Hydrogen production through sorption-enhanced steam methane reforming and membrane technology: A review

With the rapid development of industry, more and more waste gases are emitted into the atmosphere. In terms of total air emissions, CO2 is emitted in the greatest amount, accounting for 99wt% of the total air emissions, therefore contributing to global warming, the so-called ‘‘Greenhouse Effect’’. The recovery and disposal of CO2 from flue gas is currently the object of great international interest. Most of the CO2 comes from the combustion of fossil fuels in power generation, industrial boilers, residential and commercial heating, and transportation sectors. Consequently, in the last years’ interest in hydrogen as an energy carrier has significantly increased both for vehicle fuelling and stationary energy production from fuel cells. The benefits of a hydrogen energy policy are the reduction of the greenhouse effect, principally due to the centralization of the emission sources. Moreover, an improvement to the environmental benefits can be achieved if hydrogen is produced from renewable sources, as biomass. The present paper provides an overview of the steam methane reforming (SMR) process and methodologies for performances improvement such as hydrogen removal, by selective permeation through a membrane or simultaneous reaction of the targeted molecule with a chemical acceptor, and equilibrium shift by the addition of a CO2 acceptor to the reactor. In particular, attention was focused on the sorption-enhanced steam methane reforming (SE-SMR) process in which sorbents are added in order to enhance the reactions and realize in situ CO2 separation. The major operating parameters of SE-SMR are described by the authors in order to project and then realize the innovative carbonation reactor developed in previous studies.