Suchergebnisse

Functional materials for the sorption enhanced reforming process for H2 production coupled to a Cu/CuO chemical loop have been synthesized. The performance of CuObased materials supported on Al2O3, MgAl2O4 and ZrO2 and synthesized by different routes has been analyzed. Highly stable materials supported on Al2O3 or MgAl2O4 synthesized by co-precipitation and mechanical mixing with sufficient Cu loads (around 65 %wt.) have been successfully developed. However, it has been found that coprecipitation under these conditions is not a suitable route for ZrO2. Spray-drying and deposition precipitation did not provide the best chemical features to the materials. As the Ca/Cu process is operated in fixed bed reactors, the best candidates were pelletized and their stability was again assessed. Pellets with high chemical and mechanical stability, high oxygen transport capacity and good mechanical properties have been finally obtained by co-precipitation. The good homogeneity that provides this route would allow an easy scaling up. ; 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 MINECO). ; Peer reviewed

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