Issue 16, 2017

The evolution of Fe phases of a fused iron catalyst during reduction and Fischer–Tropsch synthesis

Abstract

The reducing temperature and gas hourly space velocity were varied to obtain different Fe phase compositions for a fused-iron catalyst. These model catalysts were subject to the Fischer–Tropsch synthesis (FTS) and phase evolution was monitored. The BET surface area decreased as the reduction temperature was increased from 350 °C to 650 °C, and the pore diameter changed by the opposite trend. XRD and Mössbauer spectroscopy were used to quantitatively determine the phase composition. They indicated that a high reduction temperature and high GHSV (gas hourly space velocity) favored the transformation from Fe3O4 to α-Fe, although a higher reduction temperature led to larger α-Fe crystallite sizes. Furthermore, α-Fe gradually transforms to an iron carbide (χ-Fe5C2) phase in a period of 12 h when exposed to syngas (CO + H2). After a 500 h run in the FTS, the partial carbide regenerated into Fe3O4 again. Magnetite had negligible catalytic activity for the FTS, whereas iron carbide was active. Nonetheless, the activity was proportional to the surface area of iron carbide. Higher reduction temperatures guaranteed lower methane selectivity and a higher olefin to paraffin ratio for C2–4 hydrocarbons, and possibly high reducibility and large pore sizes as well.

Graphical abstract: The evolution of Fe phases of a fused iron catalyst during reduction and Fischer–Tropsch synthesis

Supplementary files

Article information

Article type
Paper
Submitted
18 May 2017
Accepted
16 Jul 2017
First published
17 Jul 2017

Catal. Sci. Technol., 2017,7, 3626-3636

The evolution of Fe phases of a fused iron catalyst during reduction and Fischer–Tropsch synthesis

J. Zhang, M. Abbas and J. Chen, Catal. Sci. Technol., 2017, 7, 3626 DOI: 10.1039/C7CY01001J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements