Validation of the H 2 production stage via SER under relevant conditions for the Ca/Cu reforming process practical application

Abstract The joint performance of a CaO-based sorbent and a Ni-based commercial catalyst has been assessed under relevant conditions for the SER stage in the Ca/Cu H 2 production process. These conditions comprise processing CH 4 space velocities suitable for the scaling up of the process, operation of the system at pressure, and testing materials that had experienced up to 200 oxidation/reduction cycles. The system, catalyst and CaO-based sorbent, was able to fulfil the SER equilibrium composition up to 2.5 kg CH 4  h −1  kg cat −1 , CH 4 space velocity that would allow the scaling up of the process. In this way, a gas stream containing up to 95% vol. H 2 was obtained at 923 K, steam to carbon ratios of 3.2 and 4, sorbent to catalyst weight ratios from 4 to 15 and for operation pressures between 1 and 9 bar. The effect of oxidation/reduction cycles on catalyst performance was assessed, and the mixture sorbent and aged catalyst was able to process up to 2.5 kg CH 4  h −1  kg cat −1 , corroborating the operational limit determined for the fresh materials. The total operation pressure (from 1 to 9 bar) did not have an important influence on H 2 yield, and/or materials performance. Sorbent carbonation reaction rates up to 4.42 * 10 −2  kmol h −1  kg sorb −1 were determined in the experiments, being this parameter responsible of the limit in CH 4 space velocity that can be successfully converted through this sorbent/catalyst system. The experimental results have been successfully described by a pseudo-homogeneous reactor model that incorporates the main kinetic expressions of the reactions involved in the SER stage.