Thermodynamic analysis of hydrogen production via Sorption-Enhanced Chemical-Looping Reforming

Abstract

Hydrogen production via Sorption-Enhanced Chemical-Looping reforming combines hydrocarbon (in this case methane) reforming, by chemical-looping autothermal reforming, with water-gas shift and carbonation reactions. Both H2 production rate and concentration depend on the chemical equilibrium that is established in the fuel reactor and that is influenced by several parameters (temperature, pressure, H2O/CH4 content and presence/absence of CaO). This report focus its attention, in a first part, on understanding, through an Aspen Plus model, the influence that those parameters have on the equilibrium composition, as well as in the thermal optimization of the process, so that no heat no heat demand occurs. In a second part, experiments were carried out, in a bench-scale fluidized bed reactor, in order to demonstrate the feasibility of this process, as well as the effects created by some of those previously mentioned parameters. For the thermodynamically balanced system it was possible to produce a high purity H2 (> 95%) at 650°C and 5 atm, using a H2O/CH4 ratio of 2. At these conditions, the process efficiency was 77,8% and the CO2 capture rate of 95,0%.