Gold modified cobalt-based Fischer-Tropsch catalysts for conversion of synthesis gas to liquid fuels

Abstract

The addition of Au as a promoter/modifier for alumina supported Co catalyst has been studied by combined in-situ high temperature, high pressure Fourier transform infrared (FTIR) and on-line gas chromatography. The combination of these tools permitted the state of the active catalyst surface to be monitored while following the elution of reaction products during the first 5–7 h on stream of the catalyst. The catalysts under study were a 10%Co/Al₂O₃ and a 2.5%Au/10%Co/Al₂O_3. Samples were characterised before use using Raman and temperature programmed reduction (TPR). During the initial stages of reaction, hydrocarbons were built up on the surface of the catalyst as monitored by FTIR and the nature and amount of these species were assessed in terms of CH₂/CH₃ ratio and the density of these alkyl fragments by employing absorption coefficients for the individual components. The nature and reducibility of the Co particles were modified by the presence of Au while the later also shifted the CO/H₂ balance by acting as an effective water-gas shift catalyst during the early stages of reaction. This characteristic was lost during reaction as a consequence of redistribution of the two metallic phases.

Keywords

gold modified catalyst / conversion of synthesis gas

References

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Acknowledgments

We thank T. Majchrowski for recording of the Raman spectra and R. Brown, A. Ata-lariot and N. Ahmad and A. McNab for their contribution to initial data collection and establishing the experimental set-up.

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg