Hydro-deoxygenation of CO on functionalized carbon nanotubes for liquid fuels production

Abstract

Syngas produced through gasification of carbonaceous materials has provided a gateway to a host of processes for the production of various chemicals including transportation fuels. The basis of the production of gasoline and diesel-like fuels is the Fischer Tropsch Synthesis (FTS) process. It has been argued that only transition metal catalysts (usually Co or Fe) are active toward the CO hydrogenation and subsequent chain growth in the presence of hydrogen. In this paper, we demonstrate that carbon nanotube (CNT) surfaces are also capable of hydro-deoxygenating carbon monoxide and producing long chain hydrocarbons similar to those obtained through the FTS but with orders of magnitude higher activity than the present state-of-the-art FTS catalysts. Using advanced experimental tools such as XPS and microscopy techniques to characterize CNTs, C-O functional groups have been identified as the active sites for the enhanced catalytic activity. Furthermore, quantum Density Functional Theory (DFT) calculations confirm that C-O groups (on CNT surfaces) are catalytically active sites for the reduction of CO with H2, and capable of sustaining chain growth. These findings create a new paradigm for CNT-based hydrogenation catalysts and provide a new route for obtaining clean, earth abundant, alternative fuels through the use of efficient and renewable catalyst.