Reduced cobalt phases of ZrO_2 and Ru/ZrO_2 promoted cobalt catalysts and product distributions from Fischer-Tropsch synthesis

摘要

Co/SiO_2 catalysts were promoted with 4% and 8% ZrO_2. Small amounts (0.07%) of Ru were impregnated onto 4%ZrO_2/Co/SiO_2. Catalysts resulting from time-resolved XANES reduction showed mixed phases of Co and CoO, with the highest percentages of Co resulting from Ru/4%ZrO_2/Co/SiO_2 and the highest percentages of CoO resulting from 8%ZrO_2/Co/SiO_2. Product distributions of n-alkanes, iso-alkanes and alkenes during Fischer-Tropsch Synthesis (FTS) were used to investigate the catalyst performance of 4%ZrO_2/Co/SiO_2 8%ZrO_2/Co/SiO_2 and Ru/4%ZrO_2/Co/SiO_2. FTS steady state was studied by growth probabilities of n-alkane products. No 1-alkene was produced from Ru/4%ZrO_2/Co/SiO_2, indicating high availability of Fischer-Tropsch sites for long chain hydrocarbon growth, despite high methanation. Branched alkanes produced from the secondary reaction were related to the high CoO percentages on 8%ZrO_2/Co/SiO_2. Alkene readsorption sites were high, corresponding to the high CoO percentages, causing a high probability of forming branched alkane products.