Effects of reduction atmosphere on structure and catalytic activity of Co-ZrO2 catalyst for Fischer-Tropsch synthesis

The effects of reduction atmosphere on the structure of the Co-ZrO2 coprecipitation catalyst and its catalytic activity for Fischer-Tropsch synthesis were investigated by means of X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and temperature-programmed reduction. The reduction of the Co-ZrO2 catalyst in CO atmosphere led to an increase in BET surface area but obvious decrease in syngas atmosphere. The cubic metallic cobalt species (2 theta = 44.4 degrees) was observed for the catalyst reduced in H-2. After the reduction of the catalyst in either syngas or CO, both the cubic metallic cobalt and hexagonal metallic cobalt (2 theta = 41.7 degrees and 47.5 degrees) appeared with the presence of the carbon deposition. No catalytic activity was detected for the catalyst sample reduced in CO owing to the severe carbon deposition. The catalyst samples reduced in either syngas or H-2 showed the similar CO conversion though the carbon deposition was observed for the former, and its high CH4 selectivity could be attributed to the presence of carbon deposition.