In the hope of finding a more energy efficient steam reforming process for hydrogen production, researchers at the University of Leeds recently reported optimal production from the steam reforming of glycerol at 500°C with in situ carbon dioxide (CO2) removal using calcined dolomite as the sorbent.
The system, developed by the researchers, uses the cyclic oxidation of a bed of nickel-based material with the simultaneous regeneration of a CO2 sorbent under airflow. This provides the heat necessary for the steam reforming reaction.
What makes this approach unique is the use of in-situ removal of CO2 and ex-situ regeneration of CO2 adsorbent. This enables the continuous operation of the reactor as well as direct delivery of hydrogen at the reactor pressure and the use of relatively low capacity adsorbent.
As the effluent gas of the fuel/steam step is much higher in hydrogen than it is in the single reactor equivalent conventional process, the oxidised catalyst is regenerated by reduction from exposure to the fuel. The carbon produced during the steam reformation is burned under the airflow and the process is not sensitive to the gradual loss of conversion efficiency.
This work has been based on an earlier Engineering and Physical Sciences Research Council funded project which showed the sequence via which the various reactions involved in the cycle proceeded. This found clear evidence of the insensitivity of the process to coking. Now the improved process opens up opportunities to use a whole range of fuels with coking tendencies such as the combustible liquid mixtures that come from biomass.
According to the researchers, led by Dr Valerie DuPont, the process can be economical on a small scale and unlike the conventional steam reforming process it could be used in distributed power generation.
