Validation of the H2 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 sys- tem 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, sor- bent 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 cat- alyst 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. ; This work acknowledges the support by European Union Seventh Frame Programme FP7 under grant agreement n° 608512 (ASCENT Project). Laura Díez acknowledges the FPI fellowship (ENE 2012-37936-CO2-01, BES-2013-064616 financed by MICINN). The authors want also to thank the support from the Regional Aragon Government (DGA) under the research groups support program ; Peer reviewed