2-C4 paraffin and 30,3% C5+ selectivity on average. Therefore, considering the aim of the study to contribute literature to reduce dependence on crude oil and meet the world's fuel requirements, CoZ@600-ZnOx has been evaluated as one of the most proper candidate catalysts for the production of long hydrocarbon chains.