Influence of CO2 co-feeding on Fischer–Tropsch fuels production over carbon nanofibers supported cobalt catalyst

• Fischer–Tropsch synthesis in either H2-deficient or CO2-rich was studied.
• Co/CNF is an interesting alternative to classic Fischer–Tropsch catalysts.
• CO hydrogenation produces fuels, whereas CO2 hydrogenation produces CH4.
• The presence of CO2 in the feed stream decreased the catalytic activity.
• The presence of CO2 on the feed stream favored the formation of lighter hydrocarbons.

Nowadays, the syngas which is obtained from the reforming of coal, biomass or natural gas contain significantly amounts of CO2 that cannot be separated and consequently, it can take part into the Fischer–Tropsch (FTS) catalytic activity. Therefore, the presence of CO2 in the syngas flow should be taken into account. In the present study, the FTS CO hydrogenation process was compared to that of CO2 on a carbon nanofibers supported Co catalyst. The influence of CO2 content in the feed stream (H2/CO/CO2 ratio) on the reaction performance in terms of conversion and selectivity to the different products was described. Both the support and the prepared catalyst were characterized by nitrogen adsorption–desorption, temperature-programmed reduction (TPR) and X-ray diffraction (XRD). Results showed that CO hydrogenation was controlled by a Fischer–Tropsch regime, whereas CO2 hydrogenation was controlled by a methanation process. When feed was composed of CO and CO2 mixtures, the catalytic activity decreased with respect to that obtained with a CO2-free feed stream. Moreover, the presence of CO2 in feed stream favored the formation of lighter hydrocarbons and could block the production of further CO2 via Water-Gas-Shift (WGS) reaction.

The presence of CO2 in Fischer–Tropsch feed stream decreases the catalytic conversion of CO and favored the formation of lighter hydrocarbons. The production of valuable fuels is technically feasible by Fischer–Tropsch synthesis on Co/CNFs catalyst using different H2/CO/CO2 feed ratios.Figure optionsDownload as PowerPoint slide