Coke formation and minimisation during steam reforming reactions

Abstract

The formation of coke during the steam reforming of light hydrocarbons results mainly from catalytic reactions. It is believed that the process is endemic to steam reforming in that the same intermediates are involved in the main reaction as are involved in coking. As a result, control of coking depends on the control of the kinetics of intermediate reactions. On an industrial scale, coking can be controlled by controlling steam/carbon ratios in the feed. It can also be minimised by ensemble size control on nickel surfaces and/or by interfering with the reactions leading to carbon. Doping with traces of sulphur or with small amounts of metals that concentrate on the nickel surface is found to reduce significantly the formation of coke. Further improvements may be possible as a result of detailed studies of support effects in the catalysis.