Highly dispersed Co-based Fischer-Tropsch synthesis catalysts from metal-organic frameworks

The influence of pore texture and nitrogen species of the carbon support for the Fischer-Tropsch synthesis was investigated using well-defined catalysts derived from metal-organic frameworks (MOFs). Two typical MOFs were employed in the carbonization process to prepare the target catalysts, i.e. nitrogen-rich ZIF-67 and nitrogen-free Co-MOF-74. The Co-MOF-74-derived nanocomposite (Co@C) showed a carbon monoxide (CO) conversion of 30%, whereas the ZIF-67-derived nanocomposite (Co@NC) exhibited a CO conversion of 10%. The nitrogen-free Co@C composite showed 65% selectivity for long-chain hydrocarbons (C-5(+)) and 10% selectivity for short-chain hydrocarbons (C-2-C-4) after 100 h on stream; on the other hand, the Co@NC composite showed 31% selectivity for C-5(+) products and 37% selectivity for short-chain hydrocarbons (C-2-C-4) after 100 h on stream. The excellent CO conversion was attributed to the large pore size of the carbon support, which facilitates the diffusion of the hydrocarbons. The high C-2-C-4 selectivity originates from the influence of nitrogen species in the carbon support. This study is expected to open a new avenue for the design of new catalysts for the Fischer-Tropsch synthesis with high activity and superior selectivity via choosing suitable MOFs precursors.