The three main reaction stages of a H 2 production process based on the combination of the CaO/CaCO 3 and Cu/CuO loops have been experimentally studied in a lab scale fixed bed reactor. The solid bed contained the three functional materials required to run the process, namely a commercial Ni-based catalyst, a CaO-Ca 12 Al 14 O 33 CO 2 sorbent and a CuO-Al 2 O 3 material in a proportion that resulted in a bed with 43.3 % wt. CuO, 25.6 % wt. CaO and 1.7 % wt. Ni. The system was able to convert 13.5 kg CH 4 h-1 kg Ni-1 , at 675 ºC producing a gas stream with a 93.5 % vol. H 2 at 10 bar. The Cu-based material presented high oxidation kinetics, being totally converted in a narrow reaction front with a highly diluted air stream at 10 bar. The Cu-based material presented also fast reduction kinetics and it was completely converted with a fuel gas with typical composition of a SMR stage at high temperature. A Cu/Ca molar ratio of 2 allowed for calcination efficiencies over 85 % molar basis at the CO and H 2 breakthrough , and 95 % of the CO 2 from CaCO 3 exited the reactor at CH 4 breakthrough. The experimental results have been validated with a pseudo homogeneous reactor model for the three reaction stages that *Manuscript Click here to view linked References

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In this work, the oxidation reaction of high loaded CuO-based materials was investigated under atmospheric and pressurized conditions. The oxygen transport capacity of the materials was firstly tested in the TGA and no losses greater than 5% were observed along 100 oxidation/reduction cycles. The kinetic parameters governing the oxidation reactions of the selected CuO-based materials were determined using a shrinking core model with chemical reaction control. The experimental results suggested that a SCM with chemical reaction control is able to predict the oxidation conversion of high loaded CuO-based materials in powder and pellet form. On the other hand, the effect of total pressure on materials reactivity was analyzed. The kinetic parameters obtained under atmospheric conditions were applied to fit the experimental data obtained under pressurized conditions. The results confirmed that the pressure has not an important effect on the oxidation kinetics of high loaded CuO-based materials and the parameters obtained at atmospheric pressure can be applied to study the oxidation under pressurized conditions.

Functional materials for the sorption enhanced reforming process for H 2 production coupled to a Cu/CuO chemical loop have been synthesized. The performance of CuObased materials supported on Al 2 O 3 , MgAl 2 O 4 and ZrO 2 and synthesized by different routes has been analyzed. Highly stable materials supported on Al 2 O 3 or MgAl 2 O 4 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 ZrO 2. 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.

 The reduction reaction kinetics of highly loaded CuO-based materials using H 2 , CO and CH 4 have been determined in a TGA both in powder and pellet form  A shrinking core model (SCM) with kinetic control has been successfully applied to describe the evolution of the reduction conversion of particles and pellets  The possibility of using different reducing gases in the reduction/calcination stage has been analyzed using the kinetic parameters previously obtained  The energy released by one pellet during reduction and the energy demand required for calcination evolve very close with time indicating that the reaction fronts can proceed together